الفهرس 
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Abstract
Water is very essential for all living beings and safe drinking water is vital for
all forms of life. Even though the majority of the earth’s surface is covered with water,
there is a serious scarcity of drinking water in most countries. Fresh water shortage has
become a major issue influencing the economic and social development in many nations
because of the fast-rising demand for water resources. As a solution, desalination of
seawater is recommended. A wide range of conditions can benefit from advanced
desalination systems that treat seawater and brackish water. There are numerous
challenges to desalination, including significant energy consumption. Solar
desalination would be a helpful long-term operation to produce fresh water and has
gained many interests in several applications.
In this context, photo-thermal membranes have been produced and they can be
a fascinating way that can effectively harvest and convert sunlight into localized heat
and then vaporize water to generate steam in a technique called direct Solar Steam
Generation (DSSG) technology. Developing of eco-friendly and low-cost membranes
with an acceptable production rate of clean water using the DSSG technology is a
tedious equation which could be managed through the current work. In this regard, the
main goal of the thesis is the preparation and characterization of composite gel
membranes for water treatment using solar energy. Different composite gel membranes
were prepared from different ratios between natural and synthetic polymers, in the
presence of two different solar absorbers.
The five natural polymers are chitosan, cellulose, cellulose acetate, gum Arabic
and sodium alginate, while the only the synthetic polymer is polyvinyl alcohol using
graphene oxide or polypyrrole as solar absorber. All the prepared materials and
membranes are characterized using FTIR,UV-Vis,contact angle goniometer and SEM.
The results demonstrated that sodium alginate is the most effective polymer
with an evaporation rate of 4.33 kg m-2
h
-1
at the 3:1 ratio of (SA:PVA). The evaporation
rates are improved by using photo-absorber (PPy or GO) and BioCuO nanoparticles to
increasing membrane absorption capacity for solar energy, improving the evaporation
rate and membrane performance.
The thesis is presented in four main chapters as the following:
The first chapter: includes introduction of the thesis presenting the world water crisis,
freshwater scarcity, and its solutions.
The second chapter: presents the literature survey on the previous works concerning
direct steam generation and photo-thermal membranes with their compositions.
The third chapter: discusses the experimental methods used in the work. First, the
preparation of absorber materials, marine extract, and photothermal membranes.
Second, characterization of all prepared materials (graphene oxide, polypyrrole and
marine extract and the prepared membranes) using SEM, FTIR, UV and contact angel
goniometer. Finally, the chapter evaluates the performances of the prepared gel
membranes through evaporation experiments, by recording the evaporation rates and
measuring the concentrations of major ions before and after the experiment.
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The fourth chapter: presents the results and discussion including: characterization of
the prepared materials and membranes. Studying the effect of different polymers
(sodium alginate, gum Arabic, chitosan, cellulose and cellulose acetate) on the
evaporation rate in order to find the most effective membrane. The work demonstrated
that the composite membranes from sodium alginate, PVA at the all the ratios, in
particular (3:1), are the most effective. Also, the chapter involves the positive impacts
of using additives and different absorbers (graphene oxide and polypyrrole) on the
evaporation rates