A photoinitiated catalytic self-degrading composite material for efficient and stable Cu(II) directional adsorption was constructed based on the bridging synergy strategy.

The rapid development of industry has led to increasingly serious copper ion pollution caused by the discharge of copper-containing wastewater. Traditional adsorption materials have the risk of secondary pollution due to the fact that directional adsorption is easily disturbed, and the bonding stability is poor. This study uses sulfamic acid to modify polyvinyl alcohol/sodium alginate composite material (SPS). The aim is to construct a multiple cross-linked system to enhance the confinement effect and improve the selective adsorption capacity for Cu(II). Meanwhile, a sulfur source is introduced, and the S-Cu-O bridging effect is utilized to effectively improve the degree of electronic localization, transforming a single adsorption site into a continuous adsorption site with higher electronegativity, thereby significantly increasing the adsorption capacity. This mechanism enables Cu(II) to achieve stable anchoring through electronic structure reorganization rather than simple surface adhesion. SPS demonstrated excellent acid resistance and photocatalytic degradation resistance after adsorption of Cu(II), further verifying the above mechanism. In adsorption experiments, the removal rate of Cu(Ⅱ) by SPS can reach 95.96%, and the maximum adsorption capacity can reach 426.82 mg/g. After 5 cycles, it still keeps above 90%. After desorption, SPS can be completely degraded in 9 h under illumination, which has considerable practical application value. This study proposes a novel composite material with both high adsorption selectivity and photocatalytic self-degradation functions, achieving efficient removal of copper ions and green recycling of adsorbents, providing an innovative solution for the treatment of copper-containing wastewater.