Mehdi Sedighi; Majid Mohammadi
Abstract
Consistent with the US Environmental Protection Agency, heavy metals are classified as carcinogenic to humans. Their numerous agricultural, industrial, domestic, medical, and technical requirements have resulted in their widespread dissemination in the environment. This article examines a new green adsorbent ...
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Consistent with the US Environmental Protection Agency, heavy metals are classified as carcinogenic to humans. Their numerous agricultural, industrial, domestic, medical, and technical requirements have resulted in their widespread dissemination in the environment. This article examines a new green adsorbent for the removal of two hazardous heavy metals, lead and mercury. The impact of contact time, pH, initial concentration, and temperature on the adsorption capacity of Pb2+ and Hg2+ were evaluated. Experimental data were analyzed by adsorption models. The equilibrium data were well adapted to the Langmuir adsorption model. The results show that the adsorption is homogeneous and localized in a monolayer. In addition, the maximum adsorption capacity was 277.78 mg/g for Pb2+ and 64.52 mg/g for Hg2+ from Langmuir isotherm. Thermodynamic data, including free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) variations were also considered. The important point is that the negative value of ΔG° signifies the spontaneity of the adsorption process of the heavy metals−NiO/ZSM-5 system.
Taher Yousefi; Mohammad Abas Mohsen; Hamid Reza Mahmudian; Meisam Torab-Mostaeidi; Mohammad Ali Moosavian; Hassan Aghayan
Abstract
In the current work, the natural zeolite was modified with cobalt hexacyanoferrate and employed for adsorbent of Pb(II) ions from aqueous solution. The modification was approved by XRD and FTIR techniques. The Pb(II) adsorption capacity enhanced by 1.8 times from 60 mg/g (natural zeolite) to 100 mg/g ...
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In the current work, the natural zeolite was modified with cobalt hexacyanoferrate and employed for adsorbent of Pb(II) ions from aqueous solution. The modification was approved by XRD and FTIR techniques. The Pb(II) adsorption capacity enhanced by 1.8 times from 60 mg/g (natural zeolite) to 100 mg/g (modified zeolite) at optimal conditions. Factors such as time, pH, temperature, adsorbent dosage and initial concentration were investigated to optimize the adsorption condition. A fast sorption was observed in the initial contact time and equilibrium was achieved in less than 120 min. The optimum pH for lead removal was between 3 and 6. The adsorption capacity was increased and reached the maximum of 90 % at 2 g/L adsorbent dosage. Also, the adsorption increased as the concentration increased up to 500 mg/L and the sorption became constant at higher concentration. It was found that the double-exponential model describes the lead sorption kinetics and the Langmuir–model describe the isotherms.
Zahra hassanzadeh Siahpoosh; Majid Soleimani
Abstract
This investigate presents the extraction-preconcentration of Lead, Cadmium, and Nickel ions from water samples using Ghezeljeh montmorillonite nanoclay or “Geleh-Sar-Shoor” (means head-washing clay) as a natural and native new adsorbent in batch single element systems. The Ghezeljeh clay ...
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This investigate presents the extraction-preconcentration of Lead, Cadmium, and Nickel ions from water samples using Ghezeljeh montmorillonite nanoclay or “Geleh-Sar-Shoor” (means head-washing clay) as a natural and native new adsorbent in batch single element systems. The Ghezeljeh clay is categorized by using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy-Energy Dispersive Spectrometer Operating (SEM-EDS), X-ray Diffractometry (XRD), X-ray Fluorescence (XRF), Cation Exchange Capacity (CEC) measurements, Surface property valuation (SBET) by the BET method from nitrogen adsorption isotherms and Zeta potential. According to BET theory, the specific surface area of Ghezeljeh nanoclay was computed as 19.8 m2 g-1 whereas the cation exchange capacity was determined as 150 meq (100 g-1). The results of XRD, FT-IR, XRF, zeta potential, BET surface area and CEC of the Ghezeljeh clay confirm that montmorillonite is the dominant mineral phase. Based on SEM images of clay, it can be seen that the distance between the plates is nm level. For all three ions, the limit of detection, the limit of quantification, dynamic linear range, preconcentration factor, and the adsorption capacity were obtained. The result of several interfering ions was considered. The Ghezeljeh nanoclay as a new adsorbent and experimental method were effectively used for the extraction of heavy metals (Lead, Cadmium, and Nickel) in a variety of real water samples.