Zn 0.94 Mn 0.06 O for adsorption and photo-degradation of methyl orange dye under visible irradiation: Kinetics and isotherms study.

Three photocatalyst-adsorbents consist of Zn _0.97 Mn _0.03 O, Zn _0.94 Mn _0.06 O, and Zn _0.92 Mn _0.08 O were synthesized by hydrothermal method and calcined at 800 °C. The structural and optical properties of the sample Zn _0.94 Mn _0.06 O were characterized by using XRD; TEM; SEM; EDS; DLS; and DRS. The surface of the sample Zn _0.94 Mn _0.06 O consists of nano-particles (<100 nm) and nano-holes (18.4 nm), also the band-gap of it was obtained 2.89 eV. Adsorption and photo-degradation of methyl orange (MO) dye was investigated in darkness and under visible light irradiation (200 W tungsten). The sample Zn _0.94 Mn _0.06 O showed the most decolorization efficiency in the shortest time, so that 0.15 g of it adsorbed and destroyed the MO dye molecules (99 ± 1 %) in 40 s under irradiation. The most adsorption capacity of Zn _0.94 Mn _0.06 O was obtained 30.06 mg/g and the mechanism of the dye adsorption was investigated by using BET analysis and zeta potential. Also the adsorption isotherm and kinetics were calculated for describing the adsorption of MO onto the Zn _0.94 Mn _0.06 O.
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