Sustainable transformation of electroplating waste Cu(II) into sulfonic acid-functionalized HKUST-1 for high-efficiency Pb(II) recovery from lead-acid battery wastewater

The development of adsorbents with high adsorption capacity and selectivity is essential for Pb(II) recovery from lead-acid battery recycling effluents. This study developed an innovative "Waste-Treats-Waste" strategy, utilizing copper ions from high-acidity Cu-containing electroplating wastewater to synthesize sulfonic acid-functionalized Cu-MOFs (W-HKUST-1-SO 3 H-x) for Pb(II) recovery from lead-acid battery wastewater. A series of materials were successfully synthesized by synergistic coordination with 1,3,5-benzenetricarboxylic acid (H 3 BTC) and sodium 5-sulfoisophthalic acid (H 3 -5-SIP) as dual ligands. Partial incorporation of H 3 -5-SIP not only increases the adsorption sites but also enhances the adsorption stability and purity of the MOF. Furthermore, the sulfonic acid-functionalized Cu-MOFs exhibited similar physicochemical properties to the commercial MOF (C-HKUST-1). W-HKUST-1-SO 3 H-0.2 demonstrated an excellent Pb(II) recovery capacity of 645.14 mg·g −1 , along with higher adsorption stability in both five-cycle tests and fixed-bed experiments. Experimental results and theoretical analysis indicated that W-HKUST-1 and C-HKUST-1 without sulfonic acid modification mainly adsorbed Pb(II) by ion exchange, while W-HKUST-1-SO 3 H-0.2 adsorbed Pb(II) mainly through coordination with the sulfonic acid group. This study provides a novel strategy for the development of efficient adsorbents and demonstrates the promising potential for practical Pb(II) recovery from lead-acid battery wastewater. • Utilized Cu(II) from acidic electroplating wastewater to synthesize sulfonated Cu-MOFs for Pb(II) recovery. • Enhanced sites/stability via synergistic H3-5-SIP coordination. • Optimized adsorbent showed high Pb(II) capacity and multi-cycle stability. • Sulfonic groups shifted adsorption mechanism to coordination dominance.