Controlled release of 2,4-D from granule matrix formulations based on six lignins
1997
Ferraz, A. | Souza, J.A. | Silva, F.T. | Goncalves, A.R. | Bruns, R.E. | Cotrim, A.R. | Wilkins, R.M.
Six lignins were used to obtain granular controlled release matrix formulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The water insoluble lignins were sourced from sugar cane (Saccharum officinarum) bagasse and Eucalyptus sp. and Pinus sp. woods. Each lignin was characterized by its functional groups and molecular weight distributions. The formulations were prepared by melting the 2,4-D and mixing in the lignins individually and then granulating (to 0.7-1.0 mm) the glassy matrix. Release rates determined in static water were correlated to a diffusion-controlled mechanism according to the square root of time. Principal component regression of the slopes of these lines showed that these depend inversely on the molecular weight and the total and aliphatic hydroxyls of the lignins. For the other functional groups (aromatic hydroxyls, methoxyls, and carbonyls), the higher their contents, the higher the diffusion and release rates.
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