Abstract:

A microwave digestion method applied to the determination, without using Ag(Ⅰ) and Hg(Ⅱ) , of the COD in alcohol molasses waste liquid has been investigated. The mixture catalyst of CuSO₄ and MnSO₄, whose mass ratio is 2∶1, instead of using Ag₂SO₄, and Bi(NO₃)₃ is used as the masking agent for Cl^- instead of HgSO₄. The mixed acid of H₂SO₄ and H₃PO₄, whose volume ratio is 5∶1, is used to control the acidity in the digestion solution. The optimum conditions for the digestion and the determination are fixed by orthogonal experiment. When the volume of the sample is 3 mL, the volume of 0.2500mol/L 1/6K₂Cr₂O₇ is 3 mL, the total mass of the catalyst is 0.03 g, the volume of the mixed acid is 5 mL, and the microwave digestion time is 4 min. According to the test, 0.01 g Bi (NO₃)₃ can mask 300 mg/L Cl^- . The determination results for the standard sample (KC₈H₅O₄, COD 250 mg/L) coexisting with 300 mg/L Cl^- ranged from 245 mg/L to 255 mg/L. The RSD of this method is 0.79%. The determination results for the alcohol molasses waste liquid by this method are identical with the standard method.

Key words: chemical oxygen demand, microwave digestion, alcohol molasses waste liquid

摘要：

研究了一种微波消解无银无汞快速测定废水COD的方法。该方法用m(CuSO₄)∶m(MnSO₄)=2∶1的混合物作为催化剂代替了经典方法中的Ag₂SO₄，以Bi(NO₃)₃代替HgSO₄作为Cl^-掩蔽剂，用V(H₂SO₄)∶V(H₃PO₄)=5∶1的混酸作为介质。通过正交试验，确定了消解试样和测定的最佳条件。当试样体积为3mL时，0．2500mol／L1／6K₂Cr₂O₇的用量为3mL，催化剂总用量为0．03g，混酸总体积为5mL，微波消解时间为4min。在对含氯离子300mg／L以下的COD理论值为250mg／L的邻苯二甲酸氢钾溶液进行测定时，测定值在(250±5)mg／L范围内，RSD=0．79％。本法对糖蜜酒精废液测定的结果与标准方法一致。

关键词: 化学耗氧量, 微波消解, 糖蜜酒精废液

CLC Number: 

• X832