Equilibrium and kinetic studies of adsorption of phosphate onto ZnCl2 activated coir pith carbon

C Namasivayam; D Sangeetha

doi:10.1016/j.jcis.2004.08.015

Equilibrium and kinetic studies of adsorption of phosphate onto ZnCl2 activated coir pith carbon

J Colloid Interface Sci. 2004 Dec 15;280(2):359-65. doi: 10.1016/j.jcis.2004.08.015.

Authors

C Namasivayam¹, D Sangeetha

Affiliation

¹ Environmental Chemistry Division, Department of Environmental Sciences, Bharathiar University, Coimbatore 641 046, India.

PMID: 15533408
DOI: 10.1016/j.jcis.2004.08.015

Abstract

Phosphate removal from aqueous solution was investigated using ZnCl(2)-activated carbon developed from coir pith, an agricultural solid waste. Studies were conducted to delineate the effect of contact time, adsorbent dose, phosphate concentration, pH, and temperature. The adsorption equilibrium data followed both Langmuir and Freundlich isotherms. Langmuir adsorption capacity was found to be 5.1 mg/g. Adsorption followed second-order kinetics. The removal was maximum in the pH range 3-10. pH effect and desorption studies showed that adsorption occurred by both ion exchange and chemisorption mechanisms. Adsorption was found to be spontaneous and endothermic. Effect of foreign ions on adsorption shows that perchlorate, sulfate, and selenite decreased the percent removal of phosphate.