BRACKISH GROUNDWATER DESALINATION USING THE SYNTHETIC PA-g-AAC/TIO2 MEMBRANE

Abstract

The possibility of producing drinking water from brackish groundwater using synthetic polyamide grafted acrylic acid/ titanium oxide (PA-g-AAc/TiO2) membrane was studied. The optimum conditions for preparation of the synthetic membrane were PA concentration (7 % w/v of solvent), LiCl concentration (40 % w/w of PA), AAc concentration (20 % w/w of PA), TiO2 concentration (3 % w/w of PA), evaporation time (24 hr.) and temperature (70 °C). Brackish groundwater sample was taken from El-Maghara area, Mid. Sinai, Egypt and analyzed by the standard methods. The obtained results showed that the total dissolved solids (TDS) and ionic composition of permeate water decrease as the operation time increases. The cations and anions rejection (R %) showed that the divalent cations and anions are more rejected than the monovalent ones, where the order of cations rejection was R Mg 2+ > R Ca 2+ > R Na + , while the anions rejection was in the order R SO4 2->R HCO3 -> R Cl -. After the desalination process, the hypothetical salts of such sample do not change; but the change was only in its concentration expressed as TDS. The sequence of salts rejection (Rs %) related to initial concentration of each salt arranged was Rs MgSO4> Rs MgCl2 > Rs CaSO4 > Rs Ca (HCO3)2 >Rs NaCl. This can be explained according to Donnan theory.The produced water permeate has a low value of TDS (933 ppm), where the salt rejection and water flux are 70 % and 10.28 x10 -5 g/cm 2 .sec., respectively. This produced water is accepted by international standards for drinking water.