Two-step modification of sepiolite (SDS/isep) and its performance for remediation of Pb contaminated water

Abstract To enhance the remediation capability of lead (Pb) polluted water, our approach involved a two-step modification of the initial sepiolite (sep) through inorganic mixed solutions and sodium dodecanesulfonate (referring as SDS/isep), and then the modified sepiolite (SDS/isep) is used to remove Pb2+ in Pb-contaminated water. Adsorption experiments showed that the SDS/isep had a significantly higher adsorption capacity for Pb2+ than natural sepiolite (the adsorption capacities before and after modification were 19.04 and 49.10 mg g− 1). A series of characterizations combined with adsorption kinetics and thermodynamics analysis revealed the adsorption mechanism of SDS/isep for Pb2+. The analysis results show that the monolayer adsorption of SDS/isep to Pb2+ is mainly carried out by ion exchange, surface hydroxyl complexation, chemical precipitation, and electrostatic attraction, and this adsorption reaction is a spontaneous exothermic process. The above positive results indicate the superiority of the two-step modification strategy of natural sepiolite proposed in this study.