Preparation, characterization of nano ZnO-blended cellulose acetate-polyurethane membrane for photocatalytic degradation of dyes from water

•Photocatalytic degradation was studied under sunlight.•Degradation studies of Reactive Red 11 and Reactive Orange 84 dyes were carried out.•ZnO blended CA-PU membrane is preferred over CA-PU membrane as the former has improved characters like higher water flux.•The prepared CA-PU/ZnO membrane exhibit superior photocatalytic activities.•The maximum degradation efficiency was shown by the catalyst - at neutral pH.

Effluents from dyeing and finishing processes of textile industry contain strong colour, dissolved solids, high pH and possibly heavy metals. Conventional treatments are applied to treat dyes but the secondary pollution problem is not addressed. Consequently, one of the novel advanced oxidation processes, the heterogeneous photocatalytic oxidation process has a special interest especially when solar light is used. In this work a cellulose acetate-polyureathane (CA-PU) membrane impregnated with nano ZnO as a photocatalyst was prepared by blending technique. The structure and morphology of the prepared CA-PU membrane impregnated with ZnO were analyzed by FTIR, SEM with EDAX, TG-DTA, AFM and pure water flux (PWF). The photocatalytic degradation of dyes using this CA-PU/ZnO membrane was investigated towards the removal of Reactive Red (RR 11) and Reactive Orange (RO 84) using UV-light with different parameters. The maximum degradation of dyes was achieved at 40 min with an optimum pH 7. The kinetic model of Langmuir-Hinshelwood well describes the photodegradation capacity. The photocatalytic degradation of dyes RR 11 and RO 84 exhibited pseudo-first order kinetics. ZnO impregnated CA-PU membrane inherited not only the photocatalytic ability of nano-ZnO, but also good thermal stability and mechanical property.

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