Abstract
Changes of bentonite surface structure under the influence of direct microwave irradiation during adsorpion of Cu2+ from concentrated solutions were investigated by X-ray and EDS analysis. The microwave treated bentonite (MTB) has been proved to have enhanced adsorption capacity for copper due to improved pore structure and some peculiarities of adsorption mechanism. The non-linear fitting of experimental data to the theoretical isotherms have demonstrated that the adsorption on natural bentonite fitted the Toth model, whilst microwave-treated bentonite fitted the Langmur-Freundlich model. The isotherm modeling allowed predicting the maximal adsorption capacities 44.8 mg/g. XRD and SEM analysis of MTB sample after adsorption indicated formation of microcrystals of individual copper compound. The adsorption on MTB sample takes place not only in pores or in monomolecular layer on the bentonite surface, but the prevalent mechanism is surface-induced co-precipitation of copper as microcrystals of individual copper compound.
Highlights
Heavy metal water pollution is an important environmental concern due to its negative impact on human health, plants and animal lives
Simulated standard solution The stock solution of copper sulfate was prepared from dry CuSO4 · 5H2O (1.593 g) and double distilled water (500 ml)
X-ray diffraction analysis of natural bentonite has been described in detail in our previous work [24]
Summary
Heavy metal water pollution is an important environmental concern due to its negative impact on human health, plants and animal lives. Heavy metals are toxic and prone to bioaccumulation [1,2,3]. Cu is frequently present in industrial wastewater such as mine drainage, galvanizing plants, natural ores and municipal wastewater treatment plants. Copper is not biodegradable and travels through the food chain via bioaccumulation. The increase of Cu (II) in human body causes brain, skin, pancreas and heart diseases [4]. The problem of reducing copper content in industrial wastewater is relevant
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