Synthesis and Characterization of Modified Zeolite 4A As Slow-Release System for Methomyl

Date of Award

5-2022

Document Type

Thesis

Degree Name

Master of Science in Chemistry

First Advisor

Ronaldo M. Fabicon, PhD

Abstract

Fertilizers and pesticides are widely used by developing countries such as the Philippines for agricultural purposes. One commonly used pesticide is methomyl, a broad- spectrum carbamate with high water solubility. It targets from immature stages to adult insects, but its strong hydrophilic nature results in surface and groundwater contamination and residues were also detected in various crops. Advantages of the use of agrochemicals come with negative impacts thus, versatile tools to reduce these problems are explored. One of which is the slow delivery technology. This technique is used to control the release of active compounds and direct certain chemical properties such as solubility, biocompatibility, and degradability. Zeolite is a crystalline aluminosilicate material formed from the linking of tetrahedral aluminate and silicate sharing common oxygen. Structure of zeolite allows sites for ion exchange, adsorption of small molecules, and porous sites for water molecules giving zeolite a molecular sieve framework. Cage-like zeolite is also used as delivery system for molecules that are very hydrophilic and reacts readily with the environment. Microwave-assisted modification of zeolite 4A with carboxymethylcellulose as modifying agent was done in this study to serve as delivery system for methomyl. Characterization of modified zeolite showed a decrease in crystallinity as evident in the broadened peaks in the XRD pattern. Methomyl was incorporated into the modified zeolite as confirmed by thermogravimetric analysis (TGA) and the loading efficiency determined by reverse-phase HPLC was 11.99%. Release profile of the loaded pesticide sample following leachate test using soil column showed significant difference compared to the commercially available methomyl. Further study on improving the loading efficiency will lead to increased concentration of the incorporated pesticide that will be delivered slowly through modified zeolite as the carrier material.

Keywords: zeolite, microwave-assisted, slow-release, methomyl

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