Study of Iranian natural clay as an effective adsorbent in removal of chloride from aqueous solutions, thermodynamic and kinetic investigations

High chloride concentrations in freshwater can be harm for human, plants and aquatic organisms. Many techniques have been adopted to reduce the amount of chlorides in wastewater. Natural clays are abundantly available low-cost natural resource which is nontoxic to the ecosystem. In this research, we study two areas' clay (Malek-Siah-Kouh and Hormak clay) as a sorbent for chloride ion removal. Quantitative measurments are accomplished by UV/Vis technique. The influential variables were studied on absorption including; rotation temperature, grain sizes, pH of the solution, adsorbent amount, initial concentration of chloride ion and contact time of the removal process. The optimum values of the rotation(al) speed, temperature, grain size, absorbent amount and the contact time for Malek-Siah-Kouh were estimated at ۱۰۰rpm, ۴۰ œ C, ۲۰۰- ۳۲۵, ۰.۴g and ۱۵ min, and for Hormak were estimated at ۱۰۰rpm, ۳۰ œ C, <۵۰۰, ۰.۱g and ۱۵ min, respectively. Kinetic studies showed that a pseudo-second order kinetic model is followed. The adsorption followed Freundlich isoterm. As a result we found that Malek-Siah-Kouh and Hormak clays could be used in water and wastewater treatment processes as cheap, environmentally friendly, and safe natural chloride adsorbents.

Keywords:

chloride removal , clay , kaolinite , adsorption.