Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/1999
Publication Date: N/A
Technical Abstract: Sorption of dicamba by organoclays (OCls) was studied at different dicamba concentrations and pH levels to determine the ability of diverse OCls to sorb this ionizable herbicide. Three smectites varying in surface properties were saturated with different alkylammonium cations and sorption-desorption isotherms were measured using the batch equilibration technique. Results indicated that the organoclays were effective sorbents for dicamba and sorption was the result of hydrophobic interactions between dicamba and organic cations. Sorption was greater for OCls with high layer charge, basal spacing, organic carbon content, alkylammonium size, and organocation saturation close to CEC. Desorption isotherms were reversible, except for those organoclays with primary alkylammonium groups, for which there was moderate hysteresis. pH studies at two concentration levels (0.05 and 1 mM) indicated molecular dicamba was the main species sorbed. OCls have potential as supports for controlled release formulations. It should be noted that when dicamba contaminated soil was mixed with large quaternary alkylammonium OCls at different rates, the decreased aqueous CaCl2 extractability of dicamba, suggests that OCls also have potential as immobilizing agents for remediation of dicamba contaminated soils.