Advanced Fenton Process Research Articles

Direct Blue 71 Degradation in the Presence of ZVI and H<sub>2</sub>O<sub>2</sub> Advanced Fenton Process: Determination of Optimum Conditions and Kinetics

Direct Blue 71 Degradation in the Presence of ZVI and H<sub>2</sub>O<sub>2</sub> Advanced Fenton Process: Determination of Optimum Conditions and Kinetics

Experimental design approach for petrochemical waste water treatment using solar assisted photo Fenton process

In this study, the effect of photo-Fenton process on the treatment of petrochemical waste water treatment was investigated. The influence of process conditions were determined by factorial design. Optimization of the process conditions were performed by central composite design. Under, optimized conditions lab scale and solar assisted pilot scale of petrochemical waste water treatment was performed. Three factors namely initial pH, H2O2 concentration (mM) and Fe2+ concentration (mM) executed the essential role in petrochemical waste water treatment. Central composite design resulted in the prediction of optimized value as 6.5 initial pH, 15.65 mM of H2O2 concentration and 2.09 mM of Fe2+ concentration. Under these conditions, the reduction in chemical oxygen demand (COD) percentage reached about 68.67 ± 2.8% after 280 min in pilot scale of solar assisted photo Fenton process of petrochemical waste water treatment. Thus, experimental design combined with advanced Fenton process can become a feasible unconventional method for petrochemical waste water treatment.

Comparison of performances of hydrodynamic cavitation in combined treatments based on hybrid induced advanced Fenton process for degradation of azo-dyes

In the present work, the degradation of azo-dyes in aqueous solutions by using hydrodynamic cavitation is performed. Methyl orange was chosen as colorant model pollutant. During the experimental tests, the effect of various operating parameters on the decolourization efficiency was investigated. In the first series of experiments, the hydrodynamic cavitation was optimized in terms of operating inlet pressure and cavitation number to get the maximum decolorization yields of the dye, at the constant temperature of 20 °C and with an initial methyl orange concentration equal to 5 ppm. It was observed that there was an optimum inlet pressure value (4 bar) to get the best decolourization efficiency (about 32%). For the optimal configuration, in correspondence of 4 bar, a first order kinetic equal to 0.0054 min −1 and a value of electrical energy per order EEO of 3793.81 kW h m-3 were calculated. Subsequently, the combined effect of hydrodynamic cavitation and hydrogen peroxide on dye degradation has been studied. The efficiency of the HC-H2O2 system, under optimal conditions, was more than 50% in terms of dye decolourization. Finally, a series of experiments have been performed by combining hydrodynamic cavitation with the addition of hydrogen peroxide and metal ions (iron and nickel) in solution. The dye degradation became greater than 90%; this increase was explained by supposing that an induced advanced Fenton process has been generate thus improving the performance of the entire cavitation system.

Intensification of landfill leachate treatment by advanced Fenton process using classical and statistical approach

The intensification of complex landfill leachate treatment using advanced Fenton process (AFP) (H2O2 + Fe(II) + Ozone) was investigated with classical One Factor At a Time (OFAT) and Statistical Experimental Design (SED) approach. The Classical OFAT was employed to identify the range of operating parameters whereas SED using the Box-Behnken Design model (BBD) with Response Surface Methodology (RSM) was employed to optimise the operating parameters. In the OFAT model, the optimum dosage of operating parameter viz. Fe(II) (0.06 mol/L), H2O2 (0.6 mol/L), ozone (30 gm/m3) and pH (3) have shown COD and colour removal efficiency of 89.74% and 81.33% respectively within 120 min of reaction. Furthermore, in BBD, the optimum dosage at operating parameter viz. Fe(II) (0.06 mol/L), H2O2 (0.55 mol/L), ozone (25 gm/m3) and pH (3) have shown COD and colour removal efficiency of 89.74% and 82.9% respectively. SED model also confirms the correlation between factors and their responses in line with OFAT. The present intensification approach has helped to achieve efficient way for complex landfill leachate treatment compared to other published studies.

Mineralization of N‐Methyl‐2‐Pyrrolidone by UV‐Assisted Advanced Fenton Process in a Three‐Phase Fluidized Bed Reactor

N‐Methyl‐2‐pyrrolidone (NMP), a commonly used solvent in industries, is treated with zero‐valent iron (Fe0) and hydrogen peroxide (H2O2) under UV irradiation. The reaction is carried out in a three‐phase fluidized bed reactor to ensure the smooth and continuous circulation of the Fe0 powder. The results reveal that NMP can be efficiently mineralized by UV‐assisted Fe0/H2O2 process (advanced photo‐Fenton process) with aeration. The mineralization process is properly fitted with the pseudo‐first order kinetics (R2 > 0.93). To determine the optimum conditions for NMP mineralization, the effects of pH, Fe0 dosage, H2O2 concentration, and initial NMP concentration are investigated. Addition of 0.05 g L−1 Fe0 and 0.1 M H2O2 yields 85.2% total organic carbon removal of NMP (10 mM) in 6 h at pH 4.0 ± 0.2. To explore the changes of the nitrogen species, released NO2−, NO3−, and NH4+ are also monitored during the reaction. The present study provides an effective method for the mineralization of NMP‐containing wastewater.

Heterogeneous Sono-Fenton treatment of decabromodiphenyl ether (BDE-209): Debromination mechanism and transformation pathways

Polybrominated diphenyl ethers, used as flame retardants are a cause of concern over past several years, due to their toxicity, bioaccumulation and widespread distribution. In this work, the combination of ultrasound and advanced Fenton process was investigated for the degradation of Decabromodiphenyl ether (BDE-209). The effect of pollutant concentration, solution pH, ultrasonic power density and loading of Fenton’s reagent on the extent of BDE-209 degradation were studied. The results indicated an enhancement in the degradation of BDE-209 during Sono-Fenton treatment, leading to a complete degradation within 80 min of treatment, whereas only 40% and 25% degradation were achieved during ultrasound and Fenton treatment alone. To understand the degradation mechanism, analytical techniques including High performance liquid chromatography and Gas chromatography mass spectroscopy were employed to monitor the concentrations of parent compound along with degradation products. The degradation mechanism was proposed based on the identified degradation products. Total organic carbon (TOC) analysis demonstrated 60% TOC removal within 80 min of treatment. The obtained results suggest that the initiation of BDE-209 degradation during Sono-Fenton treatment followed thermal decomposition at bubble-vapor interface along with reductive debromination at iron surface, accompanied by oxidative degradation of lower brominated congeners at liquid bulk. This work illustrated an effective method for the removal of BDE-209 and hence providing an efficient wastewater treatment solution for recalcitrant pollutants.

Removal of COD from landfill leachate by advanced Fenton process combined with electrolysis

Zero-valent iron (ZVI) was used as the iron source for the advanced Fenton treatment of landfill leachate in an electrochemical cell. In this process, Fe0 was dissolved from the surface of ZVI powder and then the generated Fe2+ would activate the added H2O2 to produce hydroxyl radical (OH), which is a strong oxidant and can lead to the removal of COD from landfill leachate. The effect of initial pH, H2O2 dosage, Fe0 dosage, current density and inter-electrode gap on the COD removal of landfill leachate was investigated. The results indicate that COD removal followed pseudo-second order kinetic model. The rate constant and efficiency of COD removal increased with Fe0 dosage being increased from 0.524 to 1.745 g/L, but decreased when initial pH rose from 2 to 4. The optimal conditions of H2O2 dosage, current density and inter-electrode gap were determined to be 0.187 mol/L, 20.6 mA/cm2 and 1.8 cm, respectively. The humic acid-like organics in the leachate were effectively degraded and over 70% of COD could be removed from the leachate, showing high efficiency of the electro-advanced Fenton process.

Laboratory-scale study of the advanced Fenton process for silica removal from brackish underground water in arid areas in Saudi Arabia

Laboratory-scale study of the advanced Fenton process for silica removal from brackish underground water in arid areas in Saudi Arabia

Removal of selenite by zero-valent iron combined with ultrasound: Se(IV) concentration changes, Se(VI) generation, and reaction mechanism

In this paper, the performance and application of zero-valent iron (ZVI) assisted by ultrasonic irradiation for the removal of selenite (Se(IV)) in wastewater was evaluated and reaction mechanism of Se(IV) with ZVI in such systems was investigated. A series of batch experiments were conducted to determine the effects of ultrasound power, pH, ZVI concentration, N2 and air on Se(IV) removal. ZVI before and after reaction with Se(IV) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ultrasound can lead to a significant synergy in the removal of Se(IV) by ZVI because ultrasound can promote the generation of OH and accelerate the advanced Fenton process. The primary reaction products of ZVI and Se(IV) were Se0, ferrihydrite, and Fe2O3.

Hydrometallurgical recovery of heavy metals from low grade automobile shredder residue (ASR): An application of advanced Fenton process (AFP)

To investigate the leaching and recovery of heavy metals from low-grade automobile shredder residue (ASR), the effects of nitric acid (HNO3) and hydrogen peroxide (H2O2) concentrations, liquid/solid (L/S) ratio, leaching temperature and ASR particle size fractions on the heavy metal leaching rate were determined. The heavy metals were recovered by fractional precipitation and advanced Fenton process (AFP) at different pHs. The toxicity characteristic leaching procedure (TCLP) test was also performed in the residue remaining after heavy metal leaching to evaluate the potential toxicity of ASR. The heavy metal leaching efficiency was increased with increasing HNO3 and H2O2 concentrations, L/S ratio and temperature. The heavy metal leaching efficiencies were maximized in the lowest ASR size fraction at 303 K and L/S ratio of 100 mL/g. The kinetic study showed that the metal leaching was best represented by a second-order reaction model, with a value of R2 > 0.99 for all selected heavy metals. The determined activation energy (kJ/mol) was 21.61, 17.10, 12.15, 34.50, 13.07 and 11.45 for Zn, Fe, Ni, Pb, Cd and Cr, respectively. In the final residue, the concentrations of Cd, Cr and Pb were under their threshold limits in all ASR size fractions. Hydrometallurgical metal recovery was greatly increased by AFP up to 99.96% for Zn, 99.97% for Fe, 95.62% for Ni, 99.62% for Pb, 94.11% for Cd and 96.79% for Cr. AFP is highly recommended for the recovery of leached metals from solution even at low concentrations.

Phenol degradation by advanced Fenton process in combination with ultrasonic irradiation

In this study, a successful degradation of phenol was achieved by means of coupling nano-sized zero-valent iron (NZVI), H2O2 and 20kHz ultrasound irradiation. The effect of H2O2 concentration, initial pH, ultrasonic irradiation time and NZVI addition on the degradation efficiency was investigated and the kinetics of the process was discussed. The results showed that the degradation rate increased by increasing the H2O2 concentration and the irradiation time but decreased with the increase of the initial pH value. These results clearly indicate that the degradation of phenol is intensified in the presence of NZVI and H2O2, which can be attributed to enhanced production of OH radicals in the system. The degradation rate in the presence of NZVI was faster than in its absence. Thus, an appropriate selection of operating conditions will lead to an economical and highly efficient technology with eventual large-scale commercial applications for the degradation of organic pollutants in aqueous effluents.

Application of Fe0 aggregate in ultrasound enhanced advanced Fenton process for decolorization of methylene blue

A successful decolorization of methylene blue (MB) was achieved through advanced Fenton's process (AFP) coupled with sonolysis (sono-AFP) using zero-valent iron (Fe0) aggregate as a catalyst. The decolorization was dependent on the pH, Fe0, H2O2 doses, and acoustic power. Fe0 aggregate was reusable. A modified pseudo-first order equation was developed to describe the decolorization kinetics. To save electricity, short ultrasound irradiation was applied to the system. MB was completely degraded in the sono-AFP under optimized condition. The decolorization was obviously inhibited by the presence of Cl−, but it was unaffected by the presence of H2CO3, H2PO4−, ClO4−, NO3−, and SO42−

Zero valent iron (ZVI) mediated Fenton degradation of industrial wastewater: Treatment performance and characterization of final composites

A heterogeneous advanced Fenton process (AFP) based on the use of zero valent iron (ZVI) has been investigated for the treatment of a real industrial wastewater, generated from a drug manufacturing plant. The effluent consists of a complex mixture of organic substances which are refractory to conventional treatments. The concentration of ZVI and oxidant (H2O2) were studied. The use of moderate concentrations of oxidant and ZVI commercial catalyst led to total organic carbon (TOC) reductions of 70% and 55% of diluted (TOC0 0.1gL−1) and as-received pharmaceutical wastewater (TOC0 5gL−1), respectively, with a remarkable enhancement of the biodegradability in all cases. Apart from that, it was demonstrated a notable effect of the magnetic agitation system (speed and size of the stir bar) on the catalytic performance of the ZVI/H2O2 system. The aggregation of ZVI particles on the magnetic stir bar surface, due to its intrinsic magnetic properties makes that the availability of active ZVI particles was somewhat controlled by the size of the magnetic stir bar. For the best operation conditions, a higher TOC conversion was accomplished during the first minutes of reaction, slowing down afterwards, probably due to passivation of the ZVI catalyst. The different stratified layers of iron/hydrous oxides covering the metallic ZVI surface formed under the different reaction conditions were studied by XRD, TPR and XPS characterization techniques.

Pillared clays as catalysts for methyl parathion removal by advanced oxidation processes

Mineralisation of methyl parathion by the advanced Fenton process.

Enhancement of the advanced Fenton process by weak magnetic field for the degradation of 4-nitrophenol

A superimposed WMF could significantly improve the oxidative ability of Fe0/H2O2 and widen its applicable pH range.

Decontamination of unsymmetrical dimethylhydrazine waste water by hydrodynamic cavitation-induced advanced Fenton process

A pilot scale hydrodynamic cavitation (HC) reactor, using iron metal blades, as the heterogeneous catalyst, with no external source of H2O2 was developed for catalytic decontamination of unsymmetrical dimethylhydrazine (UDMH) waste water. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The effects of the applied catalyst, pH of the initial solution (1.0–9.7), initial UDMH concentration (2–15mg/l), inlet pressure (5.5–7.8bar), and downstream pressure (2–6bar), have been investigated. The results showed that the highest cavitation yield can be obtained at pH 3 and initial UDMH concentration of 10mg/l. Also, an increase in the inlet pressure would lead to an increase in the extent of UDMH degradation. In addition, the optimum value of 3bar was determined for the downstream pressure that resulted to 98.6% degradation of UDMH after 120min of processing time. Neither n-nitrosodimethylamine (NDMA) nor any other toxic byproduct (/end-product) was observed in the investigated samples. Formic acid and acetic acid, as well as nitromethane, were identified as oxidation by-products. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton’s chemistry can be effectively used for the degradation of UDMH.

Degradation of imidacloprid containing wastewaters using ultrasound based treatment strategies

The present work deals with application of sonochemical reactors for the treatment of imidacloprid containing wastewaters either individually or in combination with other advanced oxidation processes. Experiments have been performed using two different configurations of sonochemical reactors viz. ultrasonic horn (20kHz frequency and rated power of 240W) and ultrasonic bath equipped with radially vibrating horn (25kHz frequency and 1kW rated power). The work also investigates the effect of addition of process intensifying agents such as H2O2 and CuO, which can enhance the production of free radicals in the system. The combination studies with advanced oxidation process involve the advanced Fenton process and combination of ultrasound with UV based oxidation. The extent of degradation obtained using combination of US and H2O2 at optimum loading of H2O2 was found to be 92.7% whereas 96.5% degradation of imidacloprid was achieved using the combination of US and advanced Fenton process. The process involving the combination of US, UV and H2O2 was found to be the best treatment approach where complete degradation of imidacloprid was obtained with 79% TOC removal. It has been established that the use of cavitation in combination with different oxidation processes can be effectively used for the treatment of imidacloprid containing wastewater.

Degradation of imidacloprid using combined advanced oxidation processes based on hydrodynamic cavitation

The harmful effects of wastewaters containing pesticides or insecticides on human and aquatic life impart the need of effectively treating the wastewater streams containing these contaminants. In the present work, hydrodynamic cavitation reactors have been applied for the degradation of imidacloprid with process intensification studies based on different additives and combination with other similar processes. Effect of different operating parameters viz. concentration (20–60ppm), pressure (1–8bar), temperature (34°C, 39°C and 42°C) and initial pH (2.5–8.3) has been investigated initially using orifice plate as cavitating device. It has been observed that 23.85% degradation of imidacloprid is obtained at optimized set of operating parameters. The efficacy of different process intensifying approaches based on the use of hydrogen peroxide (20–80ppm), Fenton’s reagent (H2O2:FeSO4 ratio as 1:1, 1:2, 2:1, 2:2, 4:1 and 4:2), advanced Fenton process (H2O2:Iron Powder ratio as 1:1, 2:1 and 4:1) and combination of Na2S2O8 and FeSO4 (FeSO4:Na2S2O8 ratio as 1:1, 1:2, 1:3 and 1:4) on the extent of degradation has been investigated. It was observed that near complete degradation of imidacloprid was achieved in all the cases at optimized values of process intensifying parameters. The time required for complete degradation of imidacloprid for approach based on hydrogen peroxide was 120min where as for the Fenton and advance Fenton process, the required time was only 60min. To check the effectiveness of hydrodynamic cavitation with different cavitating devices, few experiments were also performed with the help of slit venturi as a cavitating device at already optimized values of parameters. The present work has conclusively established that combined processes based on hydrodynamic cavitation can be effectively used for complete degradation of imidacloprid.

Treatment of steam-assisted gravity drainage water using low coagulant dose and Fenton oxidation

The use of coagulation and Fenton oxidation was studied for total organic carbon (TOC) and silica removal from steam-assisted gravity drainage (SAGD) water at 80°C and two different concentrations replicating the stream feeding the warm lime softening unit having 675 mg/L TOC and 350 mg/L silica and the blowdown of the once through steam generator having 3700 mg/L TOC and 2585 mg/L silica. Coagulation was carried out by the addition of FeCl3, Al(NO3)3 or Ca(NO3)2. The results showed that Fe(III) salt outperformed Al(III) and Ca(II) salts. A two-stage addition of 2.5 g FeCl3 per g TOC intermediated by a filtration unit resulted in approximately 72% TOC removal and more than 80% silica removal while maintaining low solid waste. Comparing results pertaining to coagulant concentration and final pH, it can be easily concluded that silica removal is governed by the resultant pH, whereas TOC removal was accomplished through surface neutralization and localized enmeshment coagulation. Fenton oxidation is proposed to further treat the filtrate obtained from the second stage Fe(III) coagulation. An additional 10% TOC removal could be achieved; at seven times lower H2O2 dose in the presence of Fe 2+ or Fe0 reagent. Moreover, the advanced Fenton process resulted in high silica removal as a result of adsorption onto Fe(OH)3 precipitate, which formed at the equilibrium pH of the system.

Enhancement of the advanced Fenton process by ultrasound for decolorisation of real textile wastewater

Successful decolorisation of real textile wastewater was achieved by means of the advanced Fenton process in conjunction with ultrasound technology. A synergy factor of 6.9 for this combined method was determined. The decolorisation followed zero‐order kinetics, and the rate increased with increasing zero‐valent iron dose and decreasing pH and hydrogen peroxide concentration. The optimum conditions for an American Dye Manufacturers Institute decolorisation value of 1638 ADMI was found to be a pH of 3.0, an ultrasound frequency of 47 kHz, a zero‐valent iron dose of 1.0 g l−1, and a hydrogen peroxide concentration of 1.03 × 10−2 m. Under these conditions, the estimated operating cost to decolorise 96% true colour was estimated to be $US 4.51 m−3. The study demonstrated that the given combined method could be applied to decolorise textile wastewaters.