Study on desalination by a flowing liquid membrane
Desalination is characterized by rapidly evolving technologies. These technologies are divided mainly into thermal and membrane processes. Thermal processes, however, have numerous limitations, which include intensive use of energy and corrosion problems while membrane processes suffer from membrane fouling and high membrane cost and other problems. Liquid membrane (LMs), on the other hand, which have been discovered in 1968 by Li have no pores to be blocked and cannot be fouled like solid membranes. They also exhibit higher permeabilities and higher selectivities than solid membranes. However, their main problem is the method of containing the liquid between the two miscible but separated donor phase (DP) and receptor phase (RP). LM techniques include mainly emulsion LMs, supporting LMs, bulk LMs, hollow fiber contained LM, electrostatic pseudo LM, spirally wound LMs, and flowing LM sectâ ¦. Desalination using emulsion LMs has been accomplished effectively and for the first time, by Naim (2001) and has been investigated using a supported LM by Naim and Monir (2002). In the present work desalination was attempted using the flowing LM in which the saline DP and RP are made to flow either co- or counter- currently to each other while being separated by two cellophane sheets that are made to contain the organic membrane liquid. Variables, which could affect the degree of desalination, have been investigated in this work. The variables included volume ratio of DP to RP, presence of sequestrant in the RP, type and quantity of sequestering agent, presence or absence of LM, type of membrane liquid, type of organic LM, presence or absence of mobile carrier (MC) in the LM and its quantity, flow rate of DP and RP, and presence of supporting screens to support the cellophane sheets that contain the LM. In all the experiments simulated seawater was used (35-41 g NaCl/L). The results showed that all the variables had an effect on the progress of desalination to different extents, but the factors of prime importance were flow rates of DP and RP, volume ratio of DP to RP, quantity and type of complexation agent in RP, and type of membrane liquid. The results also showed that actual flow of the LM would have surely improved the results, but which could not be fulfilled due to technical difficulties.
- Conference Paper