采用萃取剂[Omim][BF_4]分离提取铬渣中的Cr_2O_7^(2-)

Separation and extraction of Cr_2O_7^(2-) from chromic slags using [Omin][BF_4] as extractant

铬渣是重要的工业固体废物,具有极其严重的环境危害性,分离提取铬的资源化利用是减少铬渣环境污染和资源浪费的有效途径。以1-辛基-3-甲基咪唑四氟硼酸盐离子液体([Omim][BF_4])为萃取剂,戊醇为稀释剂,对铬渣酸浸液进行萃取和反萃取实验。在萃取实验过程中,分别考察萃取剂浓度、时间、pH等条件的影响作用。采用斜率法及红外光谱分析进行了萃取机理研究,最后进行了反萃取实验研究。结果表明:在萃取剂浓度ρ([Omim][BF_4])=50.0 g/L、6.0 min、pH为1.408~2.006条件下,Cr_2O_7^(2-)的萃取率达到94.81%;[Omim][BF_4]对Cr_2O_7^(2-)的萃取主要是根据软硬酸碱理论通过离子缔合形成萃合物达到较高的萃取率;在pH=10、反萃取剂为0.5mol/L NaBr+0.5 mol/L(NH_4)_2SO_3、15.0 min的条件下,铬的反萃率达到99.35%。实现了铬渣中铬资源的分离提取。

Chromic slags are vital industrial solid wastes which possess extremely serious environmental perniciousness.Separating and extracting chromium is effective means to reduce its environmental pollution and resources waste.The extraction behavior of chromium from chromium slag acidic leaching solution with[Omim][BF4]dissolved in pentanol was studied as concentration of extractant,time,acidity,and so on.The results show that extraction rate of chromate can reach up to 94.81%under the conditions of[Omim][BF4]concentration of 50.0 g/L,shaking time of 6.0 min,pH of 1.408-2.006.The extraction mechanism results show that the extraction proceeds via ionic association based on HSAB to product adduct.The back-extraction rate of chromate can reach up to 99.35%under the conditions of pH=10,stripping agent 0.5 mol/L NaBr＋0.5 mol/L（NH4）2SO3,shaking time 15.0 min.The purification of chromium from chromium slags is achieved.