Promoting catalytic ozonation of phenol over graphene through nitrogenation and Co3O4 compositing

Fabrication of electrochemically-modified BiVO4-MoS2-Co3O4composite film for bisphenol A degradation

A new electrochemically-modified BiVO₄-MoS₂-Co₃O₄ (represented as E-BiVO₄-MoS₂-Co₃O₄) thin film electrode was successfully synthesized for environmental application. MoS₂ and Co₃O₄ were grown on the surface of BiVO₄ to obtain BiVO₄-MoS₂-Co₃O₄. E-BiVO₄-MoS₂-Co₃O₄ film was achieved by further electrochemical treatment of BiVO₄-MoS₂-Co₃O₄. The as-prepared E-BiVO₄-MoS₂-Co₃O₄ exhibited significantly enhanced photoelectrocatalytic activity. The photocurrent density of E-BiVO₄-MoS₂-Co₃O₄ thin film is 6.6 times that of BiVO₄ under visible light irradiation. The degradation efficiency of E-BiVO₄-MoS₂-Co₃O₄ for bisphenol A pollutant was 81.56% in photoelectrochemical process. The pseudo-first order reaction rate constant of E-BiVO₄-MoS₂-Co₃O₄ film is 3.22 times higher than that of BiVO₄. And its reaction rate constant in photoelectrocatalytic process is 14.5 times or 2 times that in photocatalytic or electrocatalytic process, respectively. The improved performance of E-BiVO₄-MoS₂-Co₃O₄ was attributed to the synergetic effects of the reduction of interfacial charge transfer resistance, the formation of oxygen vacancies and sub-stoichiometric metal oxides and higher separation efficiency of photogenerated electron-hole pairs. E-BiVO₄-MoS₂-Co₃O₄ is a promising composite material for pollutants removal.

Study of catalytic ozonation for tetracycline hydrochloride degradation in water by silicate ore supported Co3O4

Tetracycline hydrochloride (TCH) degradation by cobalt modified silicate ore (CoSO) catalytic ozonation in aqueous solution was investigated. CoSO catalyst was synthesized by an impregnation method using Co(NO₃)₂ as the precursor and natural silicon ore (SO) as the support. The key catalyst preparation conditions (i.e., impregnation concentration, calcination temperature and time) were optimized. The activity and stability of CoSO catalyst and its catalytic ozonation mechanism for TCH degradation were studied. The results showed that Co₃O₄ was successfully coated on the silicon ore and the CoSO catalyst was highly efficient in catalytic ozonation for TCH degradation. The TCH removal by CoSO/O₃ could reach 93.2%, while only 69.3% by SO/O₃ and only 46.0% by O₃ alone at 25 min. The reaction of TCH degradation followed pseudo-first order kinetics. TOC removal rate by CoSO/O₃ was 2.0 times higher than that by SO/O₃, and 3.5 times higher than that by O₃ alone. The reaction conditions (TCH initial concentration, catalyst concentration, pH and temperature) for catalytic ozonation were systematically investigated. The possible mechanism for the CoSO catalytic ozonation process was proposed, where hydroxyl radical oxidation mainly accounted for the substantial TCH degradation. Furthermore, CoSO showed great durability and stability after seven reaction cycles.

Antibiotic tetracycline hydrochloride was efficiently degraded by CoSO-catalytic ozonation and the catalytic oxidation mechanism was elucidated.

Graphene-based materials supported advanced oxidation processes for water and wastewater treatment: a review

Advanced oxidation processes (AOPs) received much attention in the field of water and wastewater treatment due to its ability to mineralize persistent organic pollutants from water medium. The addition of graphene-based materials increased the efficiency of all AOPs significantly. The present review analyzes the performance of graphene-based materials that supported AOPs in detail. Recent developments in this field are highlighted. A special focus has been awarded for the performance enhancement mechanism of AOPs in the presence of graphene-based materials.