Degradation Of Carbofuran Research Articles

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

Adaptation of biomixtures for the accelerated degradation of carbofuran in a tropical environment

Degradation of carbofuran by Trametes versicolor in rice husk as a potential lignocellulosic substrate for biomixtures: From mineralization to toxicity reduction

Biopurification systems for the treatment of pesticide-containing wastewaters contain a biomixture constituted by low-cost materials (soil, lignocellulosic substrates and humic components). In particular, the use of bioaugmented lignocellulosic materials as part of the biomixture components has been scarcely studied. The use of the fungus Trametes versicolor grown in rice husk (RH) was evaluated as an option of lignocellulosic bioaugmented substrate of potential application in biomixtures for carbofuran (CFN) elimination. RH supported growth and activity of the fungus, as evidenced visually and by laccase activity. The system was able to degrade 55.1% CFN in 34 d with a half-life of 29.9d, and produced 3-hydroxycarbofuran (but not 3-ketocarbofuran) as a transformation product. This metabolite was successfully eliminated during the process. Moreover, a small fraction of CFN was mineralized (7.4%) within 64d. Toxicological evaluation revealed a marked detoxification during the process, achieving an 89% decrease in the toxicity after 34d. Overall performance of the bioaugmented substrate indicates that RH/T. versicolor is an interesting option to take into account in the design of biomixtures for pesticide degradation.

Degradation of selected agrochemicals by the white rot fungus Trametes versicolor

Use of agrochemicals is a worldwide practice that exerts an important effect on the environment; therefore the search of approaches for the elimination of such pollutants should be encouraged. The degradation of the insecticides imiprothrin (IP) and cypermethrin (CP), the insecticide/nematicide carbofuran (CBF) and the antibiotic of agricultural use oxytetracycline (OTC) were assayed with the white rot fungus Trametes versicolor. Experiments with fungal pellets demonstrated extensive degradation of the four tested agrochemicals, at rates that followed the pattern IP>OTC>CP>CBF. In vitro assays with laccase-mediator systems showed that this extracellular enzyme participates in the transformation of IP but not in the cases of CBF and OTC. On the other hand, in vivo studies with inhibitors of cytochrome P450 revealed that this intracellular system plays an important role in the degradation of IP, OTC and CBF, but not for CP. The compounds 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA) and 3-phenoxybenzoic acid (PBA) were detected as transformation products of CP, as a result of the breakdown of the molecule. Meanwhile, 3-hydroxycarbofuran was detected as a transformation product of CBF; this metabolite tended to accumulate during the process, nonetheless, the toxicity of the system was effectively reduced. Simultaneous degradation of CBF and OTC showed a reduction in toxicity; similarly, when successive additions of OTC were done during the slower degradation of CBF, the fungal pellets were able to degrade both compounds. The simultaneous degradation of the four compounds successfully took place with minimal inhibition of fungal activity and resulted in the reduction of the global toxicity, thus supporting the potential use of T. versicolor for the treatment of diverse agrochemicals.

Accelerated biodegradation of selected nematicides in tropical crop soils from Costa Rica.

Degradation and mineralization behavior of selected nematicides was studied in soil samples from fields cultivated with banana, potato, and coffee. Degradation assays in most of the studied soils revealed shorter half-lives for carbofuran (CBF) and ethoprophos (ETP) in samples with a history of treatment with these compounds, which may have been caused by enhanced biodegradation. A short half-life value for CBF degradation was also observed in a banana field with no previous exposure to this pesticide, but with a recent application of the carbamate insecticide oxamyl, which supports the hypothesis that preexposure to oxamyl may cause microbial adaptation towards degradation of CBF, an observation of a phenomenon not yet tested according to the literature reviewed. Mineralization assays for CBF and terbufos (TBF) revealed that history of treatment with these nematicides did not cause higher mineralization rates in preexposed soils when compared to unexposed ones, except in the case of soils from coffee fields. Mineralization half-lives for soils unexposed to these pesticides were significantly shorter than most reports in the literature in the same conditions. Mineralization rates for soils with a previous exposure to these pesticides were also obtained, adding to the very few reports found. This paper contributes valuable data to the low number of reports dealing with pesticide fate in soils from tropical origin.

Photocatalytic Oxidation of Carbofuran Pesticide Using Zinc Oxide

In recent years, the application of ultraviolet irradiation and zinc oxide (UV/ZnO) process water and wastewater treatment has gained removal activity of the persistence organic compounds. The degradation of carbofuran pesticide was investigated under ultraviolet irradiation and zinc oxide (UV/ZnO) process. Likewise, the effect of the operational parameters such as reaction volume, initial concentration of catalyst, initial carbofuran concentration, light intensity and pH were studied. In this study the (UV/ZnO) process at different initial concentrations (50-250 mg/L), 5 different initial pH and 5 different initial concentration of catalyst was investigated. Analyses were performed by gas chromatography mass spectroscopy. Results showed that the carbofuran initial concentration of 50 mg/L, ZnO concentration of 300 mg/L, pH of 8, light intensity of 125 watts and reaction volume of 150 mL, were the optimum condition for degradation of carbofuran by UV/ZnO system. This study demonstrated that carbofuran could be effectively degraded by ultrasonic irradiation.

Degradation of the pesticide carbofuran on clay and soil surfaces upon sunlight exposure

In the present study, the photolysis of carbofuran has been undertaken under sunlight conditions and at the surface of model supports such as clay films and different soils collected from two different sites in Morocco (Tirs and Dahs). In all conditions, an efficient degradation occurred owing to direct light absorption and also to photoinduced processes involving either clays or natural organic matter moities. On kaolin films, the photodegradation kinetics appears to follow a first-order process that clearly depends on the film thickness. The diffusion of carbofuran from the lower part to the illuminated surface was found to be negligible when compared to the photolysis process within the range of 20-70 μm. Thus, the photolysis rate constant at the surface of the solid support, k (0), was evaluated to be 7.0 × 10(-3) min(-1). Under these experimental conditions, the quantum yield was found equal to 2.1 × 10(-4). On soil surfaces, the disappearance rate constant was mainly attributed to photoinduced processes arising from natural organic matter. From the analytical point of view, the products were formed through (1) hydroxylation on the aromatic ring, (2) homolytic scission of the carbamate C-O bond leading to radical species formation, and (3) photohydrolysis of the carbamate C-O bond.

Microwave-granular activated carbon (MW-GAC) system for carbofuran degradation: Analysis of characteristics and recyclability of the spent GAC

Granular activated carbon (GAC) is frequently used to remove pollutants from wastewater. However, the mechanism of pollutant removal by GAC is by adsorption and hence spent GAC should be regenerated and used for several cycles for minimizing the cost of treatment. In the present study, the characteristics of GAC and carbofuran removal mechanism were explored in a microwave-GAC (MW-GAC) system. Carbofuran removal by adsorption was 52% at a GAC loading of 0.8 g/L. However, complete carbofuran degradation from aqueous solution as well as from GAC surface was obtained within 30 min in a MW-GAC system. In addition, A COD removal efficiency of 72% was observed in the MW-GAC system at pH 8 and 80°C after 30 min. The degradation occurred mainly through cleavage of carbamate group and oxidation of furan ring. Carbofuran removal by adsorption was enhanced with MW exposed GAC due to the improvement in the surface property on exposure to MW. On the other hand, recyclability of MW exposed GAC in the MW-GAC system indicated > 99% degradation of carbofuran in all the three cycles tested. As a whole, complete degradation of carbofuran and the effective recycling of the spent GAC could be achieved in the MW-GAC system.

Degradation and Persistence of Carbofuran in Peanut and Soil in Field Trails as Determined by GC-MS

This paper investigated the analytical method of degradation and persistence of carbofuran, its metabolite 3-hydroxy carbofuran in peanut seeds, fronds and soils in field trial using gas chromatography mass spectrometry (GC-MS). Carbofuran 3GR formulation (3g a.i./100g) was applied at dosages of 2250 and 3375g ha-1in furrow at sowing peanut seeds in the fields of Langfang, Hebei province and Jinan, Shandong province, China, respectively. The soil and the plant samples were collected at different intervals and the residues of carbofuran and 3-hydroxy carbofuran were analyzed by GC-MS. The degradation kinetic result showed that the degradation of carbofuran in peanut fronds in Jinan and Langfang can be well predicted with equation: C=1.2839e-0.1733tand C=0.5731e-0.1567t, with a half-life about 4.0 and 4.4 days respectively. For the degradation of carbofuran in soils, the result coincides well with equations: C= 4.2057e-0.2229t, and C= 5.4014e-0.1499t, with half-life of 3.1 and 4.6 days for Jinan and Langfang, respectively. The pH, organic matter and clay content as well as the climatic temperature play an important role in the degradation of carbofuran in soils. 3-hydroxy carbofuran dissipated rapidly both in peanut fronds and soils, it was not detectable 7 days after treatment for all treatment, the concentration of carbofuran and 3-hydroxy carbofuran in peanut seeds at harvest time were lower than either the maximum residue limit in China or the EUs maximum residue limit of 0.1 mg kg1. Based on the data from this investigation, the use of carbofuran in peanut could be considered to be safe.

Comparative bioremediation of carbofuran contaminated soil by natural attenuation, bioaugmentation and biostimulation

This study investigated the effect of bioremediation treatments including natural attenuation, bioaugmentation, combined biostimulation and bioaugmentation and biostimulation on carbofuran degradation in rice field soil. Experiments were conducted in soil microcosms at the initial carbofuran concentration of approximately 20 mg kg−1 soil. Mixed-cultures isolated from soil that was collected from rice fields with a history of carbofuran application were used as inoculum in bioaugmentation technique in comparison to a specific carbofuran degrader, Burkholderia cepacia PCL3. Sludge from a production process of renewable energy including hydrogen (HY), ethanol (ET) and methane (ME) were used as organic amendments in the biostimulation technique. The shortest half-lives (t1/2) of carbofuran (1.60 days) was observed in soil inoculated with both mixed-cultures and PCL3 followed by soil inoculated with PCL3 (3.62 days) and soil inoculated with mixed-cultures (4.02 days), respectively. HY was the most effective amendment to biostimulate carbofuran degradation in soil giving a short t1/2 of 9.53 days followed by ET (t1/2 of 12.68 days) and ME (t1/2 of 13.24 days). Combined bioaugmentation and biostimulation provided the effective carbofuran degradation with the short t1/2 in soil of 2.20–4.90 days when PCL3 or PCL3 together with mixed cultures; was used as the inoculum while the prolonged t1/2 of 7.08–9.37 days were observed when only the mixed cultures was used as the inoculum.

Photocatalytic degradation of carbofuran in TiO2 aqueous solution: Kinetics using design of experiments and mechanism by HPLC/MS/MS

The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the concentration of carbofuran, were selected to determine the dependence of degradation efficiencies on independent variables. Response surface methodology modeling results indicated that the degradation efficiency of carbofuran was highly affected by the initial pH value and the concentration of carbofuran. Then nine degradation intermediates were detected by HPLC/MS/MS. The Frontier Electron Densities of carbofuran were calculated to predict the active sites on carbofuran attacked by hydroxyl radicals and photoholes. Point charges were used to elucidate the chemisorption pattern on TiO2 catalysts during the photocatalytic process. By combining the experimental results and calculation data, the photocatalytic degradation pathways of carbofuran were proposed, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain.

Biodegradation of carbamate pesticides by natural river biofilms in different seasons and their effects on biofilm community structure

This study investigated the ability of natural river biofilms from different seasons to degrade the carbamate pesticides methomyl, carbaryl and carbofuran in single and multiple pesticide systems, and the effects of these pesticides on algal and bacterial communities within biofilms. Spring biofilms had the lowest biomass of algae and bacteria but showed the highest methomyl degradation (>99%) and dissipation rates, suggesting that they might contain microorganisms with high methomyl degradation abilities. Degradation of carbofuran (54.1–59.5%) by biofilms in four seasons was similar, but low degradation of carbaryl (0–27.5%) was observed. The coexistence of other pesticides was found to cause certain effects on pesticide degradation and primarily resulted in lower diversity of diatoms and bacteria than when using a single pesticide. The tolerant diatoms and bacteria potentially having the ability to degrade test pesticides were identified. River biofilms could be suitable biomaterials or used to isolate degraders for bioremediating pesticide-contaminated water.

Biodegradation of carbofuran in sequencing batch reactor augmented with immobilised Burkholderia cepacia PCL3 on corncob

The performance of sequencing batch reactors (SBRs) augmented with immobilised Burkholderia cepacia PCL3 on corncob for biodegradation of carbofuran in basal salt medium (BSM) was studied. A 2.0-L SBR with a working volume of 1.5 L was operated for a total cycle of 48 h, consisting of 1.0 h fill phase, 46 h react phase and 1.0 h decant phase. The initial pH of the feed medium was 7.0. Air was fed into the reactor at a controlled flow rate of 600 mL·min −1. The effect of hydraulic retention time (HRT) (14 to 6 days) on carbofuran-degradation efficiency was investigated at a carbofuran concentration in the feed medium of 20 mg·L −1. The shortest HRT resulting in complete degradation of carbofuran was 8 days. At 75% of the optimum HRT (6 days), the effects of biostimulation using organic amendments, i.e. molasses, cassava pulp, rice bran and spent yeast, and the effect of carbofuran concentration in the feed medium (20–80 mg·L −1) were investigated. The optimum conditions for SBRs were an initial carbofuran concentration of 40 mg·L −1 and 0.1 g·L −1 of rice bran as a biostimulated amendment. Complete degradation of carbofuran with a first-order kinetic constant (k 1) of 0.044 h−1 was achieved under these optimum conditions.

Solar photo-Fenton treatment of carbofuran: Analysis of mineralization, toxicity, and organic by-products

The degradation of the pesticide carbofuran (CBF) using solar photo-Fenton treatment, at both the laboratory and the pilot scale, was evaluated. At the laboratory scale, in a suntest reactor, the Fe2+ concentration and H2O2 concentration were evaluated and optimized using the surface response methodology and the Pareto diagram. Under optimal conditions experiments were performed to evaluate the evolution of the substrate removal, oxidation, subsequent mineralization, toxicity and the formation of chloride ions during the treatment. The analysis and evolution of five CBF by-products as well as several control and reactivity tests at the density functional theory level were used to depict a general scheme of the main degradation pathway of CBF via the photo-Fenton system. Finally, at the pilot scale, a sample of the commercial CBF product Furadan was eliminated after 420 min by the photo-Fenton system using direct sunlight. Under these conditions, after 900 min 89% of toxicity (1/E50 on Vibrio fischeri bacteria), 97% of chemical oxygen demand, and 90% of dissolved organic carbon were removed.

Electro-enzymatic degradation of carbofuran with the graphene oxide–Fe3O4–hemoglobin composite in an electrochemical reactor

In this paper, the degradation of carbofuran with graphene oxide–ferroferric oxide–hemoglobin (GO–Fe3O4–Hb) composite in an electrochemical–enzyme system was reported. The graphene oxide–Fe3O4–hemoglobin composite was fabricated by a two-step process. First, graphene oxide–Fe3O4 (GO–Fe3O4) composite was prepared via a simple and effective chemical precipitation method. Then, hemoglobin was covalently immobilized onto the graphene oxide–Fe3O4 by glutaraldehyde (GA). The GO–Fe3O4–Hb composite showed improved enzyme thermal stability and wider active pH range compared with Fe3O4–Hb and soluble Hb. Furthermore, the GO–Fe3O4–Hb composite can be easily separated under a magnetic field from the reaction solution and reused. To evaluate the electro-enzymatic degradation of carbofuran, electrolytic experiments were carried out with 1U/mL GO–Fe3O4–Hb composite at 0.007A, and oxygen flow rate 25mL/min. Under the optimum conditions by the electrogeneration of hydrogen peroxide (H2O2), the removal efficiency of carbofuran reached 94.6%. Compared with electrochemical and biochemical methods, the removal of carbofuran through electroenzymatic method was comparatively favorable.

Degradation intermediates and reaction pathway of carbofuran in leaching water using TiO2 and ZnO as photocatalyst under natural sunlight

Abstract In this work the solar-photocatalytical degradation of carbofuran in leaching water has been studied using zinc oxide (ZnO) and different mixed-phase (rutile/anatase) titanium dioxide (TiO2) at pilot plant scale. Comparison of catalysts showed that ZnO is the most efficient for catalyzing the removal of carbofuran and their main organic intermediates. The residual levels of carbofuran at the end of the experiment (240 min) were 0.1, 22.4, 62.8, 68.4 μg L−1 for ZnO, TiO2 P25 Degussa (70A/30R), TiO2 rutile (25A/75R) and TiO2 anatase (90A/10R), respectively. The primary degradation of carbofuran followed pseudo-first order kinetics. The analysis and evolution of the intermediates suggest that oxidation of the C O bond on the carbamate group and 3C position of the furan ring as the main metabolic pathway.

Optimization of photo-Fenton process parameters on carbofuran degradation using central composite design

Carbofuran, one of the most toxic and biorefractory carbamate compounds, is widely used in insecticides in Taiwan (9–18% of total insecticides production per year). In the present study, a central composite design experiment was used to study the effect of photo-Fenton treatment on carbofuran solution and to optimize the process variables such as carbofuran concentration (1–100 mg L−1), H2O2 dosage rate (0.25–6 mg L−1 min−1) and Fe3+ dosage (1–50 mg L−1), which influenced the efficiency of carbofuran degradation and mineralization. The results indicated that all the variables investigated in this study had significant roles in the degradation and mineralization of carbofuran in solution. The carbofuran degradation and mineralization efficiencies were increased with increase in H2O2 dosage rate and Fe3+ dosage, and with decrease in carbofuran concentration. Furthermore, optimum values of both H2O2 dosage rate and Fe3+ dosage were found to shift to higher values as carbofuran concentration increased. Based on the model obtained in this study, optimum H2O2 dosage rate and Fe3+ dosage were found to be 4 mg L−1 min−1 and 20 mg L−1, respectively, for 51 mg L−1 of carbofuran concentration. Under these conditions, carbofuran was completely removed within 30 min and coupled with 78% mineralization at the end of experiment.

Degradation of carbofuran and carbofuran-derivatives in presence of humic substances under basic conditions

The influence of humic aggregates in water solution upon the chemical stability of carbofuran (CF) and the carbofuran-derivatives, 3-hydroxy-carbofuran (HCF) and 3-keto-carbofuran (KCF), has been investigated in basic media. An inhibition upon the basic hydrolysis of 3-hydroxy-carbofuran and 3-keto-carbofuran (∼1.7 and ∼1.5-fold, respectively) was observed and it was rationalized in terms of the micellar pseudophase model. Nevertheless, non-significant effect upon the carbofuran stability was found in the presence of humic substances. These behaviors have been compared with the corresponding ones in other synthetic colloidal aggregates.

Bioremediation of carbofuran by isolated bacteria from soil

Among available pesticides, carbofuran is widely used as a pesticide in all parts of Sri Lanka to improve the quality and yield of food crops by protecting against pests. Lack of knowledge on the fate and behaviour of pesticides in the Sri Lankan environment has contributed to public perceptions, fueled by local media about increasing adverse health effects due to exposure to pesticides. In the present study laboratory experiments were conducted to isolate carbofuran degradable bacteria in soil samples collected from cultivation land in Medirigiriya where carbofuran is used as a major pesticide for agriculture. Seventeen bacteria strains were isolated from soil enrichment experiments by pour plate method. Tentative identifications were done using morphological and chemical analysis and it was confirmed that all bacteria isolates belong to gram negative and rod shape. Out of twelve, three isolates namely BC–3, BC–12 and BC–15 were selected for degradation study based on their morphological differences. Others were kept on agar slant and degradability of carbofuran by bacteria was detected by GC analysis. The bacteria isolates BC–3 and BC–12 showed a significant degradability of carbofuran, while the isolate BC–15 bacteria did not. BC–3 isolate removed 50% (±2) of the carbofuran thirteen days after incubation at 37°C (± 2) when the concentrations of pesticide were at 0.3 ppm and 0.5 ppm. The bacterial strain BC–15 showed a slow rate of degradation of carbofuran when compared with the BC–3 and BC–12 strains. In BC–15 inoculated experiment, residual carbofuran was detected even after three weeks of incubation. BC–3 bacteria showed a half life of thirteen days for 0.3 ppm and 0.5 ppm concentrations. In all bacteria strains showed high half life when concentration of carbofuran was 0.1 ppm. In contrast, variation in half life values were detected for the three different concentrations of carbofuran for BC–12 bacteria. The results of the present study suggest that some bacterial strains in soil play an important role in biodegradation of carbofuran along with other photochemical and hydrological reactions. Further studies are being conducted to ascertain the potential impact of bacterial isolates on carbofuran.

Thermodynamics of carbofuran adsorption on pyrite

Thermodynamic parameters of carbofuran adsorption on pyrite were determined from experimental data. In order to minimize the dissolution of pyrite as well the degradation of carbofuran, all experiments were restricted to (15 to 20)min. The maximum adsorption capacity of carbofuran varied with both pH and temperature in the order: ΓcarbmaxpH1.77>ΓcarbmaxpH2.70>ΓcarbmaxpH4.01. The Dubinin–Radushkevick (D–R) model was used to assess the degree of site heterogeneity. The interactions between carbofuran and surface sites can largely be ascribed to specific chemical interactions.