Removal of Pb(II) and Zn(II) from aqueous solution by ceramisite prepared by sintering bentonite, iron powder and activated carbon

Abstract

Heavy metal pollution has become a major global problem, which threatens the environment and human life by its toxicity. Development of novel low-cost adsorbents for heavy metals removal has attracted great attention. In this study, bentonite, iron powder (IP) and activated carbon (AC) were used to prepare Fe2O3–ceramisite (FOC) by sintering at 800°C. Effects of weight ratio of raw materials on physical properties of FOC including bulk density (BD), 1-h water adsorption rate (WAR), acid solubility (AS), BET surface area and average pore size (APS) were examined. Experiments were conducted to determine the factors affecting sorption of Pb(II) and Zn(II) on FOC including initial metal ion concentration, contact time and initial solution pH. Experimental data were tested using different kinetics models. Results revealed that: With an increase of AC rate, WAR, AS, APS and BET surface area increased linearly, while BD linearly decreased. Hematite (Fe2O3) was the main crystalline phase emerging in FOC, which promoted the removal of Pb(II) and Zn(II) by formation of Pb(II)/Zn(II)-containing crystalline phases in the reacted FOC. The cation-ion exchange reaction played an important role in the removal of Pb(II) and Zn(II). The pseudo-second order model was most applicable to describe the removal process of Pb(II) and Zn(II).