萃取法脱除火电厂脱硫废水中氯离子实验研究

Experimental study on the removal of chloride ions from desulphurisation wastewater of thermal power plant by extraction method

中国火力发电发展迅速,同时也产生了大量的含氯脱硫废水,高浓度氯离子不仅对脱硫设备有腐蚀性还会降低脱硫系统的脱硫效率。本文基于某燃煤电厂实际废水中氯离子浓度,以模拟脱硫废水为研究对象,采用溶剂萃取法脱除含氯脱硫废水中的氯离子,考察了改质剂种类、萃取液配比、萃取液与废水体积比、萃取反应时间、硫酸溶液体积等单因素对氯离子萃取脱除效率的影响规律,分析了各单因素均为最佳条件下的氯离子萃取脱除效率。研究结果表明:正癸醇为最佳改质剂,具有最佳的一级萃取效率(46.67%)和二级萃取效率(88.57%);三辛癸烷基叔胺(N235):磷酸三丁酯(TBP):正癸醇的最佳配比为6∶3∶1,是最佳萃取剂;萃取液与废水的最佳体积比(O/A)为1∶4;一级最佳萃取时间为0.5 min,二级最佳萃取时间为1 min;萃取液与硫酸溶液的最佳体积比为4:3。在上述最佳萃取条件下,经过二级错流萃取后,模拟脱硫废水中氯离子萃取效率可达到89.04%。

China's thermal power generation has developed rapidly,and a large amount of chlorine-containing desulfurization wastewater has also been produced.High concentration of chloride ions is not only corrosive to desulfurization equipment,but also reduces the desulfurization efficiency of desulfurization system.Based on the chloride ion concentration in the actual wastewater of a coal-fired power plant,this work took the simulated desulfurization wastewater as the research object,and used the solvent extraction method to remove the chloride ion in the chlorine-containing desulfurization wastewater.The effects of single factors such as the type of modifier,the ratio of extraction liquid,the volume ratio of extraction liquid to wastewater,the extraction reaction time,and the volume of sulfuric acid solution on the removal efficiency of chloride ion extraction were investigated.The removal efficiency of chloride ion extraction under the optimal conditions of each single factor was analyzed.The results showed that n-decyl alcohol was the best modifier,which had the best primary extraction efficiency(46.67%)and secondary extraction efficiency(88.57%).The optimum ratio of tertiary amine(N235):tributyl phosphate(TBP):n-decanol was 6∶3∶1,which was the best extractant.The optimum volume ratio(O/A)of the extract to the wastewater was 1∶4.The optimum extraction time of the first stage was 0.5 min,and the optimum extraction time of the second stage was 1 min.The optimum volume ratio of the extraction solution to the sulfuric acid solution was 4:3.Under the above optimal extraction conditions,the extraction efficiency of chloride ions in simulated desulfurization wastewater could reach 89.04%after two-stage cross-flow extraction.