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الثلاثاء، 5 أغسطس، 2014

Desalination Using Different Pertration Techniques

Author        : Wesam Gaber Nasr Kandeel
Degree        : M.Sc. Chemical
Title: Desalination Using Different Pertration Techniques

 Abstract
SUMMARY In the present work, desalination using the present type of supported liquid membrane (SLM) and the bulk liquid membrane (BLM) techniques have been investigated in the desalination of saline water. For the SLM, a simple apparatus devised and constructed in our lab, was used to conduct the experiments. Various factors that would affect the progress of desalination were studied and these were: concentration of simulated sea water in DP, presence of emulsifier or mobile carrier (MC) in the LM, concentration of MC in LM, presence of polyelectrolyte (sequestering agent (SA)) in the RP, presence of magnetic stirring, and speed of stirring. The volume ratio ofDP to RP was kept constant at 2:1. Type and thickness of LM (1,2 dichloroethane) was kept constant. Cellophane constituted the support for the LM. The results obtained indicated that the present type of SLM desalination is not a promising technique, which requires further profound study and investigation. The most important findings emphasized the importance of the presence of a MC in the LM to enhance mass transfer through the LM and that an optimum concentration of MC existed. Also the importance of stirring in promoting mass transfer by minimizing the boundary layer adjacent to the cellophane support was clarified. The best conditions arrived at were, MC = 0.1286 g (Crown ether (CE)), SA = 0.5 g (soluble starch (S.S)), slow stirring (100 rpm) of DP and using DCE as LM, 2 mm thick. The minimum time was found to be very long, during which total desalination might have taken place. As regards desalination using the BLM, a simple apparatus devised and constructed in our lab was used to conduct the experiments. Variables, which would affect the degree of desalination were investigated, and these were: volume ratio of DP to RP, presence of SA in the RP, quantity and type of organic LM and presence ofMC in the LM and its quantity. Stirring speed and volume ofLM were kept constant at 100 rpm and 130 ml respectively. The results showed that all the variables had an effect on the progress of desalination to different extents. The results were presented as (Ct/Co)-time curves, concentration-time curves and mass-time curves in the DP and RP and in the LM phases. It was found that desalination using the BLM technique was much more promising and rapid than the SLM technique. Using the BLM technique, complete desalination could be effected in almost 8 hrs under the best conditions used in the present work which were, DP = 150 ml and RP = 50 ml (DP : RP = 3 : 1), MC = 0.175 g , SA = 0.5 g of soluble starch, DCE as LM and volume ofLM = 130 ml, accompanied with slow stirring (100 rpm) ofLM.

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