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As the
process of industrialization and the development of urbanization are in rapid
rise, the water quality in rivers of Malaysia is unfortunately not the same. According
to the Environmental Quality Report 2010, 48% of river water is polluted in
Malaysia. Environmental pollution on a global scale, particularly water
pollution, has received scientists’ attention for environmentally clean and
friendly chemical processes. Advanced oxidation process (AOP) is recently known
as the most effective water treatment method. As mentioned by Leong et.al (2014),
AOP is an environmental friendly water
treatment driven by suitable light source depending on the type of catalyst. One of the downsides of AOPs is that it is associated with
the costs of chemicals and energy needed for their use. Alternatively,
hybrid processes are considered to improve the treatment efficacy and to reduce
cost (AIChE, 2015).

 

On the contrary, photocatalytic membranes
have indicated great potential for the application in energy-saving water
purification and waste water treatment since they incorporate the physical
separation of membrane filtration and the organic degradation; antibacterial
properties are achieved by photocatalysis in a single unit (AIChE, 2015). Titanium dioxide (TiO2)
is the most commonly used material for the fabrication of photocatalytic
membranes due to its low cost, nontoxicity, and high chemical stability (AIChE, 2015). In the presents of ultraviolet (UV) light, Titanium dioxide is the most
studied semiconductor for photocatalytic applications where it produces
electrons and holes which has strong reduction and oxidation. When TiO2 is irradiated with photons,
electron–hole pairs are created (Teh et al. 2011). In aqueous system, holes
react with H2O or OH? which is adsorbed at the surface of
the semiconductor to produce OH radicals which are the most
oxidizing species in this process. On the other hand, electrons are trapped at
surface sites and removed by reactions with adsorbed molecular O2 to
form superoxide anion radical O2? (or H2O at
lower pH) (Vulliet et al., 2003). Some of the bacteria and viruses will be destroyed
by them which give TiO2 its antimicrobial property (Rahim et al.
2012).

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 The photocatalytic material can be used in a wide
range of degradation of organic pollutants in water, which adsorbs the pollutants
in the catalyst surface and then, CO2 and H2O are created
while not causing secondary pollution (Fujishima et.al, 2000 & Mital & Manoj, 2011). Photocatalytic membranes are the better choice compared to
the conventional membranes in terms of reducing membrane fouling and enhancing membrane
quality. The TiO2 photocatalytic process creates hydroxyl
radicals without adding any chemicals such as ozone or hydrogen peroxide,
whereby it is one of the most promising methods for removing pollutants from
water. (Hashimoto et.al, 2005). Hydroxyl radicals
(OH–) are the strongest oxidant after fluorine.

 

Heterogeneous
photocatalysis is a significant procedure for water treatment, because it allows
the degradation of organic compounds (Herrmann,1999). Unless the pollutants are
correctly removed, the polluted water will affect the photosynthetic activity
in marine life due to reduction in light penetration from the surface of water.
However, photocatalysis is still not routinely implemented for wastewater
treatment due to the low quantum efficiency resulting from inefficient solar
light harvesting and engineering aspects associated with large-scale use (Szabó
et.al, 2013).

 

Nowadays, natural based organic
membrane have noteworthy properties as they are biodegradable, environmentally
friendly, and stable to be incorporated with titanium dioxide for degradation
of organic pollutants in water. In this study, photocatalytic activity of
titanium dioxide – based natural organic membrane is examined. The main purpose
of this study is to entrap TiO2 powder onto organic membrane. Based on
this, it is necessary to form a natural membrane based on cotton linter and wool,
compare the ability of TiO2 entrapment on the membrane formed and compare the
performance of photocatalytic activity of TiO2 based membranes on organic dye. 

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