文献类型：期刊文献

英文题名：Chromium (VI) reduction in the nano-or micron-sized iron oxide - Citric acid systems: Kinetics and mechanisms

作者：Yang, Jiewen[1];Zhong, Laiyuan[1];Liu, Liming[2]

机构：[1]Guangdong Ocean Univ, Coll Agr, Dept Resources & Environm Sci, Zhanjiang 524088, Peoples R China;[2]China Agr Univ, Coll Resources & Environm Sci, Dept Land Resources Management, Beijing 100193, Peoples R China

年份：2017

卷号：5

期号：3

起止页码：2564

外文期刊名：JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING

收录：SCI-EXPANDED(收录号：WOS:000405370200050)、、EI(收录号：20172003668589)、Scopus(收录号：2-s2.0-85018862700)、WOS

基金：This work was supported by the National Natural Science Foundation of China (grant nos. U1401234, 41671235, 41371316).

语种：英文

外文关键词：Cr(VI) reduction; Nano iron oxide; Environmental catalysis

外文摘要：The unique surface properties exhibited by engineered iron oxide nanoparticle have been widely exploited in heterogeneous catalysis and environmental remediation of different pollutants. In the current study, commercial available 50 nm gamma-Fe2O3 and 5 mu m alpha-Fe2O3 were examined with respect to their adsorption for Cr(VI) and the effect on Cr(VI) reduction by citric acid. Adsorption capacity of Cr(VI) on nano-sized particles was higher than that on micron-sized particles. Adsorption of Cr(VI) onto the surfaces of 50 nm gamma-Fe2O3 particle would be inhibited with the increase in ionic strength, while which shows no influence on that for 5 mu m gamma-Fe2O3 particles. The difference in ATR-FTIR spectra between aqueous and adsorbed Cr(VI) on iron oxide surfaces indicated the formation of inner-sphere complexes on the surfaces. Reduction of Cr(VI) by citric acid alone proceeded slowly, while the addition of iron oxide could markedly accelerate the transformation of Cr(VI) to Cr(III) with the rate for 50 nm gamma-Fe2O3 particles more faster than that for 5 mu m a-Fe2O3 particles. The mechanisms were ascribed to the auto-reduction of aqueous Fe(III)-citrate complexes and the subsequent Fe(III)/Fe(II) redox cycle. The different reaction rate mention above was related with the amounts of Fe(III) released from the iron oxides dissolution. Kinetic results confirmed the direct electron transfer between adsorbed Cr(VI) and citric acid on the surfaces could be ruled out because Cr(VI) adsorption was completely suppressed by the co-existing anionic solutes. The findings above indicated the environmental risk posed by Cr(VI) could be alleviated when iron oxide and organic acids were present, which accordingly be helpful for formulating remediation strategy of Cr(VI)polluted soils.