TiO2 coating procedures
There are various methods available to coat TiO2 onto the surface of the membrane. I will explain briefly some of them, and the method I used.
Ion assisted deposition
This method was used for coating on super-hydrophobic porous teflon membrane. The author stated that the coating of TiO2 by the chemical wet process such as a sol-gel method is very difficult. The method involved acceleration voltage, temperature, and oxygen. Heated at 523 K.
Phase Inversion Method
This was used to make TiO2 entrapped membrane. Casting solution were n-methyl-2-pyrrolidone (NMP, Aldrich), cast with 200 micrometer casting knife onto polyester non-woven fabric. Membrane was then evaporated at 25 +- 1 degree C for 30 s, then immersed in 18 +- 1 degree C deionized water coagulation bath.
Dipping and Pressurize method
For making TiO2 deposited membrane. Membrane was dipped into 1% TiO2 aqueous solution for 1 min, then pressurized at 400 kPa for 2 h using compressed nitrogen gas.
Followed are methods can be employed, obtained from Byrne et al., (1998), these will not be discussed here:
Sol-Gel Methods
Oxidation of parent metal: electrochemical and thermal
Anodisation of TiCl3
Electrophoretic coating
Plasma spray
Aerosol powder coating
sputtering
liquid phase deposition
Various variations may be employed to obtain better performance. However, only few mentioned above that describe immobilization for Titanium based membrane. The method I used was sol-gel method, employing Triton-X (Octyl Phenol Ethoxylate, Baker Analyzed, reagent), P25 Degussa TiO2, pure water milli-Q and acetyl-acetone. Stirring and heating are the next step.
Reference(s):
Bae, T.H., T.M. Tak. Effect of TiO2 nanoparticles on fouling mitigation of ultrafiltration membranes for activated sludge filtration. J. Membrane Science 249 (2005) 1-8
Byrne, J.A., B.R. Eggins, N.M.D. Brown, B. McKinney, and M. Rouse. Immobilisation of TiO2 powder for the treatment of polluted water. Applied Catalysis B: Environmental 17 (1998) 25-26
Yamashita H., H. Nakao, M. Takeuchi, Y. Nakatani, and M. Anpo. Coating of TiO2 photocatalysts on super-hydropobic porous teflon membrane by an ion assisted deposition method and their self-cleaning performance. Nuclear Instruments and Methods in Physics Research B 206 (2003) 898-901
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