A preliminary study of chemical property and thermal stability of potassium chloride encapsulated in starch-alginate matrix

A potassium controlled-release fertilizer was fabricated in a starch-alginate matrix by using calcium chloride as a cross-linker. 16 formulas were designed with varying amounts of alginate and potassium chloride with the same amount of starch and calcium chloride, and most of the formulas can form beads successfully. High sodium alginate and low potassium chloride assembled better shape and higher encapsulation efficiency. The highest encapsulation efficiency ratio of starch, sodium alginate, and potassium chloride was 5:1:10 in the 16 formulas. The bonding of alginate and starch, and calcium chloride were evidenced by FTIR, and the study of TGA revealed good thermal stability and compatibility between the polymers and potassium chloride.