Copperphthalocyanine immobilized Zn/Al LDH as photocatalyst under solar radiation for decolorization of methylene blue

Zn/Al hydrotalcite-like compounds (HTlcs) with Zn/Al molar ratios of 2:1, 3:1, 4:1 were synthesized by co-precipitation method and were used as supports for the immobilization of Cu(II) tetrasulphonated phthalocyanine (CuPcTs). XRD and UV-vis DRS were used to characterize the solids after adsorption of CuPcTs on HTlcs. The photocatalytic decolorization of methylene blue (MB) was studied under solar radiation over Zn/Al (2:1)-(CuPcTs) and the corresponding dark control was also carried out for comparison purposes. The effect of time, pH, adsorbate concentration, catalyst dosage, H2O2, potassium persulphate and sodium chloride amount was studied as a function of the percentage of decolorization. The percentage of decolorization increases with the increase in pH of solution. A maximum of 75% decolorization of methylene blue was achieved at 4 h solar irradiation as against 33% in dark control. The process obeys pseudo-first order kinetics. (c) 2006 Elsevier B.V. All rights reserved.