萃取法去除燃煤电厂脱硫废水中的氯离子

Extraction method to remove chloride ion in desulfurization wastewater of coal-fired power plant

针对燃煤电厂脱硫废水中Cl^(-)浓度高、达不到回用要求的特点,采用液-液萃取法进行去除脱硫废水中Cl^(-)的研究。系统地考察了萃取剂种类、萃取液组分配比、萃取液与水相体积比(O/A)、废水初始pH、萃取温度、反萃取剂种类等因数对Cl^(-)去除效率的影响。结果表明,当萃取液中N235,改制剂、稀释剂的体积比为7∶2∶1,O/A比为1∶4,萃取时间2 min,pH=4,25℃(常温)的适宜条件下,经过3次错流萃取的重复性实验,可以使得脱硫废水中的Cl^(-)浓度从12396 mg/L降到1000 mg/L以下,去除率可达94%;反萃取体积比O/A为12∶1,经过氨水2次错流反萃取的重复性实验,可以使得反萃取效率达到65%以上。

Aiming at the high concentration of Cl^(-) in the desulfurization wastewater of coal-fired power plants,which does not meet the requirements of reuse,using liquid-liquid extraction to study the removal of Cl^(-) in the desulfurization wastewater.The effects of factors such as the type of extractant,the composition ratio of the extract,the volume ratio of the extract to the water phase(O/A),the initial pH of the wastewater,the extraction temperature,and the type of stripping agent have been systematically investigated on the Cl^(-)removal efficiency.Under suitable conditions,the results show that when the volume ratio of N235,modified preparation,and diluent in the extract is 7∶2∶1,O/A ratio is 1∶4,extraction time is 2 min,pH=4,and 25℃(normal temperature),after three repeated experiments of cross-flow extraction,the Cl^(-) concentration in the desulfurization wastewater can be reduced from 12396 mg/L to 1000 mg/L,and the removal rate can reach 94%;The back extraction volume ratio O/A is 12∶1,after the repeated experiment of the secondary cross-flow back extraction of ammonia water,the back extraction efficiency can reach more than 65%.