Abstract
The mobility of the microcapsules in saturated granular media was estimated on the basis of conventional breakthrough experiments in vertical columns packed with sands for various physical and chemical conditions. Four types of microcapsules have been tested, all of them were found to have reasonable mobility in clean quartz sand, but not in sandy soil. The immobility in the sandy soil was attributed to some production deficiencies in terms of shape, size and quality of the coating surface. The size of the microcapsules should be considerably smaller than those produced with an order of magnitude of a few micrometers. They should also be more spherical and with a smoother surface. The addition of a proper dispersant had stabilized the microcapsules suspension, and facilitated their transport in the sand. A major flow factor affecting microcapsules mobility is the water flux. The microcapsules should be applied at a high irrigation rate, which also implies a high water content in the soil profile. Considering solely the mobility aspect, it seems that the prospect for successful application of the new method for weed control is limited to granular soils with a high hydraulic conductivity at/or near saturation. However, for the time being the most limiting problem is the production of quality microcapsules with good physical and chemical properties.
Similar content being viewed by others
References
Chalmers, D. R., Hopen, H. J. and Turgeon, A. J.: 1987, Controlled-release pre-emergence herbicide formulations for annual grass control in Kentucky Bluegrass (Poa pratensis) Turf,Weed Science 35, 533-540.
Coffman, C. B. and Gentner, W. A.: 1980, Persistence of several controlled release formulations of trifluralin in greenhouse and field, Weed Science 28, 21-23.
Connick, W. J. Jr., Bradow, J. M., Welles, W., Steward, K. K. and Van, T. K.: 1984, Preparation and evaluation of controlled-release formulations of 2,6-dichlorobenzonitrile, J. Agri. Food Chem. 32, 1199-1205.
Friedman, S. P.: 1993, Transport of microcapsules and slow release in saturated and unsaturated granular soil, PhD Dissertation, Hebrew University of Jerusalem.
Ison, C. R. and Ives, K. J.: 1969, Removal mechanisms in deep filtration, Chem. Engng. Sci. 24, 717-729.
Kydonieus, A. F.: 1980, Controlled Release Technologies: Methods, Theory and Applications, Vol. 1, 2nd edn, CRC Press, Boca Raton, Florida.
Lahav, N. and Tropp, D.: 1980, Movement of synthetic microspheres in saturated columns, Soil Science 130, 151-156.
O'Mellia, C. R. and Stumm, M.: 1967, Theory of water filtration, J. Am. Water Works Assoc. 59, 1393-1412.
Rajagopalan, R. and Tien, C.: 1976, Trajectory analysis of deep-bed filtration with the sphere-in-cell porous media model, Am. Inst. Chem. Eng. J. 22, 523-533.
Song, L. and Elimelech, M.: 1993, Dynamics of colloid deposition in porous media: modeling the role of retained particles, Colloids and Surfaces 73, 49-63.
Spielman, L. A.: 1977, Particle capture from low-speed laminar flows, Ann. Rev. Fluid Mech. 9, 297-319.
Tanguary, A. C. and Lacey, R. E.: 1974, Controlled Release of Biological Active Agents, Plenum Press, New York.
Trimnell, D. and Shasha, B. S.: 1990, Controlled release formulations of atrazine in starch for potential reduction of groundwater pollution, J. Controlled Release 12, 251-256.
Yao, K. M., Habibian, M. T. and O0Mellia, C. R.: 1971, Water and waste water filtration: concepts and applications, Environ. Sci. Tech. 11, 1105-1112.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Friedman, S.P., Mualem, Y. Research Note: Mobility of Herbicide Microcapsules in Saturated Granular Media. Transport in Porous Media 36, 121–130 (1999). https://doi.org/10.1023/A:1006545718608
Issue Date:
DOI: https://doi.org/10.1023/A:1006545718608