Adsorption of Pb (II) and Cu (II) by Attapulgite/(La+Fe)

Abstract

With the rapid development of Chinese industry, the discharge of heavy metal-containing wastewater is increasing. Heavy metal-containing wastewater is complex, polluting and difficult to degrade, posing a serious threat to human health. Attapulgite is a kind of silicate mineral rich in Magnesium and Aluminum. It has the nanochannel structure, a very large specific surface area and a certain ion exchange property, therefore, attapulgite has good adsorption capacity. In this paper, attapulgite was modified by acid, La(NO3)2 and FeCl3•6H2O loading and thermal to adsorb simulated heavy metal-containing wastewater. The effects of different attapulgite usage, solution concentration, pH and adsorption time on the adsorption of heavy metals were studied. The results show that 0.4g is the optimum usage of attapulgite; the adsorption is decreases with the increase of the concentration of standard solution; with the increase of pH, the adsorption is increases and then decreases, 4 is the optimum pH for adsorbing Cu(II), 5 is the optimum pH foradsorbing Pb(II); the adsorption also decreases with the increase of concentration, and finally it tends to balance; with the adsorption time increases, the adsorption is increases and then tends to remain unchanged. At the same time, attapulgite and modified attapulgite were characterized by scanning electron microscopy and X-ray diffraction. In addition, the best adsorption model was found to be Freundlich by isothermal adsorption experiments. Through the kinetic experiments, the adsorption kinetics of the attapulgite is described as the most consistent with the quasi-secondary kinetics, so as to understand the adsorption mechanism of the attapulgite.