Electrochemical degradation of ethidium bromide using boron-doped diamond electrode

Ethidium Bromide Degradation by Cold Atmospheric Plasma in Water and the Assessment of Byproduct Toxicity for Environmental Protection

Ethidium bromide (Et-Br) is a widely used fluorescent dye in molecular biology and biotechnology laboratories for visualizing nucleic acids in agarose gel electrophoresis. However, concerns have been raised about its environmental impact and potential health risks due to its persistence and toxicity. The potential accumulation and long-term effects on the environment necessitate the removal of Et-Br from water. This study investigates the potential of novel cold plasma technology for the degradation of Et-Br. Cold atmospheric plasma (CAP) is an environmentally friendly technology that does not produce secondary pollutants and generates a variety of potent chemical reactive oxidants such as hydroxyl radicals (•OH), H2O2, NO2, and NO3. In this study, Et-Br was treated with CAP for 15 min without the addition of any chemicals, resulting in substantial removal of Et-Br. The degradation kinetics revealed that the CAP-treated Et-Br followed a pseudo-first-order reaction, dependent on the treatment time of CAP. The degradation of Et-Br by CAP is distinctly evident through the results obtained from both high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses, providing clear evidence of the occurrence of degradation. Furthermore, toxicity analyses of the degradation products were conducted by evaluating the Et-Br intercalation ability with DNA before and after treatment of Et-Br with CAP. To supplement the assessment, the binding of Et-Br with BSA has also been studied before and after CAP treatment. The impact of CAP-treated Et-Br on the growth and colony-forming unit (CFU) counts of Escherichia coli was also evaluated. Results indicated an increase in bacterial growth with an increase in CAP treatment time, suggesting that the degradation products of Et-Br using CAP were nontoxic. This study highlights the potential of CAP as a clean and efficient technology for the degradation of Et-Br, presenting a promising solution for mitigating its environmental and health risks.

Anodic oxidation by electrical power pulses for alachlor degradation

This article explores the benefits of electrochemical oxidation in pulsed mode, using potential, current, and power pulses. While potential and current pulse electrochemical technology has been previously studied for wastewater treatment, no study has included power pulses until now. The objective of this work is to highlight the advantages of power pulses by applying this pulse type to the electrochemical oxidation of a probe molecule, alachlor. For this aim, the influence of operating parameters and the comparison of the different pulse modes were investigated and compared to the results obtained with the electrochemical oxidation of alachlor in continuous mode. The study shows that the best results were obtained with the power pulse electrochemical oxidation with 100% alachlor degradation after 180 min and a mineralisation yield of 38.3% after 240 min. These results were better than those reported in the literature for treatments with continuous current input using platinum electrodes. This new technique could be an effective and efficient way to treat contaminated water and reduce the pressure on freshwater reserves.

Investigation into the electrochemical advanced oxidation of p-arsanilic acid: Peculiar role of electrolytes and unexpected formation of coupling byproducts

Although banned in some countries, p-arsanilic acid (ASA) is still widely used as feed additive in poultry production. As a result, ASA is usually released into the aquatic environment without any treatments. Although ASA exhibits low toxicity, it can be transformed into highly toxic aromatic amines and inorganic arsenic species (As (V) as H2AsO4- and HAsO42-) under natural environmental conditions. Hence, it is necessary to develop efficient technologies for its removal or degradation. In this contribution, electrochemical advanced oxidation technology with boron-doped diamond (BDD) had been initially used to degrade ASA pollutants. A five-level central composite rotatable design (CCRD) was implemented to optimize the various influencing factors involved, among applied current density, NaCl concentration, Na2SO4 concentration and NaHCO3 concentration on the oxidation efficiency; the latter was assessed in terms of ASA degradation percentage. The results obtained highlighted the unique and important roles of electrolytes during the electrolytic oxidations. Meanwhile, the major degradation byproducts detected were also strongly dependent on the electrolyte adopted. In particular, several oligomer byproducts with novel structures were initially identified in BDD-treated ASA solutions. Two different electrochemical transformation pathways of ASA on BDD anode were thus proposed. This study demonstrated the effectiveness of BDD technology in the degradation of ASA, as well as the potential minor risk of its application in actual ASA wastewater treatment.

Adsorption and removal of ethidium bromide from aqueous solution using optimized biogenic catalytically active antibacterial palladium nanoparticles

Due to being low cost and eco-friendly, biological nanomaterial synthesis and development have made broad spectral progress. This study aimed to optimize the phytomediated synthesis of catalytically active, antibacterial palladium nanoparticles (PdNPs) for adsorption-based removal of ethidium bromide (EtBr) from an aqueous solution. Optimization of synthesis demonstrated that a precursor to extract ratio of 4:1, pH 3, and incubation at 80 °C for 60 min were the optimum conditions that led to the synthesis of negatively charged, highly stable, polycrystalline, spherical, and monodispersed PdNPs of 5-10 nm. When tested as catalysts, PdNPs successfully catalyzed Suzuki-Miyaura cross-coupling between aryl halides and arylboronic acids resulting in the synthesis of 4-acetylbiphenyl. Furthermore, the antibacterial activity test demonstrated that biogenic PdNPs were most effective and potent against Staphylococcus aureus and Proteus vulgaris followed by Escherichia coli, Bacillus subtilis, and Bacillus cereus. In addition, PdNPs were found as an excellent adsorbent for adsorption of EtBr from water as the adsorption reaction obeyed pseudo-second-order kinetics with a linear regression coefficient (R² > 0.995). The adsorption reaction fitted well with the Freundlich and Temkin isotherm models, indicating multi-layer adsorption. Estimating thermodynamic parameters resulted in a positive value of ΔH⁰ and ΔG⁰, demonstrating adsorption was non-spontaneous and endothermic.

Chromatin extracted from common carp testis as an economical and easily available adsorbent for ethidium bromide decontamination

The waste of ethidium bromide (EtBr) used in the laboratory will bring a great burden to the environment, which need to be solved urgently. In the present paper, an efficient and inexpensive method for EtBr removal using chromatin extracted from common carp testis was investigated. The observation of fluorescence microscopy showed that chromatin had similar property to DNA for selective adsorption of EtBr. The results of batch adsorption showed that the removal efficiency of EtBr by chromatin exceeded 99% at pH 7.4 and 30 °C for 3 min with the EtBr concentration of 2 mg L⁻¹ and the chromatin dosage of 0.5 g L⁻¹, and the maximum adsorption amount of chromatin was 45.73 mg g⁻¹. Further, the analysis of kinetic and isotherm suggested that the adsorption followed Pseudo-second-order kinetics and Langmuir isotherm model, and the calculated maximum theoretical adsorption amount of chromatin to EtBr was 48.08 mg g⁻¹. According to thermodynamic analysis, chromatin adsorption of EtBr was a spontaneous process dominated by hydrogen bonding and van der Waals forces. This work will not only offer an adsorbent for EtBr decontamination, also provide a possibility for EtBr analogs removal.

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The inexpensive bio-adsorbent was prepared from common carp testis by-production.

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The bio-adsorbent was applied in EtBr decontamination.

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The maximum adsorption amount of EtBr by chromatin was up to 45.73 mg g⁻¹, while the maximum adsorption amount of EtBr by activated carbon was only 0.46 mg g⁻¹.

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The adsorption of EtBr by chromatin followed Pseudo-second-order kinetics and Langmuir isotherm model.

Comparative electrochemical oxidation of the secondary effluent of petrochemical wastewater with electro-Fenton and anodic oxidation with supporting electrolytes

Electro-Fenton (EF) oxidation has high oxidation abilities and is widely used in the treatment of biorefractory and chemically refractory organic wastewater. However, it generates a large amount of iron sludge, which limits large-scale application. In this work, the comparative study of EF oxidation and anodic oxidation (AO) of the secondary effluent of petrochemical wastewater using boron doped diamond anode is carried out. In EF oxidation, the effects of Fe²⁺ concentration, pH value, and current density are investigated. The optimal conditions consist of the following: Fe²⁺ concentration of 1.5 mmol·L^-1, pH of 4, and current density of 10 mA·cm^-2. In AO process, the effect of adding SO42-, Cl^-, NO3-, PO43-, and CO32- is investigated; the optimal conditions can be obtained by adding a Na₂SO₄ solution (0.075 mol·L^-1). When compared with AO, although EF oxidation has a higher treatment efficiency, its energy consumption is higher, and the generated effluent (with 155 g of iron sludge·m^-3) dramatically increases the post-treatment cost, thereby limiting its large-scale application. For AO with Na₂SO₄ solution (0.075 mol·L^-1) and a COD removal efficiency of 70%, the corresponding treatment time is 1.34 h and the energy consumption is 2.44 kWh·m^-3.

Mechanisms and pathways of ethidium bromide Fenton-like degradation by reusable magnetic nanocatalysts

Ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanthridinium bromide, EtBr) is a carcinogenic compound widely used for staining nucleic acids that is difficult to treat. In this study, magnetic nanocatalysts (MNCs) were synthesized for the heterogeneous Fenton-like degradation of EtBr. The initial pH, MNC content, and H₂O₂ concentration were the key factors affecting the EtBr degradation performance and dynamics. An EtBr removal efficiency of 98.97% was achieved within 4 h under optimal conditions (initial pH, 3.0; MNC content, 1 g/L; H₂O₂ concentration, 50 mM), and the degradation followed the ring-open pathway with (2E,4Z,8E)-3-amino-N-ethyl-7,9-dihydroxynona-2,4,8-trienamide as an intermediate, as determined by liquid chromatography and mass spectrometry (LC/MS). Unexpected and satisfactory Fenton-like oxidation of EtBr occurred under basic conditions, which was explained by a novel denitration pathway with 2-[nitro(phenyl)methyl]-(1,1'-biphenyl)-4,4'-diamine as an intermediate. The MNCs retained 62.17% of their degradation efficiency after five consecutive reaction and harvest cycles. Our work elucidated the mechanisms and pathways of EtBr removal in a Fenton-like reaction using MNCs, and comprehensively discussed the optimal reaction conditions and its potential for re-use.

Decomposition of DNA staining agent ethidium bromide by gamma irradiation: Conditions, kinetics, by-products, biological activity, and removal from wastewater

Ethidium Bromide (Eth-Br) is an intercalating agent commonly used in medical and biological laboratories as a DNA staining dye. Despite its popular use, aqueous solutions containing Eth-Br showed high toxicity, mutagenic capacity, and deactivate DNA transcription. In this study, the removal of Eth-Br from aqueous solutions by gamma irradiation has been fully investigated. Gamma irradiation was capable of achieving a near complete removal of Eth-Br in neutral and non-buffered aqueous solutions at an absorbed dose of 15 kGy. Various experimental conditions were studied and showed that the removal efficiency is not diminished. The addition of hydrogen peroxide (2 %) to the irradiated solutions reduced the D₅₀ and D₉₀ by 50 %. Modeling Eth-Br decomposition showed that the reaction followed pseudo first-order kinetics and reaches at least 90 % removal under all experimental conditions. TOC and HPLC measurements confirmed that Eth-Br is fully mineralized when the absorbed dose reaches 15 kGy. The biological activity of Eth-Br after irradiation treatment was investigated with synthetic DNA and natural DNA. The biological activity of Eth-Br was deactivated at an absorbed dose as low as 5 kGy. Toxicity measurement with E-coli bacteria also confirmed that the absorbed dose of 5 kGy was sufficient to remove Eth-Br toxicity.

Conductive diamond: synthesis, properties, and electrochemical applications

This review summarizes systematically the growth, properties, and electrochemical applications of conductive diamond.

Efficient removal of ethidium bromide from aqueous solution by using DNA-loaded Fe3O4 nanoparticles

Ethidium bromide (EtBr) is widely used as DNA-staining dyes for the detection of nucleic acids in laboratories and known to be powerful mutagens and carcinogens. In the present paper, the removal of EtBr from aqueous solutions in a batch system using DNA-loaded Fe₃O₄ nanoparticles as a simple and efficient method was investigated. DNA was covalently loaded on the surface of Fe₃O₄ magnetic nanoparticles, which was confirmed by FT-IR analysis and zeta potential measurements. The morphology and crystal structure were characterized by SEM, TEM, and XRD. The influence factors on the removal efficiency such as initial EtBr concentration, contact time, adsorbent dose, pH, and temperature were also studied. The removal process of EtBr can be completed quickly within 1 min. The removal efficiency was more than 99% while the EtBr concentration was routinely used (0.5 mg L^-1) in biology laboratories and the dosages of nanoparticles were 1 g L^-1. For the different EtBr concentrations from 0.5 to 10 mg L^-1 in aqueous solution, the goal of optimized removal was achieved by adjusting the dosage of DNA-loaded Fe₃O₄ nanoparticles. The optimum pH was around 7 and the operational temperature from 4 to 35 °C was appropriate. Kinetic studies confirmed that the adsorption followed second-order reaction kinetics. Thermodynamic data revealed that the process was spontaneous and exothermic. The adsorption of EtBr on DNA-loaded Fe₃O₄ nanoparticles fitted well with the Freundlich isotherm model. These results indicated that DNA-loaded Fe₃O₄ nanoparticles are a promising adsorbent for highly efficient removal of EtBr from aqueous solution in practice.

Adsorption of ethidium bromide from aqueous solution onto nutraceutical industrial fennel seed spent: Kinetics and thermodynamics modeling studies

Dye pollutants from research laboratories are one of the major sources for environmental contamination. In the present study, a nutraceutical industrial fennel seed spent (NIFSS) was explored as potential adsorbent for removal of ethidium bromide (EtBr) from aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Through batch experiments, the operating variables like initial dye concentration, adsorbent dosage, temperature, contact time, and pH were optimized. Equilibrium data were analyzed using three number of two-parameter and six number of three-parameter isotherm models. The adsorption kinetics was studied using pseudo-first order and pseudo-second order. The diffusion effects were studied by film diffusion, Webber-Morris, and Dumwald-Wagner diffusion models. The thermodynamic parameters; change in enthalpy (ΔHº), entropy (ΔSº), and Gibbs free energy (ΔGº) of adsorption system were also determined and evaluated.

Chemometric study on the electrochemical incineration of diethylenetriaminepentaacetic acid using boron-doped diamond anode

The electrochemical incineration of diethylenetriaminepentaacetic acid (DTPA) with boron-doped diamond (BDD) anode had been initially performed under galvanostatic conditions. The main and interaction effects of four operating parameters (flow rate, applied current density, sulfate concentration and initial DTPA concentration) on mineralization performance were investigated. Under similar experimental conditions, Doehlert matrix (DM) and central composite rotatable design (CCRD) were used as statistical multivariate methods in the optimization of the anodic oxidation processes. A comparison between DM model and CCRD model revealed that the former was more accurate, possibly due to its higher operating level numbers employed (7 levels for two variables). Despite this, these two models resulted in quite similar optimum operating conditions. The maximum TOC removal percentages at 180 min were 76.2% and 73.8% for case of DM and CCRD, respectively. In addition, with the aid of quantum chemistry calculation and LC/MS analysis, a plausible degradation sequence of DTPA on BDD anode was also proposed.

Magnetic Activated-ATP@Fe3O4 Nanocomposite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of Ethidium Bromide

Magnetic attapulgite-Fe₃O₄ nanocomposites (ATP-Fe₃O₄) were prepared by coprecipitation of Fe₃O₄ on ATP. The composites were characterized by scanning electron microscopey, X-ray diffractometry, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, energy dispersive spectrometer and transmission electron microscopy. Surface characterization showed that Fe₃O₄ particles with an average size of approximately 15 nm were successfully embedded in matrix of ATP. The capacity of the Fe₃O₄-activated ATP (A-ATP@Fe₃O₄) composites for catalytic degradation of ethidium bromide (EtBr, 80 mg/L) at different pH values, hydrogen peroxide (H₂O₂) concentrations, temperatures, and catalyst dosages was investigated. EtBr degradation kinetics studies indicated that the pseudo-first-order kinetic constant was 2.445 min⁻¹ at T = 323 K and pH 2.0 with 30 mM H₂O₂, and 1.5 g/L of A-ATP@Fe₃O₄. Moreover, a regeneration study suggested that A-ATP@Fe₃O₄ maintained over 80% of its maximal EtBr degradation ability after five successive cycles. The effects of the iron concentrations and free radical scavengers on EtBr degradation were studied to reveal possible catalytic mechanisms of the A-ATP@Fe₃O₄ nanocomposites. Electron Paramagnetic Resonance revealed both hydroxyl (∙OH) and superoxide anion (∙O₂⁻) radicals were involved in EtBr degradation. Radical scavenging experiment suggested EtBr degradation was mainly ascribed to ∙OH radicals, which was generated by reaction between Fe²⁺ and H₂O₂ on the surface of A-ATP@Fe₃O₄.

Definitive screening design applied to electrochemical degradation of Chromotrope 2R with BDD anodes

Here, a novel three-level definitive screening design (DSD) was initially employed to investigate the electrochemical degradation of Chromotrope 2R (C2R) with boron-doped diamond (BDD) anodes. Experiments were performed using a synthetic C2R solution containing five supporting electrolytes (Na₂SO₄, NaCl, Na₃PO₄, NaNO₃ and Na₂CO₃). The effects of nine quantitative parameters on C2R removal rate: initial C2R concentration (50-100 mg L^-1), applied current density (1.29-3.87 mA cm^-2), Na₂SO₄ concentration (0-10 mM), NaCl concentration (0-10 mM), Na₃PO₄ concentration (0-10 mM), NaNO₃ concentration (0-10 mM), Na₂CO₃ concentration (0-10 mM), flow rate (300-500 mL min^-1) and temperature (10-50 °C), were investigated. The model obtained was validated and used to select three most significant variables for further investigation. Interestingly, the differing roles of electrolytes during the electrolysis revealed the ion-selective nature of BDD anode system. A five-level central composite rotatable design (CCRD) was then employed to describe the C2R conversion as a function of applied current density, NaCl concentration and temperature. The results obtained confirmed the strong capability of DSD to separate and identify the significant variables in BDD technology. Moreover, the strategy (DSD plus CCRD) employed here enabled a significant reduction in the number of experiments (from over 500 to only 38) compared to traditional screening methods. The possible degradation mechanism of C2R in BDD anode cells was also proposed.

Parabens abatement from surface waters by electrochemical advanced oxidation with boron doped diamond anodes

The removal efficiency of four commonly-used parabens by electrochemical advanced oxidation with boron-doped diamond anodes in two different aqueous matrices, namely ultrapure water and surface water from the Guadiana River, has been analyzed. Response surface methodology and a factorial, composite, central, orthogonal, and rotatable (FCCOR) statistical design of experiments have been used to optimize the process. The experimental results clearly show that the initial concentration of pollutants is the factor that influences the removal efficiency in a more remarkable manner in both aqueous matrices. As a rule, as the initial concentration of parabens increases, the removal efficiency decreases. The current density also affects the removal efficiency in a statistically significant manner in both aqueous matrices. In the water river aqueous matrix, a noticeable synergistic effect on the removal efficiency has been observed, probably due to the presence of chloride ions that increase the conductivity of the solution and contribute to the generation of strong secondary oxidant species such as chlorine or HClO/ClO ^-. The use of a statistical design of experiments made it possible to determine the optimal conditions necessary to achieve total removal of the four parabens in ultrapure and river water aqueous matrices.

Performance of electrochemical oxidation process for removal of di (2-ethylhexyl) phthalate

Di (2-ethylhexyl) phthalate (DEHP) is the most detected and concentrated plasticizer in environment and wastewaters, worldwide. In this study, different operating parameters such as current intensity, treatment time, type of anodes, and supporting electrolytes were tested to optimized the electro-oxidation process (EOP) for the removal of DEHP in the presence of methanol as a dissolved organic matter. Among the anodes, the Nb/BDD showed the best degradation rate of DEHP, at low current intensity of 0.2 A after 90 min of treatment time with a percentage of degradation recorded of 81 %, compared to 70 % obtained with the Ti/IrO2-RuO2. Furthermore, due to the combination of direct and indirect oxidation, the removal of DEHP in the presence of 1 g/L Na2SO4 was higher than NaBr, even though the oxidant production of NaBr was 11.7 mmol/L against 3.5 mmol/L recorded in the presence of sulfate at 0.5 A and after 60 min of electrolysis time. Under optimal condition (current intensity = 0.5 A, time = 120 min, using Nb/BDD anode and Na2SO4 as supporting electrolyte), the removal of 87.2 % of DEHP was achieved. The total cost of 0.106 US$/m(3) of treated water was achieved based on economical optimization of reactor with current intensity of 0.2 A and 1 g/L Na2SO4.

Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode

This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed.

Detection of a specific biomarker for Epstein-Barr virus using a polymer-based genosensor

This paper describes methodology for direct and indirect detections of a specific oligonucleotide for Epstein-Barr virus (EBV) using electrochemical techniques. The sequence of oligonucleotide probe (EBV1) revealed a high sequence identity (100%) with the EBV genome. For the development of the genosensor, EBV1 was grafted to the platform sensitized with poly(4-aminothiophenol). After that, the hybridization reaction was carried out with the complementary target (EBV2) on the modified electrode surface using ethidium bromide as DNA intercalator. The oxidation peak currents of ethidium bromide increased linearly with the values of the concentration of the complementary sequences in the range from 3.78 to 756 μmol·L⁻¹. In nonstringent experimental conditions, this genosensor can detect 17.32 nmol·L⁻¹ (three independent experiments) of oligonucleotide target, discriminating between complementary and non-complementary oligonucleotides, as well as differentiating one-base mismatch, as required for detection of genetic diseases caused by point mutations. The biosensor also displayed high specificity to the EBV target with elimination of interference from mix (alanine, glucose, uric acid, ascorbic acid, bovine serum albumin (BSA), glutamate and glycine) and good stability (120 days). In addition, it was possible to observe differences between hybridized and non-hybridized surfaces through atomic force microscopy.