POTASSIUM ADSORPTION BY NATURAL ZEOLITE IN KNO3 SOLUTIONS
Abstract
Natural zeolite – clinoptilolite – is widely used for improving soil properties and for increasing the soil ion exchange capacity. Clinoptilolite with adsorbed potassium ions can be used as a cheap environmentally friendly fertilizer containing one of the main plant nutrients. The adsorption of potassium by the natural clinoptilolite occurs due to ion exchange with calcium, sodium and magnesium. The adsorption was found to take place relatively soon at the beginning and then to slow down. Ion exchange equilibrium was not reached and potassium adsorption was in progress even after 400 hours. This was due to the slow desorption of calcium ions from deeper zeolite
channels. The adsorption level was increased up to 15 mg/ml concentration of K+ in the KNO3 solution. When the concentration of solution was higher, adsorption of potassium ions increased slightly. Natural zeolite containing 6% of K2O was obtained, and it can be used as a potassium fertilizer.
