Efficient adsorption and reduction of Cr(VI) from aqueous solution by Santa Barbara Amorphous-15 (SBA-15) supported Fe/Ni bimetallic nanoparticles

Nanoscale zero-valent iron (nZVI or Fe0) can rapidly reduce Cr(VI) contaminants in the water environ-ment, but the agglomeration and passivation of the Fe0 system have adverse effects on its application. In this study, a novel mesoporous Santa Barbara Amorphous-15 supported Fe/Ni bimetallic composite (SBA-15@Fe/Ni) is proposed to remove Cr(VI). The proposed material can enhance the stability and removal capacity of the nZVI system. The results show that the unique six-way through-hole structure of SBA-15 provides a place for the dispersion of Fe0 particles. Meanwhile, SBA-15 effectively alleviates the accumulation of Fe0 particles. The removal efficiency of SBA-15@Fe/Ni is better than two single sys-tems (SBA-15 and Fe/Ni). The removal efficiency of SBA-15@Fe/Ni towards Cr(VI) can reach 97.62% after 60 min at pH 4.0. SBA-15@Fe/Ni still maintains excellent performance in the presence of various compet-itive ions (Cl-, SO42-, CO32-, NO3-). At 298 K, the maximum removal capacity of SBA-15@Fe/Ni towards Cr(VI) is 180.99 mg/g. The possible removal process of SBA-15@Fe/Ni towards Cr(VI) is divided into the follow-ing steps: First, Cr(VI) is attracted into the vicinity of the SBA-15@Fe/Ni channel by the electrostatic attraction; Second, the reduction of Cr(VI) occurs after contacting with the Fe/Ni system, and its driving force mainly comes from nZVI and Fe(II); Furthermore, the introduction of Ni can promote Cr(VI) reduc-tion through electron transfer and catalytic hydrogenation. In conclusion, adopting SBA-15@Fe/Ni to treat chromium contamination is an effective and promising approach.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study proposes a novel mesoporous Santa Barbara Amorphous-15 supported Fe/Ni bimetallic composite (SBA-15@Fe/Ni) for the removal of Cr(VI) contaminants in the water environment. The results show that SBA-15@Fe/Ni exhibits better stability and removal efficiency, and maintains excellent performance in the presence of various competitive ions.