Preparation of multi-defect calcite based environmental materials from high-alumina fly ash: Mechanism of performance enhancement for Pb removal

Abstract

In this study, a novel material M-AER with multiple lattice defects was produced through phase reconstruction (i.e. Al recovery and mechanical activation) of high-alumina coal fly ash (HAFA). M-AER demonstrates significant potential for the advanced removal of heavy metals from water. The results showed that M-AER was rich in calcite and dicalcium silicate, and ball milling enhanced the immobilization of Pb²⁺ on its surface, improved its specific surface area, microform and lattice defects, and its maximum immobilizing capacity of Pb(II) was increased from 10.72 mg/g to 69.42 mg/g. Under the low concentration (20 mg/L, pH: 5), the amount of M-AER powder was 0.5 g/L, and more than 99.5 % of soluble lead could be immobilized in 60 min. The removal efficiency of Hg(II), Cu(II), and Cd(II) can also reach 60 %. The surface calcification of M-AER could generate lead-containing compounds through the exchange of calcium ions with heavy metals, so that the metals, such as lead, could be combined with carbonate and silicate at the interface of liquid-solid. This study provides a new vision to realize the resourceful utilization of HAFA and the efficient immobilization of heavy metals.