高浓度含酚废水中酚类的转化回收及脱除

Recovery and Removal of Phenols from High Concentration Phenolic Wastewater

以含量30 g/L的苯酚水溶液为模型,提出氯化联合氧化工艺,实现对高浓度含酚废水中苯酚的转化回收及残余酚类的氧化脱除。首先以pH值作为指示,向溶液中引入足够量的氯离子和氢离子,通过加入氯酸钠与之反应定量产生氯气;在所控制的实验条件下,氯气与溶液中的苯酚选择性反应转化为低溶解度的三氯苯酚沉淀,经气相色谱-质谱(GC-MS)面积归一法测得其含量可达97.76%;过滤所得滤液化学需氧量(COD)降低至1125 mg/L,苯酚回收率约98.7%。采用Fenton氧化技术对该滤液进行氧化降解,结果表明,在优化的实验条件pH=3、Fe2+浓度为1 mmol/L下,H2O2用量为15 mL/L时,残余的氯酚类即可以被有效降解,降解后的水样经调碱性将铁或亚铁离子沉淀后为无色透明的溶液;联合处理后,水样COD减小到52 mg/L,该值满足国家工业污水排放标准。

A chlorination combined oxidation process was proposed to recover and remove phenolic compounds from simulated wastewater containing 30 g/L phenol. First, enough chloride and hydrogen ions were introduced into the phenolic solution by adding hydrochloric acid under indication with a pH meter; sodium chlorate was then added to react with above ions to produce chlorine qualitatively. Under controlled experimental conditions, the chlorine combined with phenol and selectivity converted to the insoluble trichlorophenol, which was confirmed by GC-MS and its content was measured to be 97. 76% through area normalization method. The chemical oxygen demand（COD） of filtrate obtained after the above process declined to 1125 mg/L, and the recovery of phenols was up to 98.7% by calculations. Later, Fenton oxidation technology was used to further remove the phenolic compounds in filtrate. The results show that under optimized conditions （pH = 3, c（Fe2~） = 1 mmolfL）, the residual chlorophenols can be degraded effectively with H202 consumption of 15 mL/L, and the degraded solution is colorless and transparent when adjusting its pH to 10 to precipitate the ferrous and ferric irons. After combined treatments, the COD reduces to 52 mg/L, which the value can meet the national sewage effluent discharge standards.