Selective capture of mercury

We herein aim to construct a novel sorbent (DT-S) possessing adsorption selectivity to mercury(II) in aqueous media. Silanized purified diatomite (DT-N) was first synthesized by grafting 3-aminopropyltrimethoxysilane (APS) onto purified diatomite (DT). Nanoporous DT-S was then constructed through successively grafting epichlorohydrin (ECH) and allyl thiourea (AT) onto DT-N. FTIR, elemental analysis (EA), Brunauer-Emmett-Teller (BET), XRD, SEM, and pH at the zero point of charge (pH.sub.zpc) results demonstrated that DT-S had ample -OH, -NH.sub.2, and C=S, specific surface area of 5.52 m.sup.2/g, small pore diameter (16.10 nm), porous structures, and pH.sub.zpc of 5.80, favorable for Hg(II) capture. Optimal adsorption parameters were determined through batch tests. Capture behavior was interpreted preferably by pseudo-second-order kinetic and Liu isothermal equations. DT-S' capture features, e.g., monolayer, spontaneity, chemisorption, and endothermic reaction, were evidenced by the data obtained. DT-S had 56.30 mg/g of maximum adsorption capacity for Hg(II), exceeded some sorbents available. Competitive adsorption tests displayed remarkably selective ability to capture Hg(II) (> 80.01%). FTIR and XRD analyses validated a possible capture mechanism, i.e., chelation reactions took place between mercury ions and nitrogen, oxygen, or sulfur atom in solid-liquid interface. Altogether, DT-S with high removal efficiency, capture selectivity, and excellent reusability is expected to be new sorbent applied to Hg(II)-contaminated water purification.