壳聚糖包被纳米铁催化降解罗丹明B研究

Study on Catalytic Degradation of Rhodamine B by Chitosan Coated Nano-iron

针对纳米零价铁(NZVI)催化过硫酸盐(PS)的高级氧化技术中,NZVI易团聚、易被氧化和难以重复利用等问题,采用中和法制备了壳聚糖包被纳米零价铁(CS@NZVI),作为过硫酸盐的催化剂,对其进行了表征,并以罗丹明B(RhB)为目标污染物,研究催化过硫酸盐降解RhB的优化条件和降解反应动力学。结果表明,优化降解条件为:RhB、PS初始质量浓度分别为8 mg/L、3g/L,CS@NZVI投加量为0.7 g/L,初始pH=2.5,温度为55℃,在此条件下,1 h降解率为91%,反应速率常数为0.040 9 min-1。催化降解行为均符合1级动力学模型。PS-CS@NZVI体系使反应活化能从20.4 kJ/mol下降到10.9 kJ/mol,证明了材料对过硫酸根的催化作用。该催化剂可重复使用4次,反应速率常数均在0.0360 min-1以上。

Aimed at nano-zero-valent iron （NZVI） advanced oxidation ofpersulfate （PS） technology, the NZVI was easy agglomeration, easy to be oxidized and difficult to reuse, the neutralization method was used to prepare chitosan coated nano zero-valent iron （CS@NZVI） as a persulfate catalyst. The catalysts were characterized, and Rhodamine B （RbB） was as the target pollutant, the optimization conditions and degradation reaction kinetics of RhB degradation by persulfate were studied. The results showed that the optimal degradation conditions were as follows： initial mass concentration of RhB and PS was 8 mg/L and 3 g/L respectively, CS@NZVI dosage was 0.7 g/L, initial pH was 2.5, temperature was 55 ℃, the degradation rate was 91% after 1 h under this conditions and the reaction rate constant was 0.040 9. The catalytic degradation behavior was consistent with the first-order kinetic model. The PS-CS@NZVI system reduced the activation energy of the reaction from 20.4 kJ/mol to 10.9 kJ/mol, demonstrating the material had catalysis on persulfate. The catalyst could be reused four times and the reaction rates was all above 0.036 0 min^-1.