Zeolite Synthesis from Spodumene Leach Residue and Its Application to Heavy Metal Removal from Aqueous Solutions

This study presents an approach to synthesizing LTA-type zeolite from spodumene residue generated during a lithium extraction process. A residue was obtained after leaching β-spodumene with 2 mol/L phosphoric acid. After solid–liquid separation, the delithiated residue was first treated with 2 mol/L sodium hydroxide and then subjected to hydrothermal synthesis using sodium aluminate as an additional aluminum source. The resulting material was characterized by XRD, SEM-EDS, XPS, and FTIR, which collectively confirmed the formation of a crystalline material exhibiting the structural features, elemental composition, and morphological characteristics consistent with LTA-type zeolite. Additional analyses, including BET surface area, particle size distribution, and zeta potential measurements, were performed to further evaluate the physicochemical properties of the synthesized zeolite. The spodumene leach residue (SLR)-derived zeolite was further tested for its adsorption performance in heavy metal ions removal from a mixed ion solution containing Pb2+, Cu2+, Zn2+, and Ni2+ ions. The zeolite demonstrated a high selectivity for Pb2+, followed by moderate uptake of Cu2+, while Zn2+ and Ni2+ adsorption was minimal. These findings demonstrate that spodumene residue, a waste by-product of lithium processing, can be effectively upcycled into LTA zeolite suitable for heavy metal remediation in water treatment applications.