Peroxide Dosage Research Articles

Preparation of three-dimensional ordered macroporous Ag/LaFeO3 and heterogeneous photo-Fenton degradation of penicillin G potassium

ABSTRACT 3DOMLaFeO3 was prepared by template method combined with sol-gel method using monodisperse polystyrene (PS) microspheres as template, and Ag/3DOMLaFeO3 perovskite catalyst was prepared by impregnation method combined with sodium borohydride reduction method. The catalysts were characterised by means of TG, XRD, SEM, BET, XPS, UV-vis DRS, etc. The photo-Fenton catalytic performance, stability and catalytic reaction mechanism of Ag/3DOMLaFeO3 were studied with penicillin G potassium (PEN G) as the model pollutant. The results indicated that the as-prepared Ag/3DOMLaFeO3 exhibited a three-dimensional ordered macroporous (3DOM) structure, and the light capture and mass transfer were enhanced through abundant pores and large specific surface area. Based on the surface plasmon resonance effect (SPR), Ag loading enhanced the absorption of the material in the visible light region, and inhibited the recombination of photogenerated carriers, which improved the photocatalytic performance of 3DOMLaFeO3 under visible light. Under the conditions of hydrogen peroxide dosage of 1.5 mL·L−1, initial pH of 5, PEN G initial concentration of 100 mg·L−1, catalyst dosage of 300 mg·L−1, xenon lamp irradiation, the degration ratio of PEN G and the removal rate of TOC reached 99.99% and 85.45% within 120 min, respectively. In addition, it had a wide range of pH application, excellent stability and practical application value. The quenching experiment and ESR test showed that ·OH and ·O2 − were the reasons for high catalytic degradation. The least square method was used to fit the experimental data, and the results displayed that the degradation of PEN G was approximately in line with the first-order kinetic reaction.

Effects of hydrogen peroxide and calcium hypochlorite on chemical oxygen demand solubilization and disintegration of waste activated sludge by electro-chemical pretreatment

ABSTRACT The combination of electrochemical (EC) pretreatment with hydrogen peroxide (HP) and calcium hypochlorite (CHC) was investigated in this study for their effect on soluble chemical oxygen demand (CODs) and disintegration degree (DD) of waste activated sludge (WAS). For this aim, response surface methodology (RSM) and Box–Behnken design (BBD) were applied the determination of the optimum operational conditions. Operational conditions were varied between 0.2 and 2.0 mmol/g SS for HP and CHC dosages, 1–5 A for the applied current, 2–10 for the initial pH, and 15–45 min for the treatment time. Obtained results for each treatment were accurate and significant with correlation coefficients (R2) of 0.8639% and 0.9189% for EC combined with HP pretreatment and EC combined with CHC pretreatment, respectively. According to the obtained results, CODs increased in comparison to the raw sludge (168 mg/L) noting that CODs for EC – CHC (1155 ± 21 mg/L) was higher than EC – HP (811.5 ± 15 mg/L) at optimized conditions (for EC-HP pretreatment: HP dosage: 0.34 mmol/g TSS, Applied current:5 A, Initial pH:10, Time: 45 min, For EC-CHC pretreatment: CHC dosage: 0.23 mmol/g TSS, Applied current:4.83 A, Initial pH:10, Time: 40 min). Besides, the DD in terms of COD, total nitrogen (TN) and total organic carbon (TOC) (DDCOD, DDTN and DDTOC) registered increased values after the application of the EC treatment with both oxidants. The highest DDCOD, DDTN and DDTOC values were obtained with EC-CHC pretreatment for 11.34%, 20.34% and 9.18% respectively compared to EC-HP pretreatment (DDCOD: 7.37%, DDTN: 15.18% and DDTOC: 6.94%).

Low-Dose Oxidant Toxicity and Oxidative Stress in Human Papillary Thyroid Carcinoma Cells K1

Medical gas plasmas are of emerging interest in pre-clinical oncological research. Similar to an array of first-line chemotherapeutics and physics-based therapies already approved for clinical application, plasmas target the tumor redox state by generating a variety of highly reactive species eligible for local tumor treatments. Considering internal tumors with limited accessibility, medical gas plasmas help to enrich liquids with stable, low-dose oxidants ideal for intratumoral injection and lavage. Pre-clinical investigation of such liquids in numerous tumor entities and models in vitro and in vivo provided evidence of their clinical relevance, broadening the range of patients that could benefit from medical gas plasma therapy in the future. Likewise, the application of such liquids might be promising for recurrent BRAF(V600E) papillary thyroid carcinomas, resistant to adjuvant administration of radioiodine. From a redox biology point of view, studying redox-based approaches in thyroid carcinomas is particularly interesting, as they evolve in a highly oxidative environment requiring the capability to cope with large amounts of ROS/RNS. Knowledge on their behavior under different redox conditions is scarce. The present study aimed to clarify resistance, proliferative activity, and the oxidative stress response of human papillary thyroid cancer cells K1 after exposure to plasma-oxidized DMEM (oxDMEM). Cellular responses were also evaluated when treated with different dosages of hydrogen peroxide and the RNS donor sodium nitroprusside (SNP). Our findings outline plasma-oxidized liquids as a promising approach targeting BRAF(V600E) papillary thyroid carcinomas and extend current knowledge on the susceptibility of cells to undergo ROS/RNS-induced cell death.

Enhanced photodegradation of methyl orange dye under UV irradiation using MoO3 and Ag doped TiO2 photocatalysts

Titanium dioxide (TiO 2 ) semiconductor-based photocatalysts have been widely utilized in the last few decades for water treatment because of their higher photocatalytic performance. Recently, most researchers have focused on the improvement of TiO 2 semiconductors’ photocatalytic performance through doping and co-doping with different metals and nonmetals during synthesis. The current study was conducted to synthesize TiO 2 based photocatalysts, construct TiO 2 photocatalysts based immobilized borosilicate glass (BG) reactors and applied the reactors for methyl orange (MO) dye treatment under UV irradiation. Based on XRD results, the dominant phase was anatase in all the photocatalysts. The largest amount anatase phase (82.43%) of Ag/MoO 3 /TiO 2 photocatalyst in comparison to TiO 2 (70.44%), MoO 3 /TiO 2 (74.18%) and Ag/TiO 2 (80.59%) photocatalysts were observed. The photocatalytic degradation of 10 ppm MO dye was found 59.5%, 63.1%, 70.6% and 75.8%, for TiO 2 , MoO 3 /TiO 2 , Ag/TiO 2 , and Ag/MoO 3 /TiO 2 photocatalysts, respectively, for a particular dose of photocatalyst (0.12 g) immobilized on BG at pH (7.0) after 5.5 h of UV-irradiation. The efficiency of the photocatalyst (Ag/MoO 3 /TiO 2 ) was decreased with the increase of pH and initial dye concentrations. However, increasing photocatalyst and hydrogen peroxide doses in the BG reactor resulted in a better performance as expected. The first-order reaction rate constants were 0.003, 0.002, 0.003, and 0.004 min −1 for TiO 2 , MoO 3 /TiO 2 , Ag/TiO 2 , and Ag/MoO 3 /TiO 2 , respectively, for 0.12 g of photocatalyst dose. The outcomes suggest future possibilities of applying Ag/MoO 3 /TiO 2 nanocomposite in the treatment of textile wastewater under UV irradiation. • Ag/MoO 3 /TiO 2 nanocomposites were synthesized by the sol–gel method. • XRD analysis shows anatase phase with tetragonal structure of Ag/MoO 3 /TiO 2 . • 75.8% of MO dye was degraded using Ag/MoO 3 /TiO 2 under 5.5 h UV irradiation. • % removal increased from 62.6 to 96.5% with the decrease of pH from 11.0 to 3.0. • Dye removal was increased with the addition of H 2 O 2 .

Wastewater Treatment Using a Photoelectrochemical Oxidation Process for the Coffee Processing Industry Optimization of Chemical Oxygen Demand (COD) Removal Using Response Surface Methodology

The elimination of organic compounds in coffee processing effluent utilizing electrochemical oxidation (ECO) as well as a combination of electrochemical oxidation (ECO) and ultraviolet and hydrogen peroxide (UV/H2O2) was explored. Then, the percentage reduction of chemical oxygen demand (COD) was investigated. The effect of different experimental factors such as solution pH, sodium chloride (NaCl) concentration, calcium chloride (CaCl2) concentration, electric current, electrolysis duration, and hydrogen peroxide dosage on the percent removal efficiency of the hybrid electrochemical oxidation (ECO) with the ultraviolet and hydrogen peroxide (UV/H2O2) process has been investigated. The response surface methodology (RSM) based on central composite design (CCD) was used to organize the trial runs and optimize the results. The hybrid electrochemical oxidation (ECO) with the ultraviolet and hydrogen peroxide (UV/H2O2) process removed 99.61% of the chemical oxygen demand (COD) with a low power usage of 1.12 kWh/m3 compared to the other procedures, according to the experimental data analysis. These findings were obtained with a pH of 7, a current of 0.40 A, 1.5 g of CaCl2, and a total electrolysis period of 40 minutes. When it came to eliminating organic compounds from coffee manufacturing effluent, CaCl2 outperformed NaCl. Analysis of variance (ANOVA) with 95% confidence limits was used to examine the significance of independent variables and their interactions.

Removal of Phenol by Electro-Fenton Process

In this study, removal of phenol from wastewater using Electro-Fenton method was achieved. The effect of operational parameters such as current density, initial concentration of phenol, and hydrogen peroxide dosage on the removal of phenol were investigated. The removal efficiencies were determined using chemical oxygen demand (COD) concentrations. The results showed that, the removal of phenol was dependent on the concentrations of hydrogen peroxide and applied current. Increasing the applied current resulted in higher removal efficiency (RE) of phenol. On the other hand, the energy consumption also increased with the increasing the current density. Thus when the optimal current density and potential have been selected, either higher removal rate or lower energy consumption can be preferred. The phenol removal significantly increased by increasing H2O2 dosages from 1500 to 2500 mg L-1. The phenol concentration of 300 mg L-1 was removed with the removal efficiency of 93% at the current density of 40 mA cm-2 with the using of 2500 mg L-1 H2O2. Increasing of initial phenol concentration resulted in decreasing of removal efficiency. Removal efficiency decreased from 75% to 62 % when the initial phenol concentration increased from 100 to 500 mg L-1 after 45 min of operating time. As a result of the study, it can be said that, the removal of phenol was successfully achieved using Electro-Fenton method.

Effect of calcium peroxide dosage on organic matter degradation, humification during sewage sludge composting and application as amendment for Cu (II)-polluted soils

In this research, it was the first time to investigate the effect of two dosages (5% (T1) and 10% (T2), w/w) of calcium peroxide (CP) on organic matter degradation, humification during sewage sludge composting. Additionally, the complexation of Cu to humic substance (HS) derived from CP-compost compared to no CP addition-compost (CK) was also studied. Results showed that compared to CK, T1 and T2 significantly enhanced organic matter degradation and promoted the formation of HS. Two-dimensional correlation Fourier transform infrared spectroscopy (2D-FTIR-COS) and Parallel factor (PARAFAC) analysis revealed that the addition of CP accelerated the synthesis of HS with high aromatization degree and molecular weight than those in CK, owing to the oxidation of small molecules to form carboxyl. The stability constant (log KM) of Cu with CP-derived HS (log KM = 4.22–5.13) indicated a greater complexation ability than CK-derived HS (log KM = 4.05–4.45), due to the faster response of polysaccharides binding to Cu (II) and the higher humification degree of CP-derived HS. This study revealed the potential mechanisms of CP addition on the synthesis of HS and utilization of CP-compost product might provide an effective way to remedy Cu (II)-contaminated soils.

Response surface modeling for the treatment of methylene blue from aqueous media using electro-Fenton process before determination by UV-VIS spectrometer: Kinetic and degradation mechanism

In the present study, response surface methodology was employed to investigate the effects of main variables, including the initial MB concentration, hydrogen peroxide dosage, current density, and electrolysis time on the removal efficiency of MB using the electro-Fenton (EF) process. The MB concentration determination by UV-VIS spectrometer. The EF process degrades the MB contaminant molecules by the highly oxidizing species of the •OH. A quadratic regression model was developed to predict the removal of MB, where the R2 value was found to be 0.9970, which indicates the satisfactory accuracy of the proposed model. ANOVA analysis showed a non-significant lack of fit value (0.0840). Moreover, the predicted correlation coefficient values (R2=0.9915) were reasonably in agreement with the adjusted correlation coefficient value (R2=0.9958), demonstrating a highly significant model for MB dye removal. In addition, the obtained results showed 95.8% MB was removed in the optimum removal efficiency, including the initial MB concentration of 20 mg L-1, H2O2 dosage of 400 μL, and the current density of 7.0 mA cm-2, and electrolysis time of 10 min which was agreed with the predicted removal efficiency of 98.3%. Electrical energy consumption was found to be 0.163 kWh m-3.

Model-based investigation of the chemical phosphorus removal potential of the peroxide regenerated iron-sulfide control technology.

In this study, the potential of using peroxide regenerated iron-sulfide control (PRI-SC®) for chemical phosphorus removal utilizing the existing iron sulfide found in wastewaters was investigated in batch tests and compared in full-scale facility-wide simulations to using iron salts. PRI-SC is a combination treatment that utilizes iron salts and hydrogen peroxide in a synergetic fashion, where hydrogen peroxide is used in regenerating the spent iron salt in situ in the form of iron sulfide, yielding ferric iron and colloidal sulfur. A simplified kinetic model was developed, calibrated, and integrated into a facility-wide model to simulate the process at the full-scale. Experimental results showed that dosing hydrogen peroxide, even at doses lower than the stoichiometrically required to oxidize iron sulfide, freed, and oxidized sulfide bound ferrous iron to ferric iron, which was consequently hydrolyzed and affected phosphorus removal. Higher dosing of hydrogen peroxide did not affect change in the speciation of sulfur remaining predominantly as elemental sulfur. Simulations showed that the application of PRI-SC with supplemental ferric iron dosing was able to cut the costs of chemicals addition up to 53% while maintaining a steady-state effluent phosphate concentration below 0.01 mg/L. PRACTITIONER POINTS: The kinetic model was used to optimize ferric iron and hydrogen peroxide dosing. The developed model can be integrated in existing wastewater process simulators. Dosing hydrogen peroxide effectively oxidized ferrous iron to ferric iron. The combination of hydrogen peroxide and iron salts can reduce the chemical addition cost by 53%.

The effect of hydrogen peroxide concentration and water temperature on yellowtail kingfish Seriola lalandi in a repeated bathing treatment

Hydrogen peroxide is routinely used in commercial yellowtail kingfish culture to treat monogenean infections. As the culture of this species expands into warmer geographical areas, this study aimed to compare the effects of a repeated exposure to different hydrogen peroxide concentrations at two rearing temperatures, 18 and 26 °C. The repeat bath occurred 14 days after the initial bath in line with commercial treatment regimes. The three concentrations tested were 85, 170 and 340 mg L−1, with bathing conducted for 30 min. Mortality occurred following the second bath at 340 mg L−1 at 26 °C.The highest hydrogen peroxide dose caused epithelial lifting in gill filaments and significantly reduced the size and abundance of common mucus cells within the skin epithelium following the repeat bath in warm water. Despite the highest dose causing gill damage and mortality in warm water, there were no significant effects of hydrogen peroxide concentration on any of the conventional blood parameters, except in moribund fish. A novel measurement of plasma thiol oxidation, however, was found to be significantly elevated at the highest bathing concentration.Whilst yellowtail kingfish appeared to be tolerant of the high concentration of hydrogen peroxide tested in the current study at ambient water temperature, these fish were not infected with monogeneans, and any such burden is likely to increase the susceptibility of the fish to the effects of hydrogen peroxide.

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H 2 O 2

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H ₂ O ₂

Optimization of Fenton Oxidation Process for Degradation of 1-Butyl-3 Methyl Imidazolium Chloride (BMIMCL) Using Response Surface Methodology

The degradation of 1-butyl 3-methyl imidazolium chloride (BMIMCl) ionic liquid (IL) by Fenton oxidation has been studied. The optimization of operating parameters for maximum degradation of BMIMCl has been carried out using the Central Composite Design (CCD) of Response Surface Methodology (RSM). The three independent input parameters selected were the dosage of Hydrogen Peroxide (H2O2), the dosage of iron (Fe2+), and the pH of the output or response selected was Total Organic Carbon (TOC) removal efficiency. Experiments were carried out according to the experimental design provided by CCD. For TOC Degradation, the model’s R2 and R2adj correlation coefficients between experimental and model-predicted values were 0.9769 and 0.9561, respectively. This indicates a satisfactory correlation of experimental results with model-predicted values. The optimum values of operating parameters for maximum degradation were found to be H2O2=307 mM (X1), Fe2+=1.1 mM (X2), and (pH)=3.3 (X3), for a reaction time of 120 min. For these operating parameters, the experimental result for TOC removal efficiency was found to be 72.89% as compared to the model-predicted value of 73.67%. These results indicate that the values were closely correlated with each other and thus the model was validated satisfactorily. Overall, the results indicate that the BMIMCl ionic liquid can be effectively degraded by the Fenton oxidation process.

Degradation of Reactive Yellow 18 Using Ionizing Radiation Based Advanced Oxidation Processes: Cytotoxicity, Mutagenicity and By-Product Distribution

The degradation of Reactive Yellow 18 (RY-18), induced by gamma radiation in aqueous medium, was carried out as a function of gamma radiation dose (5–20 kGy) and concentration of hydrogen peroxide, the initial dye concentration and pH of the solution were optimized for the maximum degradation efficiency. Gamma radiations alone and in combination with H2O2 were used to degrade the RY-18. A degradation rate of 99% was achieved using an absorbed dose of 20 kGy, 0.6 mL H2O2 in acidic pH. Variations in the functional groups of untreated and treated RY-18 were determined by FTIR analysis. The LCMS technique was used to determine the intermediates formed during the degradation process. The cytotoxicity and mutagenicity of RY-18 were studied by hemolytic and Ames tests, respectively. There were significant reductions in cytotoxicity and mutagenicity in response to gamma radiation treatment. Cytotoxicity was reduced from 15.1% to 7.6% after treatment with a 20 kGy absorbed dose of gamma radiations with 0.6 mL H2O2. Mutagenicity was reduced by 81.3% and 82.3% against the bacterial strains TA98 and TA100 after treatment with a 20 kGy absorbed dose with 0.6 mL H2O2. The advanced oxidation process efficiency was evaluated using the byproduct formations, which were low-molecular-weight organic acid units, which through further oxidation were converted into carbon dioxide and water end products. Based on RY-18 degradation, cytotoxicity and mutagenicity reduction, the gamma radiation in combination with H2O2 has potential for the removal of dye from the effluents.

Modelling of the photo-Fenton process with flexible hydrogen peroxide dosage: Sensitivity analysis and experimental validation

The supply of hydrogen peroxide (H2O2) controlling the amount of highly oxidant hydroxyl radicals is the most critical operational issue for the photo-Fenton process. Accordingly, this study addresses the development of a model for photo-Fenton processes including a flexible H2O2 supply given as a function of time. The model is aimed at its future exploitation in treatment optimization and the determination of the optimal profile for H2O2 supply. The work has adopted a photo Fenton model previously reported that includes the inlet flow (fed-batch) and describes the system dynamics under a flexible dosage. Thus, model global sensitivity analysis (GSA) and parameter estimation were performed using Simulink® to examine the behavior of the model under flexible H2O2 dosage. GSA was carried out using partial rank correlation methods and the Latin hypercube sampling to assess to which extent variations of the model parameters affect each measured response (H2O2, total organic carbon, TOC, and dissolved oxygen, O2 –the experimentally available information). Hence, the model is discussed in regard of its hypothesis and chances for reducing its complexity. This resulted in the rejection of two reactions of the initial model. Next, a set of 12 kinetic, stoichiometric and operative parameters was estimated through the fitting of H2O2, TOC, and O2 profiles. Discussion on model fitting includes computational issues, the role of initial values for the estimation process, the goodness of fit criteria, and the sampling method. The model was fit to experimental data with assorted H2O2 supply profiles and validated, and Root Mean Square Error (RMSE) below 0.009 mM, 0.42 mM, and 0.127 mM were obtained for TOC, H2O2 and O2, respectively. Therefore, this work contributes a practical model aimed at providing model-based optimization for the H2O2 dosage profile of the photo-Fenton process.

Effects of acute and chronic oxidative stress on the blood–brain barrier in 2D and 3D in vitro models

Oxidative stress is a shared pathology of neurodegenerative disease and brain injuries, and is derived from perturbations to normal cell processes by aging or environmental factors such as UV exposure and air pollution. As oxidative cues are often present in systemic circulation, the blood–brain barrier (BBB) plays a key role in mediating the effect of these cues on brain dysfunction. Therefore, oxidative damage and disruption of the BBB is an emergent focus of neurodegenerative disease etiology and progression. We assessed barrier dysfunction in response to chronic and acute oxidative stress in 2D and 3D in vitro models of the BBB with human iPSC-derived brain microvascular endothelial-like cells (iBMECs). We first established doses of hydrogen peroxide to induce chronic damage (modeling aging and neurodegenerative disease) and acute damage (modeling the response to traumatic brain injury) by assessing barrier function via transendothelial electrical resistance in 2D iBMEC monolayers and permeability and monolayer integrity in 3D tissue-engineered iBMEC microvessels. Following application of these chronic and acute doses in our in vitro models, we found local, discrete structural changes were the most prevalent responses (rather than global barrier loss). Additionally, we validated unique functional changes in response to oxidative stress, including dysfunctional cell turnover dynamics and immune cell adhesion that were consistent with changes in gene expression.

Preparation and properties of ethylene-vinyl acetate grafted acrylonitrile

Ethylene-vinyl acetate copolymer (EVA) was functionalized to varying degrees with acrylonitrile (AN) by melt grafting processes. Fourier transform infrared spectra (FT-IR) confirmed that AN was successfully grafted onto the EVA. High resistance meter, electronic universal testing machine, etc have studied the influencing factors of grafting process and the effect of grafting rate on oil resistance, mechanical properties and electrical properties. The results show that the optimal grafting process is that the dosage of AN is 8.0 wt%, the dosage of styrene (St) is 5.0 wt%, the dosage of Dilauroyl peroxide (LPO) is 0.4 wt% of the total amount of AN and St, and the grafting rate is 1.24%. With the increase of the amount of LPO and AN, the grafting rate first increased and then decreased. The grafting rate increases, so that the oil resistance, volume resistivity, and breakdown field strength of the grafted product are gradually increased. When the grafting rate is 1.24%, the volume resistivity is 1.63 × 1013 Ω·m, which is significantly improved compared with pure EVA, and the breakdown field strength is 23.26 kV mm−1, which is 12.3% higher than pure EVA.

Extraction and Characterization of Bamboo Shoot Shell Fibers by Sodium Percarbonate Assisted Degumming

ABSTRACT The bamboo shoot shell fibers were extracted by using environmental protection oxidant sodium percarbonate combined with alkali oxygen bath method. To explore the influence of various factors on its degumming, the efficiency of degumming through single-factor and orthogonal experiments was assessed. The results showed that the used method had a good effect on the degumming of bamboo shoot shell fiber, and most of the non-cellulose components such as hemicellulose, lignin, and pectin had been removed. After the treatment, the cellulose content and crystallinity were 73.19% and 61.40%, respectively. Taking the degumming rate as the index, the factors such as dosage of sodium percarbonate and hydrogen peroxide, soaking temperature, and time in alkali boiling treatment were optimized. The results showed that the degumming rate was 69.17% when the scouring temperature was 90°C, the alkali boiling time was 120 min, the dosage of sodium percarbonate was 24 g/L, and the dosage of hydrogen peroxide was 40 mL/L. The structure and properties of bamboo shoot shell fiber were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analyzer (TGA). The prepared bamboo shoot shell fibers would be considered as a promising and sustainable raw material for the textile industry and other prospects in the future.

English

The need for a complementary short-term mutagenicity bioassay with robust endpoints to the Ames assay has become increasingly crucial to in order to avoid false negative results. The alternative short-term test  (STT) used in conjunction with the Ames increases the validity and decreases the number of false positive outcomes. As a result, Caco-2 cells (Human intestinal epithelial cell model) and RAW264.7 cells (mouse microphage-like cell line) were treated for 24 h with graded doses of hydrogen peroxide (0, 5, 10, 20, and 40 µM) (oxidative stress-inducing mutagen). Single- and double-strand DNA damage was quantified using single-cell gel electrophoresis (Comet assay). The head intensity, tail intensity, tail migration, and tail moment of the damaged DNA were analysed using an epifluorescence microscope with a gated camera and installed comet IV image analysis software. In Caco-2 and RAW264.7 cells, a significant drop in head intensity and a corresponding dose-dependent increase in tail intensity, tail migration, and tail moment are seen when were quantified w compared to the solvent control. The single cell gel electrophoresis (Comet assay) is a very sensitive, robust, and statistically reliable method for determining DNA damage utilising many parameters. As such, the comet assay is advised as a complement to existing short-term bioassays for mutagenicity, such as the Ames assay. Key words: Mutagenicity, hydrogen peroxide, RAW264.7 cells, Caco-2 cells, single cell gel electrophoresis (Comet assay)

Fenton oxidation as pretreatment for biomass gasification condensate: cost and biomass inhibition evaluation

Abstract Gasification transforming organic compounds into energy-rich pyrolytic gas, is a climate-friendly treatment option for biological solid wastes. The condensates arising from the pyrolytic gas valorization is owing to high concentrations of small molecular phenols, cyanides, nitrogen-heterocyclics, aromatics and ammonium, posing an environmental and health hazard. In this paper, the watery phase of the biomass gasification condensate from spent mushroom compost (SMC), with a chemical oxygen demand (COD) of 16.4 g/L and total nitrogen of 2.3 g/L, was pretreated by Fenton oxidation. The experiments were conducted at room temperature with an initial pH value of 3, 5 and 8.9, hydrogen peroxide (H2O2) dosages between 15 and 100% of the normalized stoichiometric ratio (NSR), and Fe2+ dosages corresponding to molar ratio of H2O2:Fe2+ between 10 and 30. Through respiration inhibition assays, the best operational condition for detoxification was determined at an initial pH 5 with 30% NSR H2O2 dosage and molar ratio of H2O2:Fe2+ at 15:1. The specific operational cost of the Fenton oxidation was calculated at 2.17 €/kg CODelimination. In respiration inhibition assay, the oxygen consumption of wastewater after Fenton oxidation was increased by 316% in 3 days. In a 20 days’ biogas production test, the biogas production was increased by 81%.

Effect of hydrogen peroxide and ferrous ion on the degradation of 2-Aminopyridine

Pharmaceutical compounds 2-Aminopyridine were detected in drinking water, surface water, and groundwater. 2-Aminopyridine is a colourless solid used for manufacturing drugs, sulphapyridine which is extremely poisonous and carcinogenic. Its appearance in drinking water needs prior treatment to dispose of safely. Fenton, Photo-Fenton oxidation processes were carried out to degrade 2-Aminopyridine. Parameters like pH, the dosage of Hydrogen peroxide, and Iron are optimized for the effective degradation of a 2-Aminopyridine compound in water. The effect of the initial concentration (10-80) mg/L of a 2-Aminopyridine pharmaceutical compound on degradation was studied. Drug at initial concentration of 10 mg/L, 40 mg/L and 80 mg/L is 100% degraded in 30 mins,45 mins and 120 mins respectively. Similarly, COD removals of 94.6%, 88.6% and 81% were detected at 10 mg/L, 40 mg/L and 80 mg/L of initial drug dosage. The degradation was enhanced by photo-Fenton oxidation. Both the drug degradation and COD reduction were improved by UV-C-assisted photo-Fenton oxidation processes.