The Application of Cation Exchange Membranes in Electrochemical Systems for Ammonia Recovery from Wastewater

Electrochemical processes are considered promising technologies for ammonia recovery from wastewater. In electrochemical processes, cation exchange membrane (CEM), which is applied to separate compartments, plays a crucial role in the separation of ammonium nitrogen from wastewater. Here we provide a comprehensive review on the application of CEM in electrochemical systems for ammonia recovery from wastewater. Four kinds of electrochemical systems, including bioelectrochemical systems, electrochemical stripping, membrane electrosorption, and electrodialysis, are introduced. Then we discuss the role CEM plays in these processes for ammonia recovery from wastewater. In addition, we highlight the key performance metrics related to ammonia recovery and properties of CEM membrane. The limitations and key challenges of using CEM for ammonia recovery are also identified and discussed.

Study on Electrochemical Stripping Method of Graphene Electrode and Its Capacitive Properties

Graphene has excellent properties, such as excellent conductivity, more pores, stable chemical and structural properties, high specific surface area, so it is usually used in the battery fields. In order to further explore the capacitive properties of graphene, this experiment used electrochemical stripping method, the electrochemical electrode was characterized by constant potential treatment methods, cyclic voltammetry curve, and constant current charging–discharging curve. The capacitive performance of modified graphene at different potentials was compared. If a constant potential peeling treatment is performed, the interlayer spacing of graphene increases, and this time, the specific surface area is enlarged, and the electrical properties of the graphene electrode material are correspondingly improved. Cyclic voltammetry curve results show that the graphene electrode exhibits better capacitance performance after being treated with a constant potential in neutral electrolyte. When treating with 3.1 V constant potential and voltage range of -1.1 V–1.1 V, capacitance can reach 327.273 F. The chronopotentiometry curve results show that 3.1 V graphene electrode mass ratio capacitance can reach 218.182 F/g under voltage range of -0.3 V–0.3 V, meeting the energy storage requirements of the battery industry, and it is expected to become an ideal electrode material in the field of supercapacitors.