Development of Novel Zeolite-Based Controlled-Release Zinc Fertilizers: Synthesis, Characterization, and Release Kinetics

Increasing demand of zinc fertilizers for sustainable food production and low micronutrient fertilizer use efficiency (2–3%) advocate the development of controlled-release fertilizers to enhance the efficacy of inputs and mitigate the environmental pollution caused by leaching losses. In the present work, an ecofriendly zeolite Y-based zinc fertilizer was synthesized via a facile reflux method. The structural and morphological characteristics of the synthesized zinc fertilizer were examined by Fourier transform infrared, X-ray diffraction, field emission scanning electron microscopy–energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller techniques. The characterizations confirmed the presence of 4.9% (wt) zinc in the synthesized fertilizer without alteration in the zeolite framework structure. Langmuir and Freundlich models were used to study the zinc adsorption of zeolite. The Langmuir isotherm was found to best fit the experimental data with a maximum zinc adsorption capacity of 130.72 mg/g. The zinc release studies were carried out in water as well as in soil, and the zinc release mechanism was studied by fitting different release kinetic models. About 55% of the zinc was released in water in 10 days, while in soil, it was found that about 0.017% of the zinc was leached out in 21 days. The mechanism of zinc release from the zeolite-based zinc fertilizer followed the Korsmeyer–Peppas model, indicating zinc diffusion from the synthesized fertilizer as a non-Fickian process, and the zinc release in soil followed the Higuchi model, describing the zinc release through dissolution and diffusion, confirming the controlled release properties of the synthesized fertilizer. Hence, the present findings offer new opportunities for the development of zeolite Y-based fertilizers for controlled utilization of plant nutrients for environmentally friendly and sustainable agriculture.