The Photocatalytic Properties Of Cu-Al₂O₃@AD And Its Adsorption Performance On Cr⁶⁺

Cu-Al₂O₃ and Cu-Al₂O₃@AD were prepared by coprecipitation method and characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）,specific surface and porosity analyzer etc.At the same time,the photocatalytic properties and adsorption performance of modified diatomite,Cu-Al₂O₃ and Cu-Al₂O₃@AD were studied.Firstly,Cu-Al₂O₃ and Cu-Al₂O₃@AD were successfully prepared.The results of phase analysis show that the positions of the characteristic diffraction peaks of Cu-Al₂O₃@AD are consistent with the standard cards of Al₂O₃ and diatomite respectively,indicating that Cu-Al₂O₃ has been successfully loaded on the diatomite.The results of morphology analysis show that the modified diatomite is disc-shaped,with pores on its surface,and Cu-Al₂O₃ has been successfully loaded into the pores of the diatomite.And Compared with Cu-Al₂O₃,the particle size of Cu-Al₂O₃@AD increases obviously,and the particle size distribution is relatively centralized and uniform.The adsorption/desorption isotherms of modified diatomite and Cu-Al₂O₃@AD are in accordance with type II adsorption isotherm and H3 hysteresis loop,indicating that both modified diatomite and Cu-Al₂O₃@AD belong to mesoporous materials.Secondly,the photocatalytic properties of Cu-Al₂O₃@AD were investigated.The results show that when the amount of Cu-Al₂O₃@AD is 5 mg,the concentration of H₂O₂ is 64 mmol/mL,and the concentration of substrate is 10 mg/L,the photocatalytic performance is the best.Among the three catalysts,the photocatalytic effect of Cu-Al₂O₃@AD is better than that of modified diatomite and Cu-Al₂O₃,and the photocatalytic effect for Rhodamine B is 95%.Finally,the adsorption performance of Cu-Al₂O₃@AD on Cr⁶⁺was investigated,and the influence of pH value,adsorption time and temperature on adsorption were also studied.Under the same conditions,the adsorption efficiency of Cu-Al₂O₃@AD is significantly higher than that of modified diatomite and Cu-Al₂O₃.The static adsorption experiment show that when the catalyst dosage is 0.5 g,the pH value is 3,the initial concentration of Cr⁶⁺is 2μg/mL,and the reaction temperature is 20℃,the adsorption performance of Cr⁶⁺is the best,and the highest adsorption efficiency is up to 90%.The adsorption process of Cr⁶⁺accords with the pseudo first-order kinetic model.Compared with Freundlich adsorption model,Langmuir adsorption model can describe the adsorption behavior of adsorbent for Cr⁶⁺more accurately.Both chemical adsorption and physical adsorption exist in the adsorption process.