Electrocatalytic dechlorination method for parachloronitrobenzene

Abstract

The invention discloses an electrocatalytic dechlorination method for parachloronitrobenzene. The method comprises the following steps: loading precious metal palladium on a foam nickel material with a three-dimensional structure by an impregnation method to obtain a cathode of an electrocatalytic reactor; and introducing parachloronitrobenzene-containing wastewater into the electrocatalytic reactor to fill the whole reactor, wherein electrochemical treatment is started under constant current, the parachloronitrobenzene experiences a reduction reaction in a cathode chamber and is reduced into parachloroaniline under the effect of hydrogen radical, and then a dechlorination effect can be realized to form aniline due to the excellent performance of the palladium-containing foam nickel electrode. In the invention, metal reduction is replaced by electrocatalytic reduction, the problems of easy passivation and low mass transfer efficiency of metals are solved, the difficulty in dechlorination of parachloronitrobenzene in the traditional electrode is overcome, and the chlorine group of chloronitrobenzene is effectively removed.

Description

Technical field [0001] The invention relates to a method for removing highly toxic organic matter, in particular to an electrochemical method for removing p-chloronitrobenzene in water. Background technique [0002] P-Chloronitrobenzene exists in industrial wastewater (generally with a concentration of 0.05-200mg / L), and it is difficult to degrade in nature. It has been detected in some major water bodies in my country. P-chloronitrobenzene can cause methemoglobinemia in humans and animals, and has weak carcinogenic and mutagenic effects. As a high-risk, difficult-to-degrade, persistent environmental organic pollutant, my country has strict standards for its discharge. In my country's GB8978-1996 "Integrated Wastewater Discharge Standard", the first-level emission standard of p-chloronitrobenzene is 0.5mg / L, the secondary standard is 1.0mg / L, and the tertiary standard is 5.0mg / L. Therefore, due to the toxicity and stability of chloronitrobenzene, its residue and accumulation in...

AI Technical Summary

Problems solved by technology

Due to the existence of chlorine and nitro group, the electrophilic attack of aerobic biological oxidase on benzene ring is blocked, so the treatment efficiency of p-chloronitrobenzene is very low; the process of anaerobic microbial reduction dechlorination is slow, and the dechlorination effect is low. Difference

Improper treatment of pollutants after adsorption enrichment and separation will lead to secondary pollution

Advanced oxidation technologies such as Fenton oxidation, photocatalytic oxidation, and ultrasonic cavitation have developed rapidly, but there are still defects such as low processing efficiency and high cost, and there is still a big gap from popularization and use.

The treatment of p-chloronitrobenzene by the metal reduction method is affected by many factors such as pH, metal particle size and specific surface area, mixing speed, etc., and there are defects such as easy passivation of the metal, low mass transfer efficiency, and formation of highly toxic end products.

[0004] Due to the existence of the para-nitro group, the chlorine on the benzene ring requires a large activation energy, and the structure is stable and difficult to remove

The existing reduction technology for the reduction product of p-chloronitrobenzene is mostly p-chloroaniline, which still has high toxicity and stability, which is not conducive to the subsequent biochemical or oxidation treatment

It was reported before that in the study of electrochemical reduction of o-chloronitrobenzene, the use of a titanium plate as the cathode cannot produce dechlorination, the reduction product is o-chloroaniline and the reaction takes a long time and the reaction efficiency is low, while p-chloronitrobenzene The structure is more stable, and electrochemical dechlorination is more difficult

However, in some studies on the reduction of p-chloronitrobenzene by electrobiological methods, the reduced product is mainly p-chloroaniline, and the dechlorination effect cannot be achieved.

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