M. Malik and J. Letey - Dept. of Soil and Environmental Sciences University of California Riverside, CA 92521, USA
Quantitative information on adsorption- desorption of polymers on soil helps in predicting the depth of effective polymer treatment. Desorption of six tritium labeled polymers from three soils and an acid washed quartz sand was measured. Three anionic polyacrylamide (PAM) polymers whose charge density was in the order of 40J>21J>2J; two cation polysaccharide (guar) polymers whose charge density was greater for T-4141 than for CP-14; and an anionic polysaccharide (T-4246) were investigated. After 30 g of soil has been equilibrated with 20 mL of polymer solution, the supernatant was replaced by distilled water and the amount of polymer desorbed was calculated. Additionally, one soil was dried under the laboratory hood after decanting the supernatant before adding distilled water. Very little or no desorption occured when the material was kept wet. All 2J and 59 to 76 percent of the other polymers left in solution after decanting became irreversibly bonded to the soil by drying the soil.
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