Recovery of K+ from concentrates from brackish and seawater desalination with modified clinoptilolite

Using modified clinoptilolite, column sorption-elution was carried out for recovering potassium from concentrates, a simulative by-product of brackish and seawater desalination. A breakthrough curve was obtained, and then the total and breakthrough capacity values of the modified clinoptilolite were calculated. The K+ on the zeolite was quantitatively eluted with 25% NaCl solution, and the concentration of K+ in the obtained primary K+-enriched solution was 7.5730 g/L at levels above six times of raw concentrates. Three consecutive sorption-elution cycles were implemented, and the total capacity values remained almost constant, demonstrating the good reusability of modified clinoptilolite. Both Thomas and Yoon-Nelson models could describe the breakthrough curves well, and some column parameters required for the process design were determined. All these could give some contributions to utilization of chemical resources in seawater.