Process Optimization for the Production of Potassium-Carrageenan Nanofertilizer by Ionic Crosslinking

The effects of nutrient loading, mixing temperature, time and type of drying method (freeze and oven drying) on the total K content of the potassium-carrageenan fertilizer formulated through ionic crosslinking was evaluated. Direct effect on the total K was observed at varying nutrient loading at nutrient-to-carrier mass ratios 1:2 and 2:1 with no significant effect at varying mixing conditions and drying. Instead, variations are observed on the qualitative properties of potassium-carrageenan such as viscosity due to the thermoreversible properties of kappa-carrageenan. A linear model based on the significant factor was generated to predict the potassium content at the range of nutrient ratio adjusted to 1:2 to 1.5:1 to obtain a center ratio 1:1, with a maximum predicted value of 26.64% w/w. Potassium and carrageenan crosslinking yield an organized helix structure based on SEM micrograph with crystalline structure. Freeze dried fertilizers yield smaller particle sizes about 300nm due to its easily size reducible physical appearance than in oven-drying where film like particles are observed. Further, a decrease in absorbance is observed at increased potassium concentration. Evaluation of release pattern using buffer system shows slower release of nutrient using carrageenan carrier compared to conventional fertilizer at pH sensitive environment