Controlled release formulations of alachlor based on calcium alginate

Pepperman, Armand B.; Kuan, Jui-Chang W.

doi:10.1016/0168-3659(94)00111-7

Cited by 46 publications

(32 citation statements)

References 7 publications

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“…The leaching of pesticides during the preparation of alginate beads has been improved by synthesizing bi-polymeric beads of alginate with other natural polysaccharides. Alginateclay complexes have been used for various pesticides: diquat bromide [7], 2,6-dichlorobenzonitrile [8], carbofuran [9], thiobencarb [10], metribuzin and alachlor [11,12] and diuron [13]. Starch has been incorporated into alginateclay formulations of thiram [14,15].…”

Section: Introductionmentioning

confidence: 99%

Environmentally Friendly Formulations of Trifluralin Based on Alginate Modified Starch

Onyido¹,

Sha’Ato²,

Nnamonu³

2012

JEP

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In line with global efforts towards sustainable agriculture, the use of starch modified with alginate in the preparation of slow release formulations of the herbicide trifluralin was investigated. Trifluralin was encapsulated in starch-alginate beads, and the resulting slow release formulations (SRFs) characterized using scanning electron microscopy (SEM) and Fourier Transform infrared (FTIR) spectroscopy. Herbicide release from the SRFs was studied in water and compared to release of technical grade trifluralin. Three sets of formulations were made by extrusion into 0.25 M calcium chloride solution: starch/alginate (SSTRF), amylose starch/alginate (ASSTRF) and amylose starch/alginate/groundnut oil (ASTRGNO) beads, and the fourth was from gelatinized starch at 75˚C (SSTRF2). The results showed highly porous spherical beads, the amylose/alginate beads bigger and less porous than the starch/alginate beads with diameters of 2.79 ± 0.01 and 2.37 ± 0.01 mm; porosity of 54.67 ± 0.2 and 60.59% ± 0.2% and swelling of 54.09 ± 0.2 and 61.22% ± 0.2%, respectively. All sets of beads exhibited reduced crystallinity of trifluralin. FTIR revealed a shift to lower wavelength of the carbonyl stretching vibrations from 1750 to 1725 cm -1 and a reduction in intensity of the carboxylate peaks of alginate, suggesting interactions between the formulation components that make for good slow release. 96% of technical grade trifluralin (TGTRF) was released into a 50:50 pH 6.5 Buffer/Methanol aqueous medium in 24 hrs. However, for the starch/TRF formulation, SSTRF, only 9.33% herbicide was released after 24 hrs and 34.94% after 672 hrs (28 days). The amylose starch/TRF formulation released 13.61% herbicide in 24 hrs and 46.95% in 672 hrs, a 12% increase in release of TRF over the starch formulation. Encapsulation in starch produced 65% slow release of TRF and gelatinization achieved 84% retardation. Use of amylose starch as matrix caused 53.15% delay and addition of groundnut oil resulted in 80.87% retardation of TRF release. Encapsulation of TRF in starch/alginate beads is a veritable way of reducing negative environmental effects.

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Section: Introductionmentioning

confidence: 99%

Environmentally Friendly Formulations of Trifluralin Based on Alginate Modified Starch

Onyido¹,

Sha’Ato²,

Nnamonu³

2012

JEP

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“…Desta forma, pode-se reduzir a lixiviação do xenobiótico e seus metabólitos ao longo do perfil do solo, bem como as perdas por evaporação e fotólise. 15,16 Consequentemente, esta prática pode contribuir para a mitigação do impacto ambiental causado pela intensa utilização destes produtos na agricultura brasileira.No Brasil alguns estudos que investigam herbicidas de liberação controlada empregando silício no sistema carreador, que é um elemento abundante no solo, já foram realizados. Para os pesticidas 2,4-D e diuron, imobilizados em superfície de sílica-gel tendo como…”

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Formulações de atrazina em xerogéis: síntese e caracterização

Ávila¹,

Leite²,

Dick³

et al. 2009

Quím. Nova

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Recebido em 16/6/08; aceito em 27/3/09; publicado na web em 10/8/09 ATRAZINE FORMULATIONS IN XEROGELS: SYNTHESIS AND CHARACTERIZATION. In this study, controlled release formulations of Atrazine (ATZ) were synthesized by the sol-gel method and characterized by elemental, FTIR, SEM, BET and DSC analyses. The release kinetic of ATZ from the formulations in CaCl 2 0.01 mol L -1 medium was monitored by UV/Vis spectroscopy. In all formulations, ATZ was physically dispersed on the Si-polymer, and the dispersion grade decreased with increasing amount of herbicide. The ATZ release kinetics was controlled mainly by dissolution, and the data could be fitted to the Korsmeyer -Pepper model. The ATZ as xerogel presents a lower affinity for soil than as granulated form.Keywords: sol-gel; sorption; soil. INTRODUÇÃOA atrazina ([2-cloro-4-(etilamino)-6-(isopropilamino)-1, 3,5-triazina]) é um herbicida empregado principalmente nas culturas de canade-açúcar e de milho, as quais ocupam, respectivamente, o segundo e o terceiro lugar da produção anual nacional.1 Aproximadamente 17.10 6 hectares do território nacional são utilizados para estas culturas, sendo as mesmas responsáveis por 36,5% do consumo anual nacional de herbicidas. 1O uso intensivo da atrazina no mundo e sua considerável mobilidade nos solos têm contribuído para que níveis acima do limite permitido sejam frequentemente detectados em águas de superfície e subterrâneas na Europa 2,3 e nos Estados Unidos. 4 Os limites máximos permitidos para a atrazina em águas para consumo humano são de 3 µg L -1 nos Estados Unidos 5 e 0,5 µg L -1 na Europa. O tempo de meia vida da atrazina pode variar de 2 meses a 6 anos, dependendo das condições do meio. Este herbicida apresenta vários metabólitos, que possuem diferentes graus de toxicidade e tempo de meia vida, sendo os mais comuns a hidroxiatrazina e a dietilatrazina. 6 Uma molécula de herbicida ao alcançar o solo pode ser absorvida pelas plantas, manifestando seus mecanismos de ação; sofrer transformações químicas que promovem sua volatilização e decomposição fotocatalítica; ser degradada pela ação de micro-organismos ou enzimas (biodegradação); ser sorvido pelo solo ou por resíduos vegetais. 7O produto sorvido pode ser removido por percolação ou pela erosão até corpos de água adjacentes, onde pode persistir contaminando e afetando a vida aquática. Por outro lado, a sorção do herbicida no solo pode retardar ou impedir o movimento das moléculas no meio, afetando os processos de transformação e transporte, a eficiência agronômica do ativo e a contaminação do ambiente. A recomendação da dose de aplicação de um herbicida de baixa solubilidade em água, tal como a atrazina, é geralmente feita baseando-se no teor de matéria orgânica do solo, que é o seu principal sorvente. Quanto maior o teor de matéria orgânica maior a retenção do herbicida e, portanto, maior será a dose recomendada para que seja atingido o efeito biocida almejado. 8 O processo de sorção de um herbicida pode ser caracterizado quantitativamente pelo coeficiente de distribu...

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“…Alachlor has been classified as human carcinogen and its maximum contaminant level (MCL) was established at 2 µg/L by the United States Protection Agency (USEPA) in 1992. An evaluation of rural drinking water sources in the United States indicated that 97% is derived from underground sources, along with 55 % of all livestock water and 40 % of all irrigation water (Pepperman and Kuan, 1994). Ground water studies in Virginia by Gallagher et al (1996) indicated the presence of alachlor in 18 percent of the samples at levels mostly < 1 µg/L.…”

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Time-Related Analysis of Alachlor Concentrations in Florida Wells

Simons¹,

Fisher

1997

Bulletin of Environmental Contamination and Toxicology

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Cohen et al, 1986 reported alachlor detections in four states (Iowa, Nebraska, Pennsylvania, and Maryland) at concentrations between 1 and 10 µg/L (parts per billion). Alachlor is a herbicide used in corn, soybean, and peanut production. 2.4 million acres were treated in 1994 with alachlor and 6.6 million pounds were used (The Ground Water Gazet). Alachlor(2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide is a herbicide widely used in the United States Both has been determined in the ground water (Aga et a1.,1994). Alachlor has been classified as human carcinogen and its maximum contaminant level (MCL) was established at 2 µg/L by the United States Protection Agency (USEPA) in 1992. An evaluation of rural drinking water sources in the United States indicated that 97% is derived from underground sources, along with 55 % of all livestock water and 40 % of all irrigation water (Pepperman and Kuan, 1994). Ground water studies in Virginia by Gallagher et al (1996) indicated the presence of alachlor in 18 percent of the samples at levels mostly < 1 µg/L. Richards et al (1995) sampled nearly 35,000 wells in Ohio, Indiana, Illinois, West Virginia, and Kentucky. 1.1 percent of the wells were above 2 µg/L for alachlor in this survey. No information was given on the persistence of alachlor in well water that can be expected once contamination has been detected. The following observations are therefore being reported. Over 200 wells were sampled in Florida and 16 wells containing alachlor at levels near or over 2 µg/L were sampled since 1989 to present. Alachlor concentrations remained > 2 µg/L in all but four wells. One well which was initially < 2 µg/L went over that level in 1994. The mean of alachlor in all wells was 13 µg/L and 9 µg/L, in 1994 and 1995, respectively. All alachlor use in Florida was canceled before the 1991 use season but sampling periods did not indicate a discernable trend. As a group, the concentrations of the alachlor were not significantly different with time no matter how sampling intervals were analyzed.

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Controlled release formulations of alachlor based on calcium alginate

Cited by 46 publications

References 7 publications

Environmentally Friendly Formulations of Trifluralin Based on Alginate Modified Starch

Environmentally Friendly Formulations of Trifluralin Based on Alginate Modified Starch

Formulações de atrazina em xerogéis: síntese e caracterização

Time-Related Analysis of Alachlor Concentrations in Florida Wells

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