Abstract
The research is supported by a Project Funded by the brand professional project form Yancheng teachers college (2016) and the teaching reform and practice of medicinal chemistry (2018YCTUJGY006) and the Flagship Major Development of Jiangsu Higher Education Institutions”(PPZY2015B113) 。 Abstract Potassium dichromate method was used to determine the high concentration of Hg 2+ , Ag + , Cr(VI), Cr 3+ and H 2 SO 4 in COD waste liquid. The waste liquid of COD was determined by potassium dichromate method, and the aluminum was used to replace Ag+ in the waste liquid to generate Ag and precipitate out, Cr(VI) was reduced to Cr 3+ , and then alkali neutralization, filtration and other measures were added to carry out treatment and recovery of useful substances, which not only reduced environmental pollution, but also recovered resources, with both economic and environmental benefits. Keywords Potassium dichromate method; Waste liquid; Reduction; Neutralization DOI : 10.7176/CER/11-10-08 Publication date: November 30 th 2019
Highlights
There are many methods to determine COD, including classical reflux method, spectrophotometry and coulomb method [1]
According to the relevant standards for CODcr determination in China's water samples (GB-3838-2002), a certain amount of water samples to be measured were taken, and H2SO4-Ag2SO4 solution was added as a catalyst
(2) After a bucket of waste liquid is restored, stir it fully, make the silver powder sink completely, suck out most of the liquid with siphon, filter the remaining waste liquid, and wash it with 0.1% sulfuric acid for 3-5 times
Summary
There are many methods to determine COD, including classical reflux method, spectrophotometry and coulomb method [1]. By the standard method in our country as a standard method for the determination of COD in wastewater [2-3], standard method can be widely used for a long time, is because it has the following several advantages: 1. Due to the use of precious silver halide catalytic oxidation of volatile organic compounds, and use of toxic mercury sulfate complexing Cl -, CODCr waste any emissions, will lead to Ag, H g and contains a lot of low pH value of waste liquid cause secondary pollution to environment, at the same time brings great damage on the economy. Some laboratories even did not make treatment, will be discharged into the sewer, some with alkali neutralization and back into the sewer, or collection buried underground In this way, it causes serious environmental pollution, and wastes valuable resources such as silver, so the disposal of waste liquid is a major problem worthy of attention [4-7]. The COD waste liquid is measured, through reduction, neutralization and other measures, the treatment and the recovery of useful substances, reduce the pollution of the environment, and the recovery of resources, with economic and environmental benefits
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