Synthesis of novel magnetic pitch-based hypercrosslinked polymers as adsorbents for effective recovery of Ag+ with high selectivity

Abstract

Silver is an important precious metal with superior ductility, electrical and thermal conductivity, photosensitivity, and antibacterial properties. However, without proper recycling and treatment, silver emissions may pose a threat to the human health and subsistence environment due to their toxicity. Therefore, it is environmentally and economically important to recover Ag from waste electronic equipment and anode slime. Herein, carboxyl functionalized modified magnetic nanoparticles (Fe₃O₄@3-phenylglutaricacid nanoparticles) were designed and prepared to obtain the low-cost magnetic pitch-based HCP adsorbents (MPHCP and P-MPHCP). The novelty of present work is that superior adsorption capacity and magnetic responsiveness of adsorbent can be obtained by a simple one-step Friedel-Crafts reaction with very low-cost raw material. The maximum Ag⁺ adsorption capacity of MPHCP and P-MPHCP were 321 and 353 mg/g, respectively. The adsorption was completed within a short duration of 15 min for MPHCP and P-MPHCP at an initial Ag⁺ concentration of 100 mg/L. Moreover, the most selective is P-MPHCP wherein Ag⁺ is α = 61 times more selective than Pb²⁺ at a concentration of 100 mg/L.The adsorption capacity of MPHCP and P-MPHCP towards Ag⁺ still maintains above 89% after ten cycles of adsorption-desorption. This study not only provides new guidance for the development of porous polymeric adsorbents but also provides technical feasibility for the field of recovery and reutilization of precious metals, which has a very extensive practical application prospect.

Keywords: HCP adsorbents; Heavy metal ions; High selectivity; Magnetic; Pitch-based.