Enhanced selective removal of lead from battery industry wastewater using MoS₂@PbCO₃ composite seeds via a nucleation...

Removal of lead ions (Pb^2 +) from wastewater produced by lead-acid batteries is crucial, however, limited due to low selectivity. This study used the MoS₂@PbCO₃-0.6 lead-specific seeds (LSS) as fillers in nucleation crystallization pelleting (NCP) process, resulting in a remarkable capacity for selective Pb²⁺ removal. After 180 h of continuous operation, the total removal efficiency of Pb²⁺ stabilized at 94.3 % in the form of lead carbonate (PbCO₃), while the coexisting cobalt (Co²⁺) and cadmium (Cd²⁺) ions were removed at less than 10 %. Further investigation revealed that Pb²⁺ removal was enhanced by increasing the influent water temperature and maintaining a moderate pH (pH=8), whereas it was inhibited by higher concentrations of coexisting anions (SO₄^2- and Cl^-) due to the competition with carbonate ions for free Pb²⁺. The combination of FTIR, SEM-EDS, XPS analyses, and DFT calculations, revealed the molecular-level mechanisms for recovering Pb²⁺. This process is largely governed by the surface-selective enrichment and induced precipitation, attributed to the stronger affinity of LSS for Pb²⁺, evidenced by its significantly higher distribution coefficient K_d compared to other ions (7.2 ×10⁷ mL/g). In addition, the experiments conducted with actual lead-containing wastewater also yield promising results. This study highlights a promising method for Pb²⁺ removal from lead-acid battery wastewater and provides insights into developing advanced LSS for improved Pb²⁺ enrichment through interface mechanisms.