Removal of N-nitrosopyrrolidine from GAC by a three-dimensional electrochemical reactor: degradation mechanism and degradation path.

Nitrogen-containing disinfection by-products (N-DBPs) produced in the process of drinking water disinfection are widely concerning due to the high cytotoxicity and genotoxicity. It is due to the difficulty of natural degradation of N-DBPs in water and the fact that conventional treatment systems do not effectively treat N-DBPs in drinking water. In this study, N-nitrosopyrrolidine (NPYR) in water was electrocatalytically degraded by a three-dimensional electrode reactor (3DER). This system applied graphite plates as anode and cathode. The granular activated carbon (GAC) was used as third electrode. The degradation of NPYR using a continuous flow three-dimensional electrode reactor was investigated by examining the effects of flow rate, current density, electrolyte concentration, and pollutant concentration on the degradation efficiency, energy consumption, and reaction kinetics of GAC particle electrodes. The results showed that the optimal operating conditions were flow rate = 0.45 mL/min, current density = 6 mA/cm2, Na2SO4 concentration = 0.28 mol/L, and NPYR concentration = 20 mg/L. Under optimal conditions, the degradation of NPYR exceeded 58.84%. The main contributor of indirect oxidation was deduced from free radical quenching experiments. NPYR concentration was measured by GC-MS with DB-5 capillary column, operating in full scan monitoring mode for appropriate quantification of NPYR and intermediates. Based on the identification of reaction intermediates, a possible pathway for the electrochemical oxidation of NPYR on GAC particle electrodes was proposed.

Aqueous rechargeable ammonium ion batteries based on MoS2/MXene with a ball-flower morphology as an anode and NH4V4O10 with a layered structure as a cathode.

Due to the small hydrated ionic radius and light molar mass of ammonium ions, aqueous ammonium ion batteries attract much attention, providing high security, environmental friendliness and low cost. However, the lack of suitable electrode materials with high specific capacity is a big challenge for practical application. Therefore, in view of this problem, we fabricated an anode applying a MoS2 material with a ball-flower morphology anchored to MXene nanoflakes, and it shows excellent rate capability in a novel aqueous ammonium ion battery. The corresponding charge capacities of composite electrodes are 279.2, 204.4, 173.2, 118.7, and 80.5 mA h g-1 at 20, 50, 100, 200, and 500 mA g-1, respectively. Meanwhile, polyvanadate was selected as a cathode material for a full aqueous ammonium ion battery, and interestingly it was discovered that the size of this material decreases with increasing synthesis temperature. The discharge capacities of NH4V4O10 electrodes fabricated at 140 °C, 160 °C, and 180 °C at 50 mA g-1 are 88.6, 125.1 and 155.5 mA h g-1, respectively. Furthermore, we also explore the corresponding electrochemical mechanism using XRD and XPS. A full aqueous ammonium ion battery based on both electrodes shows superior ammonium ion storage properties and provides new ideas for the development of this strategy.