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The Role of Sodium Sulfate Supporting Electrolyte in Ammonium Transport and Reduction at Interface Between Platinum Cathode and Solution

preprint
submitted on 20.10.2019 and posted on 23.10.2019 by Linji Xu, Yunsong Pang, Dezhao Huang, Huichuan Zhuang, Wenzong Liu, Tengfei Luo, Po-Heng Lee, Li Feng, Junchi Lu
Ammonium is a potential hydrogen fuel and can be recovered from high ammonium wastewater via electrodeionization (EDI) process. Since NH4+ is a weak acid ion, sodium sulfate (Na2SO4) is used as a supporting electrolyte to improve electrolyte’s conductivity. This manuscript investigated the NH4+ behaviors in high Na2SO4 solution through electrochemical analysis methods and molecular dynamics (MD) simulations. Ionic strength increased, leading to a decreased ionic activity, and thus negatively influenced NH4+ transportation with the increasing concentration of Na2SO4 solution. Na+ competitively occupied the place of electric double layer (EDL) and impeded NH4+ to get closer to the electrode surface. Besides, water molecules played a critical role in determining the net charge density and the potential drop. The experimental tests and theoretical simulation demonstrated that NH4+ reduction (NH4(aq)+ + e- → 0.5 H2(g) + NH3(g)) in the cathode was strengthened in the low concentration range (0-0.25 M Na2SO4) but inhibited in the concentration range of 0.5-1.5 mol L-1.

Funding

Chongqing Science and Technology Bureau (cstc2018jszx-zdyfxmX0016)

Chongqing Ecology and Environment Bureau (2019-89)

History

Email Address of Submitting Author

ypang@nd.edu

Institution

Chongqing Academy of Ecology and Environmental Sciences

Country

China

ORCID For Submitting Author

0000-0003-0522-4292

Declaration of Conflict of Interest

The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

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