Intensified degradation of tartrazine dye present in effluent using ultrasound combined with ultraviolet irradiation and oxidants.

Effluent containing tartrazine can affect the environment and human health significantly prompting the current study into degradation using a sonochemical reactor operated individually and combined with advanced oxidation processes. The optimum conditions for ultrasound treatment were established as dye concentration of 10 ppm, pH of 3, temperature as 35 °C, and power as 90 W. The combination approach of H2O2/UV, H2O2/US, and H2O2/UV/US resulted in higher degradation of 25.44%, 57.4%, and 74.36% respectively. Use of ZnO/UV/US approach increased the degradation significantly to 85.31% whereas maximum degradation as 93.11% was obtained for the US/UV/Fenton combination. COD reduction was found maximum as 83.78% for the US/UV/Fenton combination. The kinetic analysis showed that tartrazine dye degradation follows pseudo first-order kinetics for all the studied processes. Combination of Fenton with UV and US was elucidated as the best approach for degradation of tartrazine.

The organic output from mechanical-biological treatment plants as a source of microplastics: Mini-review on current knowledge, research methodology and future study perspectives.

Plastic pollution is one of the biggest environmental problems facing the world. In recent years, microplastics, polymer particles from 1 µm to 5 mm, have been getting much attention. The presence of microplastics has already been confirmed in aquatic and marine ecosystems, soil, atmosphere, biota, and others. The organic output from mechanical-biological treatment (MBT) plants was added to the list of microplastics sources only recently. However, according to preliminary estimates, it may be the second-largest source of microplastics. This article presents an overview of already published investigations on this microplastics source and explains the supposed pathway of microplastics in the MBT plants. The main waste treatment processes that can affect the amount of microplastics in the organic output have been identified as shredding, sieving and, to a lesser extent, aerobic or anaerobic processing. This mini-review also includes methods used in the scientific literature for microplastics extraction, purification, and identification in organic-rich samples, their advantages and limitations. Particular attention is paid to the methods of identifying the small microplastics, less than 1 mm, since the methods for particles 1-5 mm have been more extensively studied. Furthermore, future research needs are highlighted.

Transformation Products of Organic Contaminants and Residues-Overview of Current Simulation Methods.

The formation of transformation products (TPs) from contaminants and residues is becoming an increasing focus of scientific community. All organic compounds can form different TPs, thus demonstrating the complexity and interdisciplinarity of this topic. The properties of TPs could stand in relation to the unchanged substance or be more harmful and persistent. To get important information about the generated TPs, methods are needed to simulate natural and manmade transformation processes. Current tools are based on metabolism studies, photochemical methods, electrochemical methods, and Fenton's reagent. Finally, most transformation processes are based on redox reactions. This review aims to compare these methods for structurally different compounds. The groups of pesticides, pharmaceuticals, brominated flame retardants, and mycotoxins were selected as important residues/contaminants relating to their worldwide occurrence and impact to health, food, and environmental safety issues. Thus, there is an increasing need for investigation of transformation processes and identification of TPs by fast and reliable methods.

Continuous Flow Homolytic Aromatic Substitution with Electrophilic Radicals: A Fast and Scalable Protocol for Trifluoromethylation.

We report an operationally simple and rapid continuous flow radical C-C bond formation under Minisci-type reaction conditions. The transformations are performed at or below room temperature employing hydrogen peroxide (H2 O2 ) and dimethylsulfoxide (DMSO) as reagents in the presence of an FeII catalyst. For electron-rich aromatic and heteroaromatic substrates, C-C bond formation proceeds satisfactorily with electrophilic radicals including . CF3 , . C4 F9 , . CH2 CN, and . CH2 CO2 Et. In contrast, electron-poor substrates exhibit minimal reactivity. Importantly, trifluoromethylations and nonafluororobutylations using CF3 I and C4 F9 I as reagents proceed exceedingly fast with high conversion for selected substrates in residence times of a few seconds. The attractive features of the present process are the low cost of the reagents and the extraordinarily high reaction rates. The direct application of the protocol to dihydroergotamine, a complex ergot alkaloid, yielded the corresponding trifluoromethyl ergoline derivative within 12 seconds in a continuous flow microreactor on a 0.6 kg scale. The trifluoromethyl derivative of dihydroergotamine is a promising therapeutic agent for the treatment of migraines.

Improving sludge dewaterability by combined conditioning with Fenton's reagent and surfactant.

The effect of Fenton's reagent combined with dodecyl dimethyl benzyl ammonium chloride (DDBAC) on sludge dewaterability was studied. The capillary suction time (CST) and water content (WC) of sludge cake were used to evaluate sludge dewaterability. Bound water content (W B), extracellular polymeric substance (EPS) concentration, and organic acid concentration in the sludge supernatant were measured to explain the change of dewaterability in the conditioning process. Results indicated that Fenton's reagent combined with DDBAC could enhance sludge dewaterability significantly. When the dosage of Fe2+, H2O2, and DDBAC were 40, 40, and 60 mg g-1 at pH 4, WC of 57.17 % and CST of 17.2 s could be achieved. The protein (PN) and polysaccharide (PS) concentrations in each layer of EPS decreased during the composite conditioning, especially in tightly bound EPS (TB-EPS) and slime layer EPS (S-EPS). And, approximately 68 % of the bound water was released in this process. Further studies through high-performance liquid chromatography (HPLC) demonstrated that the composite conditioning process could oxidize and hydrolyze EPS into small organic molecules, resulting in an increase of small-molecule organics in the species and quantities.

Treatment of laundrette wastewater using Starbon and Fenton's reagent.

The use of grey water for a variety of purposes is gaining increased popularity as a means of preserving scarce freshwater resources. In this work, catalytic oxidation over Fenton's reagent and adsorption techniques using Starbon (mesoporous material derived from polysaccharides) has been applied. These novel techniques are used as an alternative to already studied treatments of grey water such as filtration and/or biological processes. In this study, grey water, collected from a commercial laundrette, has been used. Treatment efficiency was determined by changes in the chemical oxygen demand (COD) of the grey water. Experiments using Fenton's reagent at optimum conditions of Fe(3+) = 40 mg L(-1); H2O2 = 400 mg L(-1) and pH 3 were very successful, resulting in a 95% COD removal after 15 min. Treatment with Starbon adsorption was also effective, reaching up to 81% COD removal at pH 3 within 1 h. The combined treatment with Fenton's reagent and Starbon resulted in a 93% COD removal at a significantly reduced concentration of Fenton's reagent compared to the treatment with solo Fenton's reagent. This lower chemical dose has the advantage of reducing costs and lowering sludge generation.

Combined treatment of olive mill wastewater by Fenton's reagent and anaerobic biological process.

This work presents the application of Fenton's reagent process combined with anaerobic digestion to treat an olive mill wastewater (OMW). Firstly, OMW was pre-treated by chemical oxidation in a batch reactor with Fenton's reagent, using a fixed H2O2/COD ratio of 0.20, pH = 3.5 and a H2O2/Fe(2+) molar ratio of 15:1. This advanced oxidation treatment allowed reaching reductions of 17.6 and 82.5% of chemical oxygen demand (COD) and total polyphenols (TP), respectively. Secondly, OMW treatment by anaerobic digestion was performed using previously adapted microorganisms immobilized in Sepiolite. These biological tests were carried out varying the substrate concentration supplied to the reactor and COD conversions from 52 to 74% were obtained. Afterwards, Fenton's reagent followed by anaerobic digestion was applied to OMW treatment. This combined process presented a significant improvement on organic load removal, reaching COD degradations from 64 to 88%. Beyond the pollutant load removal, it was also monitored the yield of methane generated throughout anaerobic experiments. The methane produced ranged from 281 cm(3) to 322 cm(3) of CH4/g COD removed. Additionally, a methane generation kinetic study was performed using the Monod Model. The application of this model allowed observing a kinetic constant increase of the combined process (kFN = 0.036 h(-1)) when compared to the single anaerobic process (kF = 0.017 h(-1)).

Fenton Oxidation Kinetics and Intermediates of Nonylphenol Ethoxylates.

Removal of nonylphenol ethoxylates (NPEOs) in aqueous solution by Fenton oxidation process was studied in a laboratory-scale batch reactor. Operating parameters, including initial pH temperature, hydrogen peroxide, and ferrous ion dosage, were thoroughly investigated. Maximum NPEOs reduction of 84% was achieved within 6 min, under an initial pH of 3.0, 25°C, an H2O2 dosage of 9.74×10-3 M, and a molar ratio of [H2O2]/[Fe2+] of 3. A modified pseudo-first-order kinetic model was found to well represent experimental results. Correlations of reaction rate constants and operational parameters were established based on experimental data. Results indicated that the Fenton oxidation rate and removal efficiency were more dependent on the dosage of H2O2 than Fe2+, and the apparent activation energy (ΔE) was 17.5 kJ/mol. High-performance liquid chromatography and gas chromatograph mass spectrometer analytical results indicated degradation of NPEOs obtained within the first 2 min stepwise occurred by ethoxyl (EO) unit shortening. Long-chain NPEOs mixture demonstrated a higher degradation rate than shorter-chain ones. Nonylphenol (NP), short-chain NPEOs, and NP carboxyethoxylates were identified as the primary intermediates, which were mostly further degraded.

A Comparison of RML Prion Inactivation Efficiency by Heterogeneous and Homogeneous Photocatalysis.

Prions are proteinaceous pathogens responsible for a variety of devastating diseases in mammals, including scrapie in sheep and goats, chronic wasting disease in cervids, and Creutzfeldt-Jakob disease (CJD) in humans. They are characterized by their exceptional persistence to common inactivation procedures. This applies to all possible sources of prion contamination as prions may be present in the tissues and biological fluids of infected individuals. Hence, efficient prion inactivation procedures are still being sought to minimize the risk of intra- or inter-species transmission. In the past, photocatalytic treatment has been proven to be capable of efficiently oxidizing and inactivating prions. In the present study, the efficacy of homogeneous photo-Fenton-based photocatalysis as well as heterogeneous photocatalysis with TiO2 in reducing RML mouse scrapie infectivity was evaluated. Prion inactivation was assessed by means of a bioassay, and the results were confirmed by in vitro experiments. While the prion infectivity of the RML mouse scrapie was reduced after treatment with the photo-Fenton reagent, the heterogeneous photocatalytic treatment of the same prion strain completely eliminated prion infectivity.

Ferrocene-functionalized zirconium-oxo clusters for achieving high-performance thermocatalytic redox reactions.

The Zr(IV) ions are easily hydrolyzed to form oxides, which severely limits the discovery of new structures and applications of Zr-based compounds. In this work, three ferrocene (Fc)-functionalized Zr-oxo clusters (ZrOCs), Zr9Fc6, Zr10Fc6 and Zr12Fc8 were synthesized through inhibiting the hydrolysis of Zr(IV) ions, which show increased nuclearity and regular structural variation. More importantly, these Fc-functionalized ZrOCs were used as heterogeneous catalysts for the transfer hydrogenation of levulinic acid (LA) and phenol oxidation reactions for the first time, and displayed outstanding catalytic activity. In particular, Zr12Fc8 with the largest number of Zr active sites and Fc groups can achieve > 95% yield for LA-to-γ-valerolactone within 4 h (130 °C) and > 98% yield for 2,3,6-trimethylphenol-to-2,3,5-trimethyl-p-benzoquinone within 30 min (80 °C), showing the best catalytic performance. Catalytic characterization combined with theory calculations reveal that in the Fc-functionalized ZrOCs, the Zr active sites could serve as substrate adsorption sites, while the Fc groups could act as hydrogen transfer reagent or Fenton reagent, and thus achieve effectively intramolecular metal-ligand synergistic catalysis. This work develops functionalized ZrOCs as catalysts for thermal-triggered redox reactions.

In situ acid production by organic matter induced with trace homogeneous Fenton reagent for membrane fouling control.

The homogeneous Fenton process involves both coagulation and oxidation, but it requires added acidity, so it is rarely used to control membrane fouling. This work found that the pH of neutral simulated wastewater sharply declined to 4.1 after pre-treatment with 0.1 mM Fenton reagent (Fe2+:H2O2=1:1) without added acidity. This occurred mainly because the trace homogeneous Fenton reagent induced in situ acid production by organic matter in the wastewater, which supplied the acidic conditions required for the Fenton reaction and ensured that the reaction could proceed continuously. Then, oxidation during the pre-Fenton process enhanced the electrostatic repulsion forces and effectively weakened the hydrogen bonds of organic matter at the membrane surface by altering the net charge and hydroxyl content of organic matter, while coagulation caused the foulants to gather and form large aggregates. These changes diminished the deposition of foulants onto the membrane surface and resulted in a looser fouling layer, which eventually caused the membrane fouling rate to decline from 83 % to 24 % and the flux recovery rate to increase from 44 % to 98 % during 2 h of filtration. This membrane fouling mitigation ability is much superior to that of pre-H2O2, pre-Fe2+ or pre-Fe3+ processes with equivalent doses.

Removement of thiocyanate from industrial wastewater by microwave-Fenton oxidation method.

The microwave radiation oxidation process, Fenton as catalytic agent, was used to remove the thiocyanate from the industrial wastewater. The effects of microwave power, radiation time, pH and the feeding in ways of catalyst on the degradation rate of synthetic wastewater were investigated using the microwave radiation oxidation process by orthogonal experiment. The results show Fenton catalyst ratio was 1:20, the microwave radiation power was 900 W, the microwave radiation time was 7 min and the value of pH was 3. Under the optimum conditions, the removal of KSCN can reach over 90%. The apparent kinetics of removal was studied, which conformed to kinetics first-class reaction. In short, for the thiocyanate from the industrial wastewater, microwave-Fenton oxidation method is feasible and effective.

Ageing characteristics and microplastic release behavior from rainwater facilities under ROS oxidation.

Reactive oxygen species (ROS) are ubiquitous in the natural environment that are generated by chemical or biochemical processes. Plastic rainwater facilities, as an important part of modern rainwater systems, are inevitably deteriorated by ROS. As a consequence, microplastics will be released. However, information on how ROS affect the ageing characteristics of plastic rainwater facilities and the subsequent microplastic release behavior is still insufficient. To address this knowledge gap, Fenton reagents were used to simulate the reactive oxygen species (ROS) induced ageing process of three typical plastic rainwater components (rainwater pipe, made of polyvinyl chloride; modular storage tank, made of polypropylene; inspection well, made of high-density polyethylene) and the subsequent microplastic release behavior. After 6 days of Fenton ageing, an increase in sharpness, holes, and fractures on the rainwater facilities' surface was observed by scanning electron microscope (SEM). The functional group changes on the rainwater facilities' surface were analyzed by Fourier transform infrared spectrometer (FTIR) and two-dimensional correlation spectroscopy (2D-COS) and compared with the results of X-ray photoelectron spectroscopy (XPS). During the ageing process, oxygen-containing functional groups were generated and the carbon chains were broken, which promoted peeling and the release of microplastics. The amount of released microplastics (ranging from 158 to 6617 items/g facility) varied with the type of rainwater facilities, and the order was modular storage tank > inspection well > rainwater pipe. The release amount increased with ageing time, and a significant linear relationship was observed (r2 > 0.91). The particle size of the released microplastics ranged from 2 to 1362 µm, among which 10-30 µm particles accounted for the largest proportion (62.7 %). The release amount increased exponentially with decreasing particle size (r2 > 0.71). This study indicates that large amounts of microplastics could be released from plastic rainwater components during ROS-induced ageing.

Preparation of Auricularia auricula polysaccharides and their protective effect on acute oxidative stress injury of Caenorhabditis elegans.

This research enhanced the extraction procedure for Auricularia auricula crude polysaccharides by utilizing a modified Fenton reagent as a solvent, and obtained A. auricula polysaccharides (AAPs-VH) via alcohol precipitation and deproteinization. The HPLC profile revealed that the purified AAPs-VH using Sepharose 6FF was mainly a heteropolysaccharide, consisting primarily of mannose, glucuronic acid, glucose, and xylose. The Mw and Mn of the purified AAPs-VH were 87.646 kDa and 48.854 kDa, respectively. The FT-IR and NMR spectra revealed that the purified AAPs-VH belonged to pyranose and were mainly formed by (1 â†’ 3)-linked-ß-D glucan formation. In vivo experiments conducted with Caenorhabditis elegans, AAPs-VH was found to notably influence the lifespan, improve the antioxidant system, and decrease the level of cell apoptosis. This might be achieved by up-regulating the expression of genes in the IIS and TOR pathways. The study concludes that the modified Fenton reagent can increase Auricularia auricula polysaccharide solubleness and active sites, which may be an essential prompt for future studies.

Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics.

Owing to environmental concerns, microplastics pollution has been the object of increasing attention. Currently, the chemical composition of microplastics is commonly detected using Raman spectroscopy. Nevertheless, the Raman spectra of microplastics may be overlaid by signals derived from additives (e.g., pigment), resulting in serious interference. In this study, an efficient method is proposed to overcome the interference of fluorescence during Raman spectroscopic detection of microplastics. Four catalysts of Fenton's reagent (Fe2+, Fe3+, Fe3O4, and K2Fe4O7) have been investigated for their capacity to generate hydroxyl radical (•OH), thus potentially eliminating the fluorescent signals in microplastics. The results indicate that the Raman spectrum of microplastics treated with Fenton's reagent can be efficiently optimized in the absence of spectral processing. This method has been successfully applied to the detection of microplastics collected from mangroves, featuring a range of colours and shapes. Consequentially, after 14 h of treatment with sunlight-Fenton (Fe2+: 1 × 10-|6 M, H2O2: 4 M), the Raman spectra matching-degree (RSMD) of all microplastics were >70.00 %. The innovative strategy discussed in this manuscript can greatly promote the application of Raman spectroscopy in the detection of real environmental microplastics, overcoming interfering signals derived from additives.

Sulfadiazine degradation by combination of hydrodynamic cavitation and Fenton-persulfate: parametric optimization and deduction of chemical mechanism.

This paper reports the degradation of the sulfadiazine (SDZ) drug with a hybrid advanced oxidation process (AOP) of heterogeneous α-Fe2O3/persulfate coupled with hydrodynamic cavitation. The major objectives of the study are parametric optimization of the process and elucidation of the chemical mechanism of degradation. The optimum conditions for maximum SDZ degradation of 93.07 ± 1.67% were as follows: initial SDZ concentration = 20 ppm, pH = 4, α-Fe2O3 = 181.82 mg/L, Na2S2O8 = 348.49 mg/L, H2O2 = 0.95 mL/L, inlet pressure = 0.81 MPa (8 atm), orifice plate configuration: hole dia. = 2 mm and number of holes = 4. Density functional theory (DFT) calculations revealed that the atoms of SDZ with a high Fukui index (f 0) were potentially active sites for the attack of •OH and [Formula: see text] radicals. Fukui index calculation revealed that atom 11 N has a higher value of f 0 (0.1026) for oxidation at the α-amine group of the sulfadiazine molecule. Degradation intermediates detected through LC-MS/MS analysis corroborated the results of DFT simulations. Using these results, a chemical pathway has been proposed for SDZ degradation.

Experimental study on Fenton oxidation regeneration of adsorbed toluene saturated activated carbon.

In this study, Fenton reagent has been adopted to oxidize and regenerate the resin based spherical activated carbon (SAC) adsorbed with toluene saturation. The effects of the mole ratio of Fe2+ and H2O2, the dosage of H2O2, pH value, temperature, regeneration time and the like on the regeneration rate of activated carbon have been exploited, the adsorbent used in the experiment is spherical activated carbon with a maximum adsorption capacity of 512.25 mg/g produced by Cui hong Taiyuan Science and Technology Co. The results show that the highest regeneration rate of activated carbon can reach 95.69%. The optimal regeneration condition is that the molar ratio of Fe2+ and H2O2 is 1/25, the concentration of H2O2 is 175 mmol/L, the pH is 2, the temperature is 20℃∼30℃, and the regeneration time is 180 min. The influence of regeneration process on the characterization of activated carbon has been studied by BET analysis as well as SEM analysis.

Effects and Impacts of Different Oxidative Digestion Treatments on Virgin and Aged Microplastic Particles.

Although several sample preparation methods for analyzing microplastics (MPs) in environmental matrices have been implemented in recent years, important uncertainties and criticalities in the approaches adopted still persist. Preliminary purification of samples, based on oxidative digestion, is an important phase to isolate microplastics from the environmental matrix; it should guarantee both efficacy and minimal damage to the particles. In this context, our study aims to evaluate Fenton's reaction digestion pre-treatment used to isolate and extract microplastics from environmental matrices. We evaluated the particle recovery efficiency and the impact of the oxidation method on the integrity of the MPs subjected to digestion considering different particles' polymeric composition, size, and morphology. For this purpose, two laboratory experiments were set up: the first one to evaluate the efficacy of various digestion protocols in the MPs extraction from a complex matrix, and the second one to assess the possible harm of different treatments, differing in temperatures and volume reagents used, on virgin and aged MPs. Morphological, physicochemical, and dimensional changes were verified by Scanning Electron Microscope (SEM) and Fourier Transformed Infrared (FTIR) spectroscopy. The findings of the first experiment showed the greatest difference in recovery rates especially for polyvinyl chloride and polyethylene terephthalate particles, indicating the role of temperature and the kind of polymer as the major factors influencing MPs extraction. In the second experiment, the SEM analysis revealed morphological and particle size alterations of various entities, in particular for the particles treated at 75 °C and with major evident alterations of aged MPs to virgin ones. In conclusion, this study highlights how several factors, including temperature and polymer, influence the integrity of the particles altering the quality of the final data.

Degradation of commercial glyphosate-based herbicide via advanced oxidative processes in aqueous media and phytotoxicity evaluation using maize seeds.

Glyphosate is a herbicide that acts as a broad-spectrum, non-selective, post-emergence systemic pest controller. Its continuing, increasing, and excessive use in many countries in recent years poses a significant threat to the environment and human health due to the prevalence of this herbicide in water bodies and its impact on non-target organisms. In this context, it is essential to develop processes aimed at the non-selective degradation of glyphosate and its by-products. In this study, various advanced oxidative processes were applied: Fenton, electro-Fenton, photoelectro-oxidation, and photoelectro-Fenton, with the objective of oxidizing glyphosate in the commercial product Roundup®. The resultant oxidation products and the phytotoxicological effect on maize seed germination were also analyzed. Following each treatment, chemical oxygen demand (COD), total organic carbon (TOC), glyphosate degradation, and oxidation by-product formation were analyzed. The treated solutions were used to germinate maize seeds for 7 days in a germination chamber applying a photoperiod of 12 h at 24 °C. The % of germination, protein and hydrogen peroxide (H2O2) content, lipid peroxidation extent (MDA), and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities were determined. The photoelectro-Fenton treatment was the most effective in degrading glyphosate, operating synergistically to break glyphosate bonds, thereby generating non-toxic short-chain molecules. Maize seed germination was satisfactory (> 50 %), but the persistent formation of reactive oxygen species (ROS) led to increased antioxidant activities of SOD, CAT, and POD enzymes acting in a compensatory manner against ROS, thus sustaining the photosynthetic apparatus. Hormesis, a stimulatory effect of glyphosate, was also observed in the presence of low concentrations of glyphosate.

Attenuation of organics contamination in polymers processing effluent using iron-based sludge: process optimization and oxidation mechanism.

The feasibility of using iron extracted from acid mine drainage (AMD) as Fenton's reagent for removal of organics pollutants from polymer and plastics manufacturing effluent was investigated in this study. AMD iron dose, H2O2 concentration and pH were evaluated as the treatment factors for their effects on organics oxidation. Optimum treatment conditions were identified using response surface methodological analysis (RSM), and of the ranges of the treatment factors examined, an optimal treatment combination was found to be AMD iron concentration: 40 mg/L and H2O2: 500 mg/L at pH 2.2, organics removal efficiency as high as 98% for TOC removal was achieved. The removal efficiency increased with temperature up to 40°C and further temperature increases resulted in lower removal efficiencies. The organics oxidation was characterized well by investigating the kinetic order and the process is following the second-order reaction kinetics. The thermodynamic parameters showed that the oxidation reaction was endothermic and non-spontaneous in nature.