文摘
A dual-core Fe2O3@carbon structure was prepared by a hydrothermal treatment of iron salt and chitosan (CS) solution. The structure exhibits microsphere-like (∼850 nm in size) morphology with dual cores at two ends. The existence of CS plays an important role in the formation of the dual-core–shell structure. The unique structure was investigated to be a CS adsorption, and subsequent carbonization induced a selective etching process. Further, the special structure was proven to be a highly efficient material for selective adsorption. The dual-core structure facilitates the exposure of the Fe2O3 surface, and the carbonaceous shell gives plenty of functional groups for selective adsorption. More importantly, the selectivity was highly dependent on pH values. It was found that the adsorbent showed higher adsorption selectivity toward Cr(VI) at lower pH values, while the selectivity transferred toward Cu(II) at higher pH values by adsorption of Cu(II) and Cr(VI) in single-component solutions. In binary-component solution, the dual-core Fe2O3@C structure revealed adsorption selectivity for Cr(VI), with the highest separator factor [αCu(II)Cr(VI)] = 1162, due to the strong electrostatic adsorption-coupled reduction interaction induced by the special structure of the adsorbent. This work not only gives deep insights into the understanding of the formation of the dual-core structure but also supplies a novel adsorbent with selective adsorption properties for water treatment.
