A composite feedstock was prepared in this work by mixing Na-titanate nanowire powder (spray dried) and TiO2 nanopowder (spray dried) for plasma spray coating. Photocatalytic degradation of methylene blue (MB) in an aqueous solution using plasma sprayed TiO2 coating has to be improved. Hydrothermally prepared Na-titanate, which has a wire-like structure, was spray dried into granules mixed with nanostructured TiO2 granules a ratio of 50(TiO2):50(Na-titanate) wt% to form the composite feedstock powder for plasma spraying. The prepared composite feedstock TiO2/Na-titanate was deposited on the metal substrate using one thermal spray coating method, plasma spray. In this coating technique, the feedstock material in powder is injected into the plasma stream, where the particles are heated and accelerated at high velocity towards the substrate. The particles are impacted, splatted, and rapidly cooled on the substrate and formed the coating. The microstructure of the coatings was observed by field emission scanning electron microscope (FESEM) and showed that the coating was composed of melted and partially melted particles. The phase composition of the coatings was analyzed by X-ray diffraction (XRD), and the result showed the presence of rutile and a small amount of anatase phase. The photocatalytic activity of the coatings was determined by measuring the degradation of methylene blue (MB) dye in an aqueous solution under UV irradiation. The MB degradation of the prepared composite coating was 67.3% after eighth UV-irradiation.

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M. Siti Mariam, A. Z. Zuhana, A. Nizam Abd, “Plasma sprayed TiO2/Na-titanate composite coating for photocatalytic degradation of methylene blue,” International Journal of Technology and Engineering Studies, Vol. 1 , no. 1, pp. 19-25, 2015.