Applications of Chemically Modified Clay Minerals and Clays to Water Purification and Slow Release Formulations of Herbicides

42 páginas.- 6 figuras.- 9 talas.- 140 referencias.- © 2020 by the authors.This review deals with modification of montmorillonite and other clay-minerals and clays by interacting them with organic cations, for producing slow release formulations of herbicides, and efficient removal of pollutants from water by filtration. Elaboration is on incorporating initially the organic cations in micelles and liposomes, then producing complexes denoted micelle- or liposome-clay nano-particles. The material characteristics (XRD, Freeze-fracture electron microscopy, adsorption) of the micelle– or liposome–clay complexes are different from those of a complex of the same composition (organo-clay), which is formed by interaction of monomers of the surfactant with the clay-mineral, or clay. The resulting complexes have a large surface area per weight; they include large hydrophobic parts and (in many cases) have excess of a positive charge. The organo-clays formed by preadsorbing organic cations with long alkyl chains were also addressed for adsorption and slow release of herbicides. Another examined approach includes “adsorptive” clays modified by small quaternary cations, in which the adsorbed organic cation may open the clay layers, and consequently yield a high exposure of the siloxane surface for adsorption of organic compounds. Small scale and field experiments demonstrated that slow release formulations of herbicides prepared by the new complexes enabled reduced contamination of ground water due to leaching, and exhibited enhanced herbicidal activity. Pollutants removed efficiently from water by the new complexes include (i) hydrophobic and anionic organic molecules, such as herbicides, dissolved organic matter; pharmaceuticals, such as antibiotics and non-steroidal drugs; (ii) inorganic anions, e.g., perchlorate and (iii) microorganisms, such as bacteria, including cyanobacteria (and their toxins). Model calculations of adsorption and kinetics of filtration, and estimation of capacities accompany the survey of results and their discussion.T. Undabeytia acknowledges financial support by the Spanish Ministry of Science and Innovation (project CTM2016-77168–R; this project received funding by the European Social Fund). S. Nir acknowledges financial support by the Ministry of Science & Technology, Israel & The Ministry of Science and Technology of the People’s Republic of China (grant No. 3-15707).Peer reviewe

Síntesis y eficacia de formulaciones de liberación lenta del herbicida Mesotriona

Ponencia presentada en el XV Congreso de la Sociedad Española de Malherbología SEMh 2015 “La Malherbología y la Transferencia Tecnológica” Sevilla, 19 al 22 de octubre de 2015[ES]: Se ha comprobado la eficacia de formulaciones desarrolladas mediante complejos surfactante-sepiolita en la reducción de la lixiviación del herbicida mesotriona. Entre las formulaciones desarrolladas se ha escogido aquella que presentaba un perfil de liberación más lento en ensayos in vitro. Al aplicarse en columnas de suelo se observó una lixiviación del herbicida y acumulación con la formulación comercial en los segmentos inferiores a diferencia de la formulación desarrollada, que se correlacionaba con un incremento de la bioeficacia en los segmentos superiores. En experimentos en parcelas de campo, a diferencia de la formulación comercial, no se observó un rebrote de las malas hierbas al usar la formulación desarrollada. [EN]: Synthesis and efficiency of slow release formulations of the herbicide mesotrione. The bioefficay of developed formulations based on surfactant-sepiolite complexes for reduced leaching of the herbicide mesotrione was tested. The formulation with a slower release pattern in in-vitro experiments was chosen for soil column and field experiments. In soil columns, the commercial formulation was leached and accumulated in the lower segments unlike the synthesized formulation, with a higher amount retained in the upper segments which was also correlated with a higher bioefficacy. In field experiments, a regrowth of weeds with the clay-based formulation was not observed, unlike the commercial formulation.Esta investigación ha recibido financiación a través de los proyectos CMT2009-07425 (MEC) cofinanciado por el Fondo Europeo de Desarrollo Regional (FEDER) y el Proyecto Bilateral Hispano-Argentino PRI-PIBAR-2011-1393 (MINECO-MINCYT). Carmen Galán agradece la beca Predoctoral disfrutada y asociada al Proyecto de Excelencia P09- RNM-4581.Peer Reviewe

Effects of soil characteristics on metribuzin dissipation using clay-gel-based formulations

Metribuzin (MTB) is a herbicide widely used for weed control in growing soybeans and other crops and has been identified in many parts of the world as a groundwater contaminant. To prepare controlled-release formulations (CRFs) of MTB, it was entrapped within a sepiolite-gel-based matrix with one of two proportions of clay/herbicide and used as either a gel or powder after freeze-drying. To determine how its persistence in soil is affected by formulation and soil type, MTB was applied as a CRF or commercial formulation (CM) to soils with different properties. MTB dissipation in all soils investigated was reduced when the herbicide was applied as CRFs, especially in the case of sandy soil and the freeze-dried formulations, with DT50 values of 57.5 and 104.1 days, respectively, versus 24.8 days for CM. A positive relationship between degradation rates, bioactivity, and soil pH was found. MTB adsorption-desorption studies on these soils were also performed, and no relationship between adsorption-desorption and the degradation rate of MTB was found, possibly because of the low adsorption capacity of the studied soils. MTB when applied as a CRF remains active longer than CM, avoiding the need to use more frequently herbicide applications.This work was supported by the Spanish Ministry of Education and Science (MEC) through Research Projects AGL 2005-00164, by Junta de Andaluc ́ıa (project P06-FQM-01909), and by AECID (project A/016047/08).Peer Reviewe

Novel system for reducing leaching of the herbicide metribuzin using clay-gel-based formulations

Metribuzin is an herbicide widely used for weed control that has been identified as a groundwater pollutant. It contaminates the environment even when it is used according to the manufacturer's instructions. To reduce herbicide leaching and increase weed control, new controlled release formulations were developed by entrapping metribuzin within a sepiolite-gel-based matrix using two clay/herbicide proportions (0.5/0.2 and 1/0.2) (loaded at 28.6 and 16.7% a.i.) as a gel (G28, G16) or as a powder after freeze-drying (LF28, LF16). The release of metribuzin from the control released formulations into water was retarded, when compared with commercial formulation (CF) except in the case of G28. The mobility of metribuzin from control released formulations into soil columns of sandy soil was greatly diminished in comparison with CF. Most of the metribuzin applied as control released formulations (G16, LF28 and LF16) was found at a depth of 0-8 cm depth. In contrast, residues from CF and G28 along the column were almost negligible. Bioassays from these control released formulations showed high efficacy at 0-12 cm depth. The use of these novel formulations could minimize the risk of groundwater contamination while maintaining weed control for a longer period.Peer Reviewe

Uso potencial de arcillas modificadas con metales para la obtención de formulaciones de liberación lenta de herbicidas.

9 páginas., 5 gráficos, 2 tablas y 9 referencias. Versión extendida de la comunicación presentada en la "XIX Reunión Científica de la Sociedad Española de Arcillas - SEA05", celebrada en Salamanca del 26 al 28 de Septiembre de 2005. Enlace a la web de la Sociedad Española de Arcillas http://www.sea-arcillas.es/publicacionesSEA.htm[EN]Abstract A slow release system of the herbicide imazapyr was designed by adsorption on pillared clays. Pillared clays based on aluminum and mixed aluminum-copper solutions were synthesized. The aim was to check whether the introduction into the pillars of a metal complexing the herbicide molecules enhanced the sorption and release properties of the clay for the herbicide. A commercial aluminum pillared clay was also examined as a potential sorbent. The chemical analysis data as well as those of X-ray diffraction show that copper from pillaring solutions was partially introduced, and the basal spacing were increased about 9 Å in good agreement with the size of the Keggin ion. The textural properties indicate a reduction in the micro- and mesoporosity of the pillared clays after pillaring with copper solutions. The largest the copper content in the mixed Al-Cu pillared clays the largest the decrease in the surface area. However, imazapyr adsorption increased up to three-fold compared to the commercial pillared clay, and desorption percentages from the Cu-Al pillared clays were three-fold lower than the commercial one, whose desorption was completely reversible. These preliminary results show the potential use of Cu-Al pillared clays for the development of slow release formulations of the herbicide imzapyr, unlike those whose pillars are only made of aluminum.[ES]Resumen En el presente trabajo se ha intentado desarrollar un sistema de liberación lenta del herbicida imazayr mediante su adsorción en arcillas pilareadas. Se han sintetizado arcillas pilareadas con aluminio y con soluciones mixtas Cu-Al, a fin de comprobar si la formación de pilares mixtos de aluminio con un metal complejante del herbicida mejoraba las propiedades de adsorción y liberación del mismo. También se ha estudiado el empleo potencial de una arcilla pilareada comercial formada con pilares exclusivos de aluminio. Los resultados de análisis químico así como de difracción de rayos X muestran que parte del cobre de las soluciones pilareantes se ha introducido en las arcillas finales, cuyos espaciados basales presentan un incremento de aproximadamente 9 Å, que se corresponde con el tamaño del ión Keggin. Las propiedades texturales indican una disminución tanto de la microporosidad como de la mesoporosidad en las arcillas tras su pilarización con soluciones de Cu-Al, que es tanto mayor cuanto mayor es el contenido de Cu. A pesar de la reducción en la superficie de estas arcillas sintetizadas con Cu, la adsorción de imazapyr incrementaba hasta 3 veces con respecto a la arcilla pilareada comercial. A su vez los porcentajes de desorción en la arcillas pilareadas con Cu-Al eran hasta tres veces inferiores a los correspondientes a la arcilla pilareada comercial, cuya desorción era prácticamente reversible. Estos resultados preliminares avalan el uso potencial de arcillas pilareadas con Cu-Al para el desarrollo de formulaciones de liberación lenta del herbicida imazapyr, a diferencia de aquellas en las que los pilares se encuentran formados únicamente por aluminio.Peer Reviewe

Effect of soil type on adsorption-desorption processes of the fungicide Thiabendazole

Se han realizado ensayos de adsorción-desorción del fungicida Tiabendazol (TBZ) en once suelos con propiedades fisicoquímicas diferentes con el objetivo de estudiar su comportamiento en el sistema suelo-agua. Las isotermas de adsorción de TBZ se ajustaron a la ecuación de Freundlich, variando el valor de Kf entre 1.41 y 107. En gran parte de los suelos estudiados las Kf se relacionaron de forma directa con el contenido en materia orgá- nica, obteniéndose un valor medio de la constante Kfoc de 1650, por lo que ésta juega un papel importante en la adsorción. Sin embargo, teniendo en cuenta todos los suelos estudiados, Kfoc varió dentro de un amplio rango (210-5474), lo que indica que en ciertos suelos hay otras propiedades que también influyen en la adsorción, tales como el pH de los mismos y la presencia de óxidos amorfos. La desorción de TBZ presentó histéresis positiva en la mayoría de los suelos, indicando la parcial irreversibilidad de la adsorción. La adsorción se mostró más irreversible cuanto menor fué la cantidad adsorbida.In order to study the behavior of the fungicide Thiabendazole (TBZ) in the soil-water system, adsorptiondesorption tests were performed in eleven soils with different physicochemical properties. TBZ adsorption isotherms were well fitted to the Freundlich equation, and Kf values varied in the range 1.41-107. Kf was directly related to organic matter content in a great part of the soils, with an average Kfoc value of 1650, playing an important role in TBZ adsorption. However, taking into account all the studied soils, Kfoc varied in a wide range (210- 5474), indicating that in some soils other properties may influence on adsorption, such as their pH and the presence of amorphous oxides. Positive hysteresis was observed in TBZ desorption in most of the soils, indicating a partially irreversible adsorption. It was showed more irreversible as lower the adsorbed ammount

Control de malas hierbas. Formulaciones de liberación lenta de herbicidas: uso sostenible con el medioambiente

5 páginas.-- 3 gráficos.-- 1 tabla.- 1 foto.-- 2 referenciasLas formulaciones de liberación lenta de herbicidas permiten una disminución en las cantidades a aplicar de la sustancia activa, con la consiguiente reducción de costes económicos y medioambientales.Peer reviewe

Adsorción competitiva entre un plaguicida catiónico y Zn y Cd sobre una montmorillonita de arizona

35 páginas.-- 12 figuras.-- 2 tablas.-- 21 referencias.-- Memoria del XXIX Curso Internacional de Edafología 1992El fenómeno de adsorción sobre los minerales de la arcilla parece ser uno de los más importantes factores que afectan el comportamiento de plaguicidas en suelos (Bailey and White, 1967; Mortland, 1975). Al mismo tiempo, el estudio de reacciones de metales pesados con los componentes minerales y orgánicos de la fracción coloidal del suelo ha aumentado enormemente (Peigneur, Maes y Cremer, 1975; Inskeep y Baham, 1983). Aunque existen muchos trabajos de adsorción sobre arcillas de plaguicidas y metales pesados independientemente, poca atención se ha dirigido a los fenómenos de adsorción que tienen lugar cuando ambos se encuentran juntos. De aqui que el objetivo de este trabajo sea contribuir a la clarificación de los efectos competitivos entre el plaguicida catiónico clordimeform y los metales pesados cadmio y zinc cuando son adsorbidos sobre montmorillonita.Peer reviewe

Organo-clay formulations of the hydrophobic herbicide norflurazon yield reduced leaching

The study aimed to reduce leaching of the hydrophobic herbicide norflurazon (4-chloro-5-methylamino-2-(alpha,alpha,alpha)-trifluoro-m-tolylpyridazin-3-(2H)-one)by adsorbing it on clays or organoclays. The surface of the clay mineral montmorillonite was modified from hydrophilic to hydrophobic by preadsorbing it with organic cations, of which thioflavin-T (TFT) at a loading corresponding to 5/8 of the cation-exchange capacity of the clay mineral yielded the highest affinity of adsorption of norflurazon. Pillared clay (PC): used without organic cations exhibited enhanced affinity for norflurazon adsorption, much higher than that of montmorillonite or sepiolite. Fourier transform infrared (FTIR) results showed interactions between aromatic moieties of preadsorbed TFT and the herbicide. Stronger interaction of the herbicide with a clay mineral or organo-day corresponded to its slower release. Formulations prepared on the basis of montmorillonite-TFT and PC were more effective in reducing herbicide leaching in soil columns in; comparison to the commercial formulation, whereas the herbicidal efficiencies were comparable.Peer Reviewe

Clay-vesicle interactions: fluorescence measurements and structural implications for slow release formulations of herbicides

6 pages, 5 tables, 2 figures, 26 references. The authors acknowledge Dr. Justo for help in the XRD section.Clay-vesicle systems exhibit a potential for environmental applications, such as herbicide formulations for reduced leaching. Clay-vesicle interactions were addressed by combining adsorption and XRD measurements with fluorescence studies for didodecyldimethylammonium bromide (DDAB), dioctadecyldimethylammonium bromide (DDOB), and montmorillonite. XRD and adsorption data indicated that the adsorbing vesicles were transformed after 3 days into paraffinic and bilayer structures. Fluorescence studies revealed that adsorption was almost complete within 5 min for a loading below the cation exchange capacity (CEC). Aggregation and sedimentation of clay-surfactant particles occurred within several minutes. Fluorescent measurements of supernatants indicated decomposition of vesicles at a high clay/surfactant ratio due to rapidly adsorbing cationic monomers. The kinetics of energy transfer between vesicles labeled by NBD-PE (1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl)) and montmorillonite labeled by rhodamine-B follows that of aggregation of surfactant-clay particles and structural changes of the vesicles at times of minutes to hours. Experiments following the reduction of NBD fluorescence by addition of dithionite indicate faster permeabilization of DDOB than DDAB vesicles, which was confirmed by leakage experiments. The faster permeabilization of DDOB vesicles in the presence of clay was correlated with their inferior suitability for the preparation of clay-based formulations of anionic herbicides for slow release.Financial support of the Spanish Ministry of Science and Technology under projects AGL2002-00993 and REN2000-1540 and Junta de Andalucia (PAI RNM166) is acknowledged herewith. Dr. Undabeytia is also grateful to the Spanish Government for a Ramon y Cajal research contract.Peer reviewe