Abstract
In the present work, a prototype was devised and constructed as a preliminary step for the development of industrial scale process in which desalination by an emulsion liquid membrane (ELM) technique takes place. The process is intended to be a breakthrough in the field of desalination, which should compete with the currently used reverse osmosis (RO) technique. A drawback of RO is the high cost of membrane and intensive pretreatment of seawater. The prototype consists of three stages: emulsion formation, desalination operation, and separation of the product into two phases (desalinated water and spent emulsion). The latter could be then adjusted and recycled for reuse in a second cycle. Several investigated factors which could affect the desalination process were: initial concentration (Ci), volume ratio of liquid membrane (LM) to receptor phase (RP), quantity of emulsifier, type of liquid membrane, type and quantity of sequestering agent (SA), time and power of ultrasonication (US), presence of mobile carrier (MC) and finally treatment ratio (ratio of volumes of donor phase (DP) to emulsion) (TR). The best conditions arrived at were: volume ratio of LM: RP = 4: 1, necessary in forming a stable emulsion. The optimum quantity of MC was found to be 6.86 g Span 80 for 80 ml chlorobenzene and 20 ml 20% soluble starch, so that best transfer of the NaCl could take place from DP to RP. Soluble starch (2% b. w.) is a suitable sequestrant for NaCl, chlorobenzene was better than chloroform, the latter is better than Soltrol 220 as LM. It was also found that 5 min at 180 Watts of US to provide a stable emulsion. The quantity of emulsifier and Ci are of crucial importance that affects directly the desalination process.