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Publication Date: 2026
Journal Of The Iranian Chemical Society (1735207X) 23(3)
Hydrazine, a volatile organic compound (VOC) widely used in various industries, has been found to have irreparable and severe effects on the human body. Therefore, identification and detection of hydrazine as one of the human carcinogens effect is an important topic. Herein, we prepared a simple, sensitive, low-cost and repeatable paper sensor based on metal organic framework (MOF). Copper (II) benzene-1,3,5- tricarboxylate (Cu-BTC) due to having high density of copper (II) ions and have the ability to coordinate with small molecules, is immobilized directly on conventional A4 paper through immersion in a suitable solvent. Scanning electron microscopy (SEM) was used to characterize paper sensor. The result showed Cu-BTC sensor has great affinity to hydrazine than the other VOCs groups such as alcohols, aldehydes and ketones. Parameters such as pH, time and temperature are optimized, because these parameters impact sensor performance. The proposed method could significantly classify different amine species with high accuracy (error rate = 0.00) in a simple and fast method. The calibration curve showed good linearity range from 20 to 1000 mg L− 1 with limit of detection 7.2 ± 0.2 mg L− 1 for hydrazine. Finally, it was successfully applied to the determination of hydrazine in municipal wastewater. © Iranian Chemical Society 2026.
Publication Date: 2025
Desalination and Water Treatment (19443994) 321
Mixed matrix membranes composed of polyvinyl alcohol (PVA) and graphene oxide (GO) were synthesized using the blending and casting method. The properties of the prepared membranes were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), tensile strength testing, and contact angle measurement. The membranes’ ability to desalinate saline solutions was investigated using the pervaporation method, focusing on two key parameters: flux and rejection. The effects of GO loading, temperature, feed solution pH and membrane thickness were studied, explained and compared with neat PVA membranes and other reported works. The results indicated that incorporating GO into PVA enhances the membrane's strength and makes it possible to use thinner membrane and finally it causes a significantly increase in flux. Desalting of different solutions containing Na+, Mg2+, Ca2+, Fe3+ and Al3+ ions, alone or together often showed the rejection values more than 99 %. Among them the best performance was achieved for a feed containing 1000 mg/L of Fe (III) at a temperature of 50°C, with an outstanding permeability value of 38.47 kg.m-²·h−1 and a rejection rate of 99.99 %. Overall, the results demonstrate these composite membranes are highly efficient and economical for water and wastewater treatment. © 2025
Publication Date: 2025
Journal of Food Science (00221147) 90(1)
Abstract: Quercetin, a key flavonoid found in many fruits and vegetables, offers notable health benefits, including antioxidant, antiviral, and antitumor properties. Yet, isolating it from complex plant materials is challenging. This research aimed to develop a selective and efficient sorbent to clean up real sample matrices and pre-concentrate quercetin, enhancing its detection using high-performance liquid chromatography (HPLC). Several metal organic frameworks (MOFs) were synthesized and initially, their abilities to sorption of quercetin from aqueous and alcohol media were examined. Among them, HKUST-1 showed the best performance. To improve the efficiency of this MOF, its composite with graphene oxide (GO) was prepared (Fe3O4@SiO2/GO/HKUST-1) and was employed for quercetin extraction through magnetic dispersive micro solid-phase extraction. The effect of different parameters was examined and the kinetic, thermodynamic, and isotherm of the sorption process was studied. The related results showed the system followed the pseudo-second-order kinetic model, with the Temkin and Langmuir isotherm models applicable in aqueous and methanol solutions, respectively. The method enabled rapid preconcentration and clean up within 20 min, with a 99.6% adsorption efficiency using just 5 mg of sorbent. The nanocomposite demonstrated an adsorption capacity of 29.3 mg/g and effectively extracted quercetin from red onion samples, achieving recovery rates between 75% and 98% for HPLC-diode array detector analysis. Practical Application: Quercetin is a common polyphenolic compound, which is widely found in plant materials such as onions. Owing to its medicinal effects including anti-inflammatory, anti-oxidant, anti-cancer, cardioprotective, anti-bacterial, anti-viral, and anti-allergic features, it has widespread usage in pharmacology and preparation of food preservers. In this study, Fe3O4@SiO2/GO/HKUST-1 nanocomposite was synthesized for extraction and preconcentration of quercetin from an onion sample. Very low amounts of this sorbent indicated high adsorption percentage and adsorption capacity for quercetin. This method was simple, fast, cost-effective, precise, and accurate, which exhibited a potential for extraction of quercetin in a large scale. © 2025 Institute of Food Technologists.
Publication Date: 2025
Scientific Reports (20452322) 15(1)
This investigation focused on the design of an advanced polymeric scaffold that integrates Ethylcellulose (EC) and Polystyrene (PS) to fabricate four novel Metal-Organic Framework/Ethylcellulose-Polystyrene (MOF/ECPS) adsorptive membranes for the aim of water desalination. These membranes were created using in situ synthesis of ZIF-8, UiO-66-NH2-EDTA, and UiO-66- NH2 in the presence of electrospun ECPS nanofibers, along with ex-situ synthesis of MIL-125-NH2/ECPS electrospun nanofibers. The NaCl removal performance of these nanocomposite adsorptive membranes was evaluated under ideal conditions. These conditions included starting NaCl content, intercalated MOF percentage, pH, temperature, dosage, and adsorbent contact time. The synthesized nanocomposites were successfully recycled 25 times without experiencing a significant reduction in adsorption capacity, except for MIL-125-NH2, which showed a decrease after 18 recycles. In this investigation, four different kinetic models were utilized: Elovich, intraparticle diffusion, pseudo-first-order, and pseudo-second-order. Adsorption characteristics were found to be in line with pseudo-second-order kinetics. Analysis of the adsorption isotherm parameters using the Langmuir and Freundlich models revealed that the surfaces of UiO-66-NH2/ECPS, UiO-66-NH2-EDTA/ECPS, and ZIF-8/ECPS nanocomposites are heterogeneous and exhibit multilayer Na+ adsorption. In contrast, the adsorption of Na+ on the MIL-125-NH2/ECPS nanocomposite follows a monolayer adsorption mechanism. Studies in thermodynamics demonstrate that adsorption occurs as an exothermic and spontaneous process that adheres to pseudo-second-order kinetics and isotherm models. © The Author(s) 2025.
Publication Date: 2023
Desalination and Water Treatment (19443994) 286pp. 16-28
An interpenetrating polymer network (IPN) membrane and its modified form with NaA zeolite were prepared using polyvinyl alcohol/polyacrylic acid and were used in desalination of saline solutions by pervaporation and reverse osmosis. The prepared membranes were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, tensile and swelling test. The effective parameters in the membrane preparation were investigated and optimized through experimental design. Then, Salt rejection and solution flux were selected as the criteria for the membrane performances. The pervaporation results showed that the flux increases with the feed temperature going up and the membrane thickness decrease. However, better rejection was achieved at less feed temperature and more membrane thickness. At the optimized conditions, flux 7.1 kg/h·m2 and rejection 99% were obtained by net IPN membrane while, these parameters were changed to 11.2 kg/h·m2 and up to 95% by IPN/NaA membrane. Reverse osmosis experiments revealed that as the pressure on the membrane increases, the amount of flux goes up, while it requires less pressure and more cross-linked membrane for having higher rejection (flux 16.2 kg/h·m2 and rejection 90%). According to the obtained results, it was found that this composite membrane has a high ability in desalination with appropriate rejection and fluxes. © 2023 Desalination Publications. All rights reserved.
Publication Date: 2023
Desalination and Water Treatment (19443994) 307pp. 18-29
Composite membranes consisting of PVA/PAA as interpenetrating polymer networks (IPN), along with various MOFs (MIL-101-Cr, Cu-BTC, UiO-66-NH2) or graphene oxide (GO), were synthesized using a sequential method. These membranes were designed for use in the pervaporation desali-nation of NaCl and MgCl2 salts. The membranes were characterized using swelling, contact angle, FTIR, tensile, and SEM tests, and the optimal preparation parameters were determined using an experiment design method. Subsequently, the optimal membranes were employed in the pervapo-ration desalination process, with salt rejection and fluxes serving as the pervaporation responses. The results showed that as the temperature of the feed increased, the water flux also increased. However, as the feed solution temperature and concentration increased, the salt rejection decreased. Under optimal conditions, the IPN/MIL-101-Cr membrane provided 15.19 and 14.59 kg/m2·h flux and 99.24% and 99.37% rejection for sodium and magnesium ions, respectively, while the GO/IPN membrane provided 13.65 and 12.98 kg/m2·h flux and 98.97% and 99.10% rejection for sodium and magnesium ions, respectively. These composite membranes also exhibited excellent performance in salt mixtures. Based on the experimental design results, preliminary evaluation tests, and comparison with other membranes, it can be concluded that the IPN/MIL-101-Cr composite membrane is highly effective for pervaporation desalination and has potential for industrial-scale applications. © 2023 Elsevier Inc.
Publication Date: 2022
Food Chemistry (0308-8146) 382
An aptamer-functionalized magnetic metal–organic framework (MMIL-Apt) was prepared and used for selective magnetic solid phase extraction (MSPE) of acetamiprid. To examine the morphology of the adsorbent, different techniques such as FT-IR spectrometry, vibrating sample magnetometery, TEM, FE-SEM and EDS were employed. The MMIL-Apt combines the advantages of aptamers and magnetic MMIL-101(Cr)–NH2 such as specific recognition of analyte, good stability and fast separation. To reach high MSPE recovery, various extraction parameters were examined and optimized. The limit of detection (LOD) was reached 0.0018 μg L-1. This method showed perfect linearity (0.006–1800 μg L-1) with a good correlation coefficient (R2 = 0.9993). The relative standard deviations for intra- and inter-day analyses were 3.61% and 8.10%. The extraction recoveries in water samples and fruit juices were obtained from 80.20% to 101.81 %. The results indicated the modified sorbent is practically applicable for the specific extraction of trace amounts of acetamiprid from different matrices. © 2022 Elsevier Ltd
Publication Date: 2022
High Performance Polymers (09540083) 34(4)pp. 377-387
New poly(amic-acid)s sorbents, bearing bipyridine chelating groups, were synthesized by reaction of benzophenonetetracarboxylic dianhydride (BTDA) with different percentages of 4,6-bis(4-aminophenyl)-2,2′-bipyridine (BAPB), and 1,4-phenylene diamine (PPD) and were characterized by FTIR and 1HNMR spectroscopies. Because of the imidization of these poly(amic-acid)s after about 10% weight loss, their thermal stability was raised to about 500°C. The glass transition temperatures of these polymers were in the range of 154–166°C. The sorption of Ni(II) by these sorbents from the aqueous solutions was investigated by varying different parameters such as the contact time, pH, and sorbent dosage. Results indicated that the optimum efficiencies of these sorbents toward Ni(II) were at 25°C, at pH = 4 and after about 75 min. According to the Langmuir equation, the maximum uptake capacity (qm) of PAA30/70 as a best sorbent for nickel was 14.66 mg.g−1. The modeling results confirmed the pseudo-second-order sorption for the metal ion. The morphology of these sorbents before and after sorption of Ni(II) was investigated using Scanning Electron Microscopy and the results confirmed the porous structure of these sorbents. (Figure presented.) © The Author(s) 2022.
Publication Date: 2020
Talanta (00399140) 217
In this work, a magnetic nanocomposite composed of graphene oxide (GO), silica-coated cobalt ferrite (CoFe2O4@SiO2) nanoparticles and amino-functionalized metal-organic framework (MIL 101 (Cr)-NH2) was fabricated and employed for ultrasonic-assisted magnetic solid phase extraction (UA-MSPE) of neonicotinoid insecticides. Various techniques such as Fourier transform infrared (FT-IR) spectrometry, vibrating sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FE-SEM) measurements were executed to investigate features and morphology of the adsorbent. The magnetic graphene oxide functionalized MIL-101 (Cr)-NH2 (MGO/MIL) combines the advantages of magnetic GO and MIL 101(Cr)-NH2 such as excellent thermal and chemical stability, high surface area, accessible coordinative unsaturated sites, sufficient stability in aqueous solutions and rapid and easy separation from the solution. Some of the important extraction factors such as type and volume of desorption solvent, desorption time, salt concentration, adsorbent amount, pH and extraction time were investigated in detail to achieve high MSPE recovery. In optimal condition, the limits of detection (LODs) for Acetamiprid and Imidacloprid were achieved 0.022 and 0.019 ng mL−1, respectively. Good determination coefficients (R2 more than 0.9990) with satisfactory linearity in the range of 0.064–3500 ng mL−1 were found for this method. The relative standard deviations for intra- and inter-day analyses were in the range of 3.93–4.56% and 7.80–8.50%, respectively. The method was successfully used for analyzing of neonicotinoid insecticides in water and fruit samples and acceptable recoveries from 82.13% to 102.27% were obtained. The results indicated that the nanocomposite is feasible for the adsorption of trace amounts of the target analytes from the fruit and water samples. © 2020 Elsevier B.V.
Publication Date: 2020
Microchemical Journal (0026265X) 154
In the present work, an organic-inorganic core-shell nanohybrid composed of octyl modified-silica coated cobalt ferrite nanoparticles (CoFe2O4@SiO2-C8) was synthesized, characterized and used as a magnetic nanoadsorbent for chromium speciation in environmental water samples. The procedure was based on the selective ultrasonic assisted-magnetic solid phase extraction (UA-MSPE) of non-charged chromium (VI)-ammonium pyrrolidine dithiocarbamate (APDC) chelate under the strong acidic solution prior to its detection by flame atomic absorption spectrometry (FAAS). Meanwhile, the total chromium ions chelated with APDC were quantitatively maintained on the sorbent at pH 6.0. The concentration of Cr (III) ions in the solution was calculated by the difference between the total Cr and the Cr (VI) level. The influences of various parameters on the extraction efficiencies including pH, ultrasonic time, amount of adsorbent and chelating agent, sample volume, and desorption conditions were studied and optimized. Good linearity was obtained in the ranges of 0.5–100 (R2 = 0.9993) and 0.4–100 µg L−1 (R2 = 0.9982) for Cr (VI) and Cr total, respectively. The limits of detection (LODs, 3δ/m) of the method were 0.15 µg L−1 and 0.13 µg L−1 for Cr (VI) and total Cr, respectively. Relative standard deviations (RSDs, n = 5) of the method for Cr (VI) and total Cr were 2.4% and 3.8%, respectively. The prepared adsorbent exhibited good chemical and mechanical stability, and selectivity towards Cr (IV) ions in the presence of other interfering ions. The developed procedure was successfully applied to chromium speciation in environmental water samples including tap, river, and wastewater samples with the recoveries in the range of 92.4–99.0%. © 2019 Elsevier B.V.
Publication Date: 2019
Soft Materials (15394468) 17(1)pp. 41-56
Cross-linked polyvinyl alcohol/polyvinyl pyrrolidone/zeolite fibers were prepared in the presence of potassium peroxodisulphate (K 2 S 2 O 8 ) under the curing process by the electrospinning technique. The narrowest nanofibers of PVA/PVP (50:50) were prepared under optimum experimental conditions of 2.5 × 10 −4 mol of K 2 S 2 O 8 , an applied voltage of 22 KV, the distance of 15 cm and the feed rate of 0.2 mL/h. The progress of the cross-linking was examined by immersion of the prepared nanofibers in water and following the swelling degrees. By raising the K 2 S 2 O 8 amount and curing time, the cross-linking density was increased. X-ray diffraction (XRD) demonstrated that the crystallinity of the nanofibers was decreased by the increase of K 2 S 2 O 8 and the lowest crystallinity was observed for PVA/PVP (70:30). The contact angle of nanofibers was decreased from 72° to 34 by increasing PVP ratio from 30 to 70. The morphology of the nanofibers before and after immersion in the simulated body fluid (SBF) was studied using electron scanning microscopy (SEM) and PVA/PVP (70:30) showed the highest changes in the morphology while the lowest one was observed for PVA/PVP (50:50). Moreover, the cross-linked PVA/ PVP with the ratio of 50:50 had the narrowest diameter of 200 ± 100 nm, and by addition of about 0.5% zeolite, it was even reduced more to 150 ± 50 nm. The cross-linked nanofibers (50:50) with 0.5 wt% and 1.5 wt% zeolite nanoparticles showed the tensile modules of 416.26 and 703.52 MPa, respectively, while in the absence of zeolite, it was209.25 MPa. Fibroblast L929 cells were cultured on the cross-linked PVA/PVP/zeolite (50:50:0.5) nanofiber, and the cell proliferation and growth was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Fibroblasts grew on the surface of scaffold showed good morphology and proliferation after seven days and the absorption amount was increased from 0.075 to 0.78. © 2018, © 2018 Taylor & Francis Group, LLC.
Publication Date: 2018
Journal of Chromatography A (00219673) 1564pp. 85-93
Aptamers, due to the inherently high selectivity towards target analytes, are promising candidate for surface modification of the nanoparticles. Therefore, aptamer-functionalized magnetic nanoparticles (AMNPs) was prepared and used to develop a magnetic solid-phase extraction procedure for clean-up of milk and dairy products samples before measuring the aflatoxin M1 (AFM1) contents by the high-performance liquid chromatography. The prepared sorbent was characterized by different instrumental methods such as FT-IR, FESEM, TEM, EDX and AGFM. The AMNPs was used in extraction and pre-concentration of ultratrace amounts AFM1 from local milk samples. The amount of sorbent, elution volume, extraction time, and salt addition were optimized. Based on the results, calibration plot is linear over the 0.3 to 1 ng·L−1 and 5 to 50 ng·L−1 AFM1 concentration ranges. The limits of detection of the developed method were obtained 0.2 ng·L−1 which is the smallest value that has been reported up to now. The results show that this new superior sorbent has a large potential to simplify the complex matrix of the samples and can used for detection, preconcentration and accurate determination of ultratrace amounts of the AFM1 from milk and dairy products. © 2018 Elsevier B.V.
Publication Date: 2017
Membrane and Water Treatment (20058624) 8(5)pp. 437-448
A high quality Na-X zeolite membrane was synthesized on a seeded α-alumina disc by the secondary growth method. Structural characterization was done by X-ray spectroscopy, FT - IR spectroscopy, SEM and AFM imaging. The performance evaluation of the membrane was firstly tested in separation of glucose/water solutions by pervaporation process. There was obtained a separation factor 182.7±8.8, while the flux through the membrane was 3.6±0.3 kg m-2 h-1 . The zeolite membrane was then used for desalination of aqueous solutions consisting of Na+, Ca2+, Cs+ and Sr2+ because of the importance of these ions in water and wastewater treatments. The effects of some parameters such as temperature and solution concentration on the desalination process were studied for investigating of diffusion/adsorption mechanism in membrane separation. Finally, high water fluxes ranged from 2 up to 9 kg m-2 h-1 were obtained and the rejection factors were resulted more than 95% for Na+ and Ca2+ and near to 99% for Cs+ and Sr2+. Based on the results, fluxes were significantly improved due to convenient passage of water molecules from large pores of NaX, while the fouling was declining dramatically. Based on the results, NaX zeolite can efficiently use for the removal of different cations from wastewaters. © 2017 Techno-Press, Ltd.
Publication Date: 2017
Chemical Engineering and Processing - Process Intensification (02552701) 118pp. 47-53
Mixed matrix membranes were prepared by uniformly dispersing of zeolite particles in a polyvinyl alcohol matrix. After membrane characterization, the ability of the prepared membranes was examined toward pervaporation dehydration of binary and ternary mixtures of acetone, isopropanol and water because of their industrial importance. The effect of different parameters on the membrane performance was investigated and the best conditions were obtained. The results showed that, NaA zeolite particles significantly improved the separation performance of the membranes. The selectivity was increased with an increase of zeolite loading up to 5% wt. The best results were obtained for dehydration of isopropyl alcohol where the separation factor was calculated as 1881. Based on the findings of the research, the incorporation of NaA zeolites into the polymer matrix can be very effective for dehydration of acetone and isopropanol. The results show that the prepared membrane can be a good candidate for removal of water in acetone production from isopropyl alcohol. © 2017 Elsevier B.V.
Publication Date: 2017
Microporous and Mesoporous Materials (13871811) 248pp. 256-265
Magnetic nanozeolites were synthesized through a new method and their abilities were evaluated toward adsorption of Pb (II) and Cu (II) from aqueous solutions. A multivariate optimization method using central composite design (CCD) was designed to obtain the best conditions of the adsorption. NaA zeolite because of its high affinity for the investigated ions was selected and was coated onto magnetic nanoparticles. The morphology and characterization of the adsorbent were studied by different techniques such as SEM imaging, FT-IR spectrometry and AGFM measurements. The most favorable conditions for Pb (II) removal was achieved in pH = 5.6 and 8 mg sorbent in a 750 mg L−1 Pb (II) aqueous solution when removal process was done in 8 min. Maximum removal of Cu (II) was attained under the optimal conditions with pH = 2.9, adsorbent amounts 16 mg, initial ion concentration 22.1 mg L−1 and sonication time 24 min. The predicted model of Design Expert software was indicated the significant main factors and the possible interactions of the factors. Based on the results, some interactions between the effecting factors were found for Pb (II) and Cu (II) ions and R2 was attained 0.99 and 0.97 for these ions respectively. Our findings clearly showed that magnetic nanozeolites can be made successfully by entering silica-coated magnetic nanoparticles into the initial solution of zeolite synthesis. Also, the coating of the magnetic nanoparticles with zeolite NaA improved effectively the adsorption of the selected ions while we can conveniently separate the nanozeolites with an external magnet. © 2017 Elsevier Inc.
Publication Date: 2017
Food Analytical Methods (1936976X) 10(6)pp. 1817-1825
Separation and determination of trace levels of low-molecular weight aldehydes are very important from water suppliers’ point of view. Modified magnetic nanoparticles can be used for this propose. Alumina-coated magnetic nanoparticles modified with sodium dodecyl sulfate (SDS/Al2O3/Fe3O4) are used for extraction of formaldehyde (FA) and acetaldehyde (AA) from drinking water samples. In this manner, the aldehydes were converted to their corresponding hydrazones by the reaction with 2,4-dinitrophenylhydrazine (DNPH). After preconcentration, the HPLC technique was used for the determination of the aldehydes and the results were compared with the commercial C18 solid-phase extraction (SPE) columns. The results showed that the extraction with SDS/Al2O3/Fe3O4 is more efficient and faster than the commercial columns. A very good repeatability (RSD was 3.3 and 2.4% for FA and AA, respectively, n = 7, C = 50 ppb) was obtained. Linear regression analysis indicated that the responses for two investigated compounds were linear over about two orders of magnitude above the LOD (LOD was 3.6 ppb for FA and 3.2 ppb for AA), with correlation coefficients >0.9990. Determination of FA and AA in tap water and various brands of bottled waters were carried out using the modified nanoparticles. Based on the obtained results, the aldehyde content of the commercial bottled waters was particularly apparent after exposure to direct sunlight. © 2016, Springer Science+Business Media New York.
Publication Date: 2016
RSC Advances (20462069) 6(18)pp. 14705-14711
Functionalized magnetic nanoparticles are increasingly attracting interest as a new and efficient sorbent for metallic contaminant elimination in environmental samples. Albumin modified magnetic nanoparticles (AMMNPs) were synthesized and characterized. This sorbent was used for removal of cationic and anionic species from the aqueous solutions. The sorbent showed a high adsorption capacity and short equilibrium time for Pb2+, Cu2+, Cd2+ and CrO42- ions removal from aqueous solutions. The effects of different parameters on the adsorption processes were investigated and isotherm curves were constructed. This study showed that AMMNPs are a proper adsorbent for the removal of the studied hazardous ions and can also be used as an efficient sorption material for preconcentration of the studied ions in trace analyses. The adsorption process was very fast and adsorbent performance was not affected clearly by the presence of other ionic species. © The Royal Society of Chemistry 2016.
Publication Date: 2016
TOXICOLOGY REPORTS (22147500) 3pp. 816-816
The authors regret as the affiliation of below authors was incorrect in the article. The correct affiliation is as below: Akbar Malekpour cDepartment of Chemistry, University of Isfahan, Isfahan, Iran Hamidreza Pourzamani bEnvironment Research Center, Department of Environmental Health Engineering, Isfahan University of Medical Sciences (IUMS), Isfahan, Iran The authors would like to apologise for any inconvenience caused. © 2015 The Author(s)
Publication Date: 2016
Food Analytical Methods (1936976X) 9(3)pp. 805-811
Simultaneous determinations of aflatoxins (AFs) in pistachio at μg/kg concentrations were performed using ultrasonic chloroform/water emulsion microextraction (USAEME) and HPLC-UV measurement. A chloroform/water emulsion was stabilized using ultrasonic agitation for the purification of AFs extracted from pistachios using methanol/water. Because the method effectively purified and concentrated AFs, the AFs could be measured directly and without further preconcentration using HPLC-UV. Preparation of AF derivatives for fluorescence measurement was not required. In the optimized procedure, the AF calibration curves were linear for all AFs with correlation coefficients that ranged from 0.9913 to 0.9994. The detection limit was between 0.3 and 1.4 μg/kg, and quantification limit was obtained between 1.1 and 3.2 μg/kg (n = 3); the largest relative standard deviation was obtained <9.78 % (n = 3) at 3 μg/kg, and recoveries ranged from 81.2 to 101.6 % at spiking levels of 0.4, 0.8, 2, and 4 μg/kg. Application of this method to the measurement of AFs in pistachio samples indicated that USAEME coupled with HPLC-UV can determine trace AF levels. The USAEME method is simple, sensitive, and cost-effective in comparison to previous methods. © 2015, Springer Science+Business Media New York.
Publication Date: 2015
Journal of Industrial and Engineering Chemistry (1226086X) 21pp. 580-586
The immobilization of alumina nanoparticles onto the NaX zeolite granules, using the sol-gel and a physical method, for the removal of Cr (III) and Co (II) was investigated. Alumina nanoparticles immobilized zeolite (ANIZ) was characterized by SEM/EDX, XRD and AAS. The results suggested the formation of nanoscale alumina (~30-50. nm) on the zeolite (loading ~8-10. wt%) and the stability of the zeolite structure after the immobilization of alumina nanoparticles. ANIZ showed a good capacity for the removal of metal ions. Kinetic and equilibrium data were best fitted with the pseudo second order model and the Langmuir model respectively. © 2014 The Korean Society of Industrial and Engineering Chemistry.
Publication Date: 2015
RSC Advances (20462069) 5(33)pp. 26246-26254
In recent years, there has been an increasing interest in the analysis of the major active components of saffron owing to their significant role in various industries, such as food, medicine and perfume. In other words, analysis of the major active components of saffron can give complete information about its chemical composition, which can be used as a reliable index for the quality control of different saffron samples (i.e., natural and commercial). The aim of the present work was to develop a simple, low cost, efficient and comprehensive strategy for the extraction and analysis of the bioactive components of saffron. In this regard, ultrasonic-assisted solvent extraction (UASE) combined with ultrasonic-assisted emulsification microextraction (USAEME) is proposed for the extraction and preconcentration of the bioactive constituents of saffron. The extracted components are then analyzed using reverse-phase high-performance liquid chromatography with diode array detector (RP-HPLC-DAD). The effective parameters on the efficiency of extraction procedure are optimized using multivariate chemometric techniques. As a consequence, the optimum extraction parameters were 79.6 mg of a saffron sample, 1.1 mL of the extraction solvent (water), 62.7 μL of the preconcentration solvent (chloroform) and 18.6 min sonication time. In optimum extraction conditions, the relative standard deviations (RSDs) were below 1.0% (n = 3) for all the components. Moreover, the enrichment factors were higher than 10 for most components. Finally, the developed analytical method is used as a reliable method for the quality control of fifteen commercial saffron samples purchased from different markets. To do this, two multivariate clustering methods, principal component analysis (PCA) and k-means, are used for determining similarities and dissimilarities between standard and commercial saffron samples, according to their HPLC fingerprints. It is concluded that the proposed method is a fast, simple, accurate and unbiased method for analyzing the bioactive components of saffron and fingerprinting commercial saffron samples, obtaining a more complete set of information from data than conventional methods. © The Royal Society of Chemistry 2015.
Publication Date: 2015
Toxicology Reports (22147500) 2pp. 1273-1280
BisphenolA (BPA) or 2,2-bis(4-hydroxyphenyl)propanepresent in polycarbonate baby bottles may have harmful effects for formula-fed infants. This study evaluated the risks associated with exposure to BPA among Iranian formula-fed infants in an urban society in Isfahan. New and used baby bottles (n= 7 and 8, respectively) as well as BPA-free marked bottles (n= 2) were collected from a retail outlet, and leaching of BPA was examined by conducting a migration test. Concentrations of BPA released from the new and used baby bottles were in the range of 0.49-8.58 and 0.63-2.47. μg/l, respectively. Next, probabilistic exposure estimation was performed. In all, 200 mothers registered with 11 health centres in Isfahan were interviewed. Data on feeding pattern, washing and sterilization practices, bottles types and manufacturers as well as the sex and weight of the infants were collected using a questionnaire. The results showed that majority of the surveyed infants were exposed to 0.1-0.3. μg/kg body weight (bw)/d of BPA, which corresponded to approximately 2-7.5% of the defined t-TDI (4. μg/kgbw/d). These results suggested that the risk of the adverse effects caused by exposure to BPA was very low in formula-fed Iranian infants even in the worst-case scenario. © 2015 The Authors.
Publication Date: 2015
Journal of Molecular Liquids (18733166) 209pp. 246-257
The removal of Cr (III) and Co (II) from various samples of ionic solutions was investigated using several sorbents such as alumina nanoparticles (Al2O3 NPs), NaX zeolite granules and a new sorbent: alumina nanoparticles immobilized zeolite (ANIZ), in batch mode. The effects of various operating parameters were studied in order to optimize the removal conditions. Results showed that the removal capacity of zeolite has been significantly improved (Cr (III): 31.76%, Co (II): 17.2%) after the immobilization of Al2O3 NPs. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) equations were examined to describe the isotherm models and their constants were evaluated. The kinetic data were analyzed using Pseudo first order, Pseudo second order, Elovich and intraparticle diffusion models. The equilibrium data showed excellent correlation for both Langmuir and Freundlich isotherm models and the Pseudo second-order model was fitted to experimental results better than the other kinetic models. Thermodynamic analyses of the equilibrium data suggested that the removal reactions were spontaneous [- ΔG°, kJ·mol- 1 = 29.37 to 43.69 for Cr (III); and 33.54. to 41.61 for Co (II)] and the spontaneity increased with increasing temperature. © 2015 Elsevier B.V. All rights reserved.
Publication Date: 2014
Applied Biochemistry and Microbiology (16083024) 50(3)pp. 292-296
In order to enhance erythritol production, mutants of Candida magnoliae DSM70638 were generated by ultraviolet and chemical mutagenesis. Erythritol productivity of samples was analyzed by TLC and HPLC with the refractive index detector. One of the mutants named mutant 12-2 gave a 2.4-fold increase in erythritol (20.32 g/L) and a 5.5-fold decrease in glycerol production compared to the wild strain. A sequence-based map of erythrose reductase gene in this mutant showed a replacement of the A321 by G321 that did not cause any amino acid exchange in protein structure. Therefore, the reason of higher erythritol production in C. magnoliae mutant 12-2 is probably the increase in expression of the open reading frame gene. This study revealed that a mutation or minor change in the sequence of genes involved in a production pathway can lead to a significant increase in protein translation. © 2014 Pleiades Publishing, Inc.
Publication Date: 2014
Carbohydrate Polymers (0144-8617) 106(1)pp. 374-383
The fructans, inulin and oligofructose, are known to exert many food and pharmaceutical applications and are widely used in functional foods throughout the world for their nutritional and techno-functional properties. In the present study, the Box-Behnken design was used to determine the optimal conditions for fructan precipitation from Eremurus spectabilis root powder (Serish) by adding ethanol that gave the maximum yield. Ethanol-to-syrup (E/S) ratio (2:1-15:1), precipitation temperature (30-60 °C) and syrup concentration (10-40°B) were considered variables of fructan precipitation. The most compatible model among mean, linear and quadratic expressions was fitted to each response and the regression coefficients were determined using least square method. There was a good agreement between the experimental data and their predicted counterparts. The optimum conditions for fractionating fructan composition of Serish by ethanol were estimated to be E/S ratio of 8.56, temperature of 23.51°C and initial syrup concentration of 40°B. Precipitation under these optimized conditions achieved the best yield (85.81%), average chain length (12.92) and purity (80.18%). In addition, principal component analysis (PCA) allowed discriminating among precipitated fructan specialties. © 2014 Elsevier Ltd.
Publication Date: 2013
International Journal of Environmental Health Engineering (22779183) 2(1)
Aims: This study was aimed to estimate the bisphenol A (BPA) intake from baby bottles, considering the diversity and the standard quality of the baby bottles distributed in an Isfahan urban society. Materials and Methods: A cross-sectional study was performed in Isfahan in 2011. Baby shops (n = 33) and drug stores (n = 7) in four district areas were included in the study. The distribution of baby bottles was investigated regarding their brand, origin, and being labeled “BPA free.” Estimation of exposure to BPA from baby bottles was made based on the national and international representative data. Results: The products marked as “BPA free” were found among the western products and limited to two of the selected areas. No “BPA free” marked baby bottle was distinguished among the Iranian made products. Of the 8% exclusively formula-fed infants, 90% may be the high consumers of BPA from polycarbonate baby bottles, with an intake of 1.5-2 µg/kg b.w./day for the moderate and 7.5-10 µg/kg b.w./day in case of worse condition. Conclusion: Considering the current globally accepted threshold daily intake (TDI) for BPA, primary exposure estimation is that feeding using non-BPA-free baby bottles is not a serious health concern in Iran. Thought that threshold level of TDI is discussed to be reduced in future, improvement and revision of the national standards can be effective in reducing the exposure to BPA in Iranian infants so as to provide large margin of safety for them. Copyright: © 2013 Moghadam ZA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Publication Date: 2012
Journal of Environmental Studies (23456922) 38(61)pp. 31-40
Introduction: Aquaculture wastewaters when discharged to the environment or another receiving body of water can create serious problems. These effluents contain large amounts of harmful material such as organic compounds, anionic and cationic species, uneaten food and etc., which have undesirable effects on the health of aquatic ecosystems and aquaculture facilities. Aquaculture systems produce large quantities of nutrients (phosphorus and sulphate) that require treatment and/or disposal. Principal sources of aquaculture wastes are uneaten foods. The presence of trace amounts of phosphate (even less than 1 ppm) in treated wastewater is often responsible for eutrophication; particularly in lakes and slow moving rivers. Sulphate and phosphorus, discharged with these effluents, result in enhanced growth of organisms associated with eutrophication. However, regulatory agencies are becoming increasingly concerned over elevated sulfate concentrations in effluents, owing largely to its impact on the salinity of receiving waters. There are several methods to treat wastewater containing sulfate anions. The removal of the anion by means of adsorption on the activated carbon, neutralization with CaCO3, biological treatment, reverse osmosis and dialysis and ion exchange were studied. Aiming for the high quality of receiving waters in aquaculture systems, various techniques such as settling systems, centrifugal systems, mechanical filters (media filter and screen filter) and biological processes have been introduced and were applied. Inorganic ion exchanger materials such as zeolites are utilized to remove ammonia from fish raring facilities. Clay is another material that can be used as an ion exchange adsorbent. However, it is utilized very poorly in the existing aquaculture wastewater treatment facilities. The use of clay as anion exchanger in aquaculture has not been considered yet. After modification, clay is also capable of removing anions and other compounds with negative charges. In this study, by using a cationic surfactant TDTMA, and acid thermo activation methods, the surface of bentonite was changed and the capability of the exchanged clay for the adsorption of anionic compounds such as sulfate and phosphate from aquaculture effluent was analyzed. Materials and Methods: Bentonite, natural clay, was acquired from Tabas Iran Co. in Tehran and was used without any further purification. All chemicals were of analytical reagent type and were used as received. The standard solutions were prepared using NaNO3, NaNO2, Na3PO4 and Na2SO4 salts in Milli-Q water. Fish culture system containing two 200-L fish tanks and a sump tank was designed and constructed. Each tank was stocked with 30 trout of 120g mean weight (9.37 Kg/m3). It also included a combined unit of sand and biological filter to remove faces and other suspended particles and biological inter-conversion of nitrogenous wastes, respectively. The X-Ray diffraction pattern of the mineral sample showed that the major clay material present in the sample is bentonite. The main mineralogical impurities are Quartz, hydrated silicates of sodium, calcium, magnesium and aluminum, Stellerite-(Na), Illite, Muscovite and Gypsum. The composition of bentonite in terms of its oxide forms provided by the manufacturer is listed in Table 1. Elemental analysis of the sample using XRF showed that the raw material had Si/Al ratio of 3.46. The Na-exchanged form of bentonite was prepared by stirring samples for 6h with a 1M aqueous solution of NaC1. Excess NaC1 and other exchangeable cations were removed from the exchanged bentonite via filtering. Then, it was washed several times with deionized water until a negative chloride test was obtained with 0.1M AgNO3. The Na-saturated bentonite (50g) was dispersed in 1L of distilled water. TDTMA-bentonite was prepared by adding quantities of the respective surfactant equal to twice the cation exchange capacity of the bentonite and was stirred for 6h. After treatment, bentonite was washed with deionized water to obtain salt-free minerals and a negative chloride test was carried out with 0.1 M AgNO3. Finally, it was dried, grounded and sieved to a size range of 0.8-1.2mm. The acid thermo activated clay was obtained from a natural sodium bentonite. The raw material was first decarbonated and homoionized. Acid thermo activation is a process that allows controlled extraction of aluminum ions from crystalline structure of clay, also introducing an acceptable acidity level. This process modifies the textural properties of clays, favoring a greater porosity and surface area. To carry out acid thermo activation, the purified clay was put in a flask with an acid solution (10 mL acid/1 g clay), stirred and refluxed and heated to 105°C for 3h. The utilized acid solution was: HNO3 (2N). Thereafter, the clay was washed with de-ionized water and dried at 70°C. The powders were ground to a particle size of 0.8-1.2mm and then heated for 4h at 300°C. The solution pH was carefully adjusted by adding small amounts of HCl or NaOH solutions and measured using a pH-meter (corning 120). The samples were filtered and the equilibrium concentrations ascertained by photometer (palintest® 8000). The amount of anions adsorbed onto TDTMA-Bentonite (SMB) was determined by the difference between the initial and remaining concentrations of anionic solutions. The distribution coefficient (Kd) was determined by using the following equation: (Equation Presented) Where C1 and Ce are the initial and the equilibrium anions concentrations (mg/L), V is the volume of solution (mL) and m is the amount of the used adsorbent (g). Results and Discussion: Structural comparisons between modified and natural bentonite imply that modification procedures have changed crystal lattice and layered structure of the mineral smoothly (Figs. 3 and 4). Heating resulted in increased distance between layers and consequently yielded higher anion uptake compared with natural bentonite. Surfactant layer grafted on surface and within the layers of mineral resulted in anions removal by the modified bentonite. The present study was set out in a laboratory condition to evaluate the anion absorption capacity of surfactant acid thermo modified bentonites so as to reveal the potential of the compound as an alternative water remediation method for aquaculture recirculation system. The research clearly suggests that modified bentonite acts as a proper adsorbent for the removal of harmful anions from aquaculture and aqueous solutions. Because of the importance of generating a viable ion uptake tool for toxic species, different studies have been carried out regarding the use of a low-cost adsorbent for the selective removal of anions from aqueous solutions. Conclusion: It has been shown that bentonite modified by TDTMA and acid thermo activation method provides a considerable ion uptake capacity. The main advantages of this procedure are as follows: 1- Natural bentonite is very cheap and abundant. 2- Results showed that bentonite modified by TDTMA was efficient for removing harmful ions from aquaculture wastewater and decreasing anions under the critical levels. 3- Since the bentonite clays even in modified forms can remove cationic species, so this adsorbent is very effective for the simultaneous removal of cationic and anionic species from aquaculture recirculation effluents. 4- This new adsorbent can be utilized as a supportive filter in RAS to remove toxic compounds such as NO3-, NO2-, PO43- and SO4 from aquaculture systems.
Publication Date: 2012
Journal Of Research In Medical Sciences (17357136) 17(11)pp. 1089-1091
Publication Date: 2011
Brazilian Journal of Chemical Engineering (01046632) 28(4)pp. 669-677
LTA and MFI zeolite membranes were hydrothermally grown on the surface of an α-alumina porous support. The synthesized membranes were used for removal of cationic and anionic species from aqueous solutions by the pervaporation method. The perfection of the membranes was improved by employing the multi-stage synthesis method. The membranes were characterized by XRD, SEM and IR methods. The membranes were initially evaluated by the pervaporation separation of water from aqueous 2-propanol mixtures. The separation factors obtained were 7081 and 105 for NaA and ZSM-5 membranes, respectively. The ability of membranes for desalination of some aqueous solutions containing I-, Cs+ and Sr2+ ions was examined in various conditions. These ionic species were chosen because of their importance in the nuclear sciences. Both membranes effectively removed (more than 99 wt%) I -, Cs+ and Sr2+ from their singlesalt solutions (0.001mol dm-3) over a temperature range of 298-338 K. The effects of parameters such as time and temperature on the separation factors and fluxes were investigated. This work shows that, due to their excellent chemical, thermal and mechanical stability, the zeolitic membranes are useful for desalination of aqueous solutions and treating saline wastewaters by pervaporation. Therefore, this method has the ability to desalinate harsh environment solutions involving strong solvent and radioactive components. © 2011 The authors.
Publication Date: 2011
Journal of Radioanalytical and Nuclear Chemistry (15882780) 288(3)pp. 663-669
Natural and modified clinoptilolite as low-cost adsorbents have been used for adsorption of Co(II) and Ni(II) from nuclear wastewaters both in batch and continuous experiments. Zeolite X was also synthesized and its ability towards the selected cations was examined. Kinetic and thermodynamic behaviors for the process were investigated and adsorption equilibrium was interpreted in term of Langmuir and Freundlich equations. The effect of various parameters including the initial concentration, temperature, ionic strength and pH of solution were examined to achieve the optimized conditions. The clinoptilolite was shown good sorption potential for Co(II) and Ni(II) ions at pH values 4-6. Based on desorption studies, nearly 74 and 85% of adsorbed Co(II) and Ni(II) were removed from clinoptilolite by HCl. The Na+ and NH4 + forms of clinoptilolite were the best modified forms for the removal of investigated cations. It is concluded that the selectivity of clinoptilolite is higher for Co(II) than Ni(II). The synthesized zeolite showed more ability to remove cobalt and nickel ions from aqueous solution than the natural clinoptilolite. The microwave irradiation was found to be more rapid and effective for ion exchange compared to conventional ion exchange process. © 2011 Akadémiai Kiadó.
Publication Date: 2009
Journal of Hazardous Materials (0304-3894) 172(1)pp. 229-233
A sensitive, simple separation and solid-phase procedure, which is sorption and desorption of cadmium on modified clinoptilolite zeolite (with surfactant and neothorine), for preconcentration of cadmium prior to analysis by FAAS is described. The sorbent has exhibited good sorption potential for cadmium at pH 5. Cadmium was eluted from the column by nitric acid which resulted in preconcentration factor of 160. Thermodynamic behaviors for the process are investigated and adsorption process is interpreted in term of Freundlich equation. A detection limit of 0.015 ng mL-1 was obtained and it is shown that calibration curve is linear from 0.01 to 4.0 μg mL-1 in the final solution. Furthermore, the effects of various parameters such as pH, flow rate of the sample and eluent solution were studied. This method was successfully applied for determination of cadmium in various plant and real water samples. © 2009 Elsevier B.V. All rights reserved.
Publication Date: 2009
Powder Technology (1873328X) 189(1)pp. 52-56
The zeolite NaA was synthesized from natural clinoptilolite as Si source and aluminum sulfate or sodium aluminate as Al source. The use of aluminum sulfate for the synthesis of zeolite A has not been reported in the literature. This study presents as the first time a synthesis approach in which the low cost and available source is used to prepare zeolite NaA. These nano particles of zeolite were prepared at different conditions in autoclave and a mixer was designed specifically for this purpose. The synthesized zeolites were characterized by instrumental analysis methods, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), transmission electron microscope (TEM) and wet chemical analysis by atomic absorption spectroscopy (AAS). Cation exchange capacity (CEC) and loss on ignition (LOI) have been also measured on the prepared samples. The influences of different parameters such as reaction time, temperature, initial gel concentration, mechanical stirring and drying conditions on the improvement of the final products were experienced and the procedure for the efficient synthesis of zeolite NaA was optimized with available quality control tests. Solubility of clinoptilolite as the Si source in alkaline solutions was also investigated. © 2008 Elsevier B.V. All rights reserved.
Publication Date: 2008
Journal of AOAC International (10603271) 91(6)pp. 1446-1452
Natural clinoptilolite was used as a sorbent material for solid-phase extraction and preconcentration of zinc. Clinoptilolite was first saturated with cadmium (II) and then modified with benzyldimethyltetradecylammonium chloride for increasing adsorption of 3-(2-arsenophenylazo)-4,5-dihydroxy-2,7-naphthalene disulfonic acid (neothorin). Zinc was quantitatively retained on the adsorbent by the column method in the pH range of 3.8-4.2 at a flow rate of 1 mL/min. It was eluted from the column with 5.0 mL 2 M nitric acid solution at a flow rate of 1 mL/min and determined by flame atomic absorption spectrometry at 213.9 nm. Zinc could be concentrated from a 0.03 μg/L solution with a preconcentration factor of 170. Relative standard deviation for 8 replicate determinations of 2.5 μg zinc in the final solution was 0.92%. The interference of a large number of anions and cations was studied in detail to optimize the conditions, and the method was successfully applied for determination of zinc in standard and real water samples.
Publication Date: 2008
Desalination (0011-9164) 225(1-3)pp. 199-208
NaA zeolite membranes were prepared by hydrothermal synthesis on a porous α-alumina support with secondary growth crystallization. These membranes were characterized by XRD, SEM, AFM and permeation tests and were used for desalination of simulated radioactive wastes through pervaporation process. The influence of several operating parameters such as synthesis time, number of zeolite layers and seeding procedure was investigated. Based on our results the performance of NaA zeolite membranes can be improved by employing a multi-stage synthesis method. Results showed that membranes which were prepared in a four-stage process (each step 3 h) can yield best separation. At first the membranes were evaluated by dehydration of water/isopropanol solutions. Results showed that a separation factor equal to 5041 with 1.2 kg/m2.h total flux can be obtained. For ionic solutions including 0.001 M of Cs+, Sr2+ and MoO42- very high rejection factors were obtained (more than 99%). This work showed that zeolitic membranes can be used for treatment of low level radioactive wastes as well as desalination and volume reduction of these solutions especially through the pervaporation process. © 2008 Elsevier B.V. All rights reserved.
Publication Date: 2007
Microporous and Mesoporous Materials (13871811) 106(1-3)pp. 192-200
In the present work, electrophoretic deposition (EPD) has been applied as the seeding method to formation of zeolite ZSM-5 layers with thicknesses about a few micrometers on the porous alumina substrates. Alumina discs were fully covered with ZSM-5 crystal seeds via this method. The resulting seeded supports were submitted to hydrothermal treatment yielding uniform dense zeolite membranes. The membranes were characterized by using scanning electron microscopy (SEM), and X-ray diffractometry (XRD). It was concluded that thickness and density of the membranes could be modified by varying the Si/Al ratio of zeolite ZSM-5 particles, concentration of seeding suspension and seeding time. The selectivity of the produced ZSM-5 membrane for i-propanol permeation over water was observed on every membrane and at some optimum conditions separation factors higher than 40 was obtained. At the same time, a total flux of about 1.75 kg/m2h was achieved which is well comparable with the published data on similar membranes. © 2007 Elsevier Inc. All rights reserved.
Publication Date: 2006
Adsorption Science and Technology (02636174) 24(6)pp. 487-496
Natural and modified clinoptilolite were used to remove zinc and cadmium ions from aqueous solution. The raw material was characterized by XRD and XRF analysis. Clinoptilolite was modified with benzyldimethyltetradecylammonium chloride (BDTA) to increase the adsorption of neothorin [2-(2-arsenophenylazo)chromotropic acid disodium salt, C10H11AsN2Na2 O11 S2]. All experiments were undertaken using a continuous method. The ultimate goal of these studies was the selective removal of trace amounts of Cd(II) and Zn(II) ions from aqueous solution using a modified form of clinoptilolite. The results obtained showed that Cd(II) and Zn(II) ions were adsorbed quantitatively onto modified clinoptilolite over the respective pH ranges of 4.0-5.4 and 3.3-4.5. The influence on the adsorption process of various parameters such as the ionic concentration, the flow rate, the particle size, the pH value and the presence of other cations was studied to obtain the optimum conditions. Although clinoptilolite and its surfactant-modified form were not capable of the selective adsorption of the cations studied, on the basis of the results obtained it was possible to selectively remove Zn(II) and Cd(II) ions from aqueous solution by modified clinoptilolite using a two-step process, i.e. initial treatment with BDTA followed by treatment with neothorin.
Publication Date: 2003
Adsorption Science and Technology (02636174) 21(4)pp. 373-381
The removal of radionuclides such as 129I and 131I from radioactive liquid wastes was studied. Two natural zeolites were modified with different quaternary alkylammonium ions to replace the exchangeable cations from the zeolite surface and used as adsorbent materials. The quaternary ions used for such purpose were hexadecyltrimethylammonium, tetradecyltrimethylammonium, dodecyltrimethylammonium, tetrabutylammonium and tetramethylammonium, respectively. Some of the modified forms exhibited an adsorption capacity much higher than those of the respective natural samples. In contrast, the adsorption capacity was negligible when tetrabutylammonium and tetramethylammonium ions were used. Adsorption experiments were conducted by batch and continuous experiments, and adsorption isotherms constructed from the data obtained. The effect of interfering anions on the adsorption capacity was also investigated as were the breakthrough behaviours of radioiodide in a column charged with the various adsorbents. Desorption of iodide from the modified zeolites into different solutions was also investigated. It was concluded that, in some cases, surfactant modification was an efficient process for the uptake and immobilization of iodide.
Publication Date: 2002
International Journal of Environment and Pollution (09574352) 18(2)pp. 181-189
Natural clinoptilolite-rich tuffs and natrolite from Iranian deposits and their different ion-exchanged forms were used for the adsorption of 99Mo as molybdate ion. The effect of pH, contact time, initial molybdate concentration, and some cationic and anionic interferences were also studied. To investigate the selectivity of zeolites and their exchanged forms, the isotherms of adsorption were constructed at room temperature. Desorption experiments were carried out to examine the ability of zeolite to retain adsorbed molybdate. It was concluded that molybdate could be considerably adsorbed by some of the exchanged forms of the zeolites (Ag+, Cd2+ and Pb2+ exchanged forms) whereas the uptake by the natural forms was negligible.
Publication Date: 2002
Journal of Radioanalytical and Nuclear Chemistry (15882780) 254(3)pp. 545-550
Two natural zeolites from Iranian deposits (clinoptilolite and natrolite) were characterized and their ability for adsorption of iodide from nuclear wastewaters was evaluated. The adsorption behavior was studied on natural and modified zeolites by γ-spectrometry using 131I as radiotracer. Adsorption isotherms and distribution coefficient (Kd) were measured. The results showed that clinoptilolite is a more promising zeolite for removal of iodide compared to natrolite. Furthermore, the adsorption was higher in silver, lead and thallium forms, whereas the lowest desorption was observed in lead modified zeolite.
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