Rapid recognition and recovery of gold(III) with functional ligand immobilized novel mesoporous adsorbent

Rapid and selective gold (Au(III)) recognition and recovery was investigated by a new type mesoporous adsorbent. The adsorbent was prepared by direct immobilization of 3-(3-(methoxycarbonyl)benzylidene)hydrazinyl) benzoic acid (MBHB) onto highly ordered mesoporous silica monoliths. The adsorbent enhanced the color formation by stable complexation as [Au(III)-MBHB]n+ complexes during recognition and adsorption operations. The several influence factors such as solution acidity, color optimization in recognition system, Au(III) adsorption capacity of the adsorbent, competing metal ions effect and Au(III) extraction/recovery behaviour were systematically studied. The effective pH for Au(III) ions recognition and adsorption was 2.0 and the maximum adsorption capacity of the adsorbent was as high as 177.94 mg/g. In addition, the simultaneous Au(III) recognition and recovery from simulated urban mining solution was investigated. The data revealed that the recognition system was in a one-step and, even ultra-trace Au(III) concentrations without using highly sophisticated instruments implied the adsorbent was novel. The adsorbed Au(III) was extracted and recovered as pure Au(III) in a two-step elution process. After extraction, the adsorbent was regenerated simultaneously and found selective to Au(III) exhibiting the same capturing capacity as fresh adsorbent after rinsing with water. Performance of the regenerated adsorbent was checked and it was found that the adsorbent can be used up to seven reuse cycles. The selectivity experiments indicated that adsorbent possessed excellent recognition and adsorption property to Au(III) ions, offering potential applications in recovery of Au(III) from multi-ionic aqueous systems.