RESUMEN
The performance of phillipsite as a matrix for slow-release formulation of oxamyl [N,N-dimethyl-2-methylcarbamoyl-oxymino-2-(methylthio)acetamide] was tested. The adsorption kinetics followed a first-order law, and the adsorption isotherm fitted well in a two-surface Langmuir model, suggesting a double mechanism of interaction between oxamyl and the sorbent. The sorption mechanism, studied by FTIR, provided two fractions of oxamyl. The first one is sorbed on the mineral surface, linked by H-bonding, and the second one is constituted by a multilayer of oxamyl molecules linked by a water bridge between them. The release kinetics of oxamyl from a substratum zeolite-oxamyl also follows a first-order law, with two stages that correspond to both fractions of oxamyl previously detected.
RESUMEN
The presence of abundant zeolites in association with volcanic pumiceous materials in Tererife (Canary Islands) prompted us to study their properties as a water purifying bed for inorganic contaminants, pathogenic bacteria, and soluble organic matter. The experimental model used was a chemical percolation reactor with a constant flux of solution, where the fixation kinetics were studied by comparing the input and the output solutions. The ammonium and phosphate retention values found after 10 days of constant percolation were 70% and 14%, respectively. In addition, a high reduction of soluble organic matter was observed, as well as the total removal of the bacteria species studied. The N-P-K values of the soluble and exchangeable nutrients indicate the potential capacity of the bed as a slow-release fertilizer.