الفهرس 
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Abstract
Fresh water is already a limiting resource in Egypt and many parts of the world. In the next decades, it will become even more limiting due to increased population, urbanization, and climate change. This limitation is caused not just by increased demand for water, but also by pollution in freshwater ecosystems. Pollution decreases the supply of usable water and increases the cost of purifying it. Major water pollutants include a variety of organic and inorganic chemicals such as heavy metals, dyes and industrial compounds. They can affect human health and/or interfere with industrial or agricultural water use. If the level of a pollutant in the water supply exceeds an acceptable level for given water use, the water is considered unsafe or too degraded for that use. Solutions to such pollution problems, therefore, usually focus on reduction of pollution at the source and/or treatment of the polluted water prior to use.
Among the physicochemical water treatment processes, adsorption is found to be highly effective, cheap and easy to adapt. It is quite selective, effective, and is able to remove various levels of soluble heavy metals in solution. The need for effective and economical removal of unwanted materials resulted in a research for unconventional methods and materials that might be useful in this field. Sawdust is one possible material because it is produced in large quantities at sawmills as a solid waste. Sawdust contains primarily lignin and cellulose. In this context, sawdust of Pinus sylvestris is particularly interesting in Egypt because of its high availability and low cost. In addition, it is a renewable resource, and does not need to be regenerated after it has been used to remove the metals.
This thesis involves three chapters include:
Chapter (I):
This chapter includes introduction which contain the presence of heavy metals in the aquatic environment, its influence and the methods of metals removal from aqueous media. Also includes the aim of the work and literature survey.
Chapter (II):
Chapter two includes experimental work which involve preparation of the standard metal solutions and adsorbent used and the instruments and apparatus which used in adsorption process and measurements. Adsorption experiments were carried out using batch technique. The influences of solution pH, contact time, initial metal ion concentrations, and adsorbent dose on the removal efficiency have been investigated.
Chapter (III):
This chapter involves review of the results and discussion, tables and figures which illustrate the results. The pH experiments showed that the removal efficiency of Pb2+ and Cd2+ ions depends on pH; it increases with the increase in pH value reaching the maximum removal at pH 6 and then remained almost constant. Increase in mass of adsorbent leads to increase in Pb2+ and Cd2+ adsorption due to increase in number of adsorption sites. from the results obtained it is apparent that, in the initial metal concentration ranges from 10 to 50 mg/l, sawdust modified with urea or thiourea has highest removal efficiencies (97.0-98.3%) for removal of Pb2+ and Cd2+ ions from aqueous solutions compared to those of raw sawdust (86.7-95 %) used in this study.
Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated. In general, the experimental equilibrium data of adsorption of cadmium and lead ions on raw and modified Pinus sylvestris sawdust fitted well to both Langmuir and Freundlich adsorption isotherms. This leads to the conclusion that the surface of sawdust is made up of small heterogeneous adsorption patches which are very much similar to each other in respect of adsorption phenomenon.
The results of treatment of some polluted water samples showed the efficiency of Pb2+ ions removal by adsorption (initial Pb2+ concentration ranged from 1 - 10 mg/l) is ranged from (86 - 86.7%); from (96 - 97.5%) and from (97.5 - 98%) using (R-SD), (U-SD) and (TU-D), respectively. In case of cadmium ions the results shows that the efficiency of Cd2+ ions removal by adsorption (initial Cd2+ concentration ranged from 1 - 10 mg/l) is ranged from (84.3 - 93.7%); from (97.6 - 98.4%) and from (97.5 - 98.3%) using (R-SD), (U-SD) and (TU-D), respectively. These facts suggest that the raw and modified sawdust present high potential to remove heavy metals from industrial wastewaters. Moreover, the removal of these kind of metal ions from industrial wastewaters is important to Egypt both environmentally or/and for water re-use.