Sorption capacity and mechanism of Cr3+ on tobermorite derived from fly ash acid residue and carbide slag

Abstract

In this study, tobermorite was successfully synthesized from two kinds of industrial wastes by single step hydrothermal method. The structural and morphological changes during synthesis show that well-crystallized tobermorite can be obtained within 6h at 180°C in this system. The carbon impurities lead to a longer synthesis time and lower crystallinity of tobermorite. The tobermorite displays attractive adsorption capacity for Cr3+ (4.87mmol/g), which is 2–3 times higher than common clay minerals. Meanwhile, Cr3+ adsorption causes the exsolution of structural Ca2+ in tobermorite channels, leading to the damage of crystallinity and decrease in sorption capacity of adsorbent. Therefore, better crystallization of tobermorite is helpful to achieve higher sorption capacity for Cr3+. These results indicate tobermorite can be used in industrial processes to adsorb heavy metals from wastewater.