Al/H_2O_2体系氧化降解甲基橙

Oxidative degradation of methyl orange by Al/H_2O_2 system

考察了Al/H_2O_2体系对甲基橙(MO)的氧化降解行为,探讨了Al粉、H_2O_2投加量、溶液初始pH以及共存阴离子等因素对MO降解的影响,并利用荧光光谱法通过证实·OH自由基的形成对降解机理进行了初步探讨.结果表明,Al/H_2O_2体系对MO的降解受溶液pH影响较大,在初始pH 3.0,铝粉投加量为4.8 g·L^(-1),H_2O_2投加量为7.2 mmol·L^(-1),对于含MO 20 mg·L^(-1)的染料废水,10 h MO降解率可达95.2%,而当初始pH>3.5时,MO的降解被强烈抑制.无机阴离子(Cl^-、SO_4^(2-)、NO_3^-)单独存在时,对Al/H_2O_2体系降解MO影响较小,MO降解率仍可达90.0%以上.无机阴离子(Cl^-、SO_4^(2-)、NO_3^-)共同存在时,对Al/H_2O_2体系降解MO具有叠加效应,MO降解率仅达60.0%左右.Al/H_2O_2体系重复利用性能良好,对MO降解经7个周期后,降解率仍可达92.0%.降解机理研究表明,Al/H_2O_2体系氧化降解MO过程中,·OH发挥了主要作用.

This paper focuses on the Al/H2O2 system in the degradation of organic wastewater containing methyl orange（MO）. Factors influencing the degradation were investigated in detail such as the dosages of Al powder and H2O2,pH,and coexisting anions,etc. Also,degradation mechanism was explored by detecting the presence of hydroxyl free radicals using fluorescence spectroscopy. The main results showed that degradation of MO using Al/H2O2 system is critically dependent on solution pH. For the effluent containing 20 mg·L-1MO,degradation rate reached95.2% within 10 h at an initial pH 3.0,dosages of aluminium powder and H2O2 were 4.8 g·L-1and7.2 mmol·L-1respectively. However,when the initial pH was higher than 3. 5,the degradation of MO was strongly inhibited. Degradation of MO decreased to a certain extent in the presence of coexisting inorganic anions（Cl-,SO42-,NO3-）,but more than 90.0% of MO was still removed by Al/H2O2 system if a single inorganic anion was present. However,the degradation was retarded and only around 60. 0% of MO was degraded due to the superposition effect exerted by coexisting inorganic anions. The reusability of Al/H2O2 system was evaluated by successive cycles. After 7cycles,92.0% of MO could still be degraded by oxidation,suggesting that Al/H2O2 system exhibits good durability. Degradation mechanism revealed that hydroxyl free radical（·OH） played a major role in MO degradation in Al/H2O2 system.