基于响应曲面法优化的臭氧/过硫酸盐/四氧化三铁工艺对结晶紫的降解

为有效去除水中结晶紫，利用臭氧/过硫酸盐/四氧化三铁工艺对结晶紫的氧化效果进行研究，设计单因素实验探索臭氧流量、过硫酸盐浓度、四氧化三铁浓度和pH对结晶紫降解的影响，依据响应曲面法的Box-Behnken Design(BBD)实验设计原理，探究臭氧流量、过硫酸盐浓度、四氧化三铁浓度和反应时间对降解效果的影响，并优化工艺参数；使用SEM-EDS、FT-IR和Raman表征了反应前后的四氧化三铁，并用EPR技术直接鉴定出工艺过程中的活性氧。结果表明：此工艺在较宽的pH区间(3~11)都具有较高的结晶紫降解能力，臭氧流量、过硫酸盐浓度和四氧化三铁浓度与结晶紫的降解率成正比；臭氧流量1.000 L·min⁻¹，过硫酸盐浓度0.968 mmol·L⁻¹，四氧化三铁浓度2.158 mmol·L⁻¹，反应时间41.702 min为预测的最佳工艺条件；在最佳工艺条件下得到的实际降解率与预测降解率相对偏差仅为−1.12%；催化反应后Fe₃O₄粒径减小，表面变得更加光滑；反应后的Fe₃O₄的铁元素质量分数由48.24％降至35.31%，而氧和硫元素质量分数由34.05%和0.39%分别增至37.59%和1.09%；臭氧/过硫酸盐/四氧化三铁工艺过程中存在SO₄^·–和·OH。由此可知，BBD优化模型预测与实际处理效果基本一致。该研究成果为可为难降解的结晶紫废水的深度处理提供参考。

Optimization of crystal violet degradation in ozone/persulfate/ferroferric oxide system by response surface methodology

In order to effectively remove crystalline violet from water, the ozone/persulfate/ferroferric oxide process was used to investigate the effects of ozone flow rate, persulfate concentration, ferroferric oxide concentration and pH on the degradation of crystalline violet, then the Box-Behnken Design (BBD) experimental design principle of response surface method was used to determine the effects of ozone flow rate, persulfate concentration, ferroferric oxide concentration and reaction time on the degradation of crystalline violet and optimize the process parameters. The tetroxide before and after the reaction was characterized by SEM-EDS, FT-IR and Raman, and the reactive oxygen species in the process was identified directly by EPR technique. The results showed that this process had a good ability on crystalline violet degradation over a wide pH range (3~11), and the ozone flow rate, persulfate concentration and tetroxide concentration were proportional to the degradation rate of crystalline violet. The model predicted that the optimum process conditions were following: ozone flow rate of 1.000 L·min−1, persulfate concentration of 0.968 mmol·L−1, ferroferric oxide concentration of 2.158 mmol·L−1, and reaction time of 41.702 min. The relative deviation of the actual degradation rate from the predicted degradation rate under the optimum conditions was only −1.12%. After the catalytic reaction, the particle size of Fe3O4 decreased and its surface became smoother, the mass fraction of Fe3O4 decreased from 48.24% to 35.31%, while the mass fractions of oxygen and sulfur increased from 34.05% and 0.39% to 37.59% and 1.09%, respectively. SO4·– and ·OH occurred in the ozone/persulfate/ferroferric oxide process. It can be seen that the prediction of BBD optimization model is basically consistent with the actual treatment effect; this study can provide a reference for the deep treatment of refractory crystalline violet wastewater.