Mahnaz Saghanejhad Tehrani

Bio: Mahnaz Saghanejhad Tehrani is an academic researcher from Iran University of Science and Technology. The author has contributed to research in topics: Adsorption & Sorbent. The author has an hindex of 4, co-authored 4 publications receiving 224 citations.

Highly efficient simultaneous ultrasonic-assisted adsorption of methylene blue and rhodamine B onto metal organic framework MIL-68(Al): central composite design optimization

Abstract: In the present work, metal organic framework MIL-68 (MIL = Material of Institute Lavoisier), with metal sites of aluminum ions (namely MIL-68(Al)), was synthesized by a simple, fast and low-cost process for simultaneous removal of Methylene Blue (MB) and Rhodamine B (RhB), regarded to be toxic and even carcinogenic, from aqueous solution. The adsorbent was characterized by FTIR, SEM, XRD, BET and TG analysis. Optimization of significant variables such as pH, adsorbent dosage, initial MB concentration, initial RhB concentration and adsorption time affecting both single and binary dye removal was developed by Central Composite Design (CCD) under response surface methodology (RSM), and the optimized values for these parameters in binary solutions were found to be 6.45, 0.014 g, 60 mg L−1, 15 mg L−1 and 9.9 min, respectively. The kinetics and isotherm of the adsorption were investigated in detail. Maximum sorption capacities of 1666, 1111, 227 and 29 mg g−1 were obtained from the Langmuir isotherms for MB and RhB in single and binary solutions, respectively. The kinetics study results suggested that the sorption of the studied dyes onto MIL-68(Al) follows the pseudo-second order model. According to the reusability test of the adsorbent, dye uploaded MIL-68(Al) can be regenerated using methanol. The regenerated sorbent was used for three cycles use with high performance. The effect of ionic strength on the removal efficiency of the sorbent was also tested with different kinds of salts. The applicability of the sorbent was examined for real samples spiked with specific quantities of both dyes in water from tap water, sea water, spring water and laundry wastewater. The short time required for dye uptake makes this MOF a promising sorbent for simultaneous and rapid removal of dyes even in the real polluted environment.

Application of central composite design for optimization of preconcentration and determination of La (III) ion in water samples using the SBA-15-HESI and SBA-15-HESI-Fe3O4-NPs sorbents

Abstract: In this study, Fe 3 O 4 nanoparticles (NPs) loaded onto SBA-15-HESI (SBA-15-HESI-Fe 3 O 4 -NPs) as a novel sorbent was prepared and subsequently was applied for dispersive solid phase magnetic extraction (MSPME) and preconcentration of La (III) ions in water samples by ICP-OES. The synthesized sorbent was characterized by FT-IR, SEM, TEM, BET, VSM, BJH and XRD techniques. The important variables such as concentration of solvent, volume of extraction solvent, desorption time, pH of the sample soloution, initial concentration of La(III) ions, sorbents dosage and adsorption time were investigated and optimized by central composite design (CCD) combined with desirability function (DF). The optimum condition, concluded from one at a time method was 2 mL of 0.1 mol L −1 HCl as extraction solvent and 5.0 min from desorption time. Linear calibration range 20–200 and 10–220 μg L −1 , detection limit 0.21 and 0.16 μg L −1 , the relative standard deviations (RSD%) of 3 and 2% were obtained for SBA-15-HESI and SBA-15-HESI-Fe 3 O 4 -NPs, respectively. The enrichment factor 7.6 and 9.8, the preconcentration factor 7.37 and 9.43, the adsorption capacity 1.27 and 2.81 mg g −1 were obtained for SBA-15-HESI and SBA-15-Fe 3 O 4 -NPs, respectively.

Synthesis, characterization and application of cyclam-modified magnetic SBA-15 as a novel sorbent and its optimization by central composite design for adsorption and determination of trace amounts of lead ions

Abstract: A novel adsorbent based on 1,4,8,11-tetraazacyclotetradecane (cyclam) loaded in mesoporous silica (cyclam-SBA-15) was synthesised and modified by Fe3O4 magnetic nanoparticles (Fe3O4@cyclam-SBA-15). Characterization was performed by scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FT-IR) and X-ray powder diffraction (XRD). The application of this sorbent was analyzed in magnetic solid phase extraction (MSPE) and adsorption of trace amounts of lead ions (Pb2+). The effects of various factors, such as adsorbent dosage, initial concentration of the lead ion, contact time and pH of the solution, on the removal efficiency were simultaneously evaluated by central composite design (CCD) under response surface methodology (RSM). The optimized conditions were found to be 0.004 g, 20 mg L−1, 40 min and 4.8, for adsorbent dosage, initial Pb concentration, contact time and pH, respectively. For the extraction experiments, the nature and volume of the eluent were also investigated to obtain the optimum conditions for the enrichment factor. Due to the high stability of the magnetic adsorbent, it can be used several times with only a slight decrease in the recovery of Pb(II) ions. The effects of matrix ions on the retention of the Pb2+ ions were also studied in order to examine the selectivity of this sorbent toward Pb(II) ions. Under the optimal conditions, the proposed method exhibited a high adsorption capacity of 625 mg g−1, a detection limit of 2.02 μg L−1 and an enrichment factor of 200 with a relative standard deviation (RSD%) of 4.14%. Finally, the application of the synthesized material was evaluated for adsorption and preconcentration of lead ions from foods and environmental water samples.

Effective Adsorption and Removal of Phosphate from Aqueous Solutions and Eutrophic Water by Fe-based MOFs of MIL-101

Abstract: Although many efforts have been devoted to the adsorptive removal of phosphate from aqueous solutions and eutrophic water, it is still highly desirable to develop novel adsorbents with high adsorption capacities. In this study, Fe-based metal-organic frameworks (MOFs), MIL-101 and NH2-MIL-101, are fabricated through a general facile strategy. Their performance as an adsorbent for phosphate removal is investigated. Experiments are performed to study the effects of various factors on the phosphate adsorption, including adsorbent dosage, contact time and co-existing ions. Both MIL-101(Fe) and NH2-MIL-101(Fe) show highly effective removal of phosphates from aqueous solutions, and the concentration of phosphates decrease sharply from the initial 0.60 mg·L−1 to 0.045 and 0.032 mg·L−1, respectively, within just 30 min of exposure. The adsorption kinetics and adsorption isotherms reveal that NH2-MIL-101(Fe) has higher adsorption capacity than MIL-101(Fe) possibly due to the amine group. Furthermore, the Fe-based MOFs also exhibit a high selectivity towards phosphate over other anions such as chloride, bromide, nitrate and sulfate. Particularly, the prepared Fe-based MIL-101 materials are also capable of adsorbing phosphate in an actual eutrophic water sample and display better removal effect.

Environmentally friendly reduced graphene oxide as a broad-spectrum adsorbent for anionic and cationic dyes via π–π interactions

Abstract: π–π interactions between graphene and organic dyes with a conjugate aromatic structure play a key role in the field of high-efficiency, broad-spectrum adsorbents for the removal of water contaminants. L-Cysteine reduced graphene oxide (RGO-Cys) has a good conjugate structure and dispersity in aqueous solution, endowing it with great adsorption efficiency towards anionic, nonionic and cationic dyes with a conjugate aromatic structure mainly via π–π interactions, as proved by the Raman spectrum and special adsorption experiments. The maximum adsorption capability for anionic indigo carmine (IC) and cationic neutral red (NR) is as high as 1005.7 mg g−1 and 1301.8 mg g−1, respectively, the former being the highest among those reported for adsorbents known to date. The total adsorption amount in mixed dye solutions is even higher (>3500 mg g−1), the highest total capability for simultaneous adsorption of anionic and cationic dyes in their solution mixtures. The π–π stacking adsorption mechanism ensures RGO-Cys to be used as a broad-spectrum adsorbent with high efficiency for many kinds of dye contaminants in water while the remnant carboxyl groups on graphene nanosheets facilitate effective adsorption towards Cu2+ with a capability as high as 139.2 mg g−1, opening up many possibilities for the use of graphene in water cleaning including disinfection, decontamination, and desalination.