草酸促进双酚A在黏土矿物悬浮液中光降解研究

Oxalate enhanced bisphenol A photodegradation in clay mineral suspensions

选择两种常见的天然黏土矿物高岭石和蒙脱石,研究了有机污染物双酚A(BPA)在其表面的吸附及草酸对黏土矿物悬浮液中BPA光降解的影响.结果表明,BPA在两种黏土矿物表面的吸附量较小,吸附符合Langmuir等温式.在250W金属卤化物灯(λ≥360nm)照射下,草酸可显著促进BPA在高岭石和蒙脱石悬浮液中的光降解,降解动力学符合Langmuir-Hinshelwood方程.降解速率受pH值的影响较大,pH=4.0时速度最快,光降解速率同时受草酸浓度的影响.最后,通过分析矿物中铁的化学环境及反应过程中铁浓度变化,分析了草酸促进BPA在黏土矿物悬浮液中光降解的可能机制.

The effects of oxalate on the adsorption and photodegradation of bisphenol A （BPA） were investigated using the natural clay minerals kaolinite and montmorillonite in a clay mineral/oxalate system. Little BPA was adsorbed onto the clay minerals, and the adsorption isotherms of BPA followed the Langmuir adsorption model. BPA photodegradation under a 250 W metal halide lamp （λ ≥ 365 nm） irradiation can be greatly enhanced by the presence of oxalate in the clay mineral suspension. The photndegradation rate of BPA fit the Langmulr-Hinshelwood equation well, and the ratio of photodegradation was dependent on the pH of the solution. BPA was most effectively degraded at pH 4. O. The results also indicated that the photodegradation rates were affected by the oxalate concentrations. The proposed mechanism of BPA photodegradation in our experiments is dependent on the presence of iron and its interaction with oxalate.