Remediation of carcinogenic arsenic by pyroaurite-based green adsorbent: isotherm, kinetic, mechanistic study, and applicability in real-life groundwater
2020
Yadav, Manoj Kumar | Gupta, Ashok Kumar | Ghosal, Partha Sarathi | Mukherjee, Abhijit
The removal of the harmful carcinogen arsenic from drinking water by a green technology is a major concern in the field of environmental engineering. The sorptive profile of arsenic remediation by calcined Mg-Fe-layered double hydroxide, fabricated by a one-pot synthesis technique, was investigated to delineate its applicability in real-life water. The physicochemical properties of adsorbent, as demonstrated from spectroscopy and microscopy, which described the existence of amorphous material with significant surface roughness possess selectivity towards arsenic. The isotherm and kinetic along with thermodynamic modeling exhibited the occurrence of spontaneous (ΔG⁰ value = − 8.084 kJ/mol to − 10.942 kJ/mol), endothermic (ΔH⁰ value = 12.135 kJ/mol), and physisorption reactions (Eₐd = 4.103–5.832 kJ/mol, Eₐ = 11.546 kJ/mol, S* = 0.0005 << 1, and ΔHₓ = 9.23–16.29 kJ/mol) with high uptake rate and adsorption potential of adsorbent. The isotherm and kinetics were demonstrated by Temkin (R² = 0.944–0.969) and Elovich (R² = 0.996–0.998) models, respectively, with high statistical significance. The intraparticle diffusion model which established the rate-limiting step is the combination of both film and pore diffusions. The applicability of layered double hydroxide (LDH) material in the real-life water was confirmed by isotherm and kinetic modeling along with the regeneration/reuse potential. The adsorptive removal of arsenic by the LDH material exhibited to be a promising technique without creating any secondary hazard.
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