基于四氰合镍(Ⅱ)配合物的紫外吸收快速测定废水中氰化物

Rapid Determination of Cyanide in Wastewater Based on the UV Ultraviolet Absorption of Tetracyanonickelate(II)Complex

基于四氰合镍(Ⅱ)配合物在267.6 nm、285.4 nm、309.0 nm有特征吸收的特性,建立了紫外光度法快速测定废水中氰化物的新方法。当底液中氢氧化钠、硫酸镍、氨浓度分别为0.04 g/L、1.0 mmol/L、0.8 mol/L时,氰化物(CN-)与二价镍快速反应生成四氰合镍(Ⅱ)配合物,A_(267.6)、A_(285.4)、A_(309.0)分别与0.16 mg/L~6 mg/L、0.46 mg/L~15 mg/L、2.7 mg/L~80 mg/L的氰化物呈现良好的线性关系(R>0.999),且三个线性范围相互重叠,因此可采用紫外光度法快速测定0.16 mg/L~80 mg/L的氰化物,检出限为0.05 mg/L。该方法能与标准方法(HJ 484-2009)中的预蒸馏程序直接对接,用于焦化废水、黄金冶炼废水中氰化物的测定,回收率在95.2%~103.3%之间,相对标准偏差小于2.6%。

A new method for rapid determination of cyanide in wastewater is established by UV spectrophotometry based on the characteristic absorption of tetracyanonickelate(II)complex at 267.6 nm,285.4 nm and 309.0 nm.When the concentrations of sodium hydroxide,nickel sulphate,and ammonia in the base solution are 0.04 g/L,1.0 mmol/L,and 0.8 mol/L,respectively,cyanide reacts quickly with nickel(II)to produce tetracyanonickelate(II)complex.A_(267.6),A_(285).4,A_(309.0)are in good linear relations(R>0.999)with the cyanide concentration within the ranges of 0.16 mg/L~6 mg/L,0.46 mg/L~15 mg/L and 2.70 mg/L~80 mg/L,respectively.Since the three linear ranges are overlapping,UV spectrophotometry can be used to rapidly determine the concentration of cyanide in the range 0.16 mg/L~80 mg/L and the detection limit is 0.05 mg/L.The method can be directly connected with the predistillation procedure provided by standard method(HJ 484-2009)and is applied to the measurement of cyanide in coking wastewater and gold smelting wastewater.The results indicate that the recovery is in the range 95.2%~103.3%and the relative standard deviation is less than 2.6%.