Study of adsorption property and mechanism of lead(II) and cadmium(II) onto sulfhydryl modified attapulgite

Study of the adsorption property and mechanism about the environmental functional material can provide theoretical guidance for its actual application. The sulfhydryl attapulgite (SH-ATP) was prepared by solution blending method. The saturated adsorption capacity to Pb2+ and Cd2+ in the experiment were 65.57 and 22.71 mg/g, which increased by 57.74% and 31.96% comparing with the attapulgite (ATP), respectively. The adsorption kinetics experiments illustrated that the adsorption of Pb2+ and Cd2+ onto SH-ATP accorded with multiple kinetic models. Among them, the pseudo second-order model had the best correlation, the correlation coefficients were all above 0.998. The adsorption thermodynamics experiments testified that the adsorption of Pb2+ and Cd2+ onto SH-ATP conformed to the Langmuir, Tempkin and Dubinin-Radushkevich models, those models indicated that the adsorption processes belonged to the monolayer adsorption, the adsorbent surface was homogeneous, and the micropore distribution of the adsorbent was also relatively uniform. Various thermodynamic parameters (Delta H > 0, Delta S > 0, Delta G < 0) under 25-45 degrees C indicated that the adsorption processes of Pb2+ and Cd2+ onto SH-ATP were endothermic and spontaneous. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of King Saud University.