Enhanced Cr(VI) reduction using highly conductive material synthesized by modified chitosan coated with natural iron-manganese minerals

This work presents a novel chitosan coated magnetite/rhodochrosite composites prepared by thermal reduction method were used to efficient remove Cr(VI) from aqueous solution. A series characterization including XPS, XRD, FTIR, SEM, TEM and electrochemical measurement were used to investigate the characterization of pre-pared materials. SEM and TEM results show that the chitosan carbon (Ch-BC) firmly coated the thermally modified rhodochrosite and magnetite, and composites prepared at 900 degrees C can further improve its specific surface area. The removal of Cr(VI) by MaRh@Ch-500, MaRh@Ch-700 and MaRh@Ch-900 are all highly pH dependent. At pH 5, MaRh@Ch-500 showed the best Cr(VI) removal capacity than others, which is 13.4, 18.1 and 9.9 times of natural magnetite, rhodochrosite and Ch-BC, respectively. Additionally, maximum adsorption capacity for MaRh@Ch-500 fitted by Langmuir model was 104.5 mg/g at pH 2, 30 degrees C. Electrochemical analysis confirmed that based on coated of Ch-BC, the MaRh@Ch-500 presented stronger redox activity, lower resistance and stronger electrical conductivity than others, which is more favorable to electron transfer. XPS results show that nearly 92.33 % Cr(VI) was converted to CrxFe1-x(OH)3/Cr2O3 and loaden on the surface of MaRh@Ch-500. Our results provide theoretical support for the development of efficient treatment of Cr(VI) polluted water.

Automated summary

This work presents a novel chitosan coated magnetite/rhodochrosite composites that efficiently remove Cr(VI) from aqueous solution. The characterization results show that the chitosan carbon firmly coats the thermally modified rhodochrosite and magnetite, and the composites prepared at 900 degrees C have improved specific surface area. The removal of Cr(VI) is pH dependent, and the composites exhibit better removal capacity than natural magnetite, rhodochrosite, and Ch-BC.