Concave polymer nano-container as a bifunctional adsorbent for extraction of As(III) and Pb(II)

Adsorption is recognized as a cost-effective, efficient, and versatile method for the treatment of heavy metal pollution, offering environmentally friendly solutions. The development of highly efficient and selective adsorbent materials is essential, with functional groups such as sulfhydryl and amine groups playing a crucial role in the effectiveness and selectivity of adsorption processes. Polymer-based materials have emerged as a promising class of selective adsorbents due to their naturally occurring amine groups. In this study, a bifunctional adsorbent with a concave morphology was developed by grafting sulfhydryl groups to selectively adsorb As(III) and Pb(II) from aqueous solutions. Maximum adsorption capacities for As(III) and Pb(II) were found to be 165.51 mg g−1 and 62.38 mg g−1, respectively, at an optimum dosage of 0.05 mg mL−1 and an original concentration of 20 mg L−1 for both metals. Notably, the concave spheres exhibited superior morphology advantages for As(III) and Pb(II) adsorption compared to hollow and solid polymers, with adsorption capacities 1.8 times higher than hollow polymers and 3.7 times higher than solid spheres for As(III) adsorption, and 3.4 times higher than solid spheres for Pb(II) adsorption. Mechanistic studies revealed that the selective capture of As(III) was primarily attributed to the proposed reaction routes between As(III) and -SH groups. Isothermal models, including Langmuir and Freundlich, suggested that monolayer adsorption on homogeneous surfaces may dominate for As(III), while multilayer adsorption is favored for Pb(II) extraction. •A concave polymer bifunctional adsorbent with naturally amine groups and sulfhydryls-grafting was designed.•The mechanism of surface complexation behaviors between As(III) and –SH groups was observed.•The concave spheres have obvious morphology advantages for As(III) and Pb(II) adsorption.