“Synthesis and Evaluation of Ahoko Kaolin-Derived Zeolite A and Phillipsite-Supported Fertilizer for Enhancing Agronomic Characteristics of Tomato (Lycopersicon esculentum)”
Abstract: This study addresses the issue of environmental pollution caused by highly leachable conventional fertilizers and the challenge of low cation exchange capacity in farmlands, leading to reduced soil fertility and agricultural yields. The objective is to synthesize and characterize Zeolite A and Phillipsite from Ahoko Kaolin and assess their capacity to delay plant nutrient release, focusing on tomato growth, fruit yield, nutritional quality, and postharvest soil residues.
Zeolite A and Phillipsite were synthesized from Ahoko Kaolin using hydrothermal methods, with optimization of synthesis parameters achieved through central composite design. The surfaces of the zeolites were modified using Hexadecyltrimethylammonium (HDTMA) via an adsorption process, and they were further enriched with Nitrogen, Phosphorous, Potassium (NPK). Isotherms, kinetics, and thermodynamics parameters of Zeolite A and Phillipsite were determined, along with the desorption rate of the synthesized zeolite-based fertilizers using percolating columns.
The effect of Zeolite A, Phillipsite-based fertilizers, and NPK 15:15:15 fertilizers on tomato crop agronomic characteristics were evaluated. The results indicated high crystallinity for synthesized Zeolite A (99.92%) and Phillipsite (72.26%), with specific surface areas of 296.178 m2/g and 361.50 m2/g, respectively. Crystallization time was found to be the most significant factor affecting crystallinity. Modification of Zeolite A with HDTMA led to a maximum adsorption capacity of 3.10 mg/g, while Phillipsite with HDTMA reached 3.40 mg/g.
Freundlich isotherm model provided the best fit for experimental adsorption data of Zeolite A, while Dubinin Radushkevich isotherm model was suitable for Phillipsite adsorption data. The pseudo-first-order model represented the adsorption kinetics for both zeolites. The Gibb’s free energy values (-27.045 kJ/mol for Zeolite A and -61.799 kJ/mol for Phillipsite) indicated the spontaneity of the adsorption processes, while the negative enthalpies suggested physical and exothermic adsorption.
The Zeolite A-based fertilizer exhibited a slow release effect for phosphate, with a rate constant k2 of 1.8 x 10-3 h-1, outperforming KH2PO4 with its rate constant of 3.84 x 10-3 h-1. Similarly, nitrate-loaded Zeolite A-based fertilizer had a slower release compared to NH3NO3. Tomato crops treated with Zeolite A and Phillipsite-based fertilizers showed significantly higher leaf counts (54.2 and 46.5, respectively) compared to NPK 15:15:15 (25.7) after 11 weeks of transplanting in 2018. Fruit yield and vitamin C content were also significantly improved with Zeolite A and Phillipsite-based fertilizers compared to NPK.
Furthermore, soils treated with Zeolite-based fertilizers retained significantly higher plant nutrients compared to NPK-treated soils post-harvest. The findings indicate that zeolite-based fertilizers substantially enhance fruit yield, nutritional content, and postharvest soil quality compared to NPK fertilizers.
“Synthesis and Evaluation of Ahoko Kaolin-Derived Zeolite A and Phillipsite-Supported Fertilizer for Enhancing Agronomic Characteristics of Tomato (Lycopersicon esculentum)”