Ma Yulin,Gu Na,Gao Jinlong,Wang Kuitao,Wu Yunxia,Meng Xiaoyu
Fe 3 O 4 -CuO@montmorillonite was prepared using coprecipitation method, and its structure was determined by XRD, IR, and transmission electron micrograph (TEM). Montmorillonite in Fe 3 O 4 -CuO@montmorillonite nanocomposite allowed the silicate layer of montmorillonite to behave as a barrier, which prevented the agglomeration and natural crystallization of Fe 3 O 4 and CuO. Furthermore, the chlorine dioxide (ClO 2 ) oxidative degradation of anthracene-contaminated soil was studied in detail using Fe 3 O 4 -CuO@montmorillonite as a magnetic heterogeneous catalyst. The operating parameters such as ClO 2 concentration, catalyst dosage, reaction time, and pH were evaluated. Compared with the conventional ClO 2 oxidation process without the catalyst, the ClO 2 catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (anthracene concentration 89.8 mg/kg, water soil mass ratio 3:1, initial pH 7, ClO 2 concentration 1 mol/kg, catalyst dosage 1 g/kg, reaction time 30 min, and reaction temperature 25 °C), anthracene degradation efficiency achieved 96.2 %. The catalyst could be easily reused by magnetic separation and used at least 8 cycles without obvious loss of activity. The kinetic studies revealed that the ClO 2 catalytic oxidation degradation of anthracene-contaminated soil with Fe 3 O 4 -CuO@montmorillonite as catalyst followed pseudo-first-order kinetics with respect to ClO 2 concentration. Thus, this study showed potential application of ClO 2 catalytic oxidation process in remediation of organic pollutant-contaminated soil.
Baojie Liu,Huali Zeng,Shuo Wang,Yunbiao Pang,Chengrong Qin,Chen Liang,Caoxing Huang,Shuangquan Yao
High-purity pulp fibers can be obtained by using chlorine dioxide to oxidize lignin. However, organic halogen compounds (AOX) are generated from chlorination side reactions during the lignin oxidation process. In this study, phenolic lignin model compounds with different substituents were selected. The effects of substituent position on the production of free radicals and oxidative ring opening in benzene rings were analyzed. It was found that the structural transformation of lignin and the reaction consumption of ClO 2 were significantly changed under high concentration of ClO 2 . The molar consumption ratio of compound to ClO 2 was increased from 1:2 to 1:3. Quinone , an intermediate product that promotes the formation of phenoxy radicals, was found to be stabilized in the reaction. This is attributed to that the benzene ring of lignin is activated through long-range electrostatic interactions . The formation of free radicals and the oxidative ring-opening reaction of benzene rings were facilitated. The efficient oxidation of lignin by ClO 2 was fulfilled. Chlorination reactions of lignin were suppressed at elevated oxidation efficiency. The pollution load of wastewater was significantly reduced. AOX generation was reduced by 69.27 %. This provides a new method for efficient oxidative degradation of lignin and preparation of high purity pulp fiber.
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