Abstract

This study focuses on the modification of corncob lignin using sodium bisulfite to introduce sulfonate groups, resulting in lignosulfonates with varying degrees of functionalization (LS-1, LS-2, and LS-3). The effectiveness of the chemical modification and the degree of functionalization were confirmed using techniques such as phosphorus 31 nuclear magnetic resonance, Fourier-transform infrared spectroscopy with attenuated total reflection, thermogravimetry, and acid-base titration. The PEUF method proved efficient for retaining Mg2+ from aqueous solutions, achieving a balance between retention percentage and hydrodynamic flow stability by adjusting parameters such as LS dosage, pH, Mg2+ feed concentration, and the presence of other metal ions. Lignosulfonates exhibited a preferential affinity for Mg2+ in various Mg2+/Li+ ratios and multicomponent solutions containing Li+, Na+, K+, Mg2+, and Ca2+. A high separation factor for Mg2+ (separation factor, alpha Mg2+/Li+ = 12.3 in binary solutions and alpha Mg2+/Li+ = 3.87 in multicomponent solutions) was achieved, demonstrating the stronger affinity of LS for Mg2+. Furthermore, LS maintained a reasonable reusability potential for up to four cycles. PEUF with LS proved to be an effective and facile method for capturing up to 692 mg g-1 of Mg2+ from aqueous solutions, with high potential for scalability and sustainability, intended for the selective and efficient separation of Mg2+ and Li+ from natural or industrial brines.