Adsorption and catalytic oxidation of poly(vinyl alcohol) textile by MnxOy/γ-Al2O3 nanoparticle catalyst

MnxOy/gamma-Al2O3 nanoparticles were prepared by a wet impregnation-calcination method and characterized using X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, energy dispersive spectrometry, and gel permeation chromatography. The heterogeneous Fenton-like process with appropriate amounts of MnxOy/gamma-Al2O3 as catalyst was observed. The variation in polyvinyl alcohol removal rate as a function of calcination temperature, adsorption temperature, MnxOy/gamma-Al2O3 dosage, H2O2 dosage, and initial polyvinyl alcohol concentration was investigated. Results showed that polyvinyl alcohol can be removed by the adsorption of MnxOy/gamma-Al2O3; the removal ratio increased with higher adsorption temperature as well as increased MnxOy/gamma-Al2O3 dosage. Moreover, the degradation of polyvinyl alcohol was promoted by increasing calcination temperature and H2O2 dosage and decreasing initial polyvinyl alcohol concentration. In this paper, MnxOy/gamma-Al2O3 nanoparticles were able to remove more than 90% polyvinyl alcohol at an initial concentration below 50 g/L, temperature of 80celcius, pH of 3.0, and H2O2 and catalyst doses of 120 mL/L and 1 g/L, respectively. Gel permeation chromatography also confirmed that polyvinyl alcohol could be effectively oxidized with a molecule decreasing rate of about 99%, from 100,773 to 1637. The nanocatalyst could be recycled by filtration and calcination, and maintained favorable catalytic ability during four uses.