Journal of Membrane Science 389 (2012) 83–90 Contents lists available at SciVerse ScienceDirect Journal of Membrane Science jo u rn al hom epa ge: www.elsevier.com/locate/memsci Rapid atmospheric plasma spray coating preparation and photocatalytic activity of macroporous titania nanocrystalline membranes Yi-Feng Lin ∗ , Kuo-Lun Tung ∗∗ , Yu-Sheng Tzeng, Jian-Hua Chen, Kai-Shiun Chang Department of Chemical Engineering, R&D Center for Membrane Technology, Chung Yuan Christian University, Chungli 320, Taiwan, ROC a r t i c l e i n f o Article history: Received 13 September 2011 Received in revised form 14 October 2011 Accepted 14 October 2011 Available online 20 October 2011 Keywords: TiO2 Atmospheric plasma spraying Photodegradation Bio-organism UV light a b s t r a c t Macroporous TiO 2 nanocrystalline (NC) membranes with average pore size of 0.35 m were successfully fabricated by coating on an alumina support via a rapid atmospheric plasma spraying (APS) approach. The as-prepared TiO 2 and P25 membranes were first tested for photocatalytic activity using Reactive Black-5 (RB5) dye in a batch reactor with UV light irradiation, respectively. RB5 dyes were completely decomposed with an irradiation time of 70 min, and the rate constants for the photocatalytic reactions using TiO 2 and P25 membranes were determined to be approximately 0.076 and 0.071 min -1 , respec- tively. The photocatalytic activity of the as-prepared TiO 2 NC membranes was slightly better than P25 membranes, indicating the APS-fabricated TiO 2 NC membranes were with a high photocatalytic activity. The TiO 2 membranes were further used for the photodegradation of dextran and humic acid (HA), and the permeate fluxes of dextran and HA increased when the membranes were exposed to UV light irradia- tion. The dominant filtration resistances of the dextran and HA solutions were pore and cake resistances, respectively, which were reduced by a photocatalytic TiO 2 NC membrane under UV light illumination. The removal percentages of HA at an initial concentration of 2 ppm were 58% and 90% in the dark and under UV light irradiation, respectively. The increase in the HA removal resulted from the photodegrada- tion of HA by the photocatalytic TiO 2 NC membrane. In this work, a rapid process of APS coating was first used for the preparation of macroporous TiO 2 NC membranes with high photocatalytic activities, which can be applied for water treatment, for example, in the photodegradation of bio-organisms and protein under UV light irradiation. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Energy, water, food and environment are the most serious prob- lems facing mankind in the next 50 years. Among them, the demand for clean water sources has become an important issue world- wide due to increasing water pollution by, e.g., hazardous organic substances of humic acid (HA), polysaccharide dextran, Reactive Black-5 (RB5) dyes and disinfectants produced by industrial and agricultural companies. Therefore, current methods for water treat- ment such as adsorption, coagulation, sedimentation, filtration, chemical and membrane technology have received a great deal of research attention in attempts to ensure pure and clean water; however, all of these methods only concentrate pollutants rather than eliminating or destroying them [1]. Compared with other methods of water treatment, membrane technology incurs high operating costs and is prone to fouling problems by pollutants, but the recovery or separation of an adsorbent, coagulator or filter aid ∗ Corresponding author. Tel.: +886 3 2654146; fax: +886 3 2654199. ∗∗ Corresponding author. E-mail addresses: yflin@cycu.edu.tw (Y.-F. Lin), kuolun@cycu.edu.tw (K.-L. Tung). is not needed. Consequently, it is necessary to discover or develop a next-generation membrane to overcome the existing problems of membrane fouling; photocatalytic membranes could meet this need. Titanium dioxide (TiO 2 ) has attracted much research attention due to its photocatalytic properties, and it has been widely used in photocatalysts [2], photovoltaics [3], water splitting [4], pho- tocorrosion resistance [5], gas sensing [6], light devices [7], and water treatment [8]. TiO 2 is a metal oxide semiconductor with three different crystalline structures: anatase, rutile and brookite. Considering the band gap position and surface structure, TiO 2 with anatase and rutile phases is commonly utilized for photocatalytic applications. To enhance the photocatalytic ability of TiO 2 , vari- ous types of TiO 2 nanostructures with high specific surface areas, e.g., nanoparticles [9], nanowires [10], nanofibers [11], nanorods [12], nanotubes [13,14], mesoporous hollow spheres [15], and nan- othorns [16], have been developed as photocatalysts by research scientists. However, the problems such as the recovery and sepa- ration of TiO 2 nanostructures from water still remain a challenge when they are used as photocatalysts for the elimination of pol- lutants in water. Immobilization of photocatalysts is one solution to the problems of recovery and separation of nanostructured 0376-7388/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2011.10.018