Controlled release of aldicarb from lignin loaded ionotropic hydrogel microspheres

Aldicarb loaded microspheres of carboxymethyl cellulose, CMC, of various co mpositions were prepared with the crosslinking action of AI(III). Into thes e microspheres, lignin was introduced as a filler to further regulate the r ate of release. The encapsulation efficiency was low (4.15-13.00%) due to t he high water solubility of aldicarb. Release into aqueous media was quite rapid and almost complete within 24h. Initial stages of the release (60% of AS released) was investigated to determine the release mechanism and it wa s found that release from the microspheres was governed by Fickian diffusio n. Among the various parameters, the ratio of lignin to CMC and aldicarb to CMC were found to be influential on the rate of release from the crosslink ed CMC-lignin microspheres. The soil behaviour confirmed the delayed releas e effect of the controlled release formulation compared to Temik (a commerc ial preparation of aldicarb), especially when lignin was incorporated.