Initial H2O2 Concentration Research Articles

Heterogeneous Photo-Fenton Degradation of Azo Dyes over a Magnetite-Based Catalyst: Kinetic and Thermodynamic Studies

Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the azo dyes Acid Red 18 (AR18), Acid Red 66 (AR66), and Orange 2 (OR2) using magnetite as a catalyst. The magnetic catalyst was synthesized via a hydrothermal process at 150 °C. Experiments were conducted at room temperature, investigating the effect of catalyst dosage, pH, and initial concentrations of H2O2 and AR18 dye. Kinetic and thermodynamic studies were performed at 25, 40, and 60 °C for the three azo dyes (AR18, AR66, and OR2) and the effect of the dye structures on the degradation efficiency was investigated. At 25 °C for 0.33 mmolL−1 of dye at pH 3.0, using 1.4 gL−1 of the catalyst and 60 mgL−1 of H2O2 under UV radiation of 16.7 mWcm−2, the catalyst showed 62.3% degradation for AR18, 79.6% for AR66, and 83.8% for OR2 in 180 min of reaction. The oxidation of azo dyes under these conditions is spontaneous and endothermic. The pseudo-first-order kinetic constants indicated a strong temperature dependence with an order of reactivity of the type OR2 > AR66 > AR18, which is associated with the molecular size, steric hindrance, aromatic conjugation, electrostatic repulsion, and nature of the acid–base interactions on the catalytic surface.

Construction of heterojunction superparamagnetic Cd0.5Ag0.5Fe2O4 nanocomposite photocatalyst for simulated textile effluent oxidation

Abstract Significant attempts have been recently made regarding nanomaterials due to their several environmental applications especially in wastewater treatment technologies. Among the available nanoparticles, ferrite based substances are gaining a special interest since their superior characteristics such as their magnetic nature, high adsorption capacity and large specific surface area. In this regard, Cd0.5Ag0.5Fe2O4 was prepared using the green simple co-precipitation route. Then, the sample is characterized via Scanning Electron Microscopy (SEM) that proved the produced material’s surface morphology. The substance is then employed as a catalyst source for Fenton reaction to oxidize textile effluent solution containing Rhodamine B (Rh-B 6G) dye. The oxidation experiment conducted under ultraviolet (UV) light with the ferrite-based Fenton catalyst supplemented with hydrogen peroxide showed an exceptional removal rate of up to 94% removals. Notably, the oxidation system is significantly impacted by the operational variables. The oxidation efficiency of the dye was maximized at pH 3.0 and 50 mg/L and 1600 mg/L for ferrite-based Fenton catalyst and H2O2, respectively. The impacts of the operational factors, i.e. initial pH value, initial dye concentration, catalyst, and H2O2 concentrations were also investigated. This perspective introduces the role of a superparamagnetic material to be a recyclable sustained catalyst.

Box-Behnken Design for Photocatalytic Degradation of Sudan Black B by Catalyst-Embedded Multiwalled Carbon Nanotubes

This research employs a Box Behnken design-based technique for photocatalytic use of Multiwalled Carbon Nanotubes (MWCNTs) derived from spray pyrolysis. This procedure was used for photocatalytic degradation applications on Sudan black dye using Citrus limonum oil as a carbon precursor and Fe/Co/Mo supported on silica as a catalyst. The influence of initial dye concentration was compared to the effects of H2O2, catalyst concentration and solar light intensity. The Response Surface Methodology was used to optimize growth parameters for higher yield and graphitization. The as-grown CNTs were exemplified using scanning and transmission electron microscopy and Raman spectroscopy. This work resulted in the identification of the optimal set of spray pyrolysis turning parameters for achieving high CNT yield and effective decolorization of Sudan black B dye by employing MWCNTs as catalyst. The degree of decolorization of Sudan black B dye increases upto a certain level with an increase in initial H2O2 concentration and subsequently declines as excess H2O2 hydroxyl radicals formed serve as scavengers, resulting in less dye decolonization.

Investigating the Efficiency of Photo-Fenton (UV/H2O2/Fe2+) in Removing the Indomethacin Antibiotic From Aqueous Solutions

Water pollution caused by antibiotics is one of the major challenges in the world today. The current research aims to investigate the effect of the Photo-Fenton process in removing indomethacin antibiotics from aqueous solutions. This experiment-based study was conducted on a laboratory scale and discontinuous manner. The influential variables affecting the removal efficiency of indomethacin include initial antibiotic concentration, pH, time, hydrogen peroxide concentration, and iron ion. The study was conducted base on standard methods (APHA, AWWA, CFWP, 2005). The Design Expert software was used to analyze the effect of independent variables on the removal efficiency of indomethacin antibiotics in the Photo-Fenton process (UV/H2O2/Fe2+) using response surface methodology (RSM) and central composite design (CCD). To ensure the repeatability of the results, each experiment was repeated three times and the reported the average. The results showed that the optimal removal conditions for indomethacin antibiotics were pH = 4, H2O2 oxidant concentration = 50 ppm, Fe2+catalyst concentration = 50 ppm, time = 75 minutes, and initial antibiotic concentration = 20 ppm, with a removal efficiency of 91.03% . The variables of initial antibiotic concentration, H2O2 concentration, and pH had the greatest impact on the removal efficiency of indomethacin. The results of this study indicate that under optimal conditions, more than 90% of indomethacin antibiotics can be removed from aqueous solutions using the Photo-Fenton process, which is a significant result for removing this pharmaceutical pollutant from aquatic environments.

Quenching residual H2O2 from UV/H2O2 with granular activated carbon: A significant impact of bicarbonate

UV/H2O2 has been used as an advanced oxidation process to remove organic micropollutants from drinking water. It is essential to quench residual H2O2 to prevent increased chlorine demand during chlorination/chloramination and within distribution systems. Granular activated carbon (GAC) filter can quench the residual oxidant and eliminate some of the dissolved organic matter. However, knowledge on the kinetics and governing factors of GAC quenching of residual H2O2 from UV/H2O2 and the mechanism underlying the enhancement of the process by HCO3− is limited. Therefore, this study aimed to analyse the kinetics and influential factors, particularly the significant impact of bicarbonate (HCO3−). H2O2 decomposition by GAC followed first-order kinetics, and the rate constants normalised by the GAC dosage (kn) were steady (1.6 × 10−3 L g−1 min−1) with variations in the GAC dosage and initial H2O2 concentration. Alkaline conditions favour H2O2 quenching. The content of basic groups exhibited a stronger correlation with the efficiency of GAC in quenching H₂O₂ than did the acidic groups， with their specific kn values being 8.9 and 2.4 min−1 M−1, respectively. The presence of chloride, sulfate, nitrate, and dissolved organic matter inhibited H2O2 quenching, while HCO3− promoted it. The interfacial hydroxyl radical (HO•) zones were visualised on the GAC surface, and HCO3− addition increased the HO• concentration. HCO3− increased the concentration of persistent free radicals (PFRs) on the GAC surface, which mainly contributed to HO• generation. A significant enhancement of HCO3− on H2O2 quenching by GAC was also verified in real water. This study revealed the synergistic mechanism of HCO3− and GAC on H2O2 quenching and presents the potential applications of residual H2O2 in the H2O2-based oxidation processes.

Water disinfection using hydrogen peroxide with fixed bed hematite catalyst - kinetic and activity studies.

A lab-scale reactor with a fixed-bed hematite catalyst for the effective decomposition of H2O2 and bacteria inactivation was designed. The bactericidal effect is the largest at a low initial bacterial count of 2·103CFU/L, which is typical for natural surface waters. When using a 5mM H2O2 solution and a residence time of 104min, the reduction in the number of E. coli bacteria is about 3.5-log. At a higher initial bacterial count of 1-2·104CFU/L, a 5mM H2O2 solution reduces the bacteria number by about 4-log. The H2O2 decomposition follows the log-linear kinetics of a first-order reaction while the bacterial inactivation does not. The kinetics of bacterial inactivation was described using the Weibull model in the modified form: log10(N0/N) =b · tn. The values of the non-linearity parameter n were found to be lower than 1, indicating that bacterial inactivation slows down over time. With increasing initial H2O2 concentration, the rate parameter b increases while the non-linearity parameter n decreases. With increasing temperature, both parameters increase. The stability of the catalyst has been proved by XRD, FTIR, SEM, and ICP-OES. The concentration of iron leaching into water during disinfection is much lower than the limit declared by WHO for iron in drinking water. The results show that technical-grade hematite is a promising Fenton-like catalyst for water disinfection. The fixed-bed reactor can be the basis of the mobile installations for water purification in emergencies.

Treatment of Coking Wastewater Using Hydrodynamic Cavitation Coupled with Fenton Oxidation Process.

Effective and economical processes for the advanced treatment of coking wastewater were urgently needed to reduce the persistent organic pollutants of external drainage. In the present work, we investigated the degradation of organic pollutants in coking wastewater through IHC/FO (imping stream hydrodynamic cavitation (IHC) coupled with the Fenton oxidation (FO) process) and IHC alone for their feasibility in the advanced treatment of coking wastewater. To select the optimum parameters, attention was paid to the effects of main operation conditions including inlet fluid pressure, medium temperature, initial pH, reaction time, and initial Fe(II) and initial H2O2 concentrations. The results showed that the effects of conditions that need energy to be maintained (such as initial pH and inlet pressure) on the organic pollutant removal efficiency through IHC/FO were less pronounced than those through IHC alone. Moreover, the application of IHC/FO could remove more organic pollutants from coking wastewater than IHC even at an energy-efficient condition. For example, the highest COD removal efficiency of 12.5% was achieved in the IHC treatment at 0.4 MPa, pH 3, and 60 min for the reaction time. In the case of IHC/FO, the maximum COD removal of 33.2% was obtained at pH 7, 0.1 MPa, 12 mmol/L H2O2, and 3 mmol/L Fe2+ after reacting for 15 min. The ultraviolet and visible spectrophotometry (UV-Vis) absorption spectra and gas chromatography and mass spectrometry (GC-MS) analysis further revealed that the kinds and amounts of pollutants (especially those that had benzenes) remaining in water treated through IHC/FO were much fewer and smaller than in water treated through IHC alone. The better performances of IHC/FO than IHC alone were likely related to the more hydroxyl radicals produced through IHC/FO. Taken together, our findings indicate that IHC/FO has great application potential in the advanced treatment of coking wastewater.

Prediction of doxycycline removal by photo-fenton process using an artificial neural network - multilayer perceptron model

This paper presents a study on the effectiveness of the Photo-Fenton Process (PF) for removing the doxycycline hyclate (DXC) antibiotic. The experiment showed that the best removal efficiency was achieved (79%) at pH 3 for 2.5 mg/L of DXC, 76.53 mg/L of H2O2, and 86.8 mg/L of Fe2+. The degradation mechanism of DXC by hydroxyl radicals was confirmed by FTIR and HPLC. To model the oxidation reaction of DXC by PF, an multilayer perceptron (MLP) based optimized artificial neural network (OANN) was used, taking into account experimental data such as pH and initial concentrations of DXC, H2O2, and Fe2+. The OANNN predicted removal efficiency results were in close agreement with experimental results, with an RMSE of 0.0661 and an R2 value of 0.99998. The sensitivity analysis revealed that all studied inputs significantly impacted the transformation of DXC.

Ibuprofen Degradation from Synthetic Wastewater Using Photo-Fenton Process

The removal of Ibuprofen antibiotics (IBU) by photo-degradation UV/H2O2/Fe+2 system was investigated in a batch reactor under different initial concentrations of H2O2 (100-500) mg/L, Fe+2 (10-40) mg/L, pH (3-9) and initial concentrations of IBU (10-80) mg/L, and their relationship with the degradation efficiency were studied. The result demonstrated that the maximum elimination of IBU was 85.54% achieved at 300 mg/L of H2O2, 30 mg/L of Fe+2, pH=3, and irradiation time of 150 min, for 10 mg/L of IBU. The results have shown that the oxidation reagent H2O2 plays a very important role in IBU degradation.

Ofloxacin degradation in water and porous media: Synergy effects via hydrogen peroxide activation by a micro electrolytic iron-carbon composite

Ofloxacin (OFL) may cause potential ecological risks since it cannot be effectively removed by conventional biological degradation. The advanced oxidation process is an efficient approach for antibiotic removal. Herein, a heterogeneous system for hydrogen peroxide (H2O2) activation by nanoscale zero-valent iron (nZVI) supported on powdered activated carbon (PAC) composite (nZVI@PAC) was proposed to proceed with the removal of OFL. Typically, OFL (25 mg/L) can be removed up to 94.7 % within 60 min ([H2O2] = 10 mM, [nZVI@PAC] = 125 mg/L, pH = 6, T = 318 K). The effects of initial OFL concentration, pH, nZVI@PAC dosage, H2O2 concentration, and different actual water matrices were examined to explore the application conditions and resistance of the nZVI@PAC/H2O2 system. Meanwhile, the quenching experiment, PMSO probe experiment, and EPR results showed •OH and FeIVO were the dominant reactive species in the system. Moreover, a sensible mechanism for OFL removal was proposed that nZVI@PAC aggregates OFL on its surface by adsorption, and then persistent free radicals (PFRs) and nZVI on the PAC degrade OFL by activating H2O2 to produce •OH and FeIVO. Furthermore, the effect of micro-electronic iron-carbon composite was proved by electrochemical experiments and density functional theory (DFT) calculations. Moreover, the degradation pathway of OFL in the nZVI@PAC/H2O2 system and the toxicity assessment of intermediates were also given. Meanwhile, sequential runs and continuous flow column experiments showed nZVI@PAC/H2O2 system had high stability. This work provides an innovative strategy of an advanced oxidation process based on heterogeneous reactions for organic contaminants removal using metal–carbon catalysts.

Degradation of reactive red 198 dye from aqueous solutions by combined technology advanced sonofenton with zero valent iron: Characteristics/ effect of parameters/kinetic studies

Dyes are one of the most common contaminants in industrial effluents, whose continuous release into the environment has become an increasing global concern. In this work, nanoparticles of zero-valent iron (NZVI) were synthesized using the chemical regeneration method ،and were utilized for the first time as a catalyst in the advanced Sono-Nano-Fenton hybrid method for the decomposition of Reactive Red 198 (RR198). The properties of zero-valent iron nanoparticles were analyzed using SEM and XRD. The effect of pH, initial dye concentration, nanoparticle dosage, zero-valent iron and H2O2 concentration on the decomposition efficiency of Red Reactive 198 was investigated. Comparing the efficiency of Reactivate 198 dye degradation in Sonolysis, Sono-NZVI, Sono-H2O2 and Sono-Nano Fenton processes showed that 97 % efficiency was achieved by the Sono-Nano Fenton process in 60 min. The kinetics of the removal process showed that this process follows pseudo-first-order kinetics and the Langmuir-Hinshelwood model. The results indicate that the effectiveness of the ultrasonic process in removing resistant organic pollutants such as dyes increases tremendously with the synergy of the Fenton process.

Rare earth dissolution from polishing powder waste in H2O2-H2SO4 system: Condition optimization and leaching mechanism

Recycling high-grade rare earth polishing powder waste (REPPW) is crucial for protecting the environment and sustainable utilization of rare earth resources. Leaching REPPW in the eco-friendly H2O2-H2SO4 suffers from the lack of understanding of the leaching mechanism. Here, the leaching mechanism was investigated under the optimal leaching conditions, i.e., T = 353 K, L/S ratio = 40 mL/g, H2SO4 concentration = 4 mol/L and initial H2O2 concentration = 0.8 mol/L, by which leaching efficiency of Ce and La reached 99.3% and 99.1%, respectively. Furthermore, pseudo steady state kinetic analysis suggested a five-step leaching mechanism involving CeO2 hydroxylation, H2O2-CeO2 coordination, ≡CeIII−H2O2 deprotonation, ≡CeIV−HO2− reduction and ≡CeIII−HO2∗ protonation, which was verified by the agreement between experimental data and the proposed reaction model. This work proposes a leaching mechanism of REPPW and would help develop an effective and sustainable recycling process for rare earth secondary resources.

Green synthesis of magnetic biochars derived from biobased orange peel materials as sustainable heterogeneous catalytic supports for the Fenton process

In this work, two magnetite-biochar composite materials obtained via hydrothermal and co-precipitation methods to degrade dyes were evaluated. The two composite materials alongside their biochar precursor were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Raman spectroscopy and N2 adsorption–desorption studies. Results of characterization showed a change in the amorphous structure of the biochar to a crystalline form after modification by both methods, the incorporation of magnetic particles into the carbonaceous matrix of the biochar precursor. In addition, the effect of solution pH, initial dye concentration H2O2 concentration, mass of composite material and the time of stirring on dye degradation were analysed by the response surface methodology. Both materials demonstrate appreciable stability over repeated cycles and more interestingly, Fe3O4-BC2 retains its catalytic efficiency much more than Fe3O4-BC1. Statistical analysis of the degradation results by ANOVA revealed a good correlation between the five parameters and the expected response with coefficients of correlation very close to unity. The degradation of reactive red-198 in the presence of both materials is best described by the second order kinetic rate law.

Facile synthesis of Co, Fe-bimetallic MIL-88A/microcrystalline cellulose composites for efficient adsorptive and photo-Fenton degradation of RhB dye

Photo-Fenton technology is effective in treatment of dye containing effluents in water under visible light illumination. The present article reports fabrication of a considerably efficient photo-Fenton catalytic system, the Co, Fe-MIL88/MCC composite, by a mild hydrothermal method. The composite containing bimetals Co2+/Co3+ and Fe2+/Fe3+ ions with coordination environments used as activators of H2O2-assited visible light photo-Fenton degradation of RhB. The effects of initial pH, catalyst dosage and H2O2 concentration on RhB decomposition were explored. Nearly 87% of RhB molecule was removed within 100 min in the Co, Fe-MIL88/MCC/H2O2/Visible system ana maintain the recyclability rate of more than 82.2% after five successive cycles. The photoinduced •O2− and •OH plays a major role in efficient removal of RhB. The excellent catalytic performance of the composite can be credited to the proficient electrons transfer by Fe2+/Fe3+ and Co2+/Co3+ redox cycles, activation of H2O2 by photoexcited electrons to generate •OH. As well, the optimal Co, Fe-MIL88 (Co/Fe in ratio 1/2 wt%)/MCC composite exhibited good recyclability and stability.

Application of UVC-LED/H2O2 in wastewater treatments: treatment efficacy on disinfection byproduct precursors and micropollutants

The applications of advanced oxidation processes (AOPs) for controlling microcontaminants are essential to meet the water quality criteria for potable or nonpotable water reuses. The objective of this study is to demonstrate the application of light emitting diode (LED) as a possible light source to substitute traditional low-pressure mercury lamp (LPUV) in UV/H2O2 processes in treating precursors of disinfection byproducts (DBPs) and pharmaceutical and personals care products (PPCPs) in wastewater. The results of this study revealed that UV fluence plays the most crucial role in the efficiency of UV/H2O2. At the same time, the initial concentration of H2O2, dissolved organic carbon (DOC), and turbidity had minimal effects, except that poor efficiency result of UV/H2O2 was observed at a solution with low DOC concentration (2.4 mg L−1). Although the concentrations of organic matter decreased after UV/H2O2 treatment, the concentration of precursors of DBPs increased in the early stage of the photolysis process and decreased after that; moreover, the profiles of precursors for trihalomethanes and haloacetic acids were different. A comparison between LPUV and UVC-LED as light sources revealed that, at a fixed UV fluence input into the UV/H2O2 process, the trends and efficiencies in the degradation of organic matter and DBP precursors were similar. Meanwhile, the photoelectric conversion efficiency of UVC-LED should be improved for future applications in water treatment. Based on the UV/H2O2 treatment results on synthetic PPCPs wastewater solution, this study showed the effectiveness of UV/H2O2 to degrade micro organic contaminants.

Evaluation of basalt powder as a natural heterogeneous catalyst in photo-Fenton like treatment of atrazine

Basalt powder was employed to degrade atrazine (ATZ) under ultra-violet (UV-C) and visible light (vis) irradiation. The characterization of clay catalyst samples was confirmed the presence of ferrous oxide responsible of the heterogeneous photo-Fenton like reactions. Initial tests, using an ATZ concentration of 20 mg L−1 and raw basalt (B-R) form, validated the photo-Fenton like process as the most efficient. The optimal conditions were identified to be: an initial pH of approximately 6, basalt sintered at 600 °C (B-600) with dosage of 0.5 g L−1 under UV-C and 0.75 g L−1 under vis, and initial H2O2 concentration of 1.6 mM. Consequently, ATZ removal (initially at 5 mg L−1) was measured at 96.0% and 55.8% under UV-C and vis light, respectively, after 180 min of irradiation, with reusability of three cycles. The efficiency of the photo-Fenton process was further investigated by monitoring the toxicity bioassays of growth bacteria inhibition and phytotoxicity of the treated solutions. The results indicated that, under both UV and Vis irradiation, even with high ATZ removal efficiency, the toxicity of the process effluent is less than the initial sample. The initial degradation products were determined by high performance liquid chromatography (HPLC), and ATZ degradation pathway in the photo-Fenton like system was proposed, in which the reaction is primarily initiated by alkylic oxidation. Finally, the reaction’s inhibition upon addition of isopropanol and chloroform as scavengers emphasized the significant role of hydroxyl radicals over superoxide in the oxidation of ATZ.

Synergistic effects of layered Ti3C2TX MXene/MIL-101(Cr) heterostructure as a sonocatalyst for efficient degradation of sulfadiazine and acetaminophen in water

In this work, different mass loadings of MXene-coupled MIL-101(Cr) (MXe/MIL-101(Cr)) nanocomposites were generated through a hydrothermal process in order to investigate the potential of this nanocomposite as a novel sonocatalyst for the elimination of sulfadiazine (SD) and acetaminophen (AAP) in aqueous media. The sonocatalytic activity of different MXe/MIL-101(Cr) compositions and surface functionalities was investigated. In addition, the sonocatalytic activities at various pH values, temperatures, pollutant concentrations, catalyst dosages, initial H2O2 concentrations, and organic matter contents were investigated. The experiments on the sonocatalytic elimination of SD and AAP revealed that MXe/MIL-101(Cr) exhibited a catalytic efficiency of ∼ 98% in 80 min when the MXene loading was 30 wt% in the nanocomposite. Under optimized reaction conditions, the degradation efficiency of MXe/MIL-101(Cr) reached 91.5% for SD and 90.6% for AAP in 60 min; these values were 1.2 and 1.8 times greater than those of MXene and MIL-101(Cr), respectively. The high surface area of the MXe/MIL-101(Cr) nanocomposite increased from 4.68 m2/g to 294.21 m2/g, and the band gap of the tagged MIL-101(Cr) on the MXene surface was minimized. The superior sonocatalytic activity of MXe/MIL-101(Cr) was attributed to the effective contact interface, the effective separation rate of e- − h+ pairs through the type II heterostructure interface, and the favorable high free •OH radical production rates that promoted the degradation of SD and AAP. The solid heterointerface between MIL-101(Cr) and MXene was confirmed through Raman and FTIR analysis and was found to promote accessible •OH radical production under sonication, thus maximizing the catalytic activity of nanocomposites. The present results present an effective strategy for the design of a highly efficient, low-cost, reliable sonocatalyst that can eradicate pharmaceutical pollutants in our environment.

Valorization of Acid Mine Drainage into an Iron Catalyst to Initiate the Solar Photo-Fenton Treatment of Municipal Wastewater

Acid mine drainage was utilized to catalyze the solar photo-Fenton treatment of wastewater coming from a sludge dewatering system. Acid mine drainage in the form of iron-rich liquid or synthesized minerals (namely magnetite, hematite, and goethite) was added in the wastewater, which was treated by means of the solar photo-Fenton process. The effects of operational parameters such as the amount of acid mine drainage, the wastewater matrix (i.e., synthetic and real wastewater), and the initial H2O2 concentration municipal wastewater’s organic content were explored. The results showed that using acid mine drainage (liquid phase) for wastewater treatment was more efficient than using the acid-mine-drainage-recovered minerals. Moreover, it was observed that the addition of acid mine drainage above 10.7 mL/L wastewater, which is equivalent to 50 mg/L iron, could substantially reduce the removal percentage of the chemical oxygen demand (COD). At the best conditions assayed, COD removal reached 99% after 90 min of photo-Fenton treatment under simulated solar light, in the presence of 30 mg/L Fe (i.e., 6.4 mL drainage/L of real wastewater) and 1000 mg/L H2O2 at a pH of 2.8. Therefore, the solar photo-Fenton treatment of municipal wastewater catalyzed by acid mine drainage may appear to be a promising method to effectively improve wastewater management, especially in areas with high solar energy potential.

Phenol degradation using combined effects of hydrodynamic cavitation and oxidant: Doehlert matrix

AbstractHydrodynamic cavitation (HC)‐based treatments have been proposed for the degradation of phenol as a toxic pollutant. The present work aimed to optimize the degradation of phenol using HC by means of Doehlert experimental design, which has not been previously addressed. Initially, operational parameters of hydraulic characteristics of the pump, inlet pressure, solution pH, and initial concentration were optimized; later, the effects of pH solution and H2O2 loading or initial pollutant concentration on phenol degradation were explored using the Doehlert experimental design. It was observed that phenol degradation is strongly dependent on the pH of the solution. Also, the acidic condition favors the formation of hydroxyl radicals and thus, the degradation of phenol. Based on the Doehlert matrix, the 94.1% phenol degradation and 68.60% total organic carbon (TOC) were obtained in 180 min at 304.5 mg/L of hydrogen peroxide at an initial concentration of 20 mg/L, 2.0 pH, and 90 psi inlet pressure, providing a cavitational yield of 6.33 × 10−6 mg/J and minimum treatment cost of US$/L 0.13. Overall, it has been observed that HC can be a promising route for the removal of pollutants (phenol) effectively using hydrogen peroxide as an additive.

Solar Photocatalytic Degradation of Diuron in Aqueous Solution by TiO2

The solar photocatalytic degradation of diuron, which is one of the herbicides, has been studied by a solar pilot plant in heterogeneous solar photocatalysis with titanium dioxide. The pilot plant was made up of compound parabolic collectors specially designed for solar photocatalytic applications. The influence of different variables such as, H2O2 initial concentration, TiO2 initial concentration, and diuron initial concentration with their relationship to the degradation efficiency were studied. Hydrogen peroxide (H2O2) found to increase the rate of diuron degradation. The best removal efficiency of heterogeneous solar photocatalytic TiO2 system was found to be 46.65 % and for heterogeneous solar photocatalytic TiO2/ H2O2 system was found to be 80.65 %. Based on these results, the solar photocatalytic degradation by TiO2/ H2O2 system could be a useful technology for the treatment of effluents containing diuron.