Synthesis and Selective Au(III) Adsorption of Ureido Polymers Containing Large Repeating Rings

Two polymers (polyBAUEE and polyBAUP) containing 25- and 20-membered rings are synthesized by the cyclopolymerization of bifunctional monomers 1,2-bis(acryloyloxyethyl-ureidoethoxyl)-ethane (BAUEE) and 1,3-bis(acryloyloxyethylureido)propane (BAUP) and studied for the adsorption of precious metal ions. PoIyBAUEE and polyBAUP selectively adsorb Au(III) with the adsorption efficiencies above 99.0% after adsorption equilibrium. PoIyBAUEE adsorbed faster than polyBAUP, and the Au(III) adsorption is selective in the presence of nine interfering metal ions with similar concentrations (ca. 1 mg/L) in an aqueous solution including Pd(II) and Pt(II). The maximum Au(III) adsorption capacities of polyBAUEE and polyBAUP are 37.6 and 31.8 mg/g, respectively. Au(III) is reduced to Au(0) nanoparticles during the adsorption process. The selective adsorption behavior depends on the controlling regioselective recognition of the ring structure and the ureido groups.

Automated summary

The polymers polyBAUEE and polyBAUP exhibit high selectivity and efficiency in adsorbing precious metal ions, with polyBAUEE showing faster adsorption rates and higher adsorption capacities compared to polyBAUP. Additionally, the adsorption process results in the reduction of Au(III) to Au(0) nanoparticles, indicating a regioselective recognition mechanism based on the ring structure and ureido groups.