Persistent Organic Compounds Research Articles

Adverse effects in Daphnia magna exposed to e-waste leachate: Assessment based on life trait changes and responses of detoxification-related genes

The sharp increase in e-waste derived from great consumption of electronic products has become a potential global environmental challenge. Limited information is available about the potential detrimental impact of e-waste on aquatic organisms. The present study investigated the expression of detoxification-related genes and life-history parameter changes in Daphnia magna exposed to e-waste leachate, simultaneously integrating with the chemical analysis of typical pollutants from e-waste leachate. The study aims at assessing impacts of e-waste to aquatic invertebrates and providing insights into its toxic mechanisms. The results showed high concentration of heavy metals like Cu (1657.14 ± 259.3 μg g−1, DW) and persistent organic compounds like polybrominated diphenyl ethers (7831.32 ± 1273.86 ng g−1, DW) in stream sediments near e-waste dismantling areas. Chronic exposure to these pollutants can affect the growth and reproduction of D. magna, resulting in significant development retardation, decreased total egg production per female, and even smaller body size. Expression of some detoxification and reproduction-related genes including DappuHR96, CYP360a, P-gp, EcR, CYP314 and Vtg exhibited different response patterns depending on the e-waste leachate concentration. E-waste leachate may affect the expression of detoxification-related and growth and reproduction-related genes and disrupt the growth and reproduction processes of D. magna.

Elucidating the catalytic degradation of enrofloxacin by copper oxide nanoparticles through the identification of the reactive oxygen species

Copper oxide nanoparticles (CuO-NPs) have been suggested as effective catalysts to degrade many persistent organic contaminants. In parallel, CuO-NPs are considered toxic to soil microorganisms, plants and human cells, possibly because they induce oxidative stress and generation of reactive oxygen species (ROS). However, the mechanism of the catalytic process and the generated ROS are poorly understood. Here we discuss the reaction mechanism of CuO-NPs during the catalytic degradation of enrofloxacin – an antibiotic pharmaceutical used in this study as a representative persistent organic compound. The degradation of an aqueous solution of the enrofloxacin exposed to CuO-NPs and hydrogen peroxide was studied showing fast removal of the enrofloxacin at ambient conditionsns. ROS production was identified by electron spin resonance and a spin trapping technique. The distribution of the free radical species indicated production of a high percentage of superoxide (O2−.) radicals as well as hydroxyl radicals; this production is similar to the “radical production” activity of the superoxide dismutase (SOD) enzyme in the presence of hydrogen peroxide. This activity was also tested in the opposite direction, to examine if CuO-NPs show reactivity that potentially mimics the classical SOD enzymatic activity. The CuO-NPs were found to catalyze the dismutation of superoxide to hydrogen peroxide and oxygen in a set of laboratory experiments.

Interaction of Environmental Pollutants with Microplastics: A Critical Review of Sorption Factors, Bioaccumulation and Ecotoxicological Effects.

Microplastics have become one of the leading environmental threats due to their persistence, ubiquity and intrinsic toxic potential. The potential harm that microplastics impose on ecosystems varies from direct effects (i.e., entanglement and ingestion) to their ability to sorb a diversity of environmental pollutants (e.g., heavy metals, persistent organic compounds or pharmaceuticals). Therefore, the toxicological assessment of the combined effects of microplastics and sorbed pollutants can produce in biota is one of the hottest topics on the environmental toxicology field. This review aims to clarify the main impacts that this interaction could have on ecosystems by (1) highlighting the principal factors that influence the microplastics sorption capacities; (2) discussing the potential scenarios in which microplastics may have an essential role on the bioaccumulation and transfer of chemicals; and (3) reviewing the recently published studies describing toxicological effects caused by the combination of microplastics and their sorbed chemicals. Finally, a discussion regarding the need for a new generation of toxicological studies is presented.

USING METAL WASTE SLAGS AS THE HETEROGENEOUS CATALYSTS OF OZONE FOR TREATMENT OF PULP WASTEWATER

Catalytic ozonation is one of the promising treatment methods for removal of persistent organic compounds from water and wastewater. In this study, some metal slags such as: iron slag, lead slag, zinc slag, cadmium slag and copper slag originated from solid waste of Thai Nguyen Non-ferrous Metals Limited Company, Vietnam were used as heterogeneous catalysts for ozonation process to remove organic compounds from pulp wastewater. The effects of the initial pH (pHi) of pulp wastewater and the metal slag dosage on efficiency of decolorization and mineralization of pulp wastewater, in term of COD were investigated. The results indicated that iron slag was the most suitable catalyst for treatment of pulp wastewater by ozonation process with the highest removal efficiency of COD, namely, after 120 min of ozonation (with flowrate of O3 of 3.038 g/h) of the pulp wastewater (initial COD 1809 mg/L), COD removal efficiency, respectively, reached 91,16%; 84%; 83,83 %; 83,91%; 83,41% and 83,14% in the presence of iron, copper, zinc, lead, cadmium slag and ozone alone. Simultaneously, the color was almost completely removed (95.55 – 98.79%) by ozonation processes with using all before-mentioned metal slags as heterogeneous catalysts and ozone alone. Maximum COD and color removal efficiency obtained at pH 7 for ozonation alone and its combinations with iron slag. Moreover, an increase in the iron slag dosage from 0.125 g/L to 2.0 g/L for O3/iron slag could enhance COD and color removal of pulp wastewater. The K values (apparent first-order rate constant values) showed that the COD removal rate followed the pseudo-first-order kinetic model. This study also indicated that the main constituent FeO presence in iron slag reaction with O3 in heterogeneous catalytic ozonation system enhances removal efficiency of color and COD of pulp wastewater.

Photocatalytic Degradation of 2,4-Dichlorophenol on NiAl-Mixed Oxides Derivatives of Activated Layered Double Hydroxides

Advanced oxidation processes such as photocatalysis have assumed enormous importance in the scientific field as viable sustainable alternatives to be applied to the elimination of persistent organic pollutants present in water reservoirs for human consumption. Persistent organic compounds like pesticides that belong to the chlorophenol family are a global public health priority since they are associated with serious diseases like cancer and can even cause death at low concentrations of prolonged exposure. This work proposes the use of activated Ni/Al layered double hydroxides as photocatalysts for the degradation of 2,4-dichlorophenol. The study variables associated with the properties of the catalysts were the Ni/Al metal ratio as well as the synthesis conditions. To determine the structural properties of catalytic precursors and catalysts, the techniques of XRD, FTIR, UV-DR, DGTA, TPD, SEM-EDS and TEM were used. The photodegradation tests were carried out in a Bach type reactor with a high energy uv lamp. The results of the photocatalytic degradation of 2,4-dichlorophenol in aqueous solution showed good photocatalytic activity with a degradation efficiency of up to 94% attributed to the presence of Ni in the crystalline and amorphous structures of NiO–NiAl2O4 oxides by means of a combined oxidation-reduction mechanism due to the effect of holes and superoxide and hydroxyl radicals not associated with the memory effect of reconstruction of layered double hydroxides.

Changes of microbial community and activity under different electric fields during electro-bioremediation of PAH-contaminated soil

Electro-bioremediation is a promising technology for remediation of soil contaminated with persistent organic compounds such as polycyclic aromatic hydrocarbons (PAHs). During electro-bioremediation, electrical fields have been shown to increase pollutant degradation. However, it remains unclear whether there is an optimal strength for the electrical field applied that is conductive to the maximum role played by microbes. This study aimed to determine the optimal strength of electric field through the analysis of the effects of different voltages on the microbial community and activity. Four bench-scale experiments with voltages of 0, 1, 2 and 3 V cm−1 were conducted for 90 days in an aged PAH-contaminated soil. The spatiotemporal changes of the soil pH, moisture content and temperature, microbial biomass and community structure, and the degradation extent of PAHs were researched over 90 days. The results indicated that the total microbial biomass and degradation activity were highest at voltages of 2 V cm−1. The concentration of total phospholipid fatty acids, used to quantify soil microbial biomass, reached 65.7 nmol g−1 soil, and the mean degradation extent of PAHs was 44.0%. Similarly, the maximum biomass of actinomycetes, bacteria and fungus also occurred at the voltage of 2 V cm−1. The Gram-positive/Gram-negative and (cy17:0+cy 19:0)/(16:1ω7+18:1ω7) ratios also showed that the intensity of electric field and electrode reactions strongly influenced the microbial community structure. Therefore, to optimize the electro-bioremediation of PAH-contaminated soil, the strength of electric field needs to be selected carefully. This work provides reference for the development of novel electrokinetically enhanced bioremediation processes.

Can metal organic frameworks outperform adsorptive removal of harmful phenolic compound 2-chlorophenol by activated carbon?

Removal of persistent organic compounds from aqueous solutions is generally achieved using adsorbent like activated carbon (AC) but it suffers from limited adsorption capacity due to low surface area. This paper describes a pioneering work on the adsorption of an organic pollutant, 2-chlorophenol (2-CP) by two MOFs with high surface area and water stability; MIL-101 and its amino-derivative, MIL-101-NH2. Although MOFs have higher surface area than AC, the latter was proven better having the highest equilibrium 2-CP uptake (345 mg g−1), followed by MIL-101 (121 mg g−1) and MIL-101-NH2 (84 mg g−1). Used MIL-101 could be easily regenerated multiple times by washing with ethanol and even showed improved adsorption capacity after each washing cycle. These results can open the doors to meticulous adsorbent selection for treating 2-CP-contaminated water.

OPTIMIZACIÓN DE LA REMOCIÓN DE COMPUESTOS ORGÁNICOS PERSISTENTES MEDIANTE EL PROCESO FOTO-FENTON

La metodología de superficie de respuesta se aplicó para evaluar la condición óptima experimental a fin de remover los compuestos orgánicos persistentes de un agua residual textil sintética usando un reactor fotoquímico en lote a escala laboratorio. Cuatro factores a tres niveles fueron estudiados: relación de reactivos Fenton H2O2/Fe2+ (11,25, 18,75, 26,25 mg/L/mg/L), potencia de lámpara UV (4, 11, 18 W), pH (2, 3, 4) y tiempo de tratamiento (60, 120, 180 min). Los niveles óptimos encontrados para los cuatro factores fueron: relación de reactivos Fenton H2O2/Fe2+ igual a 17 mg/L/mg/L, potencia de lámpara UV igual a 4 W, pH igual a 3 y tiempo de tratamiento de 180 min. Se encontró que el proceso foto-Fenton es muy efectivo para tratar el agua residual textil sintética, encontrándose una remoción de un 86 %, respecto al DQO.

Soybean peroxidase-catalyzed oligomerization of arylamines in water: optimization, kinetics, products and cost

Water contamination by refractory and persistent organic aromatic compounds such as poly-substituted mono-cyclic, 4-chloro-o-toluidine and bis-anilino compound, 4,4′-methylenebis-(2-chlororaniline), is an emerging environmental concern and the compounds are considered priority pollutants by U.S. Environmental Protection Agency. Thus, there is a search for new, efficient and eco-friendly treatment methods for converting and eliminating these pollutants at the point of release. The crude form of soybean seedcoat peroxidase, was able to catalyze the oxidation of these pollutants by generating reactive radicals which couple to form insoluble products. The reaction parameters, pH, hydrogen-peroxide-to- substrate molar ratio and minimum effective enzyme concentration were optimized to achieve ≥95 % removal of these substrates in a 3-h reaction time. The pH optima for 4-chloro-o-toluidine and 4,4′-methylenebis (2-chlororaniline) were 4.4 and 4.2, respectively. Consumption of H2O2 of both substrates was near the theoretical stoichiometric value (i.e. H2O2/substrate ≤ 1.0). For 95 % removal of 1.0 mM 4-COT and 0.1 mM MOCA, 0.009 and 0.10 U/mL of enzyme were required, respectively. The enzyme kinetic mechanism based on the Michaelis-Menten model was determined for a group of aromatic amines, p-cresidine, 4,4′-oxydianiline, 4-chloro-o-toluidine and 4,4′-methylenebis-(2-chlororaniline). The lowest KM was for 4,4′-methylenebis (2-chlororaniline), 1.70 ± 0.14 μM, indicating highest affinity for the enzyme compared to other amines studied. In addition, product analysis by mass spectrometry revealed presence of “oxidative oligomers” and “oxidized oxidative oligomers” (azo compounds) after the enzymatic treatment. A pro-forma cost estimation emphasized the feasibility of commercialization of the enzymatic treatment, showing it to be 5–8 times lower than conventional methods.

Rhizosphere and Endophytic Bacteria Associated to Ocimum basilicum L. with Decaclorobiphenyl Removal Potential

Basil (Ocimum basilicum L.) is a hyperaccumulative herbaceous plant that has the ability to grow in contaminated soils and is believed to harbor a wide variety of bacterial species resistant to recalcitrant toxic chemical compounds. The objective of this work was to evaluate the potential for removal of decaclorobiphenyl PCB-209 by bacteria associated with the O. basilicum plant. A total of 34 endophytes and 52 strains from the rhizosphere of this plant were isolated using selective culture media. The adaptive capacity of the bacteria in phenol and Arochlor 1242 was initially determined and then a set of bacteria was selected and their removal potential of decachlorobiphenyl PCB-209 was evaluated. The phylogenetic analysis of 16S rRNA gene grouped to the O. basilicum isolates within bacterial genera Acinetobacter, Bacillus, Lysinibacillus, Novosphingobium, Pseudomonas, Rhizobium, Sphingobium, Stenotrophomonas, and Terribacillus as well as bacterial strains Pseudomonas taiwanensis BS-1, Rhizobium nepotum BS-2, Terribacillus sacharophilus BS-3, Stenotrophomonas rhizophila BS-4, Bacillus arybhattai BS-5, and Lysinibacillus macroides BS-6 showed the ability to adapt and use phenol and Arochlor 1242 as source of C. The strains BS-4 isolated from the root of the plant showed a higher potential from the removal of the PCB-209 (390.75 mg L−1) at an initial concentration of 500 mg L−1 and also had the ability to synthesize biosurfactant (EI = 60%) compared to the other strains evaluated. The diversity of bacteria associated to O. basilicum had biological qualities that may contribute to their adaptation and proliferation in an environment contaminated by PCB and be used efficiently as bioremediation to relieve agricultural soils contaminated by persistent organic compounds.

Assessment of Biological and Persistent Organic Compounds in Hospital Wastewater After Advanced Oxidation Process UV/H2O2/O3

This work studies the reduction of biological and organic compounds in hospital wastewaters (HWW) by advanced oxidation process (AOP). The HWW samples were previously treated with an extended aeration process and, thereafter, a post-treatment with AOP based on UV/H2O2/O3 system with a medium pressure mercury lamp was applied. After using the AOP system, the water samples were characterized using chemical oxygen demand (COD), turbidity, color test, coliforms and E. coli test, gas chromatography coupled to mass spectrometry (GC-MS), and UV-Visible absorption spectra. The results showed that 73% of organic compounds were removed in 20 min and the HWW sample was sterilized; nevertheless, 10 persistent organic compounds and 8 by-products formed after AOP UV/H2O2/O3 were observed, some of them are toxic compounds. In this sense, current HWW treatment plants cannot eliminate all contaminants in HWW; therefore, it is necessary to improve current processes by techniques as AOP and create standards to control biological and organic compounds in HWW in Mexico

Electrospray Ionization Inlet Tandem Mass Spectrometry: A Hyphenated Method for the Sensitive Determination of Chemicals in Animal Tissues and Body Fluids.

This study demonstrates the utility of electrospray ionization inlet mass spectrometry (ESII-MS/MS) for the quantitative determination of analytes in complex animal matrices without chromatographic separation. Veterinary drugs including flunixin, its metabolite 5-hydroxyflunixin, and zilpaterol and persistent organic perfluoroalkyl compounds were determined in incurred plasma, urine, and/or tissue samples. Limits of detection (LOD) of zilpaterol in kidney, liver, lung, and muscle ranged from 0.02 to 0.06 ng/g, whereas the limit of quantitation (LOQ) for zilpaterol in all tissues was 0.1 ng/g. For urinary or plasma flunixin, 5-hydroxyflunixin, and PFOS/PFHxS, LODs ranged from 0.1 to 0.7 ng/mL while the LOQs ranged from 0.4 to 50 ng/mL. Regression coefficients for matrix-matched standard curves were 0.993-0.997, 0.977-0.999, and 0.999 for plasma, tissues, and urine, respectively. Correlations between quantitative results obtained by ESII-MS/MS and LC-MS for flunixin, 5-hydroxyflunixin, and zilpaterol ranged from 0.930 to 0.985. ESII-MS/MS provided rapid, sensitive, and accurate analyses of veterinary drugs and environmental contaminants from complex matrices without chromatographic separation.

Integrated Assessment of Bioconcentration, Toxicity, and Hazards of Chlorobenzenes in the Aquatic Environment.

The evaluation of bioconcentration, toxicity, and hazard (BTH) of persistent lipophilic organic compounds (LOCs) are generally performed as separate rather than integrated assessments. There are adequate data sets in the literature for chlorobenzenes (CBs) consisting of (a) concentrations in aquatic biota (CB) and water (Cw) in the natural environment, (b) laboratory-derived bioconcentration factors (KB) and field concentration ratios (CR), the field equivalent factor of KB, (c) measured internal lethal concentrations (ILC50) and model estimated ILC50 calculated from KB and lethal concentrations (LC50), and (d) calculated hazard quotients in aquatic biota (HQB) and in water (HQW). However, there have been no integrated studies of those parameter values based on the respective lipid-based parameters (CBL, KBL, CRL, ILC50L, HQBL) performed. This study utilized the lipid-based parameters for CBs; a group of widely occuring, bioaccumulative, and toxic LOCs, and integrated those parameters into a bioconcentration-toxicity-hazard (BTHL) index. The values of the parameters were obtained from selected literature with known lipid contents of the aquatic biota. The results showed that the laboratory derived bioconcentration factors, KBLs, were comparable to the corresponding field based factors, CRLs, and the measured internal lethal concentrations, ILC50L, showed comparable values with the estimated ones. The integrated BTHL index was less than an order of magnitude or moderately acceptable for the assessment of variability, uncertainty, and predictive power of the index. This integrated assessment can be used to support decision making dealing with CBs in specific and LOCs in general, both in regional and global aquatic environments.

Газохроматографический метод обнаружения стойких органических соединений в молочном сырье

Газохроматографический метод обнаружения стойких органических соединений в молочном сырье

Remediation on underground water pollution using Fenton Oxidation Method

Fenton oxidation, one of the advanced oxidation processes (AOP), has high efficiency in the eradication of total petroleum hydrocarbon (TPH), including those persistent organic compounds, with minimal time. Fenton oxidation is employed for further study in the remediation of hydrocarbon-contaminated groundwater sample collected from site. In this study, the efficiency of Fenton Oxidation is investigated toward the degradation of hydrocarbon in groundwater samples. The percentage removal of hydrocarbon, in terms of chemical oxygen demand (COD) in different operating condition for Fenton oxidation of contaminated groundwater was determined. The treatment parameters were selected by carrying out Factorial Design in which pH 3 to 6, concentration of hydrogen peroxide 0.01 mg/L to 0.1 mg/L, concentration of ferrous ions 0.01 mg/L to 0.5 mg/L, and Reaction Time 30 minutes to 120 minutes were proven to be significant model terms.

Photoelectrocatalyzed degradation of organophosphorus pesticide fenamiphos using WO3 nanorods as photoanode.

In this study, WO3 nanostructures were synthesized by the electrochemical anodization technique to use them on the degradation of persistent organic compounds such as the pesticide fenamiphos. The acids electrolyte used during the anodization were two different: 1.5M H2SO4 - 0.05M H2O2 and 1.5M CH4O3S - 0.05M H2O2. Once the samples have been manufactured, they have been subjected to different tests to analyze the properties of the nanostructures. With Field Emission Scanning Electron Microscopy (FE-SEM) the samples have been examined morphologically, their composition and crystallinity has been studied through Raman Spectroscopy and their photoelectrochemical behaviour by Photoelectrochemical Impedance Spectroscopy (PEIS). Finally, degradation tests have been carried out using the technique known as photoelectrocatalysis (PEC). The conditions that were applied in this technique were a potential of 1 VAg/AgCl and simulated solar illumination. The degradation process was monitored by UV-Visible and High-Performance liquid Chromatography (HPLC) to control the course of the experiment. The nanostructures obtained with 1.5M CH4O3S - 0.05M H2O2 electrolyte showed a better photoelectrochemical behaviour than nanostructures synthesized with 1.5M H2SO4 - 0.05M H2O2. The fenamiphos degradation was achieved at 2h of experiment and the intermediate formation was noticed at 1h of PEC experiment.

Electro-Oxidation as an Effective Process for Removing Antibiotics and Persistent Organic Compounds Resistant to Biodegradation

This article is a Letter to the Editor and does not include an Abstract.

Investigating the Effect of Medicago sativa L. and Trifolium pratense L. Root Exudates on PAHs Bioremediation in an Aged-Contaminated Soil

Polycyclic aromatic hydrocarbons (PAH) are persistent organic compounds of major concern that accumulate in the environment, especially soils, and require remediation. Researches to develop bioremediation and phytoremediation (alternative eco-friendly technologies) are being conducted. First, a bioaccessibility measurement protocol was adapted to a brownfield soil using Tenax® beads in order to compare PAHs bioaccessibility in soil samples. PAHs desorption kinetics were established, described by a site distribution model, and a common extraction time was calculated (48 h). Second, the role of two Fabaceae (Medicago sativa L. or Trifolium pratense L.) root exudates in enhancing PAHs bioaccessibility and biodegradation in the studied soil was evaluated during microcosms experiments (28 °C). The CO2 emissions were significantly higher in presence of T. pratense exudates; the dehydrogenase activities showed improvements of the soil microbial activity in presence of two types of root exudates compared to untreated soil samples; the PAHs residual contents decreased more in untreated samples than in the presence of T. pratense exudates; and M. sativa exudates lowered PAHs bioaccessibility but not residual contents.

Anoxic degradation of chlorpyrifos by zerovalent monometallic and bimetallic particles in solution.

The degradation of highly toxic and persistent chlorinated organic compounds by zerovalent metals (ZVMs) has received considerable attention for in situ groundwater remediation. Due to its abundance and low toxicity, iron has been mostly applied for such purposes, despite several limitations, such as rapid surface passivation and little efficacy towards certain contaminants. Given that, we evaluated monometallic zerovalent iron (ZVI), copper (ZVC) and zinc (ZVZ), and bimetallic copper-coated ZVI (ZVI/Cu) and ZVZ (ZVZ/Cu) for anoxic reductive degradation of chlorpyrifos (CP). Two approaches to enhance metal reactivity were investigated: the synthesis of bimetallic particles with copper and the comparison between micro and nanoparticles. All of the tested monometallic and bimetallic particles dechlorinated the target molecule, although complete chlorine removal was not achieved by any metal during the 30-d treatment period. Coating the zerovalent monometallic particles with copper enhanced reactivity. Reactivity was ZVC>ZVZ>ZVI for monometallic particles and ZVZ/Cu>ZVI/Cu for bimetallic microparticles. The analysis of the degradation products indicated the presence of dechlorinated compounds as well as 3,5,6-trichloro-2-pyridinol, a hydrolysis product.

Electronic Waste Recycling: Occupational Exposures and Work-Related Health Effects.

Electronic waste (e-waste) is a global public health challenge. E-waste recycling workers may be exposed to chemical, physical, ergonomic, and psychosocial hazards. This review provides an overview of recent research on occupational exposures in e-waste recycling and work-related health effects that can impact e-waste workers. E-waste workers are exposed to a variety of chemicals including metals, particulates, persistent organic compounds, and flame retardants. Exposure varies according to job task with higher exposures observed for dismantling and burning e-waste. Exposure to job stress and physical hazards (e.g., noise) also occurs. Many studies have measured workers' exposure in the e-waste recycling industry; fewer have investigated health effects. Biological measures were reported more often than external exposure measures. In order to protect workers, efforts are required to better understand exposures and their health effects. Removing hazardous materials from electronic equipment and reducing e-waste production would benefit workers, communities, and the environment.