Organochloride Compounds Research Articles

Novel method for chlorine determination in biofuel lipid feedstock by coupling a total sample introduction system (hTISIS) to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS)

BackgroundChlorine concentrations above 1 mg kg−1 in lipid feedstocks for biofuel production can generate corrosion issues in the different refining units as well as catalyst deactivation by clogging or fouling. To reach accurate analyses by inductively coupled plasma (ICP) techniques at low concentration levels, dilution in organic solvents rises as a simpler and more straightforward sample preparation methodology than conventional sample decomposition procedures (e.g., microwave-assisted acid digestion). However, matrix effects and the impact of the Cl chemical form on the signal must be overcome to obtain accurate results. ResultsIn this work, the high temperature torch integrated sample introduction system (hTISIS) operated at 350 °C is coupled to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) for the determination of Cl in lipid biofuel feedstock samples diluted in xylene and these results are compared with those reported by a conventional sample introduction system. Under optimal conditions of the hTISIS-ICP-MS/MS configuration, matrix effects are efficiently overcome (recovery values ranged from 101 to 104%) as well as the effect of the Cl chemical form on the signal for 6 organochloride compounds. Thus, an external calibration approach can be set to carry out the quantification of this element in real samples. The method is successfully validated, obtaining a good agreement in the Cl concentration reported in a standard reference material (SRM NIST 1634c) and also by comparing the concentration results obtained by external calibration and standard addition approaches in two biofuel feedstock samples. Significance and noveltyThe hTISIS coupled to an ICP-MS/MS system is used for the first time to overcome not only matrix effects but also the impact of the Cl chemical form in biofuel feedstock samples. This novel method, with a limit of quantification (LOQ) of 7.1 μg kg−1, give access to an accurate Cl determination in all kind of lipid feedstocks for clean fuel production.

Development of a novel ReaxFF reactive potential for organochloride molecules.

This article presents a new reactive potential in the ReaxFF formalism. It aims to include the chlorine element and opens up the fields of use of ReaxFF to the whole class of organochloride compounds including conjugated or aromatic groups. Numerous compounds in this family raise global awareness due to their environmental impact, and such a reactive potential will help investigate their degradation pathways. The new force field, named CHONCl-2022_weak, belongs to the aqueous branch. The force field parameters were fitted against high-level quantum chemistry calculations, including complete active space self-consistent field/NEVPT2 calculations and density functional theory calculations, and their accuracy was evaluated using a validation set. The root means square deviation against quantum mechanics energies is 0.38eV (8.91kcal mol-1). From a structural point of view, the root means square deviation is about 0.06 Å for the bond lengths, 11.86° for the angles, and 4.12° for the dihedral angles. With CHONCl-2022_weak new force field, we successfully investigated the regioselectivity for nucleophilic or electrophilic attacks on polychlorinated biphenyls, which are toxic and permanent pollutants. The rotation barriers along the bond linking the two benzene rings, which is crucial in the toxicity of these compounds, are well reproduced by CHONCl-2022_weak. Then, our new reactive potential is used to investigate the chlorobenzene reactivity in the presence of hydroxyl radicals in atmospheric condition or in aqueous solution. The reaction pathways computed with ReaxFF agree with the quantum mechanics results. We showed that, in the presence of dioxygen molecules, in atmospheric condition, the oxidation of chlorobenzene likely leads to the formation of highly oxygenated compounds after the abstraction of hydrogen radicals. In water, the addition of a hydroxyl radical leads to the formation of chlorophenol or phenol molecules, as already predicted from plasma-induced degradation experiments.

Sensing Techniques for Organochlorides through Intermolecular Interaction with Bicyclic Amidines.

Toxic organochloride molecules are widely used in industry for various purposes. With their high volatility, the direct detection of organochlorides in environmental samples is challenging. Here, a new organochloride detection mechanism using 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is introduced to simplify a sensing method with higher detection sensitivity. Three types of organochloride compounds-trichloroethylene (TCE), dichloromethane (DCM), and dichlorodiphenyltrichloroethane (DDT)—were targeted to understand DCM conjugation chemistry by using nuclear magnetic resonance (NMR) and liquid chromatography with a mass spectrometer (LC-MS). 13C-NMR spectra and LC-MS data indicated that DBN can be labeled on these organochloride compounds by chlorine–nitrogen interaction. Furthermore, to demonstrate the organochloride sensing capability, the labeling yield and limit of detection were determined by a colorimetric assay as well as micellar electrokinetic chromatography (MEKC). The interaction with DBN was most appreciable for TCE, among other organochlorides. TCE was detected at picomolar levels, which is two orders of magnitude lower than the maximum contaminant level set by the United States Environmental Protection Agency. MEKC, in conjunction with this DBN-labeling method, enables us to develop a field-deployable sensing platform for detecting toxic organochlorides with high sensitivity.

Electrochemical Decontamination Process an Effective Alternative to Treat Textile Effluents

Keeping in view the growing concern regarding aquatic pollution by effluent water from textile industries containing complex compounds, the present study was under taken with the view to study the efficiency of the removal by electrochemical oxidation. In recent year the use of electrochemistry for the investigation of environmental pollution is being thoroughly investigated. Reactive dye mainly composed of complex organic molecules are highly stable to decomposition in normal condition. Textile industry wastewater containing dyes poses a chronic and synergistic effects to environment. This study examines the electrochemical oxidation of the organic dyes. All the experiments were performed using a Filter Press Flow Cell Reactor containing Ti/Ti0.7Ru0.3O2 anode and stainless steel as cathode in which impact of the current density (5 – 20 mA cm-2), electrolytes (NaCl, Na2SO4, H2SO4), Sodium chloride concentration (0.02 – 0.10 mol L-1) were studied. The electrode used were characterized by the cyclic voltammetry experiments. The Reaction Kinetics and energy consumption parameters were studied of the electrochemical process. Results obtained in this research clearly demonstrated that the effect of the electro generated strong oxidant species active chlorine, depends on electro catalytic mechanism followed on surface of Ti/Ti0.7Ru0.3O2 resulting in the improvement of the color. Results also confirmed a high removal efficiency according to environment and electrolyte used in the process. However, there is a limit of NaCl for treating real effluents avoiding the formation of organochloride compounds; and it is a subject of critical importance, from the environmental point of view, to apply this alternative treatment. Keyword: textile effluents, contaminants, electrochemical process, Kinetics

TOXICITY STUDIES DURING THE DEGRADATION OF PENTACHLOROPHENOL BY OZONATION IN THE PRESENCE OF MnO2/TiO2

Ozone is a strong oxidant used in the water treatment to remove organochloride compounds. Given that many processes of degradation generate chemical compounds that are more toxic than initial compounds, the development of optimized ozonation processes are required. In this study, pentachlorophenol (PCP) was used as a model of an organochlorine compound and the toxicity of its degradation products generated by both non-catalytic and catalytic ozonation processes were evaluated with a fresh-water Daphnia magna (ecotoxicity) and vegetables species Lactuca sativa and Panicum millaceum (Phytoxicity). The catalytic ozonation used MnO2/TiO2 as catalyst, which was characterized by X-ray diffraction analysis showing the presence of crystalline TiO2 phases, rutile and anatase. The specific BET surface area of MnO2/TiO2 was 43 m2/g. It was found that the use of ozone as an oxidant showed a first order degradation rate constant (kobs = 0.5 ± 0.1 min- 1). The uncatalyzed reaction showed several reaction intermediates like mono- and polychlorinated phenols, and quinones. The oxidation of these compounds led to low molecular weight organic acids. From these results, we proposed a pathway of PCP degradation using ozone. The catalyzed reaction showed a more potent effect in reducing the toxicity of the treated solution. Unlike the use of only ozone which does not decrease the toxicity. It was found that the treatment with catalytic ozonation decreases the toxicity of the solutions.

Bipolar Packed-bed Electrochemical Reactor for the Degradation of Diclofenac; a Bio-refractory Organic Compound

Pharmaceuticals have low biodegradability and can retain their chemical structure for long periods of time leading to an accumulation in the environment causing irreversible changes. Electrochemical oxidation has been proved to be an environmentally friendly and economically viable solution for bio-refractory of organic molecules as well as for the disinfection of wastewaters. This paper aims to evaluate the performance of specific energy consumption for a given reduction of toxic organic compound loads in a continuous flow bipolar packed-bed electrochemical reactor and compare this with a classical parallel plate reactor. The energy cost for both the parallel plate and bipolar electrochemical reactors are similar (around 1.6 kWh m-3) lower than other advanced oxidation process reported in literature. However, the bipolar configuration is particularly suitable for low conductivity waste water and/or for avoiding the formation of organochloride compounds in a chloride rich wastewater.

Analysis of catalyst photo-oxidation selectivity in the degradation of polyorganochlorinated pollutants in batch systems using UV and UV/TiO2

Worldwide concerns of organic pollutant free water supply have attracted significant attention to the technological advances in water and wastewater treatment. Photocatalysis is one of the technologies that have been proven to be effective at degrading organic micro-pollutant to noble constituents. This study investigated the selective influence of structural conformations of multi-chlorohalogenated substituted organochloride compounds by TiO2 as a semiconductor photocatalyst in the heterogeneous photocatalytic and photolytic treatments of organics in aqueous batch systems. The chemical compounds under scrutiny were DDT (dichlorodiphenyltrichloroethane), chlordane and 2.3.4-TCB (2.3.4-trichlorobiphenyl). Photo-induced oxidation profiles were determined to adhere to structural configuration preferential selectivity in favour of smaller sized molecular compounds, where chlordane achieved the least efficiency in removal. The photocatalytic degradation process indicated partial selectivity against chlordane in favour of DDT and TCB, where maximum efficiencies were recorded for the smaller molecular structure compounds, while chlordane recorded significantly lower efficiency of reduction. The photocatalytic performance relationship was that of impeded photon delivery with increased catalyst mass loading. The Langmuir–Hinshelwood expression was used to model the photocatalytic degradation process, where the adsorption parameters were calculated from photocatalyst isothermal adsorption studies. The reaction kinetic parameters were simulated and estimated using an aquatic systems modelling software.

Decahedral anatase titania particles immobilized on zeolitic materials for photocatalytic degradation of VOC

Decahedral anatase titania particles (DAPs) immobilized on zeolites (zeolite/DAP hybrids), have been prepared by the first time. DAPs have been synthesized from titanium chloride (TiCl4) through a gas-phase reaction process by rapid heating and quenching. DAPs with well-defined {101} and {001} facets were synthetized and dispersed onto the zeolites. The incorporation of an 8wt% of DAPs into the zeolites has been achieved by means of the freezing-drying technique. Two types of zeolites (ZSM-5 and zeolite Y) with different SiO2/Al2O3 contents have been selected as adsorbents. The photocatalytic properties for the degradation of representative volatile organic compounds (VOC), i.e. acetaldehyde, formaldehyde or trichloroethylene were analyzed under batch and continuous flow reactors. Raw materials and composites were characterized by SEM, N2 adsorption-desorption, UV–vis spectroscopy, XRD, zeta potential and the amount of VOC adsorbed was measured at dynamic conditions. Zeolite/DAP hybrids combine the textural and crystalline properties of zeolite and DAPs phases. The zeolite type (crystal structure, SiO2/Al2O3 ratio and surface net charge) play a relevant role in the dispersion of DAPs. Zeolite/DAP composites show better photocatalytic performance than those prepared with commercial TiO2 due to the presence of {001} facets in the former. The composites prepared with hydrophobic ZSM-5 and DAPs, are the most versatile materials for photooxidation of aldehydes and organochloride compounds, with substantially less formation of non-desirable reaction products respect to those based on benchmark TiO2.

ESTUDIO DE LOS PROCESOS RELACIONADOS CON LA PRESENCIA DE PLAGUICIDAS ORGANOCLORADOS EN LA CIÉNAGA GRANDE DE SANTA MARTA

The aim of this paper is to have an approach to the phenomena that take place in the lagoon complex of the Ciénaga Grande de Santa Marta (CGSM), which are related to the behavior of the remaining organochloride pesticides. Besides discussing the depuration processes, precipitation/sedimentation and the damping that are present in this coastal lagoon; with an environmental managing scope. The results analyzed were those obtained from the project called “Monitoring of the environmental conditions and the structural and functional changes of the vegetal communities and fishing resources during the rehabilitation of the CGSM”. The main removal type in the CGSM water system for organochloride compounds in the water column, occurs by precipitation/sedimentation processes, as it is observed in Pajaral and Caño Clarín areas, where a decreasing up to 50% of this toxic compounds is happening, related to the unloaded levels.

Classification and characterisation of SRF produced from different flows of processed MSW in the Navarra region and its co-combustion performance with olive tree pruning residues

The scope of this work is to study the co-combustion of a solid recovered fuel (SRF) produced from household wastes and packaging wastes recovered from selective collection (SC) in the autonomous community of Navarra, located in the northeast of Spain. The municipal solid waste (MSW) is subjected to a mechanical biological treatment (MBT) in order to stabilize the organic matter and recover the recyclable materials as it is done for packaging wastes. Afterwards, rejects from this treatment plant were preconditioned and compressed by a pelletizing process to produce a secondary fuel according to quality and classification criteria of EN 15359, producing the so-called SRF. A fuel characterisation was carried out according to CEN standards and the SRF was classified as follows: NCV 2; Cl 3; Hg 1. SRF pellets were cofired with residual biomass pellets from olive tree pruning (OTP) in a bubbling fluidised bed combustor, as an option of energy recovery. The mixture of fuels, with a mixing ratio close to 50% by weight, showed a significant calorific value of 18.25MJ/kg at 8% of moisture content. In addition, elemental composition of the mixture based on nitrogen (N), sulphur (S) and chlorine (Cl) (1% N, 0.2% S and 0.4% Cl) was not far from some herbaceous biomasses. The co-combustion showed good results as an energy recovery technology because of the synergies of both fuels, improving notably the combustion conditions and reducing significantly CO concentration, regarding to the combustion of OTP, though other contaminants such as NOx and HCl increased. During eight hours of stable operation, the concentration of dioxins and furans was measured obtaining a value of 7.68ng/Nm3 (toxic equivalence: i-TEQ of 0.33ng/Nm3). Proportions of SRF lower than 50% in the mixtures should be tested in order to cut down the emissions of these pollutants, or an abatement system for organochloride compounds may be required.

Decomposition of organochlorine compounds in flue gas from municipal solid waste incinerators using natural and activated acid clays

High-temperature particle control (HTPC) using a ceramic filter is a dust collection method without inefficient cooling and reheating of flue gas treatment; thus, its use is expected to improve the energy recovery efficiency of municipal solid waste incinerators (MSWIs). However, there are concerns regarding de novo synthesis and a decrease in the adsorptive removal efficiency of dioxins (DXNs) at approximately 300°C. In this study, the effect of natural and activated acid clays on the decomposition of monochlorobenzene (MCB), one of the organochlorine compounds in MSW flue gas, was investigated. From the results of MCB removal tests at 30–300°C, the clays were classified as adsorption, decomposition, and low removal types. More than half of the clays (four kinds of natural acid clays and two kinds of activated acid clays) were of the decomposition type. In addition, the presence of Cl atoms detached from MCB was confirmed by washing the clay used in the MCB removal test at 300°C. Activated acid clay was expected to have high dechlorination performance because of its proton-rich-composition, but only two clays were classed as decomposition type. Conversely, all the natural acid clays used in this work were of the decomposition type, which contained relatively higher di- and trivalent metal oxides such as Al2O3, Fe2O3, MgO, and CaO. These metal oxides might contribute to the catalytic dechlorination of MCB at 300°C. Therefore, natural and activated acid clays can be used as alternatives for activated carbon at 300°C to remove organochloride compounds such as DXNs. Their utilization is expected to mitigate the latent risks related to the adoption of HTPC, and also to contribute to the improvement of energy recovery efficiency of MSWI.ImplicationsThe effect of natural and activated acid clays on MCB decomposition was investigated to evaluate their suitability as materials for the removal of organochlorine compounds, such as DXNs, from MSWI flue gas at approximately 300°C. More than half of the clays used in this study showed the decomposition characteristics of MCB. The presence of Cl atoms in the clay used in the MCB removal test at 300°C proved the occurrence of MCB decomposition. The results of this study suggest a novel flue gas treatment method to establish high-energy efficient MSWI systems.

BACTERIAL BIODEGRADATION OF ORGANOCHLORIDE COMPOUNDS

BACTERIAL BIODEGRADATION OF ORGANOCHLORIDE COMPOUNDS. Due to their recalcitrant nature, organochlorides are already found in environment and the search for alternatives to eliminate these compounds such as biodegradation using native microorganisms is of great interest. A screening trial to select environmental bacteria able to degrade DDD, PCP and dieldrin was conducted. Among 14 isolates, the soil bacteria Pseudomonas aeruginosa L2-1 showed the highest tolerance to increasing concentrations of the organochlorides and was selected for further studies. Biodegradation was assessed in liquid medium, varying the concentrations of glucose and the presence of rhamnolipids (RL). The best medium for the occurrence of biodegradation of the compounds contained 0.5% glucose, giving approximately 50% yield after three days of incubation. Results showed that the biodegradation rates of the organochlorides by P. aeruginosa L2-1 were greater at low concentrations of glucose and in the presence of rhamnolipids.

Acute Toxicity of Indo-Sulpin to a fresh water Gastropod Thira Lineate Changes in Rate of Respiration

Toxicity of sumithion to the fresh water field crab has been studied by Bhagya Laxmi and Ramamurti (1981), Aness (1975) and Verma et al., (1978) observed the toxicity of some organophosphate compounds. The oxygen consumption has been estimated by Alam and Lomte(1984) after exposing the gastropods. Viviparous bengalensis in zink sulphate Lowry, O. H.; Rosenbroughi, N. J.; Farr,A. L. and Randall, R. J. et. al. (1951, 1983) have observed the effects of carbaryl on oxygen consumption of the fish, Channa punctatus Chaudari.et.al. (1988) have observed rate of oxygen consumption. Considering the studies on pesticide pollution on the fresh water gastropod Thiara on the fresh water gastropod Thiara Lineata the present investigation has under taken with the view to understand the acute toxicity and the effect on the rate of oxygen consumption. Organophosphate compounds are now extensively use in place of organochloride compounds on account of their lesser residuals toxicity, but the prevention of aqutic animals' mortality remains an important object of water pollution research. Kaviraj and konar (1982) have studied the effects of heavy metals on accute toxicity of mercury, chromium and cadmium and cadmium to the fish. Tyllapia Mossambica. Mane and Akarte (1987) have studied the effects of cythion or Malathian on the estuarine Clam Catalasia optima.

Electrochemical degradation of the Disperse Orange 29 dye on a β-PbO2 anode assessed by the response surface methodology

The electrochemical degradation of the Disperse Orange 29 azo dye in a filter-press flow cell using a Ti–Pt/β-PbO2 as anode was investigated by experimental design for the variables current density, pH, [NaCl], and temperature. The electrochemical system was modeled by the charge required to attain 90% decolorization (Q90) and the chemical oxygen demand removal after 120min of electrolysis (COD120). The best conditions for Q90 were neutral to slightly alkaline solutions with low values of [NaCl] (<1.0gL−1). On the other hand, slightly acidic to neutral conditions with higher values of [NaCl] (1.2–1.7gL−1) yielded the highest COD120 values. These differences were ascribed to the possible formation of organochloride compounds that may lead to erroneous COD values. A total mass loss of only 0.1% was obtained during an accelerated life test of the Ti–Pt/PbO2 anode. Low levels of [Pb2+] were attained in neutral to alkaline conditions

English

Organochloride compounds are known to be highly toxic and persistent, causing serious water and soil pollution. Hexachlorocyclohexane (HCH) is the term which collectively identifies the eight isomers of the hexachlorocyclohexane and they are denoted by the greek letters α, β, γ, δ, etc. Among the eight isomers, gamma-hexachlorocyclohexane (γ-HCH or lindane), is the only one with insecticidal properties. γ-HCH has been mainly used in agriculture and vector control programmes. HCH isomers are recognized for their toxicity, persistence in the environment and potential carcinogenic effects. Lindane is a neurotoxin that interferes with GABA neurotransmittor function. In humans, lindane affects the nervous system, liver and kidneys, and may be a carcinogen. Because of this, lindane, a cheap and effective insecticide, is banned in many other countries, while still being used or have been banned only recently in India. Their extensive use has resulted in a widespread occurrence of residues in the environment and in food products. Residues of γ-HCH have been reported from different soil and water systems in India. Efforts have been made for the remediation of soils and groundwater contaminated with the toxic and persistent HCH isomers through biodegradation processes. Microorganisms capable of degrading HCH isomers have received considerable attention as they provide the possibility to be utilized forin situ detoxification. γ-HCH degrading microorganisms, many bacteria and a few fungi, have been isolated and employed for bioremediation of lindane contaminated soil and water systems. The genes and enzymes involved in the γ-HCH degradation pathway have been investigated. Key words: Biodegradation, gamma-hexachlorocyclohexane (γ-HCH), organochlorine pesticides, toxicity.

Decontamination of real textile industrial effluent by strong oxidant species electrogenerated on diamond electrode: Viability and disadvantages of this electrochemical technology

In a previous work [1], the treatment of dye solutions containing Remazol Red BR (RRB) and Novacron Blue C-D (NB) by anodic oxidation using boron doped diamond anode (BDD) demonstrated that the electrochemical treatment is an efficient alternative for removing color and chemical oxygen demand (COD) and this technology can be used for depuration of real effluents. More recently, these assumptions have been confirmed by oxidizing electrochemically a real textile effluent using BDD anode [2]. Then, as a further development of the research carried out in these previous studies [1,2], in the present work, it has been considered appropriate to extend the investigation to the anodic oxidation, using BDD anode, of a specific real effluent discharged by Brazilian textile industry, adding Na2SO4 or NaCl salts in order to verify the applicability of this treatment producing in situ strong oxidant species (peroxodisulfates or active chlorine, respectively).In this study, we also attempt to discuss critical evidence about the viability of peroxodisulfates or active chlorine. Results obtained in this research clearly demonstrated that the effect of the electrogenerated strong oxidant species, peroxodisulfates or active chlorine, depends on electrocatalytic mechanism followed on BDD surface, improving the color and COD removal. However, there is a limit of NaCl for treating real effluents avoiding the formation of organochloride compounds; and it is a subject of critical importance, from the environmental point of view, to apply this alternative treatment.

Application of lime and calcium hypochlorite in the dephenolisation and discolouration of olive mill wastewater

The application of hypochlorite for the removal of soluble COD, phenolic and polyphenolic like compounds, and other organic compounds responsible for the olive mill wastewater (OOWW) colour has been experimentally studied. After the OOWW filtration on a sand column, the effluent was subjected to a fast liming under optimal conditions. Lime application reduced polyphenols, COD and SS contents to half of their initial values but an important blackening of the treated OOWW was observed, especially when adding high concentrations of lime (10% (W/V) and 15% (W/V)). A second stage of treatment was applied using calcium hypochlorite. In this stage, removal of the studied compounds reached as much as 95% at higher concentrations, and particularly the colouring of OOWW which is generally difficult to eliminate was greatly reduced. The OOWW hypochloration acted through coagulation–flocculation and a rapid oxidation of the organic matter proceeded from the first 5 min. The kinetic study of the degradation of the waste polluting compounds from liming showed that Ca(ClO) 2 reacts similarly in the elimination of organic compounds, polyphenols, SS and colouration. The analysis of the organochloride compounds generated by the reaction between hypochlorite and the organic compounds showed that DDD, DDT and the heptachlor contents exceeded the values recommended by the International and European drinking water standards.

Electrochemical oxidation of acid black 210 dye on the boron-doped diamond electrode in the presence of phosphate ions: Effect of current density, pH, and chloride ions

The electrochemical oxidation of acid black 210 dye (AB-210) on the boron-doped diamond (BDD) was investigated under different pH conditions. The best performance for the AB-210 oxidation occurred in alkaline phosphate solution. This is probably due to oxidizing agents such as phosphate radicals and peroxodiphosphate ions, which can be electrochemically produced with good yields on the BDD anode, mainly in alkaline solution. Under this condition, the COD (chemical oxygen demand) removal was higher than that obtained from the model proposed by Comninellis . Electrolyses performed in phosphate buffer and in the presence of chloride ions resulted in faster COD and color removals in acid and neutral solutions, but in alkaline phosphate solution, a better performance in terms of TOC removal was obtained in the absence of chloride. Moreover, organochloride compounds were detected in all electrolyses performed in the presence of chloride. The AB-210 electrooxidation on BDD using phosphate as supporting electrolyte proved to be interesting since oxidizing species generated from phosphate ions were able to completely degrade the dye without producing organochloride compounds.

Electrochemical degradation of glyphosate formulations at DSA® anodes in chloride medium: an AOX formation study

The electrochemical degradation of different glyphosate herbicide formulations on RuO2 and IrO2 DSA® electrodes is investigated. Parameters that could influence the formation of organochloride compounds during electrolysis are studied. The effects of chloride concentration, electrodic composition, current density, and electrolysis time are reported. The influence of the oxide composition on herbicide degradation seems to be almost insignificant; however, there is a straight relationship between anode composition and organic halides formation. Commercial herbicide formulations have lower degradation rates and lead to the formation of a larger quantities of organochloride compounds. In high chloride concentrations, there is a significant increase in organic mineralization, and the relationship between chloride concentration and organic halides formation is direct. Only in low chloride medium investigated the organochloride concentration obtained was below the limit values allowed in Brazil. The determination of organic halides absorbable (AOX) during electrolysis increases significantly with the applied current. Even during long-term electrolysis, a large amount of organochloride compounds is formed.

Permeability and toxicological profile estimation of organochlorine compounds by biopartitioning micellar chromatography

This paper points out the usefulness of biopartitioning micellar chromatography (BMC) as a high-throughput primary screening tool providing key information about the oral absorption, skin permeability (K(p)), brain-blood distribution coefficient (BB) and ecotoxicological parameters such as median lethal concentration (LC(50)) and bioconcentration factors of 15 organochloride compounds. The retention data of compounds in BMC conditions were interpolated in previously developed quantitative-retention activity relationships by our research group. Results show that the compounds studied readily cross the intestinal barrier (oral absorption > 90%) and the blood-brain barrier (log BB > 0.4). In addition, the organochlorines DDE, chlorobenzene, 1,3-dichlorobenzene and 1,2-dichlorobenzene are the compounds which can more quickly cross the skin barrier (log K(p ) > -0.74 cm/h). From a ecotoxicological point of view, it can be concluded that the most retained compounds, DDE, DDD, hexachlorobenzene and dicofol, are the most toxic and bioacumulative.