Density and surface tension of aqueous solutions of adjuvants used for tank-mixes with pesticides
2012
Janku, J., Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Agroekologie a Biometeorologie | Bartovska, L., Vysoka Skola Chemicko-technologicka, Prague (Czech Republic). Ustav Fyzikalni Chemie | Soukup, J., Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Agroekologie a Biometeorologie | Jursik, M., Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Agroekologie a Biometeorologie | Hamouzova, K., Ceska Zemedelska Univ., Prague (Czech Republic). Katedra Agroekologie a Biometeorologie
Adjuvants are surface active agents that are added to pesticide formulations or tank-mix to facilitate the mixing, application, or efficacy of these products. Addition of adjuvants changes the physico-chemical properties of spray liquid. In this work, we have focused in particular on surface tension and density of aqueous solutions of different adjuvants registered for mixing with herbicides. Eleven different adjuvants were subject of this study under laboratory conditions. An equation which enables to determine the density of aqueous solutions in concentration range of 0-15 g/kg was designed. The average difference between the experimental and calculated density values amounted to +/-0.006%. The concentration dependence of surface tension was utilized to determine the critical micelle concentration (cmc). The cmc of most tested adjuvants was lower than the amount recommended by manufacturers, especially in the case of the adjuvants Dedal 90 EC and Mero 33528. For the adjuvant Trend 90 EC the recommended rate is even lower than that obtained for the cmc. Maximum reduction of the surface tension of water was achieved with the adjuvants Silwet L-77 and Break Superb.
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