论文部分内容阅读
铝能与EDTA形成中等强度的络合物,(pK=16.01)将试样强碱熔融,浸取后过滤使铁,钛等元素分离,在微酸性环境中,用过量的EDTA络合铝、铁、铜、锌、镍等金属离子后,于醋酸—醋酸钠缓冲溶液中(PH为5.5～6.0),用氯化锌溶液回滴过量的EDTA,再加入氟化钠置换铝-EDTA络合物中的EDTA,用氯化锌标准溶液滴定置换出的EDTA,以PAN为指示剂,以黄色转变为红色,即为终点。其反应式为下:H2Y2-+Al3+<=>AlY-+2H+;Al2Y-+6NaF<=>AlF3·3NaF+Y4-+3Na+;Zn2++H2Y2-<=>ZnY2-+2H+本法适用范围:Al2O3%含量在0.25%～5.0%,本法也适用于球团、铁精粉试样的分析。
Aluminum can form a medium-strength complex with EDTA (pK = 16.01). The strong alkali of the sample is melted. After leaching, the iron, titanium and other elements are separated by filtration. In a slightly acidic environment, Iron, copper, zinc, nickel and other metal ions, in acetic acid - sodium acetate buffer solution (pH 5.5 ~ 6.0), with zinc chloride solution back excess EDTA, sodium fluoride was replaced by replacement of-EDTA complex The EDTA in the solution is titrated with zinc chloride standard solution to replace the EDTA, with PAN as an indicator and yellow to red, which is the end point. The reaction equation is as follows: H2Y2- + Al3 + <=> AlY- + 2H +; Al2Y- + 6NaF <=> AlF3.3NaF + Y4- + 3Na +; Zn2 ++ H2Y2 - <=> ZnY2- + 2H + : Al2O3% content of 0.25% to 5.0%, the law is also applicable to the pellet, iron powder sample analysis.