【摘要】 研究了超临界络合萃取法去除乳酸钙中铝、砷汞等痕量金属,考察了络合剂种类、萃取压力、萃取时间对去除率的影响。结果表明,不同络合剂对不同金属的萃取效果有明显差异;在非溶解度制约阶段,单纯增加萃取压力对萃取率的提高没有明显影响;萃取时间比萃取压力的影响更为明显,表明该过程是络合萃取反应控制过程。较佳的工艺条件为:萃取温度20℃,CO2流速15.5L/h,萃取压力20MPa,萃取时间30min,溴化四丁基铵与二乙基二硫代氨基甲酸钠的复配物用量为试样质量的2%,加入乙醇作为极性溶剂。在此条件下,铅、汞、砷的总去除率达82.8%。更多还原

【Abstract】 Trace metals (Pd, As. Hg) were removed from calcium lactate by supercritical CO2 chelating extraction. The effects of chelating agent, extraction pressure and extraction time on the removal were studied. The results indicated that different chelating agents give remarkable different efficiencies in extraction; the increasing of extraction pressure is of no use to the removal while the process is outside of the solubility restriction stage; and the extraction time has more obvious influence on the process than the pressure, so that the chelating reaction is the rate-control step. The optimal extraction conditions were as follows: temperature 20℃, qv(CO2) =1. 5 L/h, pressure 20 MPa, time 30 min. the mass ratio of the mixture of tetrabutyl bromide and DDC to sample is 2% , and some ethanol is added. The total removal ratio of (As + Pd+Hg) is 82. 8%.更多还原