Physico-chemical studies of natural and synthesized biocomposites for remediation of imidazolinone herbicides
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was undertaken to study the removal of imidazolinones
herbicides from water and soil using natural and synthesized biocomposites. Under the
optimum experimental conditions, chitosan-bentonite biocomposites and treated rice husk
adsorbents were prepared, characterized and investigated for their potential to adsorb
imazethapyr and imazamox from water using batch equilibrium techniques. The adsorption
capacity of synthesized adsorbents (0.0067 x 103 to 13.279 x 103 μg1−ng−1mln) for herbicides
was greater as compared to natural adsorbents (0.0026 x 103 to 0.0142 x 103 μg1−ng−1mln).
Among the studied adsorbents, thermally treated rice husk was superior for the removal of
imazethapyr and imazamox from water in terms of adsorption capacity (6.986 x 103 to
13.279 x 103 μg1−ng−1mln) and desorption (92.82 to 99.34 %). The removal of imazethapyr and
imazamox from artificially contaminated soil was evaluated using -cyclodextrin-chitosan
biocomposites through adsorption-desorption and pot trials viz. chemical assay and bioassay.
The removal studies indicated greater efficiency of chitosan, -CD and their biocomposites to
remove imazethapyr and imazamox from soils as compared to distilled water. Among the
extractants, low molecular weight chitosan- -cyclodextrin biocomposite (LCD) had greater
removal efficiency and under optimum conditions, 59.42 to 99.44 % of adsorbed herbicides
were successfully desorbed from studied soils. Chemical assays indicated that amendment of
LCD to soils enhanced the dissipation of imazethapyr and imazamox and the residues were
below detectable limit (<0.005 μg g−1) within 5 to 21 days depending upon the physicochemical
properties of soils. Bioassay studies indicated significant reduction in growth
inhibition of Brassica juncea (L.) Czern after the amended of soils with LCD and
corroborated the findings of chemical assay.
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