Ball-milling of Talc for Disposing Ni²⁺ Contaminated Sewage

In order to achieve the efficient removal of heavy metal nickel ions in water and simultaneously recover nickel secondary resources, the natural talc mineral was modified by simple ball-milling process and directly applied for the purification of nickel-containing wastewater. The influence of activation intensity, talc dosage and initial concentration of nickel solution on the precipitation efficiency of nickel ions was systematically studied. The samples before and after reaction were tested by XRD, FTIR and SEM-EDS to clarify the mechanism of interaction between talc and nickel ions. The results demonstrated that the precipitation capacity of talc on heavy metals was significantly enhanced after ball-milling. Ball-milling of talc induced the collapse of crystal structure, with the dissolution of OH^-/Mg²⁺ from the talc structure, facilitating the interaction between OH^- and Ni²⁺ in solution to form amorphous Ni(OH)₂ precipitation on talc surface, which worked as the main mechanism for nickel fixation by ball-milled talc. This achieved a maximum precipitation capacity of nickel ions up to 198 mg/g at the conditions of milling speed at 500 r/min and the initial Ni²⁺ concentration of 1 000 mg/L, which was 10 times that of the pristine talc. This study provided a novel concept for the heavy metal pollution prevention and recovery of secondary metal resource, as well as the comprehensive utilization of talc minerals, which can possibly be a reference for the efficient utilization of resources and environmental purification.