Environmental engineering blog and diary, consulting and training services
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.
Impure water is a water that contaminated by unwanted elements. It can be particles, colloids, debris. Of course, for both drinking water or clean water for household activities, these impurities are not wanted. Thus, it is important for us to treat source water to remove these elements. That is why we need water treatment.
The result of my experiment employing TiO2-UV was not satisfying. In terms of flux, TiO2-UV membrane showed severe decline after 30, 60, and around 90 minutes. Not only that, the rejection of membrane coated by TiO2 under UV exposure was lower than naked membrane. This probably due to smaller molecule as a result of the breaking caused by photocatalysis process. After certain minutes, it is possible that TiO2-UV react with the HA, braking bonds within HA molecules, the molecules become smaller, thus it will penetrate the pore of TiO2-UV, so the DOC will be much higher than naked membrane. How about flux? my logic says if the rejection is lower, so the flux should be better as flux and rejection usually work on the opposite way. If the flux better, usually rejection worse, vice versa.
I just read my local newspaper and there were two news catching my eyes. The first one was talking about water scarce in Tiongkok, or some of you may say China. While we sometimes use water excessively and exploit water too much, there are our brothers out there who need water badly. Water scarce as reported happens in Hainan Province, South of Tiongkok due to hight dryness. More than 120 thousands people experienced clean water crisis and paddy field dry due to lack of water.
Drinking water scarce, it was the headline of popular newspaper in my city. Citizens were yelling to ask local authority to safe drinking water. The problem is, water is renewable resource, which will never be empty, always be there for water supply. So, why do these people feel that they do not get appropriate drinking that they deserve to get?
First stage of experiment has been accomplished. The result was not satisfying. I used 50, 15 and 1 kD. In terms of flux and accumulated flux, TiO2-UV displayed lower result compare to just naked membrane. Although for 50 kD and 15 kD initial flux were higher than naked membrane, but after around 30-100 minutes, they showed severe decline for flux. This also applied for 1 kD TiO2-UV membrane. I do not think that permeability plays a big role on this, since the permeability of all membranes were similar, there were not significant difference. This also proves that TiO2 does not affect the structure of the membrane.
Yesterday I was requested to join Internation Symposium held in Taiwan. One of the requirement to join is to submit abstract before due date which is next week. While I am writing my own abstract, I think it is good idea to put something here about how to write abstract.