Removal of Cs~(1+), Sr~(2+) and Co~(2+) from aqueous solutions by adsorption on natural clinoptilolite

摘要

The adsorption properties of local clinoptilolite (Serbia) towards Cs~+, Co~(2+), and Sr~(2+) were investigated by batch equilibration technique. The influence of equilibration time, initial metal cation concentration, solution pH and presence of EDTA on these properties was studied and discussed. Kinetic data were found to be well fitted with pseudo-second order kinetic model. Cs~+ is preferably adsorbed by the natural clinoptilolite, followed by Sr~(2+) and Co~(2+). The Langmuir adsorption isotherm was used to determine the adsorption capacities from both single and mixed metal solutions. At pH range of 3-12 the adsorption of Cs~+ remains almost constant, while at low pH (2-3) the adsorption is lesser. At initial pH range of 2-10 adsorption of Sr~(2+) remains approximately stable, whereas at initial pH > 10 adsorption increases significantly. The adsorption of Co~(2+) is low at low pH but increased remarkably with increasing pH and precipitated at pH > 8. Cs~+ adsorption on the clinoptilolite was not affected by the presence of EDTA, while the presence of EDTA hinders the adsorption of Co~(2+) and Sr~(2+) on clinoptilolite.