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- Title
Degradation of <sup>14</sup>C-maleic hydrazide in soil as influenced by adsorption on activated carbon.
- Authors
Helweg, Arne
- Abstract
Maleic hydrazide was found to be adsorbed on activated carbon when carbon was added to an aqueous solution of maleic hydrazide. The value for Freundlich k was 2300 µg/g. Addition of 200, 1000 and 5000 ppm of activated carbon to soil containing 20 ppm of 4C-maleic hydrazide markedly delayed the decomposition of the herbicide as determined by the evolution of 14CO2. After 4 months of incubation almost equal amounts of 14CO2 were evolved from all treatments, indicating that most of the adsorbed herbicide had gradually been made accessible to decomposition. The degradation rate of maleic hydrazide follows first-order kinetics but the larger the concentration of carbon the more the degradation rate approaches zero-order kinetics. The degradation rate of maleic hydrazide was not delayed, when it was added to soil containing activated carbon which previously had been incubated for 4 months. Thus the activated carbon seemed to have lost its capacity to adsorb maleic hydrazide during the incubation. The correlation between carbon concentration and degradation rate of 10 and 20 ppm maleic hydrazide was found to be: log x = k log 1/cads.; x = degradation rate, cads. = concentration of adsorbent (carbon), k expresses the slope of the curve.
- Subjects
MALEIC acid; ACTIVATED carbon; SOILS; HERBICIDES; CHEMICAL decomposition
- Publication
Weed Research, 1975, Vol 15, Issue 2, p129
- ISSN
0043-1737
- Publication type
Article
- DOI
10.1111/j.1365-3180.1975.tb01110.x