Abstract
before and after chemical modification and thermal activation was characterized by different techniques including X-ray diffraction, thermal analysis, Fourier transform infrared, surface area, helium pycnometry, cation exchange capacity and scanning electron microscopy. Pseudo-first order, pseudo-second order and intra-particle diffusion models were used to analyze the kinetic curves. Equilibrium data were analyzed using Langmuir and Freundlich models. The thermodynamic study indicated that lead adsorption process is endothermic and interactions between clays and solutions of lead occurred spontaneously, while cadmium adsorption revealed an exothermic and spontaneous nature. The maximum removal efficiencies were 97.62% for Cd(II) using
Highlights
The increment of human wastes mainly caused by industries, due to the constant discharge of pollutants, contributes to declining water quality
Traditional processes have been used for treating effluents that contain heavy metals, they include: ion exchange[2], reverse osmosis[3], chemical coagulation and precipitation[4], ultrafiltration[5], and adsorption[6]
Karapinar and Bonatb[18] studied the adsorption process of copper and cadmium, the results showed that the maximum removal efficiencies for Cu2+ and Cd2+ onto natural bentonite were 84.49 and 87.02%, respectively and Inglezakisa[19] reached 100% of efficiency in the removal of Pb(II) form aqueous solutions using clinoptilolite and bentonite as adsorvents
Summary
The increment of human wastes mainly caused by industries, due to the constant discharge of pollutants, contributes to declining water quality. Traditional processes have been used for treating effluents that contain heavy metals, they include: ion exchange[2], reverse osmosis[3], chemical coagulation and precipitation[4], ultrafiltration[5], and adsorption[6]. Different adsorbents have been employed in the process of adsorption: activated charcoal[8], kaolinite[9], natural and synthetic zeolites[10], rice husks[11], clays[12], among others Clays have properties such as high cation exchange capacity, they are available and low cost adsorbents, which can be recycled and reused for subsequent cycles. Bentonites are highly efficient in adsorption of heavy metals[13]
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