High selective removal towards Hg(II) from aqueous solution with magnetic diatomite-based adsorbent functionalized by poly(3-aminothiophenol): conditional optimization, application, and mechanism

Abstract

A novel diatomite-based (DMT) material was obtained by post-functionalization of DMT/CoFe₂O₄ with 3-aminothiophenol and applied to remove Hg(II) ions from aqueous solution. The obtained adsorbent of DMT/CoFe₂O₄-p-ATP was detected by various characterization means. The optimization of response surface methodology reveals that magnetic diatomite-based material of DMT/CoFe₂O₄-p-ATP has an optimal adsorption capability of 213.2 mg/g towards Hg(II). The removal process of Hg(II) is fitted well to pseudo-second-order and Langmuir models, respectively, indicating that the adsorption process is controlled by monolayer chemisorption. DMT/CoFe₂O₄-p-ATP exhibits superior affinity towards Hg(II) through electrostatic attraction and surface chelation, compared with other coexisting heavy metal ions. Meanwhile, the prepared adsorbent DMT/CoFe₂O₄-p-ATP displays excellent recyclability, good magnetic separation performance, and satisfying stability. The as-prepared diatomite-based DMT/CoFe₂O₄-p-ATP can be a promising adsorbent for mercury ions.

Keywords: Adsorption; Diatomite; Mercury ions; Poly(3-aminothiophenol); Response surface methodology.