文档介绍：液膜萃取法处理含氰废水的设计
摘要
氰化物为剧毒产品,在生产和使用过程中会产生含氰废水,该废水不经处理直接排放会对环境造成严重污染。本文对氰化物进行了风险评价计算,并采用液膜萃取法处理含氰废水。包括含氰废水生态风险评价和人体健康风险评价。考察了微乳液的配方及其稳定性,乳水比,乳水接触时间,NaOH浓度,Span-80用量,三正辛胺(TOA)用量,液体石蜡用量,油内比等因素的改变对萃取率的影响,以及乳液循环使用情况。
通过风险评价,废水中氰化物含量为166μg/L时,对整体生态风险不存在生态风险; mg/kg•d,可保证氰化物对人体无不可接受风险;在保证对人体无不可接受风险时,皮肤渗入途径的浓度限值为10-5~10-6 mg/L,~ mg/m3。
研究发现采用废水pH值为4、Span-80用量为3%、TOA用量为2%、液体石蜡用量为1%、NaOH浓度为2%、制乳转速为2300r/min、乳水比为1:7、乳水接触时间为15min,转速250r/min,油内比为1:1时,萃取率能达到95%以上。液膜性能稳定,萃取周期短,萃取效率高,乳液可循环使用,经济效益高,可进行工业推广。
关键词:含氰废水;液膜萃取;风险评价;三正辛胺(TOA)
Abstract
Due to the toxicity of cyanide, it produces waste water containing of cyanogen in the process of industy. Discharging the waste water directly without treatment could cause serious environmental pollution. This experiment makes risk assessment of cyanide waste, and uses liquid membrane extraction method to handle cyanide waste water. In article risk assessment includes ecological risk assessment and human health risk assessment. The effect of the formula and the stability of the microemulsion, volume ratio and contact time of milk phase and water phase, NaOH concentration, use level of Span-80, TOA, atolin and ratio volume of oil phase to internal phase for the extraction rate were investigated. Emulsion recycled condition was also discussed.
Through the risk assessment,there is no risk for ecological when the content of cyanide is below 166μg/ the amount of expoesd cyanide is below mg/kg•d,there is no risk for human beings. Concentration limits 10-5~10-6 mg/L for ration for skin and ~ mg/m3 for breath in.
The extraction rate can reach above 95% when waste water pH value was 4, Span-80 was 3%, TOA was 2%,NaOH was 2%, emulsifying stirring speed was 2300 r/min, volume ratio of milk phase and water phaseis was 1:7, contact time of milk phase and water phase was 15 min,the speed was 250 r/min, ratio volume of oil phase to internal phase was 1:1. The industrilization can be promoted fo