Graphene-related−TiO 2 (G−TiO 2 ) nanocomposites show enhanced photocatalytic performance, not only due to promoting photogenerated electrons migration but also by extending optical absorption to the visible light range. However, little is known about the origin of the visible light activity, which seems to depend much on the precursor of the titanium source. In this study, an efficient visible light active G− TiO 2 -413 was prepared by hydrothermally treating a graphene oxide (GO) suspension and TiO 2 sol with undergrown TiO 2 nanoparticles at 413 K. According to XRD, DRS, TEM, FTIR, Raman, and ESR analyses, when in situ growing TiO 2 nanoparticles from hydrolyzed titanium alkoxides in hydrothermal conditions, a strong chemical interaction appears at the interface of GO sheets and the underdeveloped loosely packed polymeric Ti−O−Ti skeletons, so as to facilitate retaining more alkoxyl groups, inducing crystal disorders, and creating oxygen vacancies. All of these contribute to the significantly enhanced visible light activity of G−TiO 2 -413. This sheds new light on the development of visible light responsive TiO 2 -based photocatalysts via surface modification approaches.
Abstract:Adsorption is one of the most effective technologies in the treatment of colored matter containing wastewater. Graphene related composites display potential to be an effective adsorbent. However, the adsorption mechanism and their regeneration approach are still demanding more efforts. An effective magnetically separable absorbent, Fe3O4 and reduced graphene oxide (RGO) composite has been prepared by an in situ coprecipitation and reduction method. According to the characterizations of TEM, XRD, XPS, Raman spectra and BET analyses, Fe3O4 nanoparticles in sizes of 10-20 nm are well dispersed over the RGO nanosheets, resulting in a highest specific area of 296.2 m 2 /g. The rhodamine B adsorption mechanism on the composites was investigated by the adsorption kinetics and isotherms. The isotherms are fitting better by Langmuir model, and the adsorption kinetic rates depend much on the chemical components of RGO. Compared to active carbon, the composite shows 3.7 times higher adsorption capacity and thirty times faster adsorption rates. Furthermore, with Fe3O4 nanoparticles as the in situ catalysts, the adsorption performance of composites can be restored by carrying out a Fenton-like reaction, which could be a promising regeneration way for the adsorbents in the organic pollutant removal of wastewater. Abbreviation Q e -Equilibrium adsorption capacity of adsorbent, mg/g; C i -The initial aqueous phase concentration of absorbates, mg/L; C e -The equilibrium concentration of absorbates, mg/L; V -The volume of solution, mL; M s -The mass of adsorbent, g; Q max -The maximum adsorption capacity of adsorbent, mg/g; Keywords:
Abstract:Adsorption is one of the most effective technologies in the treatment of colored matter containing wastewater. Graphene related composites display potential to be an effective adsorbent. However, the adsorption mechanism and their regeneration approach are still demanding more efforts. An effective magnetically separable absorbent, Fe3O4 and reduced graphene oxide (RGO) composite has been prepared by an in situ coprecipitation and reduction method. According to the characterizations of TEM, XRD, XPS, Raman spectra and BET analyses, Fe3O4 nanoparticles in sizes of 10-20 nm are well dispersed over the RGO nanosheets, resulting in a highest specific area of 296.2 m 2 /g. The rhodamine B adsorption mechanism on the composites was investigated by the adsorption kinetics and isotherms. The isotherms are fitting better by Langmuir model, and the adsorption kinetic rates depend much on the chemical components of RGO. Compared to active carbon, the composite shows 3.7 times higher adsorption capacity and thirty times faster adsorption rates. Furthermore, with Fe3O4 nanoparticles as the in situ catalysts, the adsorption performance of composites can be restored by carrying out a Fenton-like reaction, which could be a promising regeneration way for the adsorbents in the organic pollutant removal of wastewater. Abbreviation Q e -Equilibrium adsorption capacity of adsorbent, mg/g; C i -The initial aqueous phase concentration of absorbates, mg/L; C e -The equilibrium concentration of absorbates, mg/L; V -The volume of solution, mL; M s -The mass of adsorbent, g; Q max -The maximum adsorption capacity of adsorbent, mg/g; Keywords:
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