Efficient Cr(VI) removal from wastewater by D-(+)-xylose based adsorbent: Key roles of three-dimensional porous structures and oxygen groups.

Reducing the harm of heavy metals to the environment has been a major scientific challenge. In this study, D-(+)-xylose was used to prepare an adsorbent with rich O groups and three-dimensional porous structures for Cr(VI) adsorption. What's more, the adsorption sites of many oxygen groups in the material were combined with the three-dimensionally connected porous structures, which made the adsorption sites fully in contact with Cr(VI). At the concentration of 300 mg/L, the removal rate of Cr(VI) was 94.50%, 6.4 times that of the non-porous treatment and 9.6 times that of the non-porous and O group treatment. The adsorbent showed a high adsorption capacity (910.10 mg/g) for Cr(VI), and the adsorption model proved that the adsorbent was a multi-molecular layer adsorbent. In addition, the adsorption was controlled by chemical reaction and diffusion, which was also attributed to the three-dimensional porous structure and abundant oxygen groups of the material. XPS and FTIR indicated that four O groups participated in the adsorption reaction (-OH, C-O-C, CO, and C-O), and C-O-C and C-O were the main reaction sites. After treating wastewater from electroplating plants with X-PC, the discharged water met international and domestic discharge standards (Cr(VI) removal rate> 99.90%). This work provides a new idea for the application of sugars in the environment and the design of porous adsorbents.