Reuse of wastewater discharged from thermal-plasma decomposition of chlorodifluoromethane: Production of titanium dioxide nanopowder. (20th March 2020)

• Record Type: Journal Article
• Authors: Yoo, Hyeonseok; Kim, Moonsu; Kim, Yong-Tae; Choi, Jinsub
• Is Part Of: Journal of cleaner production. Volume 250(2020)
• Publication Date: 2020-03-20
• Subjects: Refrigerant -- Thermal decomposition -- Titanium dioxide nanotubes -- Rapid breakdown anodization -- Wastewater; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2019.119542
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Chlorodifluoromethane, a refrigerant that will be phased out in the future, is decomposed by nitrogen thermal plasmas with a 99.99% destruction and removal efficiency discharging wastewater containing halide ions. Titanium dioxide nanotubes having a pore size less than 9 nm are produced via electrochemical anodization of titanium using wastewater containing fluoride and chloride ions generated by the decomposition of chlorodifluoromethane. Titanium dioxide spontaneously detached from the substrate into the electrolyte as the period of anodization increased due to weak adhesion between the oxide and substrate. The amount of nanopowder produced was accelerated by nitrate ions, which originated from the nitrogen plasma during the thermal decomposition process. The nitrate ions, which is naturally generated in wastewater due to nitrogen plasma act as a catalyst to accelerate the mass production of TiO2 powder by up to two-fold, compared to that in an electrolyte without nitrate ions. The basic property originated by NaOH neutralizer of the electrolyte leads to the smooth surface morphology. Graphical abstract: Image 1 Highlights: The wastewater is generated from nitrogen plasma decomposition of HCFC-22. Wastewater is reused for the production of TiO2 nanopowders by anodization. The mass of TiO2 nanopowder increases as a function of applied voltage and time. The nitrate ion acts as a catalyst to accelerate the growth of the nanotubes. The pH of electrolyte effect on the surface morphology of TiO2 nanopowders.