Adsorption and catalytic oxidation of poly(vinyl alcohol) textile by Mn x O y /γ-Al 2 O 3 nanoparticle catalyst

Abstract

Mn _x O _y /γ-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 Mn _x O _y /γ-Al₂O₃ as catalyst was observed. The variation in polyvinyl alcohol removal rate as a function of calcination temperature, adsorption temperature, Mn _x O _y /γ-Al₂O₃ dosage, H₂O₂ dosage, and initial polyvinyl alcohol concentration was investigated. Results showed that polyvinyl alcohol can be removed by the adsorption of Mn _x O _y /γ-Al₂O₃; the removal ratio increased with higher adsorption temperature as well as increased Mn _x O _y /γ-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, Mn _x O _y /γ-Al₂O₃ nanoparticles were able to remove more than 90% polyvinyl alcohol at an initial concentration below 50 g/L, temperature of 80℃, 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.