| Organic dye wastewater with high chroma,complex composition and high toxicity is difficult to be degraded in water treatment.In addition,the untreated organic pollutants potentially threaten human health and ecological environment once it discharges into the aqueous system.The main techniques used to degrade dye molecules in water are microbial method,advanced oxidation process,electrochemistry,and persulfate activation and so on.The hydroxyl radicals and/or superoxide radicals can be formed through the activation of H2O2 by Fe2+ under light irradiation in photo-assisted Fenton reaction system.Similarly,the activation of persulfate can produced SO4·-radicals.In conclusion,the above free radicals have a strong ability to oxidize a variety of organic dyes under relatively mild conditions,and ultimately mineralize the organics into carbon dioxide and water.The process is considered highly efficient,environmentally benign,and relatively inexpensive.Graphene aerogel is a new category of carriers offering a porous 3D framework,large surface-to-volume ratio,superior electron mobility,excellent conductivity,mechanical stability and good adsorption.Currently,self-assembly of 3D graphene-based aerogels involves hydrothermal methods which rely on strong ?-?interaction or the chemical reduction effect.?-FeOOH@GCA was fabricated through Fe2+-induced reduction and self-assembly of GO pillared with CNTs and ?-FeOOH formed simultaneously within this structure.To date,there has been no published report of the one-step self-assembly of ?-FeOOH@GCA.The as-synthesized material was characterized by XRD,SEM,TEM,UV-Vis,and nitrogen adsorption techniques.And the ?-FeOOH@GCA was employed in photo-assist Fenton system and persulfate activation for Orange ?(O?)decolorization.The results demonstrated that both systems have superior catalytic activity in degrading O? molecules in aqueous solution.In photo-assist Fenton-like system catalyzed by ?-FeOOH@GCA,the effects of initial pH and the structural properties of organic matter on the degradation performance of O? were studied.The results show that this photo-Fenton-like system has a wide pH range,strong ability in degrading the organic compounds with different structures.Through the toxic experiment of the luminous bacteria,it was observed that the toxicity of the solution gradually decreased with the progress of the reaction.A hybrid method that combines qualitative detection(radical quenching studies)with quantitative test(fluorescence method.)was conducted for the investigation of active species participated in the process.Surface hydroxyl radicals and superoxide anions were quantitatively identified as the dominating reactive oxygen species.The LC-MS technique was employed to detect the production of intermediates.And the feasible degradation pathway and the mechanism were proposed.Finally,the catalytic ability of ?-FeOOH@GCA under visible light irradiation was studied.The results show that it has good visible light response ability and this provides theoretical support for the practical application of the catalyst.As for the persulfate activation by ?-FeOOH@GCA aerogel for discoloration of Orange ?,several parameters such as initial pH,Orange ? concentration and oxidant dosing were investigated.The results suggest that the persulfate activation by?-FeOOH@GCA system is more likely to degrade the dye under acidic conditions.The higher the concentration of the reaction solution,the slower the degradation rate of the dye is.The increase of the oxidant can improve the degradation of the dye in a certain range.It was found that SO4·-was the principal active species,and interestingly the surface-bound SO4·-was speculated the main existence form.The LC-MS technique was employed to detect the production of intermediates.And the corresponding degradation pathway and the mechanism were proposed. |
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