锌镁铝类水滑石催化臭氧氧化降解吡啶废水的工艺研究

通过尿素水热共沉淀法制备了一种锌镁铝类水滑石（LDHs），将其煅烧制得焙烧态锌镁铝类水滑石（LDOs），使用鼓泡搅拌反应器，以吡啶降解率和出水化学需氧量（COD）为评价指标研究了LDOs在臭氧氧化降解吡啶中的催化潜力，并分析了其催化臭氧氧化动力学。结果表明，与单独臭氧氧化相比，LDOs催化臭氧氧化可显著提升对吡啶的降解效果。对于初始质量浓度为300 mg/L的吡啶废水，在反应时间为40 min、催化剂用量为0.6 g/L和初始pH为10的条件下，吡啶降解率和出水COD可分别达到96.9%和71.7 mg/L，并且初始吡啶的质量浓度越低，降解速率越快。此外，LDOs还表现出优异的催化稳定性。单独臭氧和催化臭氧氧化降解吡啶的过程都近似符合伪二级反应动力学模型，同时结果表明·OH是LDOs催化臭氧氧化降解吡啶的主要自由基。吡啶的主要降解产物可能为N-甲基乙酰胺或N，N-二甲基甲酰胺有机物以及硝酸根离子、二氧化碳和水等小分子无机化合物。

The degradation of pyridine wastewater by ozonation catalyzed by calcined zinc-magnesium-aluminum hydrotalcites

Zinc-magnesium-aluminum hydrotalcites (LDHs) have been prepared by a urea hydrothermal coprecipitation method, and heated to obtain calcined zinc-magnesium-aluminum hydrotalcites (LDOs). The catalytic efficacy of LDOs in the degradation of pyridine by ozonation was studied in a bubble stirred reactor. Pyridine degradation efficiency and effluent chemical oxygen demand (COD) were used as evaluation indexes, and the kinetics of catalytic ozonation was analyzed. The results showed that the degradation of pyridine was significantly improved in catalytic ozonation with LDOs, compared with that of ozonation alone. For pyridine wastewater with an initial mass concentration of 300 mg/L, with a reaction time of 40 min, catalyst dosage of 0.6 g/L and initial pH=10, the pyridine degradation efficiency and effluent COD reached 96.9% and 71.7 mg/L, respectively. Lower initial mass concentrations of pyridine resulted in faster degradation rate. In addition, LDOs showed excellent catalytic stability. It was found that the degradation of pyridine by ozonation alone and catalytic ozonation both followed the pseudo second order kinetic model, and ·OH was the main free radical responsible for pyridine degradation. The main degradation products of pyridine are organic compounds such as N-methylacetamide or N,N-dimethylformamide, as well as small inorganic species such as nitrate ion, CO₂ and H₂O.