Study on Electrochemical Conversion of Ammonium Sulfate to Ammonium Persulfate in Acetylpyrazine Wastewater

Authors

Yi-Jie Wang, State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
Dong-Fang Niu, State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
Xin-Sheng Zhang, State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;Follow

Corresponding Author

Xin-Sheng Zhang(xszhang@ecust.edu.cn)

Abstract

Acetylpyrazine is an important spice and also plays important roles in biology, medicine and other fields. However, the wastewater containing ammonium persulfate, ferric ion (Fe³⁺), pyrazine, and a large amount of ammonium sulfate was produced during the production of acetylpyrazine. In this study, ammonium sulfate in acetylpyrazine wastewater was electrolytically converted into ammonium persulfate for economic benefits. Using platinum as an anode and graphite as a cathode, the influence factors of the electrolysis process (including the composition of the anolyte, the current density, the temperature, etc.) were firstly investigated without interference from other compositions. Under the optimal condition, namely, the anolyte (50 g) composition consisted of 37wt.% ammonium sulfate, 15wt.% sulfuric acid, and 0.06wt.% ammonium thiocyanate, and the catholyte composition was 25wt.% sulfuric acid, the current density was 8000 A·m^-2, the anolyte temperature was 30 ^oC, and the passed electric charge was 2 A·h, the current efficiency for the production of ammonium persulfate could be as high as 89.65% when the mass fraction of ammonium persulfate reached to 15.83wt.%. Then, the effects of Fe³⁺ and pyrazine on electrolysis were investigated. The presence of Fe³⁺ in the anolyte would affect the purity of ammonium persulfate precipitation, while the presence of pyrazine would affect the current efficiency for the production of ammonium persulfate, for example, the current efficiency would reduce by 10% when the concentration of pyrazine in the anolyte was only 0.015 mol·L^-1. Therefore, it is necessary to remove Fe³⁺ and degrade pyrazine in the wastewater before electrolysis. And according to the composition of acetylpyrazine wastewater, the simulated wastewater was prepared to investigate the pretreatment effect. The concentration of Fe³⁺ was dramatically reduced to 2.7 mg·L^-1 when the pH value of the simulated wastewater was adjusted to about 7 through the addition of ammonia. Meanwhile, the sulfate radical oxidation method was adopted to degrade pyrazine in the simulated wastewater, showing 98.43% of the pyrazine degradation by activating the ammonium persulfate of 0.65 mol·L^-1 to generate the sulfate radicals at 80 ^oC. Finally, the current efficiency of 85.21% was achieved by using the pretreated acetylpyrazine actual wastewater as an anolyte, which proved the feasibility of electrochemical conversion of ammonium sulfate to ammonium persulfate in acetylpyrazine wastewater.

Graphical Abstract

Keywords

acetylpyrazine wastewater, ammonium sulfate, electrolysis, ammonium persulfate, resource recycling

DOI Link

https://doi.org/10.13208/j.electrochem.210610

Publication Date

2022-04-28

Online Available Date

2021-08-05

Revised Date

2021-07-16

Received Date

2021-06-15

Recommended Citation

Yi-Jie Wang, Dong-Fang Niu, Xin-Sheng Zhang. Study on Electrochemical Conversion of Ammonium Sulfate to Ammonium Persulfate in Acetylpyrazine Wastewater[J]. Journal of Electrochemistry, 2022 , 28(4): 2106101.
DOI: 10.13208/j.electrochem.210610
Available at: https://jelectrochem.xmu.edu.cn/journal/vol28/iss4/4