Synthesis 6%Mn/ZnO as super-rapid-adsorbent-photocatalyst (SRAP): Remove azo dyes in darkness and under visible light, adsorption isotherms and kinetics study
2020
Shahbazkhany, Saeedeh | Salehi, Mehdi | Mousavi-Kamazani, Mehdi | Salarvand, Zohreh
In this study, we synthesized 6%Mn/ZnO by the hydrothermal method as a super-rapid-adsorbent-photocatalyst (SRAP) under visible irradiation. Mn(II) was doped to ZnO so that the band gap of ZnO was decreased to 1.54 eV. The mean of particles size of SRAP was obtained 460.9 nm by DLS analysis. The surface area was 0.488 m²/g obtained from BET plot. The mean and the mode pore diameter were 18.3 and 1.2 nm, respectively. Zeta potential of sample in acidic environment was −0.5 mV. The adsorption mechanism is justified by the Van der Waals forces between positive charge of nitrogen from dye molecules and negative charge of the surface of 6%Mn/ZnO in acidic pH. The maximum experimental adsorption capacity was obtained 30.05 mg/g. The Langmuir model is suitable for describing the adsorption of MO onto the 6%Mn/ZnO and its adsorption kinetics follows pseudo-second-order model. 0.05 g of SRAP removed the colour of the methyl orange (MO) solution (99%) for three min under visible light, and this amount of it had only adsorption of MO in darkness after 10 min. Furthermore, 0.15 g of SRAP dramatically degraded MO and methyl red (MR) for 40 s and 10 min under irradiation, respectively.
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