Zeolite composites with hydroxyapatite formed on the zeolite surface were prepared for use as a slow-release fertilizer. Zeolite/hydroxyapatite composites containing ammonium and potassium ions were prepared by contacting calcium type zeolite with a mixed solution of ammonium phosphate and potassium hydroxide at 40°C for 8 hours. The composite was found to slow-release ammonium, potassium, and phosphate ions on contact with distilled water, allowing good plant growth.

Ion exchange is a technology applied across various industrial fields.

This article focuses on the application of ion exchange resins in electric power generation plants and the purification of electronic materials for semiconductors. It presents examples of industrial applications of ion exchange technology that the author has been involved in. Additionally, it describes the author’s personal journey with ion exchange, from student days to participation in the management of the Japan Society of Ion Exchange.