中心组合设计优化去除多金属离子矿山污水及其资源化利用

Center combination design to optimize the removal of polymetallic ion mine sewage and resource utilization

为净化多金属离子污水,采用中心组合设计和响应面方法优化了NaOH-Na2CO3复配体系沉淀多金属离子矿山污水的去除效果,分析了离子沉积效果的原因;借助XRD、BET等分析手段表征了沉淀物焙烧后所得产物的微观结构及其光催化性能。结果表明,NaOH-Na2CO3复配溶液的优化摩尔比为1︰2.4,复配液的加入可使多金属离子污水产生协同沉淀效应,比单一的NaOH与Na2CO3溶液的沉淀效果好,所排放的清水COD值为35.6 mg/L,氨氮值为13.74 mg/L,达到国家污水综合排放Ⅰ级标准。500℃焙烧后的产物为能隙梯度型半导体金属氧化物(Fe2O3·CdO·Bi2O3·SnO2)与碱土金属碳酸盐(CaCO3·SrCO3)的复合物,其中金属氧化物有利于光催化效果的提高,而碳酸盐则起抑制作用。室温下、1 h内,样品对甲基蓝的光催化降解率依次为BNaOH(76.8%)>A(49.6%)>BNa2CO3(5.3%),沉淀物得到了有效利用。

In order to purify polymetallic ion wastewater,the removal efficiency of NaOH-Na2CO3 compound system system is optimized by using central combination design and response surface method,and the reason of ion deposition effect is analyzed.The microstructure and photocatalytic properties of calcined precipitates are characterized by XRD,SEM,BET and other analytical methods.The results show that the optimal molar ratio of NaOH and Na2CO3 compound solution is n NaOH︰n Na2CO3=1︰2.4,and the co-precipitation effect of NaOH and Na2CO3 solution is better than that of single solution of Na2CO3 or NaOH.The COD value of 35.6 mg/L and the ammonia and nitrogen of 13.74 mg/L in the discharge of wastewater are obtained,respectively,which meets the national grade Ⅰ standard for comprehensive sewage discharge.The calcined product of 500℃ is the compound of the semiconductor metal oxide (Fe2O3·CdO·Bi2O3·SnO2) with energy gap gradient and alkaline earth metal carbonate (CaCO3·SrCO3),in which metal oxide is beneficial to the improvement of photocatalytic effect,while carbonate plays an inhibitory role.At room temperature and within 1 h,the photocatalytic degradation rate of methyl blue is the order of BNaOH (76.8%)>A (49.6%)>BNa2CO3 (5.3%),the sediment has been effectively used.