Abstract: Release of the herbicide acetochlor was controlled by encapsulating it into the gel carrier that was obtained from the crosslinking of carboxylmethylcellulose (CMC) with Fe³⁺ ions, which is beneficial for reducing contamination of herbicides. The required time for 50% of acetochlor released into water (t₅₀) was used to compare the release rate. The results indicated that, the t₅₀ values from CMC hydrogels were below 8h, but the values from dried gels were improved to 100h. The less amount of herbicide loading in gel formulations resulted in a slower release rate. The release data were analyzed with a controlled release model, and the results indicated that the release of herbicide from dried gels was dominated by a diffusion mechanism. IR spectrum confirmed the interaction between CMC macromolecules and acetochlor through hydrogen bonding.

Key words: carboxymethylcellulose, controlled release, herbicide, gel