الملخص الإنجليزي
Abstract
This study aims to prepare and to test chelating dehydrated carbon (CDC) together with de hydrated carbon (DC) for the sorption of Mg * and Ca** from Brackish water. In this study, two samples of brackish water collected from farm wells in Sohar and Barka. The analysis shows high levels of salinity falling in brackish water to saline water. DC that is prepared from date palm leaflets using sulfuric acid treatment and acts as a weak cation exchanger was functionalized successfully to produce a chelating dehydrated carbon (CDC) using tetraethylenepentamine (TEPA). DC and CDC possess low surface areas of 11.25 and 6.00 m'lg, respectively with high contents of surface functional groups. Both sorbents were tested for the sorption of Mg2+ and Ca2+ from synthetic and brackish water. pH study showed better metal sorption at initial pH of 5-9 with better performance for Ca2+ than Mg2+ on both sorbents. Sorption from metal mixture showed a competitive effect decreasing the sorption of both metals. The kinetic study showed that equilibrium was obtained within 2 hours from synthetic solutions and brackish water with data fitting the pseudo second order model. Mg2+ sorption on CDC showed an extent of desorption with the progress of time. The equilibrium data were found to fit more the Langmuir model than the Freundlich model. Removal effi ciency of Ca2+ and Mg** has increased with sorbent mass increase. The study shows that Ca2+ and Mg2+ can be separated on CDC, unlike DC, from brackish water almost excluding Na*. The sorbents showed better performance at low salinity level like Barka water sample, however, it requires successive batch sorption cycles to achieve complete removal of Ca2+ and Mg2+. CDC shows promising selective sorption properties of Ca2+ and Mg2+ from brackish water in addition to being cheap, recyclable and sustainable.
