Treatment of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran production effluent by combination of biological treatments and Fenton's oxidation

High strength refractory organic stream is produced during the production of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran （One Dye Black 2, abbr. ODB 2）, a novel heat-sensitive material with a promising market. In this study, a combination of acidificationprecipitation, primary biological treatment, Fenton＇s oxidation and another biological treatment was successfully used for the removal of COD from 18000-25000 mg/L to below 200 mg/L from the ODB 2 production wastewater in a pilot experiment. A COD removal of 70%-80% was achieved by acidification-precipitation under a pH of 2.5-3.0. The first step biodegradafion permitted an average COD removal of 70% under an hydraulic residence time （HRT） of 30 h. By batch tests, the optimum conditions of Fenton＇s oxidation were acquired as： Fe^2＋ dose 6.0 mmol/L; H2O2 dose 3000 mg/L; and reaction time 6 h. The second step biological treatment could ensure an effluent COD below 200 mg/L under an HRT of 10 h following the Fenton＇s treatment.

A critical review towards the causes of the iron-based catalysts deactivation mechanisms in the selective oxidation of hydrogen sulfide to elemental sulfur from biogas

Hydrogen sulfide(H_(2)S) not only presents significant environmental concerns but also induces severe corrosion in industrial equipment,even at low concentrations.Among various technologies,the selective oxidation of hydrogen sulfide(SOH_(2)S) to elemental sulfur(S) has emerged as a sustainable and environmentally friendly solution.Due to its unique properties,iron oxide has been extensively investigated as a catalyst for SOH_(2)S;however,rapid deactivation has remained a significant drawback.The causes of iron oxide-based catalysts deactivation mechanisms in SOH_(2)S,including sulfur or sulfate deposition,the transformation of iron species,sintering and excessive oxygen vacancy formation,and active site loss,are thoroughly examined in this review.By focusing on the deactivation mechanisms,this review aims to provide valuable insights into enhancing the stability and efficiency of iron-based catalysts for SOH_(2)S.

Photoassisted fenton oxidation of refractory organics in UASB-pretreated leachate

Nearly 91% of organic pollutants in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD (chemical oxygen demand) of leachate was lowered from an average of 5620 mg/L to 1910 mg/L after the UASB treatment at 37℃, and was further lowered to 513 mg/L after fenton coagulation. The remaining refractory residues could be further removed by photochemical oxidation with the addition of H 2O 2. The BOD/COD ratio was greatly increased from 0.062 to 0.142, indicating the biodegradability of organic residues was improved. The photochemical oxidation for the fenton\|coagulation supernatant was most effective at pH 3\_4, with the addition of 800 mg/L of H 2O 2, and UV radiation time of 30 minutes. The final effluent contained only 148 mg/L of COD, 21 mg/L of BOD(biochemical oxygen demand) and 56 mg/L of TOC (total organic carbon).

Treatment of Landfill Leachate by Fenton Oxidation Process

Central composite design (CCD), the most popular design ofresponse surface methodology (RSM), was employed to investigate theeffect of total organic carbon (TOC) ratio of high molecular weightorganic matter (HMW) to low molecular weight organic matter (LMW),the LMW strength and molar ratio of hydrogen peroxide to ferrous ionon landfill leachate treatment by Fenton process. Based on theexperimental data, a response surface quadratic model in terms ofactual factors was obtained through analysis of variance (ANOVA).

A Molecular Mechanism of Fenton Oxidation Degradation of m-Xylene

Density functional theory（DFT） quantum chemical method was used to study the process of meta-xylene Fenton oxidation. The EHOMO energies of meta-xylene molecules are higher, so they have better ability to provide electron and prone to the nucleophilic reaction. M-xylene mainly reacts with OH free radical in addition reactions. And the position of C（6） is most likely to react with the OH free radical, rather than the C（3）, which is the most difficult to occur. According to all the above results, the most likely reaction mechanism of advanced oxidation degradation of meta-xylene is determined.

Treatment of Oil Field Wastewater after Chemical Flooding by Fenton Oxidation Combined with Biodegradation

Wastewater after chemical flooding is difficult to be treated by biological methods due to the residual chemicals in the wastewater. Fenton oxidation, which has been widely applied to detoxifying hazardous organic compounds and improving the biodegradability of these compounds, can solve this problem. So, in this paper, Fenton oxidation was used to enhance the biodegradability of the wastewater after chemical flooding. The op- timum operating conditions for the Fenton oxidation process were 2.5 g/L Fe2 ＋ , 600 mg/L H202 and 30 rain of treatment time. The wastewater pre- treated by Fenton oxidation was treated by aerobic activated sludge. It was found that a small amount of H202 can significantly increase both the biodegradation rate and extent of the wastewater. The effluent CODc, and HPAM contents were 260 and 94 mg/L respectively after the aerobic bio- logical process with the biodegradation time of 24 h. After Fenton oxidation combining with biodegradation, the total CODc, removal efficiency was up to 90%, and polymer and oil degrading efficiencies were 95% and 92% respectively.

Effects of Influencing Factors on Fenton Oxidation of Antibiotic Pharmaceutical Wastewater by a Statistical Design Approach

A series of batch-scale experiments were completed to investigate the effects of operational parameters on chemical oxygen demand (COD) removal by Fenton reagent for antibiotic pharmaceutical wastewater (APW). The significance of five operational factors including the mass ratio of H2O2/COD (g/g), the mole ratio of H2O2/Fe2+ (mol/mol), initial pH, oxidation temperature T, and reaction time t were evaluated statistically by Box-Behnken design (BBD). It was found that the five parameters were all significant to the COD removal efficiency by t-test, as well as the interactions between mass ratio/reaction time and oxidation temperature/reaction. The optimal COD removal efficiency (89.50%) was achieved when the mass ratio of H2O2/COD and the mole ratio of H2O2/Fe2+ were 3.00 and 5.00 respectively, with pH value of 3.68 at 298K for 72min reaction. A quadratic regression model with 0.9907 regression coefficient (R2) was developed which had good agreement to the experimental data.

Effect of different surfactants on removal efficiency of heavy metals in sewage sludge treated by a novel method combining bio-acidification with Fenton oxidation

The aim of this work was to investigate the effect of different surfactants on the removal efficiency of heavy metals in sewage sludge treated by a method combining bio-acidification with Fenton oxidation. Four surfactants were adopted such as anionic surfactant(sodium dodecyl benzene sulfonate, SDBS), nonionic surfactants(tween-20 and tween-60) and cationic surfactant(hexadecyl trimethyl ammonium chloride, HTAC), respectively. The indigenous sulfur-oxidizing bacteria in bio-acidification phase were enriched and cultured from fresh activated sludge obtained from a wastewater treatment plant. It is shown that different surfactants exhibited distinct effect on the removal efficiency of heavy metals from sewage sludge. The nonionic surfactants,especially tween-60, promotes the solubilization of heavy metals, while the anionic and cationic surfactants hinder the removal of heavy metals. Copper is efficiently leached. The removal efficiency of cadium is relatively lower than that of Cu due to the demand for rigorous p H value. Lead is leached with a low efficiency as the formation of low soluble Pb SO4 precipitates.

In situ synthesis of nanostructured titania film on NiTi shape memory alloy by Fenton’s oxidation method

Fenton’s oxidation method was successfully used to synthesize an ideal titania film in situ on NiTi shape memory alloy(SMA) for medical applications. Characterized with scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, inductively coupled plasma mass spectrometry and electrochemical tests, it is found that the titania film produced by Fenton’s oxidation method on NiTi SMA is nanostructured and has a Ni-free zone near its top surface, which results in a notable improvement in corrosion resistance and a remarkable decrease in leaching of harmful Ni ions from NiTi SMA in simulated body fluids. The improvement of effectiveness to corrosion resistance and the reduction in Ni release of NiTi SMA by Fenton’s oxidation method are comparable to those by oxygen plasma immersion ion implantation reported earlier.

The Treatment of Polymer-bearing Wastewater from Refinery by Fenton Oxidation - Activated Carbon Adsorption

To solve the problem of polymer-bearing effluent of crude oil not reaching the standard,deep treatment system of Fenton oxidation-activated carbon adsorption is established in one refinery,and the most suitable condition of Fenton oxidation reaction is determined.Operation results show that CODCrconcentration of effluent treated by the system could be lower than 50 mg/L,and ammonia nitrogen content is less than 3 mg/L,which meets design requirement.

Treatment Processes of Leachate from a Landfill by Advanced Oxidation Fenton and Ozone-UV

In this paper it is presented the results of advanced oxidation of leachates from a technified sanitary landfill located in the State of Querétaro, Mexico. One characteristic of already stabilized leachates from sanitary landfills like this case, is their difficult degradation, mainly because the organic matter contained is recalcitrant. For the samples collect, four sites were selected, where three points per site were sampled, measuring at each site the parameters: temperature, pH, conductivity, redox potential (ORP) and dissolved oxygen (DO) and leachate samples were collected. On the other hand, the Chemical Oxygen Demand (COD) of crude leachates, leachates acidified and leachates oxidized by Fenton reagent and Ozone-UV combined were analyzed. COD was used to monitor the degradation kinetics. With the results, the ArcGIS software was applied to study the distribution of temperature, dissolved oxygen and COD mainly in the leachate lagoon. For the application of Fenton reagent in the crude leachate oxidation, the pH was first adjusted and Fe2+/H2O2 ratio was optimized. The efficiency of Ozone-UV treatments was studied through COD degradation kinetics. The graphs of in (Ci/Co) vs time, showed that the kinetic processes are of order one, with very acceptable regression coefficients (R2) and extraordinarily similar speed constants (K). With Fenton oxidation, the highest percentage of COD degradation was achieved and with Ozone-UV oxidation, it was possible to practically degrade all the COD.

Operating Conditions Optimization on Indonesian ＂Batik＂ Dyes Wastewater Treatment by Fenton Oxidation and Separation Using Ultrafiltration Membrane

Broadly speaking, this study aims to develop ＂batik＂ dyes wastewater treatment technologies by hybrid process that combines Fenton oxidation and separation using ultrafiltration membranes. Specifically, the purpose of this study was to determine the effect of membrane characteristics, feed solution pH, operating pressure of ＂Dead-end＂ membrane reactor, and the frequency of membranes which uses on the percentage of COD reduction in ＂batik＂ wastewater. In this study, the filtrate from wastewater pre-treatment with Fenton oxidation, both without and with addition of activated carbon, is passed to the ultrafiltration （UF） separation system. Fenton oxidation process was carried out at optimum conditions, i.e. at pH 3, temperature 50 ℃, and the addition FeSO4·7H2O and H2O2 at 747-830 mg/L and 1,168-1,460 mg/L, respectively. The optimum reduction percentage of COD can be achieved when the membranes used for separation has a pore size of 0.01 to 0.015 lam, feed solution pH 2, operating pressure 1 atm and frequency of membranes uses I x. To determine the fouling potential on ultrafiltration membranes that are used, flux measurements were performed 3 times for each membrane. These stages can see that the flux decline reached 22.5% when the effluent filtered directly to the membrane; 17.3% when performed pre-treatment prior to separation processes using membranes and 10% when combined pre-treatment process, use of activated carbon and the separation using ultrafiltration membranes.

Kinetics of Degradation of Eosin Y by One of the Advanced Oxidation Processes (AOPs)—Fenton’s Process

Kinetics of homogeneous degradation of Eosin Y (EY), also known as Acid red 87 (CI 45380), are studied, mostly using Fenton’s process, at 30℃ by monitoring its absorbance at 517 nm (λmax of EY). This process is one of the advanced oxidation processes (AOPs). Mixture of H2O2 and Fe(II) ion in acetate buffer medium (pH 2.74 - 4.56) generates hydroxyl free radicals (?OH) which attack the dye molecules, resulting in degradation of the dye molecules. Results show that the initial rate of EY degradation decreases with the increasing of solution pH because of removal of kinetically important Fe (iron) species through formation of ferric hydroxide. On the other hand, the rate increases with increasing the concentrations of H2O2, Fe(II) and EY at low solution pH. The initial rate increases with increasing of concentration of H2O2 and, subsequently remains unaffected with further increase of its concentration at a constant Fe(II) concentration because of the enhanced scavenging environment created by H2O2 at its higher concentration. The initial rate also increases with increasing of concentration of Fe(II) at a constant H2O2 concentration and remains unaffected with its further increase. EY concentration also enhances the initial rate at low pH. However, the initial rate is significantly enhanced by UV light. This is because of formation of additional hydroxyl radicals through excitation of the dye molecules by UV light. During the period of experiment, EY in aqueous solution alone hardly suffered any degradation. Degradation mechanism of EY by the Fenton and photo-Fenton’s processes is also discussed. Statistical analysis was used to validate the experimental results. Low values of the standard deviation for both the initial rate and % degradation indicated the consistency of the experimental data.

Polyoxidovanadates a new therapeutic alternative for neurodegenerative and aging diseases

Aging is a natural phenomenon characterized by a progressive decline in physiological integrity,leading to a deterioration of cognitive function and increasing the risk of suffering from chronic-degenerative diseases,including cardiovascular diseases,osteoporosis,cancer,diabetes,and neurodegeneration.Aging is considered the major risk factor for Parkinson’s and Alzheimer’s disease develops.Likewise,diabetes and insulin resistance constitute additional risk factors for developing neurodegenerative disorders.Currently,no treatment can effectively reverse these neurodegenerative pathologies.However,some antidiabetic drugs have opened the possibility of being used against neurodegenerative processes.In the previous framework,Vanadium species have demonstrated a notable antidiabetic effect.Our research group evaluated polyoxidovanadates such as decavanadate and metforminium-decavanadate with preventive and corrective activity on neurodegeneration in brain-specific areas from rats with metabolic syndrome.The results suggest that these polyoxidovanadates induce neuronal and cognitive restoration mechanisms.This review aims to describe the therapeutic potential of polyoxidovanadates as insulin-enhancer agents in the brain,constituting a therapeutic alternative for aging and neurodegenerative diseases.

Degradation of Reactive Brilliant Red X-3B by Fenton Oxidation Method

Abstract [ Objective] The degradation conditions and course of reactive brilliant red X-3B by Fenton oxidation was investigated to understand the feasibility of using Fenton oxidation for dye removal. [Metbed] By using Fenton oxidation, the degradation conditions of reactive brilliant red X-3B wastewater was studied in different initial concentrations, then analyzed its degradation products and process through gas chromatography-mass spectrometer （GC-MS）. [ Remit] When H202：Fe2＋ （molar ratio） =3.1, the removal rate of CODc, was the highest. With the increase of Fe2＋ dos- age, the wastewater became red and more deposits generated. As CODc, of wastewater was 200,400 and 800 mg/L, the dosage of H202 was 0.5, 1.0 and 3.5 ml respectively, and the best initial pH of the wastewater was 4 -5, the removal rate of GODc, reached the maximum values. In addition, Fenton reaction was very fast, that is, most degradation occurred in the first 5 min. [ Cenclmion] Fenton oxidation technology is practical and efficient in the declradation of dves which are mineralized difficultly.

Effect of Rare Earths on the Wear Resistance and High Temperature Oxidation Resistance of H13 Steel Surface-Treated with S-N-C Co-diffusion

Steel H13 was put in non toxic salt bath with addition of CeO 2 for co diffusion of sulfur, nitrogen and carbon and followed by oxidation treatment. The effect of rare earths on the improvement of wear resistance and high temperature oxidation resistance of steel H13 was studied using scanning electron microscope, energy dispersive spectrometry and X ray diffraction. The results show that compared to the surface treatment without rare earth addition, the treatment with addition of rare earths improves the wear resistance and high temperature resistance to oxidation of steel H13. Under the conditions of 30 N and 2 h, the wear weight loss was decreased by 40%, and the friction coefficient was reduced from 0 25 to 0 22; whereas for 150 N and 0 2 h, the wear weight loss was decreased by 24%, and the friction coefficient was reduced from 0 35 to 0 32. For the oxidation at 700 ℃ and 4 h, the rate of weight gain decreased to only about 1/30 of that without rare earths.

Study on Catalytic Wet Oxidation of H_2S into Sulfur on Fe/Cu Catalyst

A wet catalytic oxidation at room temperature was investigated with solution containing ferric, ferrous and cupric ions for H2S removal. The experiments were carried out in a two step process, and the results obtained show that the removal efficiency of H2S can always reach 100% in a 300 mm scrubbing column with four sieve plates, and the regeneration of ferric ions in 200 mm bubble column can match the consumed ferric species in absorption. Removal of H2S, production of elemental sulfur and regeneration of ferric, cupric ions can all be accomplished at the same time. No raw material is consumed except O2 in flue gas or air, the process has no secondary pollution and no problem of catalyst degradation and congestion.

Enhanced electrochemical oxidation of phenol by introducing ferric ions and UV radiation

The mineralization of phenol in aerated electrochemical oxidation has been investigated.The results show that a cathodic Fenton process can occur when the Ti-0.3Mo-0.8Ni alloy material is used as cathode in solution containing ferric or ferrous ions; moreover,the reinforcement of cathodic Fenton process on the total organic carbon (TOC) removal rate of phenol is quite distinct.Among the metallic ions investigated,the ferric ion is the best catalyst for the electrochemical mineralization of phenol at initial...

Cath-KP,a novel peptide derived from frog skin,prevents oxidative stress damage in a Parkinson’s disease model

Parkinson’s disease(PD)is a neurodegenerative condition that results in dyskinesia,with oxidative stress playing a pivotal role in its progression.Antioxidant peptides may thus present therapeutic potential for PD.In this study,a novel cathelicidin peptide(Cath-KP;GCSGRFCNLF NNRRPGRLTLIHRPGGDKRTSTGLIYV)was identified from the skin of the Asiatic painted frog(Kaloula pulchra).Structural analysis using circular dichroism and homology modeling revealed a uniqueαββconformation for Cath-KP.In vitro experiments,including free radical scavenging and ferric-reducing antioxidant analyses,confirmed its antioxidant properties.Using the 1-methyl-4-phenylpyridinium ion(MPP^(+))-induced dopamine cell line and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced PD mice,Cath-KP was found to penetrate cells and reach deep brain tissues,resulting in improved MPP^(+)-induced cell viability and reduced oxidative stress-induced damage by promoting antioxidant enzyme expression and alleviating mitochondrial and intracellular reactive oxygen species accumulation through Sirtuin-1(Sirt1)/Nuclear factor erythroid 2-related factor 2(Nrf2)pathway activation.Both focal adhesion kinase(FAK)and p38 were also identified as regulatory elements.In the MPTP-induced PD mice,Cath-KP administration increased the number of tyrosine hydroxylase(TH)-positive neurons,restored TH content,and ameliorated dyskinesia.To the best of our knowledge,this study is the first to report on a cathelicidin peptide demonstrating potent antioxidant and neuroprotective properties in a PD model by targeting oxidative stress.These findings expand the known functions of cathelicidins,and hold promise for the development of therapeutic agents for PD.

Baeyer-Villiger oxidation of cyclic ketones utilizing potassium peroxydisulfate(K_2S_2O_8) or sodium perborate(NaBO_3) in acidic media

The efficient, green, facile, mild and straightforward conversion procedure for the oxidation of cyclic ketones to lactones at room temperature utilizing potassium peroxydisulfate （K2S2O8） in acidic media is satisfactory to high yields without using traditional chlorinated solvents is reported. This oxidative reagent is cheap and friendly environmental procedure for industrial purposes than use of organic peracids.