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Biodegradable, high-affinity hydrogel-based beads may prove useful in the decontamination of waters containing pesticide residue. Ethanethiol-cellulose beads, with a thiol content of up to 160 μmol -SH mL-1 bead, were synthesized by a novel method using 1,1‘-carbonyldiimidazole followed by reaction with aminoethanethiol. The use of thiol-derivatized beads to remove metolachlor from aqueous solutions, via a nucleophilic substitution reaction involving the α-carbon of the chloroacetamido group of metolachlor and the thiol group of the bead (i.e., covalent bond formation), was investigated using batch reaction conditions and fixed-bed column techniques. In batch reaction studies, ethanethiol-cellulose beads (160 μmol -SH mL-1 bead) exhibited binding capacities of up to 180 μmol metolachlor mL-1 bead (or about 1300 μmol g-1) depending on the solution pH and temperature. When the ethanethiol-cellulose beads were suspended in an aqueous solution at pH 9 and incubated at 40 °C, their binding capacity for metolachlor was about equal to that of activated carbon on a per gram adsorbent basis. Though the fixed-bed column studies revealed that the derivatized beads (131 μmol -SH mL-1 bead) possessed a large capacity for metolachlor, high effluent quality could not be maintained over extended column operation under the conditions employed. Metolachlor was not removed from solution under batch reaction conditions or in the fixed-bed columns when unmodified cellulose beads replaced thiol-derivatized beads. The results of our investigation demonstrate that ethanethiol-cellulose beads can be used to decontaminate water containing metolachlor and possibly other pesticides with reactive electrophilic centers.

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We investigated the suitability of solid state fermentation (SSF) as a means to dispose of carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate). The fate of [U‐ring‐14C] labeled carbofuran was determined in incubation chambers containing either sphagnum peat moss (limestone‐amended) or a peanut hulls/peat moss/steam‐exploded wood (1:1:1) mixture (PPW). Ethyl acetate‐extractable, and alkali soluble and insoluble fractions were evaluated for radioactivity following either a 4‐ or 8‐wk incubation period at 35°C. The majority of the radioactivity (80–98% of applied activity) was associated with the matrix materials at the end of the incubation period for both matrix materials with no significant mineralization observed. For peat, the majority of radioactivity was associated with the alkali insoluble fraction (63.5%), with only 8% of the applied activity found in the ethyl acetate extract after 8 wk. For the PPW mix, 71% of the applied radioactivity was recovered in the ethyl acetate extract, whereas 11% of the applied activity was found in the alkali insoluble fraction after 8 wk. The metabolite carbofuran‐7‐phenol, detected in the ethyl acetate extracts of the peat and PPW mix following 4 and 8 wk of incubation, was susceptible to oxidative coupling in the presence of horseradish peroxidase (HRP) and H2O2, suggesting that this metabolite had become covalently bound to organic matter during humic substance formation. These results may provide the basis for the development of an effective and economical method for detoxification or containment of waste pesticide residue.