Effect of Fe (III) on acid degradation of methylparathion

Abstract

A study was undertaken to determine the transformation kinetic of methylparathion (O, O, -dimethyl O-4 nitrophenylphosphorotioate) in the presence of Fe(III) between pH 2 and 7. The Fe(III) was not electroactive under the conditions used in this study, and polarographic signals were exhibited by methylparathion and main degradation product only. Data suggest that hydrolysis of methylparathion in an acid medium is catalyzed by Fe(III) and the pesticide did not degrade in this medium without this cation. Methylparathion degradation was observed at all the pHs studied and was independent of the predominant chemical form of Fe(III) in the aqueous medium. The reaction was first-order with pH-dependent rate constant (k) values ranging from 3.3 x 10(- 3) h(- 1) to 7.0 x 10(- 3) h(- 1). The k values increased as pH decreased, suggesting that Fe(III) acted as an electrophile in the reaction mechanism.

Efficient biodegradation of acephate by Pseudomonas pseudoalcaligenes PS-5 in the presence and absence of heavy metal ions [Cu(II) and Fe(III)], and humic acid

“…3). In addition to above, after 14 days, more than 90% increase in intensity in the peak at m/z 147 was observed, that was due to formation of ferric ion metal complex [Fe(N-P = O(S))], which further reduced to Fe(OH) 2 at m/z 89 and consistence with recent studies (Kumar et al 2015c, d;Manzanilla-Cano et al 2004, 2007Sarkouhi et al 2012Sarkouhi et al , 2016. Recent studies have revealed that phosphate can promoted the mineral dissolution, probably be due to the different affinities between metals Co [ Ni [ Cu) and phosphates (Manzanilla-Cano et al 2004, 2007Sarkouhi et al 2012Sarkouhi et al , 2016.…”

“…Formation of stable complex till 14th day at m/z 147 was due to strong interaction of iron with O and N donor sites of decomposed metabolite. These interactions were logical and expected as per HASB principle (Kumar et al 2015c, d;Manzanilla-Cano et al 2004, 2007Sarkouhi et al 2012Sarkouhi et al , 2016. The reason behind slow biodecomposition was the complex formation behavior of Fe(III) with acephate through N and O atoms of acephate.…”

Kinetic Study of the Biodegradation of Acephate by Indigenous Soil Bacterial Isolates in the Presence of Humic Acid and Metal Ions

“…The reason behind the slow bio-decomposition of acephate was the complex formation behavior of Fe(III) with acephate through O and N atoms of acephate. Here, Fe(III) may form a six-membered ring through the O of P=O and C=O, which is kinetically as well as thermodynamically stable [17].The mass study revealed that the pathway of decomposition of acephate was similar to that of decomposition without the application of metal ions. Here, the slow removal rate of acephate was attributed to the toxicity of metal ions as well as the complex-formation ability of acephate [7].…”

“…The bacterial isolates were reconfirmed by molecular biotechnology. There were various reports regarding biodegradation of OPs, including methyl parathion, ethoprophos, and chlorpyrifos [16,17]. Only a few reports are available on the bacterial-promoted biodegradation of acephate [7,9,10,12].…”

Effect of fulvic acid on the photochemical degradation of methylparathion

“…The highest proportion of degradation occurred at pH 3 and overall average pesticide degradation was 60% at pH 2-7, based on 360 min irradiation time. A mathematical model [20] was used to process the experimental results and determine the reaction order and the rate constant (k). Methylparathion photolysis in the presence of fulvic acid followed a first-order kinetic model, and Table 2 shows the k values at each pH.…”