English abstract
About 90% of fresh water in the Sultanate of Oman comes from ground water. However, in the costal wilayat of the Al Batinah region, high level of salinization of ground water is taking place. Hence, many of the water wells are becoming between brackish and saline water, affecting the agriculture in the region adversely. Ions such as Na*, Ca2+ and Mg2+ were found in high levels in almost all samples with exceptionally high levels from Al Khabura farm well. Dehydrated carbon (DC) and sulfonated dehydrated carbons (SDC) were prepared from Omani date palm leaflets in a purpose of removing the metals from brackish water. Both carbons possess low surface area of 3,6 and 1,7 m g for DC and SDC, respectively. SDC showed less surface area but higher cation exchange capacity and metal uptake than DC. Sorption was low at low pH and maximum sorption took place in the range of pH 6-7 for all metals. Kinetic study showed that equilibrium was obtained within 2 hours from synthetic solution or brackish water with sorption data fitting pseudo second order kinetic model. Equilibrium data were found to fit well the Langmuir model with better uptake for SDC than DC due to the presence of the added sulfonic groups on the surface. Na* showed sorption-desorption phenomena in binary and ternary solutions in addition to the brackish water in kinetic and equilibrium studies. Sorption preference followed the order Ca?-> Mg2+ > Nat and this is related to their respective valency, hydrated size and charge density. Sorption capacity of Na*, Mg * and Ca2+ from single solution was found to be 7.04, 22.5 and 26.7 mg g for DC, respectively, and 11.4, 23.9 and 28.4 mg g» for SDC, respectively. DC and SDC can be reused for several cycles of metal sorption with high efficiency. Dynamic sorption proved efficient in metal removal from brackish water. SDC appears promising for being utilized in metal removal from brackish water
