A. Ferraz et al., CONTROLLED-RELEASE OF 2,4-D FROM GRANULE MATRIX FORMULATIONS BASED ON6 LIGNINS, Journal of agricultural and food chemistry, 45(3), 1997, pp. 1001-1005
Six lignins were used to obtain granular controlled release matrix for
mulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The
water insoluble lignins were sourced from sugar cane (Saccharum offic
inarum) bagasse and Eucalyptus sp. and Pinus sp. woods. Each lignin wa
s characterized by its functional groups and molecular weight distribu
tions. 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 g
lassy matrix. Release rates determined in static water were correlated
to a diffusion-controlled mechanism according to the square root of t
ime. Principal component regression of the slopes of these lines showe
d that these depend inversely on the molecular weight and the total an
d aliphatic hydroxyls of the lignins. For the other functional groups
(aromatic hydroxyls, methoxyls, and carbonyls), the higher their conte
nts, the higher the diffusion and release rates.