Multifunctional pomelo peel cellulose/lysine/ZIF-8 porous foam with honeycomb structure: Adsorption performance and mechanism

Addressing the need for sustainable wastewater treatment, a novel ZIF-8-modified pomelo peel cellulose/lysine (P/L@ZIF-8) porous foam with honeycomb-like porous structure was synthesized through covalent cross-linking and in situ growth. This hierarchical design enabled mechanical robustness (compressive stress of 368.02 KPa at 80 % strain), enhanced surface area (S: 28 m/g) and complete biodegradation within 10 weeks. Furthermore, superior adsorption capacity for Congo red (CR), Cu(II), and nanoplastics polystyrene (PS) was achieved, with theoretical maximum adsorption capacities being 1467.50 mg/g, 293.82 mg/g, and 255.06 mg/g, respectively. Importantly, the foam maintained robust performance across diverse pH and practical water conditions, and the removal efficiencies for CR, Cu(II), and PS were slightly reduced from 99.60 %, 71.09 %, and 99.39 % to 93.31 %, 61.11 %, and 83.92 %, respectively, after 10 reuse cycles. Mechanistic studies combining XPS, FTIR, and density functional theory (DFT) calculations revealed the distinct adsorption mechanisms towards CR, PS and Cu(II). Component analysis identified ZIF-8 as the primary contributor to the contaminant removal. Additionally, the foam exhibited remarkable non-photocatalytic degradation capability, converting malachite green (MG) to HO and CO with 97.18 % efficiency at 100 mg/L initial concentration. These outstanding properties position the P/L@ZIF-8 porous foam as a promising, sustainable solution for complex wastewater treatment applications.