A green approach towards functional hydrogel particles from synthetic polymers via spherical capsule mini-reactors

In the present study, we firstly reported a green approach to prepare synthetic polymer-based particle adsorbents in aqueous solution. A novel spherical hydrogel capsule (SHC) was prepared through a facile method by partial ionic-crosslinking of carboxylated chitosan (CCS). Then, 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) and acrylic acid (AA) were chosen as monomers to prepare P(AMPS- co -AA) hydrogel particles by using the SHCs as sacrificial mini-reactors. Different feed monomer molar ratios of core/shell structured CCS/P(AMPS- co -AA) hydrogel particles were synthesized through free radical polymerization. After removing the shells of the core/shell particles, the obtained P(AMPS- co -AA) particles were further used as adsorbents. The maximum adsorption capacities to the metallic ions of Ni 2+ , Cd 2+ , Cu 2+ , and Ag + were 171.6, 220.5, 366.0, and 668.4 mg/g, respectively. In addition, the adsorption amount towards methylene blue (MB) reached as high as 2970 mg/g, and the removal ratio to MB by the particle columns was over 92%. Furthermore, the particles showed excellent reusability. Thus, we provide a green and economical methodology for the preparation of tunable synthetic polymer-based hydrogel particles in aqueous solution that can be used as recyclable adsorbents for water remediation.