Development of a Hydrogel-Based Reactive Matrix for Removal of Chloracetanilide Herbicides from Contaminated Water

Abstract

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.

SERS detection of environmental pollutants in humic acid–gold nanoparticle composite materials

“…Optical enhancing properties of the HA-AuNPs prepared at different pH were tested with an environmental pollutant, BT, 40 in two different ways. First, a known aliquot of the pollutant was added to the HA-AuNP suspension.…”

Functional Cellulose Beads: Preparation, Characterization, and Applications

“…The conversion of cellulose into highly reactive carbonate or carbamate intermediates ( 20 and 21 ) has been performed in order to activate beads for subsequent modification. ,− Also in these cases, the applied activation reagents are expensive and highly reactive, which implies that undesired side reactions may occur. Finally, thiol substituents have been attached to cellulose beads ( 48 ) to obtain materials that are reactive toward chlorinated compounds …”

Analysis and toxicity of methomyl and ametryn after biodegradation

“…In this respect it has been found that effluents of WWTP contain high levels of herbicides that escape treatment [12,13]. The degradation of triazine herbicides such as ametryn and insecticides such as methomyl has been well investigated and much work has been performed on the removal of pesticides from wastewater by special procedures such as oxidation or irradiation [14]. Few publications have dealt with elimination of pesticides in WWTP [15].…”