Enhanced Ni(II) Removal from Wastewater Using Novel Molecular Sieve-Based Composites

This study focuses on the efficient removal of Ni(II) from spent lithium-ion batteries (LIBs) to support environmental conservation and sustainable resource management. A composite material, known as molecular sieve (MS)-based metal–organic framework (MOF) composites (MMCs), consisting of a synthesized MS matrix with integrated MOFs, was developed for the adsorption of Ni(II). The structural and performance characteristics of the MMCs were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and N2adsorption–desorption isotherms (BET). Batch adsorption experiments were conducted to assess the Ni(II) adsorption performance of the MMCs. The results revealed that, under conditions of pH 8 and a temperature of 298 K, the MMCs achieved near-equilibrium Ni(II) adsorption within 6 h, with a maximum theoretical adsorption capacity of 204.1 mg/g. Further analysis of the adsorption data confirmed that the adsorption process followed a pseudo-second-order kinetic model and Langmuir isotherm model, indicating a spontaneous, endothermic chemical adsorption mechanism. Importantly, the MMCs exhibited superior Ni(II) adsorption compared to the MS. This study provides valuable insights into the effective recovery and recycling of Ni(II) from spent LIBs, emphasizing its significance for environmental sustainability and resource circularity.