Open AccessAmmonia Recovery from Wastewater as a Fuel: Effects of Supporting Electrolyte on Ammonium Permeation through a Cation-Exchange Membrane
Author(s) -
Linji Xu,
Dingyang Liu,
Wenzong Liu,
Jixiang Yang,
Huang Jian,
Xinzhu Wang,
Qiang He
Publication year - 2022
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.2c00700
Subject(s) - permeation , electrolyte , chemistry , ammonia , ammonium , membrane , adsorption , inorganic chemistry , concentration polarization , wastewater , ion exchange , ion , environmental engineering , organic chemistry , electrode , biochemistry , engineering
Electrodeionization (EDI) is used to recover ammonia from wastewater as a fuel, but how its performance for ammonia recovery is affected by the supporting electrolyte is not very clear. This study involved experimental tests and theoretical calculations on NH 3 recovery, NH 4 + permeation, and NH 4 + and Na + interacting with the functional groups in a cation exchange membrane (CEM) using Na 2 SO 4 as the supporting electrolyte. The results demonstrated that a low concentration (≤0.250 mol L -1 of Na 2 SO 4 ) was conducive to NH 4 + permeation, while the a concentration (0.750 mol L -1 of Na 2 SO 4 ) hindered NH 4 + permeation. A maximum recovery efficiency of ammonia of 80.00%, a current efficiency of 70.10%, and an energy balance ratio of 0.66 were obtained at 0.250 mol L -1 of Na 2 SO 4 . Numerical results indicated that an increase in Na 2 SO 4 concentration caused severe concentration polarization that resisted NH 4 + migration in the CEM. The DFT results demonstrated that competitive adsorption of Na + to the CEM hindered NH 4 + migration. The weaker interacting force between NH 4 + and the sulfonate functional group (-SOH 3 ) in comparison to that between Na + and -SOH 3 might be related to the geometric and orientation effects, which generated an additional energy barrier for NH 4 + transport. Therefore, this study suggests that the supporting electrolyte concentration should be matched with that of the desalted ions.