Initial Peroxide Concentration Research Articles

A novel continuous magnetic nano-Fe3O4/perlite fixed bed reactor for catalytic wet peroxide oxidation of dyes: reactor structure

In the present work, a continuous catalytic wet peroxide oxidation fixed bed reactor was employed to treat a simulated wastewater sample with malachite green dye, as a contaminant. Natural perlite particle-supported nano-Fe3O4 catalyst was used as a fixed bed inside a reactor, and it was immobilized by a persistent magnetic field. The range of (perlite) particle sizes was from 100 to 1000 nm. The effects of various operating parameters, including temperature of the reactor, pH, initial hydrogen peroxide concentration and initial dye concentration, were investigated on the percentage removal of malachite green dye. Load of catalyst of 2 g and volumetric flow rate of 1 L/h were selected for all the tests. Maximum malachite green degradation was 99.5 ± 0.3%. This removal percentage was attained at temperature of 80 °C, pH = 6, initial dye concentration of 6 mg/L and initial hydrogen peroxide concentration of 100 mg/L. The process was isotherm, and the catalyst showed high catalytic activity in the steady-state condition. The loss of catalyst was less than 0.3%.

Photocatalytic degradation of polyvinylpyrrolidone in aqueous solution using TiO2/H2O2/UV system

ABSTRACTThe photocatalytic degradation of high molecular weight polyvinylpyrrolidone (PVP), a water-soluble polymer, using a TiO2/H2O2/UV system was studied in an annular photoreactor using a mercury vapor lamp (125 W) as the radiation source. The effect of the initial hydrogen peroxide concentration and the operating conditions, such as initial concentration of PVP, photocatalyst dosage and initial pH, on the reaction rate was also evaluated. It was observed that the efficiency of the TiO2/H2O2/UV system was 33% higher than that of a system without H2O2, reaching total organic carbon removals of above 80% in 6 h of reaction, depending on the experimental conditions. The optimal photocatalyst dosage was found to be 0.50 g L−1. Also, the results demonstrate that the reaction rate increases as the pH and initial concentration of PVP decrease. This treatment can be carried out successfully under optimal conditions and enhance the biodegradability of the organic matter remaining at the end of the application of the TiO2/H2O2/UV system, as assessed by biochemical oxygen demand/chemical oxygen demand measurements.

Kinetics and modelling of furfural oxidation with hydrogen peroxide over a fibrous heterogeneous catalyst: effect of reaction parameters on yields of succinic acid

AbstractBACKGROUNDSuccinic acid is an important intermediate compound with high commercial significance in the chemical industry. It can be obtained from renewable resources such as furfural. This article describes the kinetic study of furfural oxidation with hydrogen peroxide over a fibrous polymer‐supported sulphonic acid catalyst (Smopex‐101). The influence of reaction temperature, initial concentration of hydrogen peroxide and furfural has been investigated in detail. Reaction kinetics has been studied both in batch and semi‐batch modes. Self‐decomposition of hydrogen peroxide and loss of carbon in the form of carbon dioxide has been thoroughly examined. Parameter estimation has been performed and comparison was made between catalytic and non‐catalytic reactions. The catalyst stabilities have been discussed.RESULTSThe results indicate that the reaction orders in hydrogen peroxide decomposition are different in catalytic and non‐catalytic reactions. Furfural presence in the reaction mixture, its interactions with the catalyst and involvement in other reactions significantly suppressed the side reactions, improving hydrogen peroxide utilization. The desired product (succinic acid) has been obtained in good yields (80%) when furfural was added in a semi‐batch mode.CONCLUSIONSThe kinetic models predicted the consumption behavior of hydrogen peroxide and furfural in both catalytic and non‐catalytic reactions and the kinetic parameters were statistically well identified. © 2017 Society of Chemical Industry

Advanced oxidation of preservative agents in H2O2/UVC system – Kinetics study, transformation products and toxicity assessment

Phenylphenol isomers (hydroxylated derivatives of biphenyl) are widely used as a preservative agents and disinfectants in many branches of industry.This work focuses on removal of phenylphenol isomers from aqueous solution using H2O2/UVC process. The influence of different operating variables such as pH, initial concentration of hydrogen peroxide, initial concentration of target compounds, fluence rate and presence of radical scavengers on degradation rate was investigated. Moreover, transformation products and toxicity of the reaction solutions were studied. The reaction rate constants of hydroxyl radicals with phenylphenol isomers were determined by using classical and competition kinetics. The value of reaction rate constant depends on the position of the hydroxyl group in the aromatic ring and follows the order: ortho- phenylphenol<meta- phenylphenol<para- phenylphenol. The main by-products of initial degradation steps were dihydroxybiphenyl isomers, phenol and isomers of 2,4-hexadienoic-6-oxo-6-phenyl acid or trihydroxybiphenyl. A properly selected degradation time led to mineralization of reaction solution, and after 2h of reaction the total organic carbon reduction was equaled to 89, 87 and 71% for ortho- phenylphenol, meta- phenylphenol and para- phenylphenol solution, respectively. The application of advanced oxidation in H2O2/UVC system led to achieving non-toxic reaction solutions.

Removal efficiency of anionic surfactants from water during UVC photolysis and advanced oxidation process in H2O2/UVC system

AbstractSurfactants after their use are discharged into aquatic ecosystems. These compounds may be harmful to fauna and flora in surface waters or can be toxic for microorganisms of the activated sludge or biofilm in WWTP. In order to determine effectiveness of different advanced oxidation processes on the degradation of surfactants, in this study the degradation of anionic surfactants in aqueous solution using photolysis by 254 nm irradiation and by advanced oxidation process in a H2O2/UVC system was investigated. Two representatives of anionic surfactants, linear alkyl benzene sulphonate (LAS-R11–14) and ether carboxylic derivate (EC-R12–14E10) were tested. The influence of pH, initial surfactant concentration and dose of hydrogen peroxide on the degradation was also studied. Results show outstanding effectiveness of the H2O2/UVC system in the removal of surfactant from aqueous solutions.

Catalytic and inhibiting effects of ferrocene on the bulk radical–coordination polymerization of methyl methacrylate from the standpoint of formal kinetics

The kinetic curves and rates of bulk radical–coordination polymerization of methyl methacrylate initiated by the benzoyl peroxide–ferrocene system at 293–373 K, initial benzoyl peroxide concentrations of 10–4–10–1 mol/L, and a constant initial ferrocene concentration of 10–3 mol/L have been calculated using a mathematical model in which the process is considered from the standpoint of formal kinetics. The calculations have demonstrated that, at low methyl methacrylate conversions, ferrocene catalyzes the process at any benzoyl peroxide concentration; at medium and high methyl methacrylate conversions, deficient amounts of ferrocene with respect to benzoyl catalyze the process as well, while excess ferrocene inhibits the process. The observed effect is explained by the specific ferrocene–benzoyl peroxide interaction, which, depending on the ferrocene: benzoyl peroxide ratio, either increases or decreases the concentration of radicals in the reaction mass.

Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater

ABSTRACTIn this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H2O2 residual in the effluent of the combined UV-C/H2O2-VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOCo) and hydrogen peroxide (H2O2o) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum conditions to achieve the maximum percentage TOC removal of 46.19% and minimum H2O2 residual of 1.05% were TOCo of 213 mg L−1, H2O2o of 450 mg L−1, and irradiation time of 9 min. The attained optimal operating conditions were validated with a complementary test. Consequently, the TOC removal of 45.68% and H2O2 residual of 1.03% were achieved experimentally, confirming the statistical model reliability. Three individual processes, VUV alone, VUV/H2O2, and UV-C/H2O2, were also evaluated to compare their performance for the treatment of the actual SWW using the optimum parameters obtained in combined UV-C/H2O2-VUV processes. Results confirmed that an adequate combination of the UV-C/H2O2-VUV processes is essential for an optimized TOC removal and H2O2 residual. Finally, respirometry analyses were also performed to evaluate the biodegradability of the SWW and the BOD removal efficiency of the combined UV-C/H2O2-VUV processes.

Controlled grafting of vinylic monomers on polyolefins: a robust mathematical modeling approach

Experimental and mathematical modeling analyses were used for controlling melt free-radical grafting of vinylic monomers on polyolefins and, thereby, reducing the disturbance of undesired cross-linking of polyolefins. Response surface, desirability function, and artificial intelligence methodologies were blended to modeling/optimization of grafting reaction in terms of vinylic monomer content, peroxide initiator concentration, and melt-processing time. An in-house code was developed based on artificial neural network that learns and mimics processing torque and grafting of glycidyl methacrylate (GMA) typical vinylic monomer on high-density polyethylene (HDPE). Application of response surface and desirability function enabled concurrent optimization of processing torque and GMA grafting on HDPE, through which we quantified for the first time competition between parallel reactions taking place during melt processing: (i) desirable grafting of GMA on HDPE; (ii) undesirable cross-linking of HDPE. The proposed robust mathematical modeling approach can precisely learn the behavior of grafting reaction of vinylic monomers on polyolefins and be placed into practice in finding exact operating condition needed for efficient grafting of reactive monomers on polyolefins.

Photocatalytic degradation of rhodamine B under visible light using nanostructured zinc doped cobalt ferrite: Kinetics and mechanism

Nanostructured Co1-xZnxFe2O4(0≤x≤0.5) catalyst synthesized by the microwave combustion method was employed for the photocatalytic degradation of rhodamine B (RhB) under visible light. Doping of Zn2+ ions in the cobalt ferrite matrices were confirmed by the diffraction peak-shift towards lower angles. The Williamson-Hall method was used to calculate the crystallite size considering the strain components. The conduction band (CB) and valence band (VB) edges of all the samples were calculated using optical studies. Photoluminescence analysis performed at an excitation wavelength of 330nm disclosed the rate of recombination of electron-hole pairs and the defects present. Photocatalytic degradation of RhB with pure cobalt ferrite system was performed at pH 2.0 by varying the time, initial concentration and addition of hydrogen peroxide to behave like a Fenton like process. However the effective photodegradation of all zinc doped cobalt ferrite were done at optimal RhB concentration of 6mg/l at identical operational conditions. Among all the samples Co0.6Zn0.4Fe2O4 exhibited an enhanced degradation efficiency of 99.9% at visible light exposure time of 210min. The degradation pathway followed first order rate rather than the second order rate kinetics. Based on the values of CB and VB edges in the Co0.6Zn0.4Fe2O4 system, possible routes for the degradation of RhB are suggested.

Degradation and mineralization of antipyrine by UV-A LED photo-Fenton reaction intensified by ferrioxalate with addition of persulfate

Abstract The intensification of the degradation of antipyrine in aqueous solution by using a UV-A-LED-photo-Fenton reaction intensified by ferrioxalate complexes and with addition of persulfate anions was studied. The efficiency of the reaction was evaluated in terms of antipyrine degradation and mineralization degree at different initial concentrations of hydrogen peroxide, ferrous ion, oxalic acid and persulfate anion. The reaction was carried out using a lab-scale photoreactor irradiated with artificial UV-A-LED light emitting at 365 nm. Artificial neural networks (NNs) were implemented for modelling the degradation process. Under optimal conditions, complete degradation of antipyrine and 93% mineralization was reached in 2.5 and 60 min, respectively. The contribution of HO radicals in this system was evaluated running the reaction in the absence and presence of appropriate quenchers such as tert-butyl alcohol and methanol. In the last step of reaction, possibly different intermediates such as 2-butenedioic acid, butanedioic acid, 4-oxo-pentanoic acid, acetate and formate can be generated which cannot be degraded by HO radicals or their reaction is very slow. This ferrioxalate-mediated system reduces the amount of H2O2 needed (100 mg L−1) for antipyrine degradation and persulfate was not necessary because it could not be activated with UV-A LED nor with Fe2+ since it is quickly converted to Fe3+ forming ferrioxalate complexes.

MINERALIZACIÓN DE ETILENGLICOL POR FOTO-FENTON ASISTIDO CON FERRIOXALATO

Se evaluo la efectividad del proceso foto-Fenton asistido con ferrioxalato para la mineralizacion de 1000 mg/L de etilenglicol presente en agua destilada y en agua residual proveniente de una planta de produccion de pinturas. Se observo que la eficiencia de mineralizacion del etilenglicol es funcion de las concentraciones iniciales de ion ferroso, oxalato y peroxido de hidrogeno. Los mayores niveles de degradacion del etilenglicol (90 y 85 %, para el agua destilada y el agua residual, respectivamente), se obtuvieron con 10 mg/L de Fe 2+ , 150 mg/L de C 2 O 4 2– y 500 mg/L de H 2 O 2 , despues de 3 h de irradiacion artificial con lamparas UV a una longitud de onda maxima de 365 nm. La descomposicion del etilenglicol produjo cantidades traza (< 136 mg/L) de acido acetico y acido formico, por lo que la disminucion en la demanda quimica de oxigeno debida a este contaminante fue practicamente total, ya que no se detecto ningun otro producto intermediario. El hierro no actuo directamente de manera catalitica en el sistema.

Enzymatic treatment of methyl orange dye in synthetic wastewater by plant-based peroxidase enzymes

The search for effective and sustainable methods to degrade and remove recalcitrant dyes from textile effluents is a major research endeavor, owing to the escalating environmental and health concerns arising from the discharge of coloured effluents into water bodies. Plant-based peroxidases represent a reliable bio-resource for sustainable treatment of coloured effluents with the capacity to offer a continuous process for high throughput operation. The present study investigates the potential use of soybean peroxidase and Luffa acutangula (luffa) peroxidase, extracted from bio-wastes of soybean hulls and luffa skin peels respectively, for enzymatic degradation of azo dye methyl orange from liquid effluents. The enzymatic dye removal process was studied based on the consistent enzymatic activities of crude soybean peroxidase and luffa peroxidase extracts, which were 0.373UmL−1 and 0.355UmL−1 respectively. The effects of several process parameters including reaction time, pH, temperature, enzyme dosage, initial dye concentration and hydrogen peroxide concentration were investigated to optimise the performance of the enzymatic treatment process. Soybean peroxidase demonstrated a maximum dye decolourisation efficiency of 81.4% under the conditions of 1h incubation at 30°C using 2mM of hydrogen peroxide, 0.5mL crude soybean peroxidase and 30mgL−1 methyl orange at pH 5.0. Also, luffa peroxidase yielded a maximum decolourisation efficiency of 75.3% under the conditions of 40min at 40°C using 2mM hydrogen peroxide, 1.5mL crude luffa peroxidase and 10mgL−1 methyl orange at pH 3.0.

Experimental investigation, modeling, and optimization of combined electro-(fenton/coagulation/flotation) process: design of experiments and artificial intelligence systems

In this study, a combined electro-(Fenton/coagulation/flotation) (EF/EC/El) process was studied via degradation of Disperse Orange 25 (DO25) organic dye as a case study. Influences of seven operational parameters on the dye removal efficiency (DR%) were measured: initial pH of the solution (pH0), applied voltage between the anode and cathode (V), initial ferrous ion concentration (CFe), initial hydrogen peroxide concentration (CH2O2), initial DO25 concentration (C0), applied aeration flow rate (FAir), and process time (tP). Combined design of experiments (DOE) was applied, and experiments were conducted in accordance with the design. The experimental data were collected in a hand-made laboratory-scaleglass cylindrical batch reactor equipped with four graphite barcathodes, an aluminum sheet anode, an aeration pump equipped with an air filter and air distributer, a 150-rpm mixer, and a DC power supply. A DR% of 98 was achieved with a pH0 of 4, V of 10, CFe of 7.5, CH2O2 of 0, C0 of 140, and FAir of 0. The data were used for modeling using normal and reduced multiple regression models (MLR & r-MLR) and artificial neural networks (ANN & r-ANN). Further statistical tests were applied to determine the models’ goodness and to compare the models. Based on statistical comparison, ANN models clearly outperformed the stepwise multiple linear regression (SMLR) models. Finally, an optimization process was carried out using a genetic algorithm (GA) over the outperformed ANN model. The optimization procedure was used to determine the optimal operating conditions of the combined process.

Heterogeneous photo Fenton-like oxidation of Procion Red MX-5B using walnut shell based green catalysts

Abstract The walnut shell based photo Fenton-like catalysts were prepared and their performances in the removal of Procion Red MX-5B in aqueous solution were investigated. The influence of several operating parameters including the catalyst loading, the initial hydrogen peroxide concentration ([H2O2]o), pH and power of UV light on the degradation and the decolorization of Procion Red MX-5B were studied. The optimum reaction conditions obtained at room temperature were 2 mM of the initial hydrogen peroxide concentration, 0.25 g/l of catalyst loading and 3 of the initial pH for an initial dye concentration of 100 ppm. Under these conditions 50% degradation and 88.3% decolorization were achieved. Iron leaching in the treated dye solution was determined as 1.98 ppm which was below the European Union limits. The toxicity which was evaluated in terms of relative root growth inhibition rate of Lepidium sativum roots was 0.6%.

Heterogeneous Fenton degradation of Orange II by immobilization of Fe3O4 nanoparticles onto Al-Fe pillared bentonite

A novel catalyst, Fe3O4 nanoparticle decorated Al-Fe pillared bentonite (Fe3O4/Al-Fe-P-B), was prepared by in situ precipitation oxidization method. The catalyst was characterized by SEM, XRD and Raman spectroscopy. The Fe3O4 nanoparticles mainly exist on the surface or enter into the pore of bentonite, with better dispersing and less coaggregation. The catalytic activity of Fe3O4/Al-Fe-P-B was investigated in the degradation of Orange II (OII) by heterogeneous Fenton-like process. The effects of initial concentration of hydrogen peroxide, catalyst loading, temperature and initial pH on the degradation of OII were investigated. The Fe3O4/Al-Fe-P-B showed higher degradation efficiency of OII than bare Fe3O4 or Al-Fe-P-B in the degradation experiment. The enhanced catalytic activity of Fe3O4/Al-Fe-P-B in heterogeneous Fenton system was due to the synergistic effect between Al-Fe-P-B and Fe3O4. The novel catalyst can achieve solid-liquid separation easily by sample magnetic separation and has a good reusability and stability.

Removal of acetaldehyde gas using wet scrubber coupled with photo-Fenton reaction

The feasibility of the combined air-cleaning method, which consisted of a wet scrubber and the photo-Fenton reaction, in the removal of gaseous acetaldehyde was evaluated. An acetaldehyde-gas removal efficiency of 99% was achieved in the one-pass test (residence time of 17 s) using an inlet acetaldehyde-gas concentration of 1000 ppb at an initial total-iron-ion concentration of 50 mg L−1 and initial hydrogen peroxide concentration of 630 mg L−1. Even at the low initial total-iron-ion concentration of 4 mg L−1, a removal efficiency of 92% was achieved. The acetaldehyde removal efficiency was relatively independent of the initial hydrogen peroxide concentration. UV irradiation further augmented the rate of the photo-Fenton reaction leading to enhanced acetaldehyde-gas removal.

Preparation of microcrystalline cellulose directly from wood under microwave radiation

The influence of the composition of solutions of peracetic acid on a change in the characteristics of cellulose during the oxidative-hydrolytic destruction of aspen and pine wood under microwave radiation was investigated. Samples of the prepared cellulose were characterized by viscometry, X-ray diffraction and IR spectroscopy. It was found that the main factor determining the rate of destruction of cellulose to a low degree of polymerization values in an acid medium at the initial concentration of peracetic acid not exceeding 15% and initial concentration of hydrogen peroxide no more than 3 mol/dm3 is the concentration of sulfuric acid. The disordering effect of microwave radiation on the crystallites of cellulose during preparation from pine wood in the presence of sulfuric acid in a concentration of 0.06 mol/dm3 and increased duration of oxidative-hydrolytic treatment from 1 to 2 h was revealed. It was shown that the characteristics of the products obtained from aspen and pine wood by oxidative-hydrolytic treatment with 15% peracetic acid under microwave radiation, the duration of the process of 1.5–2 h and the sulfuric acid concentration of 0.3–0.7 mol/dm3 correspond to partially oxidized microcrystalline cellulose.

Heterogeneous photodegradation of paracetamol using Goethite/H 2 O 2 and Goethite/oxalic acid systems under artificial and natural light

Abstract Heterogeneous photodegradation of paracetamol (PC) in the α-FeOOH (Goethite) used as a catalyst was studied in aqueous suspension up on irradiation at 365 nm and by solar light. The mechanism involves PC-Goethite system operate electron–hole pairs. The rate of photocatalytic degradation of PC is slow and follows pseudo-first order kinetics. The addition of H 2 O 2 in the previous solution leads to OH radicals formation via the Fenton system. Goethite in the presence of oxalic acid can form Goethite–oxalate complex on the surface. So under irradiation the photo-reduction of Goethite–oxalate complexes yields Fe(II) and oxalate radicals (C 2 O 4 ) − , which induces the formation of active species ( OOH\O 2 − ) leading to the Fenton reaction. The effect of catalyst loading, initial concentration of PC, hydrogen peroxide (H 2 O 2 ) and oxalic acid concentrations were determined. The optimal initial concentration of hydrogen peroxide and oxalic acid for the PC degradation with Goethite under the experimental conditions was found to be 5 × 10 −3 and 5 × 10 −4 mol L −1 respectively. The photodegradation of PC in the mixtures PC–Goethite, PC–Goethite–H 2 O 2 and PC–Goethite–oxalic acid under solar light was significantly accelerated in comparison with artificial irradiation at 365 nm.

Electrochemical Process for Diazinon Removal from Aqueous Media: Design of Experiments, Optimization, and DLLME-GC-FID Method for Diazinon Determination

In the present study, electrochemical process was studied via removal of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) as an insecticide/ acaricide organic case study. Influences of three operational parameters including initial ferrous ion concentration, initial hydrogen peroxide concentration, and initial diazinon concentration were measured and optimized in diazinon removal process. Response surface methodology (RSM) was used to design the experiments. The experimental data collected in a laboratory-scaled batch reactor equipped with four graphite bar electrodes as cathode and an aluminum sheet electrode as an anode. Quantitative analysis of diazinon was done with gas chromatography equipped with flame photometric detector. Disperse liquid–liquid microextraction was used prior to gas chromatography in order to extraction and preconcentration of diazinon from aqueous media to extraction phase. Acetone and chlorobenzene were used as disperser and extraction solvent, respectively. Maximum diazinon removal efficiency of 87% (0.85mg mass removal) in C 0 of 2mg/L and 80% (120mg mass removal) in C 0 of 300mg/L was achieved under different experimental conditions. The obtained experimental data were used for model building by RSM approach. Finally, optimization process was carried out using RSM algorithm.

Synthesis of iron/GAC catalyst for wastewater treatment using heterogeneous Fenton reaction

Iron catalyst dispersed on granular activated carbon (GAC) was prepared by impregnating Fe(NO3)3 solution on GAC. The mixed solution was annealed at 600°C in muffle furnace under ambient condition for 1 h. The structural property of the catalyst was investigated using X-ray diffraction (XRD). The catalyst’s activity and lifetime were tested using the degradation of 50 ppm methyl orange (MO) solution. In addition, the optimum conditions of the Fenton reaction such as initial pH, initial MO concentration hydrogen peroxide concentration and the amount of catalyst were also investigated. The XRD results showed that magnetite and haematite were two main compositions of the synthesized catalyst. The investigation of optimum conditions suggested that initial pH at 3 provided the highest efficiency of MO removal. In addition, the concentration of hydrogen peroxide at 8 ppm was the most suitable. The optimum condition of amount of catalyst was 5 g l−1. The efficiencies of MO removal reached 95% at 60 min of reaction time at low initial MO concentration (25–500 mg l−1). In the meantime, the removal efficiency was found to decrease with the increase in the initial MO concentration. The efficiency decreased to 70 and 30% at 1000 and 3000 mg l−1 of initial MO concentration, respectively. Additionally, after reuse the synthesized catalyst 3 times the MO removal efficiency still remained over 90%. In conclusion, the iron/GAC catalyst was successfully synthesized and applied to dye treatment using heterogeneous Fenton reaction. The catalyst showed high efficiency of MO removal and could be reused many times.