Herbicides adsorption

Leopold, A.C., van Schaik, R, and Neal, M. Molecular structure and herbicide adsorption. Weeds, 8 48-54, 1960. 

Barriuso, E. and R. Calvet (1992). Soil type and herbicides adsorption. Int. J. Environ. Anal. Chem., 46 117-128. 

Clay, S.A., W.C. Koskinen, R.R. AUmaras, and R.H. Dowdy (1988b). Differences in herbicide adsorption on soil using several soU pH modification techniques. J. Environ. Sci. Flealth B, 23 559-573. 

Majka, J.T. and T.L. Lavy (1977). Adsorption, mobility, and degradation of cyanazine and diuron in soils. Weed Sci., 25 401 -06. Mallawatantri, A.P. and D.J. Mulla (1992). Herbicide adsorption and organic carbon contents on adjacent low-input versus conventional farms. J. Environ. Qual., 21 546-551. 

Leonard, R.H., Peterson, W.H., Johnson, M.J. (1948) Lactic acid from fermentation of sulfite waste liquor. Ind. Eng. Chem. 40, 51-61. Leopold, A.C., van Schaik, R, Neal, M. (1960) Molecular structure and herbicide adsorption. Weeds 8, 48. 

Phenoxyacetic acid herbicides Mixture of several phenoxyacetic acid herbicides Adsorption Perisorb A pellicular adsorbent Hexane/acetic acid (92.5 7.5)... 

For the determination of the herbicide adsorption to the passive membranes, those were put in 100 ml of methanol (in experiments A-F) or acetone (in experiments G and H-K) and submitted to sonication with a Bandelin Sonarex Super RK102 H for lOmin. The obtained extracts were concentrated to 10ml and filtered by Acrodisc Gelman (Gelman Sciences, Inc., Arbor, MI) filters (0.45 tm in diameter) before being submitted to analysis by ELISA, in the case of atrazine (experiments A-D), or to gas chromatography with flame ionization detector (GC-FID) in the case of molinate (experiments E and F), or to HPLC with ultraviolet detection (HPLC-UV) in the case of molinate and bentazone (experiments G and H-K). 

We showed that these mesoporous silica materials, with variable pore sizes and susceptible surface areas for functionalization, can be utilized as good separation devices and immobilization for biomolecules, where the ones are sequestered and released depending on their size and charge, within the channels. Mesoporous silica with large-pore-size stmctures, are best suited for this purpose, since more molecules can be immobilized and the large porosity of the materials provide better access for the substrates to the immobilized molecules. The mechanism of bimolecular adsorption in the mesopore channels was suggested to be ionic interaction. On the first stage on the way of creation of chemical sensors on the basis of functionalized mesoporous silica materials for selective determination of herbicide in an environment was conducted research of sorption activity number of such materials in relation to 2,4-D. 

Restricted access phases are another approach to exploiting the differences in characteristics of analytes. Large analytes are excluded from an internal surface on which an adsorptive stationary phase is present. A herbicide analysis for Metsulfuron methyl, Bentazone, Bromoxynil, methylchlorophenoxy acid, and Mecoprop in the presence of humic acid was performed on restricted access reversed phase media.52 The cytostatic compound epirubicin and its metabolites were separated from plasma using a Pinkerton GFF II column.53 Gradient separations of polymers on reversed phase and on normal phase represent an alternative to gel permeation chromatography. Polyesters of noncrystalline materials were separated on a variety of such phases.54... 

In a study of adsorption of organic herbicides by montmorillonite, Bailey and colleagues138 found that none of the compounds conformed to the Langmuir adsorption equation. Of the 23 compounds tested, only a few did not conform well to the Freundlich equation. 

The adsorption solutions from the highest concentrations runs were extracted with ether. The ether extracts were concentrated and analyzed by TLC. Similarly, the corresponding soils were extracted with ether and the ether extracts were analyzed by TLC. Other soil samples were analyzed by combustion in order to determine directly the amount of adsorbed herbicide. 

Where AG is free energy, R is gas constant (1.987 cal/deg K mole-1), T is degrees Kelvin, and AS is entropy. Kd is the distribution constant of the herbicide between the solution phase and the adsorbed phase (equation 4). Thus, least squares linear regression analysis of ln(Kd) vs. 1/T yielded values for heats of adsorption (AH) for the herbicides in Keeton soil. 

Freundlich Soil Adsorption Coefficients. Control experiments indicated that all of the compounds were stable in the stock solutions, in the adsorption solutions, and in the soil during these studies. A preliminary adsorption run conducted to determine the time required for equilibration of the herbicides between water and soil indicated that ca. 3 hours shaking was adequate. 

Transport of the herbicides by vapor diffusion on moist soil was shown to be directly related to vapor pressure and inversely related to water solubility. Transport of the herbicides by leaching was shown to be inversely related to the Freundlich adsorption coefficient which in turn was directly related to the octanol/water partition coefficient and inversely related to water solubility (16). 

Carrizosa MJ, Hermosin MC, Koskinen WC, Cornejo J (2004) Interactions of two sulfonylurea herbicides with organoclays. Clays Clay Miner 52 643-649 Celis R, Hermosin MC, Cornejo J (2000) Heavy metal adsorption by functionalized clays. Environ Sci Technol 34 4593-4599 Chappell MA, Laird DA, Thompson ML, Li H, Teppen BJ, Johnston CT, Boyd SA (2005) Influence of smectite hydration and swelling on atrazine sorption behavior. Environ. Sci Technol 39 3150-3156 Chiou CT (1989) Theoretical considerations of the partition uptake of nonionic organic compounds by soil organic matter. In Sawhney BL, Brown K (eds) Reactions and movement of organic chemicals in soils. Soil Science Society of America, Madison, WI, pp 1-29... 

Studies have been made of the fate of 3-amino 1,2,4 triazole herbicide in soils [106], while adsorption of aminotriazole by clay minerals has been postulated, little is known of the interaction with pure clay minerals, particularly of the montmorillonite group. The importance of such reactions cannot be overemphasized in view of their bearing on the persistence of the herbicide in the soil. 

Wauchope and Myers [116] studied the adsorption-dispersion kinetics of Atrazine and Linuron in sediment-aqueous slurries. The resulting adsorption or desorption was very rapid, approaching 75% of equilibrium values within 3-6min. Chlorinated adsorption of the herbicide on the sediment was completely reversible after 2h of adsorption. 

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