Study On Preparation Of Graphene/TiO₂Nanotube Array Photoelectrodes For Degradation Of Alachlor

With its wide application in Agriculture, the pollution caused by the herbicide isincreasingly serious. Herbicide can be hazardous to human health through multipleways like through the accumulation of food chain or the pollution on surface water.The traditional processes have limitations on the removal of herbicide that featuresnature stability and poor biodegradability, however, the photocatalytic technologybased on TiO2nanotubes demonstrates a distinct advantage on the removal it. Thispaper conducts the adulteration of graphene on the basis of TiO2nanotubes, makes thephotoelectrode of graphene/TNAs, and studies the photocatalytic properties by meansof targeting at the alachlor as the pollution.The experiment firstly obtains the photoelectrode of graphene/TNAs with theapproaches of anodic oxidation and electrochemical deposition. This paper has madethe analysis of the structure and property on the photoelectrode of graphene/TNAswhich is obtained by a series of methods: SEM, Raman, FT-IR, UV/vis/DRS, XRD,Zeta potential, Electrochemical workstation, etc. Through the study of the influenceon the photocatalytic properties of grapheme/TNAs made under different conditions,the experimental result shows that the optimal condition is as follows: electrodespacing (2cm), graphene oxide concentration (80mg/L), deposition voltage (2V),reduction time (2min).This study makes a comparison of the effects on photocatalytic degradation ofalachlor between the photoelectrode of graphene/TNAs and the photoelectrode ofTNAs, deeply researches the factors such as degradation time, the initialconcentration of alachlor, the initial PH value, distance from the light source andInterfering ions and so on, on the effects of the photocatalytic degradation ofgraphene/TNAs, and tests the repetitive usability of the photocatalytic degradation,demonstrating that the photoelectrode of grapheme/TNAs has a better effect on theremoval of alachlor than that of pure TNA photoelectrode; with the increase of initial concentration, pH value and distance from the light resources, the removal rate ofalachlor by photoelectrode has gradually reduced; effects of interfering ions on thedegradation process is not significant; graphene/TNAs is stable on the degradation ofalachlor, the degradation rate on alachlor is still above99%after repetitive use of15times. The study establishes alachlor degradation kinetic equation and determinesthe relevant kinetic parameters, finding that the process of photocatalytic degradationof graphene/TNAs on alachlor is in line with quasi-dynamic model under differentinitial concentration, pH values and light intensity conditions.The initial study of the mechanism on photocatalytic degradation ofgraphene/TNAs on alachlor has been conducted through TOC and fluorescencespectroscopy, finding that·OH is the significant mechanism on the oxidative removalof alachlor by photocatalytic degradation of grapheme/TNAs, and the capability ofphotoelectrode of graphene/TNAs is better at producing·OH under the light that thatof TNAs. Under the condition of radiating of Xenon (150w) for one hour, the TOCremoval efficiency on alachlor by the photoelectrodes of grapheme/TNAs and TNAscan respectively achieve64.63%and55.29%.