H2O2 Process Research Articles

NiPd mediated by conductive metal organic frameworks with facilitated electron transfer for assaying of H2O2 released from living cells

Rational modification of catalysts at electrode surface is essential and vital to regulate the electrochemically catalytic capability. In this work, we established an electrochemical interface functionalized by NiPd nanoparticles (NiPd NPs) mediated by metal–organic frameworks (MOFs) of Ni3HHTP2 ([email protected]3HHTP2) towards assaying H2O2 in living cells. In contrast to NiPd NPs, [email protected]3HHTP2 exhibited greatly enhanced electrocatalytic activity towards the reduction process of H2O2 with an onset potential of 0.10 V (vs. Ag/AgCl), as well as the current density increased by 23%. Moreover, the cathodic peak current showed a good linear relationship with H2O2 concentration in a wide range of 1.0 μM to 45.0 mM with a detection limit of 0.8 μM. The developed electrochemical method demonstrated good selectivity towards various potential interferences in cell system, and good reproducibility with a current deviation of 2.1% for 10 different functionalized electrodes. Eventually, the present electrochemical sensor with high selectivity and good stability was employed to monitor the levels of H2O2 released from living cells under oxidative stress.

A Simple Colorimetric Assay for Sensitive Cu2+ Detection Based on the Glutathione-Mediated Etching of MnO2 Nanosheets.

In this paper, we developed a quick, economical and sensitive colorimetric strategy for copper ions (Cu2+) quantification via the redox response of MnO2 nanosheets with glutathione (GSH). This reaction consumed MnO2 nanosheets, which acted as a catalyst for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product (oxTMB). In the presence of Cu2+, the GSH was catalyzed to GSSG (oxidized glutathione), and the solution changed from colorless to deep blue. Under the optimum conditions, the absorption signal of the oxidized product (oxTMB) became proportional to Cu2+ concentration in the range from 10 to 300 nM with a detection limit of 6.9 nM. This detection system showed high specificity for Cu2+. Moreover, the system has been efficaciously implemented for Cu2+ detection in actual tap water samples. The layered-nanostructures of MnO2 nanosheets make it possess high chemical and thermal stability. TMB can be quickly oxidized within 10 min by the catalyzing of MnO2 nanosheets with high oxidase-like activity. There is no need of expensive reagents, additional H2O2 and complicated modification processes during the colorimetric assay. Therefore, the strategy primarily based on MnO2 nanosheets is promising for real-time, rapid and highly sensitive detection of Cu2+ under practical conditions.

Self-Enhanced Selective Oxidation of Phosphonate into Phosphate by Cu(II)/H2O2: Performance, Mechanism, and Validation.

Phosphonate is an important category of highly soluble organophosphorus in contaminated waters, and its oxidative transformation into phosphate is usually a prerequisite step to achieve the in-depth removal of the total phosphorus. Currently, selective oxidation of phosphonate into phosphate is urgently desired as conventional advanced oxidation processes suffer from severe matrix interferences. Herein, we employed 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) as a model phosphonate and demonstrated its efficient and selective oxidation by the Cu(II)/H2O2 process at alkaline pH. In the presence of trace Cu(II) (0.020 mM), 90.8% of HEDP (0.10 mM) was converted to phosphate by H2O2 in 30 min at pH 9.5, whereas negligible conversion was observed by UV/H2O2 or a Fenton reaction (pH = 3.0). The oxidation of HEDP by Cu(II)/H2O2 was insignificantly affected by natural organic matters (10.0 mg TOC/L) and various anions including chloride, sulfate, and nitrate (10.0 mM). The complexation of Cu(II) with HEDP coupling Cu(III) produced in situ enabled an intramolecular electron transfer process, which features high selective oxidation. Selective degradation of HEDP was further validated by adding stoichiometric H2O2 into an industrial effluent, where the existing Cu(II) could serve as the catalyst. This study also provides a successful case to trigger selective oxidation of trace pollutants of concern upon synergizing with the nature of the contaminated water.

Novel combined IME-O3/OH−/H2O2 process in application for mature landfill leachate treatment

Traditional wastewater treatment methods are often insufficient in the case of mature landfill leachate. Therefore novel methods are in demand. Recently, internal microelectrolysis (IME) has been recognized as an effective method besides AOPs for refractory wastewaters treatment. This study investigated the efficiency of a novel combined three-step process (IME-O3/OH−/H2O2) applied to mature landfill leachate treatment. Waste iron chips and granulated activated carbon (GAC) from nut shells were used in the process. Ozone was applied in doses from 0.28 to 1.4 g/dm3, and the mass ratios of COD/H2O2 were as follows: 1/0, 1/0.5, 1/1 1/1.5, and 1/2. Results showed that the PC is a reasonable pretreatment process before IME. However, COD and TOC removal was up to 22.4% and 37.9%, respectively. It required no additional reagents (before IME acidification is needed). The best total COD removal in the IME process was for Fe/GAC ratio 20/80 g/g in 1 dm3 (76.7%). Studies on the sorption process on GAC showed a significant share in the IME process - 11.2–62.6% of total COD removal. That was an important observation since most other authors ignored the fact of sorption. For optimal parameters of the O3/OH−/H2O2, total COD removal was 95.4%. The values of TOC, absorbance UV254, and color were highly reduced by 91.2%, 94.7%, and 98.2%, respectively. Additionally, biodegradability has been significantly improved up to 0.36.

Split dosing of H2O2 for enhancing recalcitrant organics removal from landfill leachate in the Fe0/H2O2 process: Degradation efficiency and mechanism

This study applied a simple but efficient hydrogen peroxide (H2O2) split-dosing strategy as part of a zero valent iron (Fe0)/H2O2 process to effectively remove refractory organics from landfill leachate. Results showed that both the traditional Fenton and Fe0/H2O2 processes produced comparable treatment results, but the Fe0/H2O2 process (advantageously) produced much less sludge. Furthermore, Fe0/H2O2 process using a split H2O2 dosing strategy removed refractory organics from landfill leachate better than using the same oxidant dosage in a single dose. Under optimized operating conditions (H2O2 dosage = 12 mL/L) that included four small sub-doses of H2O2, removal efficiencies of total organic carbon, light absorbance at 254 nm, and color number were 56.76%, 58.59% and 94.56%, respectively. In addition, humic-like substances as refractory organics in the leachate were almost completely removed by the improved Fe0/H2O2 process. Our results demonstrated that the split-dosing strategy substantially enhanced hydroxyl radical (•OH) production in the Fe0/H2O2 process. Overall, the catalytic mechanism of the unique Fe0/H2O2 process can be assigned to the homogeneous catalytic effect of Fe2+ from Fe0 leaching and the heterogenous catalytic effect of iron (hydro) oxides, both of which act on H2O2 to produce •OH. This study provides an efficient strategy that can enhance refractory organics removal efficiency for practical application of the Fe0/H2O2 process.

Solid-state NMR studies of sulfonated SBA-15 and the synergistic catalysis of fructose into 5-hydroxymethylfurfural with dimethyl sulfoxide

Sulfonic acid functionalized mesoporous SBA-15 was prepared using the grafting method. The structure and acid properties were comprehensively characterized using multi-nuclear and quantitative probe molecule solid-state NMR (SSNMR), together with powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption techniques. Its catalytic performance in the conversion of fructose to 5-hydroxymethylfurfural (HMF) in dimethyl sulfoxide (DMSO) was studied. Catalyst dosage, reaction time, reaction temperature and solvent effect have been investigated. A high yield of HMF up to 93% was obtained at a relatively low temperature of 373 K for 180 min. The Brønsted acid of SBA-15_SO3H together with the solvent DMSO was found to synergistically catalyze the reaction. The catalyst preserved most of its activity after five times reuse and the catalytic activity can be recovered by H2O2 process.

Multi-response optimization of cellulose fiber isolation from tapioca solid waste and its characteristics

The tapioca-based starch industry produces solid waste in abundance that has not been used optimally, especially the cellulose fraction. This study aimed to optimize the H2O2 concentration and the process temperature of cellulose fiber isolation from tapioca solid waste. Statistical regression modeling and optimization of H2O2 concentration and process temperature using the response surface methodology. A central composite design (CCD) was applied for experimental design and analysis of the effect of H2O2 concentration and process temperature on multi-response characteristics of cellulose, consisting of whiteness index (WI), yield, and α-cellulose content. Cellulose fibers were characterized, including surface morphology, crystallinity degree, and thermal stability. The results showed that the H2O2 concentration and process temperature were significantly affected by WI, yield, and α-cellulose content. The maximum WI, yield, and α-cellulose content were 63.99%, 65.73% (w/w), and 78.31% (w/w), respectively, obtained from H2O2 concentration of 22.62% (v/v) and process temperature of 93.51ºC. This cellulose has a relatively coarse fiber formation, with a high degree of crystallinity and thermal stability. Thus, cellulose from TSW might have a potential to be applied in broader fields.

The effect of isomorphic substitution on siderite activation of hydrogen peroxide: The decomposition of H2O2 and the yield of ·OH

To investigate the effect of isomorphic substitution on siderite activation of hydrogen peroxide, different X-substituted siderite (X = Mn, Co, Ca, and Mg) was artificially synthesized and utilized to activate hydrogen peroxide (H2O2) over a pH range from 5 to 9. The results indicated that the addition of siderite generally accelerated the conversion process of H2O2 to ·OH regardless of initial pH values. However, the conversion ability from H2O2 to ·OH was only enhanced under the acidic condition. Then, X-substituted siderite generally enhanced the conversion rate and inhibited the capacity of H2O2 to ·OH under neutral and alkaline conditions. The Mn, Ca, and Mg-substituted siderite facilitated both conversion rate and capacity of H2O2 to ·OH under weakly acidic conditions, while Co-substituted siderite inhibited both compared to the raw siderite. The element substitution mainly affected the stability of siderite, which resulted in the dissolution of siderite to generate Fe2+ and contributes to the H2O2 decomposition and the ·OH generation. Findings from this research suggested that the isomorphic substitution of siderite had a non-negligible impact on the transformation of H2O2 to ·OH.

Citric acid chelated Fe(II) catalyzed peroxidation for simultaneously improving sludge dewaterability and antibiotic resistance genes (ARGs) removal

Sludge contains large amounts of antibiotic resistance genes (ARGs), that reduce the efficacy of antibiotic therapies when transmitted to humans. However, conventional sludge treatment often fails to remove ARGs. Herein, critic acid chelated Fe(II) catalyzed peroxidation (CA-Fenton) was conducted to simultaneously improve sludge dewaterability and ARGs removal. As results, the CA-Fenton process exhibited significantly improved sludge dewatering performance and ARGs removal, in which the capillary suction time (CST), specific resistance to filtration (SRF) and cake moisture of sludge were reduced from 8.8 s·L/g, 5.8 × 1013 m/kg and 93.2% to 2.3 s·L/g, 5.8 × 1012 m/kg and 79.1%, respectively, and the removal efficiencies of 7 types-ARGs in sludge achieved over 90%. In addition, synergistic sludge dewatering and ARGs degradation mechanisms were elucidated with a suit of macro and spectroscopic evidence (high performance liquid chromatography-size exclusion chromatography (HPLC-SEC) and two-dimensional fourier-transform infrared correlation spectroscopy (2D-FTIR)). During CA-Fenton treatment, CA acidification enhanced permeability of the cell barrier in EPS, releasing intracellular ARGs into sludge bulk solution, which accelerated the ARGs degradation via CA chelated Fe(II) catalyzed H2O2 process. Meanwhile, destruction of secondary structure represented β-turn in proteins enhanced the hydrophobicity of EPS, which contributed the improvement of sludge dewaterability. The study not only proposed an efficient method to improve traditional Fenton oxidation for sludge treatment, but also provided a mechanistic basis for better understanding of the CA-Fenton process, and enable the harmless disposal for sludge.

Degradation of Calmagite by H2O2/UV/US, H2O2/US, H2O2, and US process

1-(1-Hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid is known as Calmagite. In this study, the degradation of Calmagite in H2O2/UV/US, H2O2/US, H2O2, and US processes were investigated separately and each was compared among themselves. The concentration of H2O2, initial dye concentration, pH, UV light, and also ultrasonic sound significantly influenced the degradation of Calmagite and these parameters were optimized. For the azo dye tested, more than 98% of degradation in H2O2/UV/US, H2O2/US, and H2O2 processes was reached in 20, 40, and 60 min, respectively in Britton Robinson buffer media at pH = 11.0. The proposed degradation pathways of Calmagite were established from the OH mediated degradation of this azo dye. The first-order rate kinetics best fit the degradation of Calmagite.

High-efficiency oxidation of norfloxacin by Fe3+/H2O2 process enhanced via vacuum ultraviolet irradiation: Role of newly formed Fe2+

Fluoroquinolones in water environments have caused worldwide concern due to negative effects on human health and ecological environment. Heretofore, synergistic mechanisms of Fe3+/H2O2 process enhanced via vacuum ultraviolet (VUV) irradiation for fluoroquinolones removal, and generation ways and contribution evaluations of reactive oxygen species (ROS) in integrated VUV/Fe3+/H2O2 were not reported systematically. This work comparatively investigated norfloxacin (NOR, typical fluoroquinolones) degradation in VUV/Fe3+/H2O2 and its sub-processes. Compared with its sub-processes, VUV/Fe3+/H2O2 process could not only increase degradation rate constant by 2.1–10.2 times and increase mineralization rate by 14.5%–49.5%, but also reduce energy consumption by 53.1%–89.9% and reduce economic cost by 33.3%–68.0%. Effect mechanisms of Fe3+ and H2O2 doses on decontamination capability of VUV/Fe2+/H2O2 were elaborated, and 3 mM H2O2 and 90 μM Fe3+ were determined as optimal doses. The synergetic factor in integrated VUV/Fe3+/H2O2 was 3.33, which was mainly ascribed to VUV photons accelerating iron cycle. In VUV/Fe3+/H2O2 process, superoxide radical and hydroxyl radical were confirmed as primary ROS, contributing 20.86% and 76.32% to NOR oxidation, separately. Organic and inorganic products of NOR and its degradation pathways in integrated VUV/Fe3+/H2O2 were also investigated. Besides, the synergistic reaction pathways in VUV/Fe3+/H2O2 were elaborated. Effects of water matrices on decontamination capability of VUV/Fe3+/H2O2 were also studied. All results indicated VUV/Fe3+/H2O2 as an efficient and cost-effective process suitable for NOR removal.

A novel UV based advanced oxidation process with electrochemical co-generation of chlorine and H2O2 for carbamazepine abatement: Better performance, lower energy consumption and less DBPs formation

To promote the performance of traditional UV/chlorine and UV/H2O2 processes, the novel UV based advanced oxidation process with electrochemical co-generation of chlorine and H2O2 (UV/E-Cl&H2O2) was for the first time used for degradation of carbamazepine (CBZ), a refractory antiepileptic drug with resistance to photodegradation and microbial degradation. Compared with UV/E-Cl and UV/E-H2O2 processes, the apparent first-order rate constant of CBZ degradation by UV/E-Cl&H2O2 process increased by 3.87 and 5.84 times respectively with a lower energy consumption (1.12 kWh/m3-log). Meanwhile, the disinfection by-products (DBPs) formation by the novel process was 21.4% less than that by UV/E-Cl process. Under the optimal condition of initial pH 7, applied current 600 mA and 15 mM NaCl, the UV/E-Cl&H2O2 process could almost completely eliminate CBZ within 4 min and obtain 57.8% TOC removal in 1 h. The mechanism of UV/E-Cl&H2O2 was investigated through processes comparison, quenching experiments, EPR analysis and determination of OH concentration. The generated radicals (i.e., OH and reactive chlorine species), especially OH, played a major role in CBZ removal. Besides, the possible degradation pathways of CBZ were proposed and the stability of UV/E-Cl&H2O2 process for CBZ removal was certified based on ten consecutive runs. The degradation of typical pollutants (sulfamethazine, rhodamine B, methylene blue, atrazine and phenol) and treatments in three kinds of real wastewater confirmed the wide application feasibility of the novel process. In summary, this study provides a novel efficient and energy-saving process for removing organic pollutants with promising perspectives..

Insights into the role of in-situ and ex-situ hydrogen peroxide for enhanced ferrate(VI) towards oxidation of organic contaminants

Recently, several studies have been conscious of the promotion effect of hydrogen peroxide (H2O2), a self-decay product of ferrate (Fe(VI)), on Fe(VI) to oxidize contaminations, but the pivotal activation mechanism has not been thoroughly evaluated. This work aims to compare and reveal the promoting mechanism of H2O2 in Fe(VI) and Fe(VI)−H2O2 processes, and to illustrate the practical use potential of Fe(VI)−H2O2 system. Many lines of evidence verified the involvement of •OH and O2•− in pollutant degradation were excluded in Fe(VI) and Fe(VI)−H2O2 systems, meaning that high dosage of H2O2 cannot trigger an activation pathway different from in-situ H2O2. The better oxidation performance of the Fe(VI)−H2O2 system than Fe(VI) alone was ascribed to the catalytic role of in-situ and ex-situ H2O2, which can directly and/ or indirectly facilitate the formation of Fe(IV) and Fe(V). Considering the structural similarity of peroxymonosulfate (PMS) and peroxydisulfate (PDS) with H2O2 as well as their universality in water pollutant remediation, the oxidation properties and reactive oxidants of Fe(VI)−PMS and Fe(VI)−PDS processes were also examined. Besides, the Fe(VI)−H2O2 system suffered from less restriction by inorganic ions and natural organic matter, and exhibited satisfactory pollutant removal effects in real water. Overall, this work provides a further and comprehensive cognition about the role of H2O2 in Fe(VI) and Fe(VI)−H2O2 systems.

Degradation of 2,6-dichloro-1,4-benzoquinone by advanced oxidation with UV, H2O2, and O3: parameter optimization and model building

Abstract Halobenzoquinones are disinfection by-products with cytotoxicity, carcinogenicity, and genotoxicity. In this study, we investigated the removal of the HBQ 2,6-dichloro-1,4-benzoquinone (DCBQ) from water using advanced oxidation processes. The removal of DCBQ from water using UV, H2O2, and O3 advanced oxidation processes individually was not ideal with removal rates of 36.1% with a UV dose of 180 mJ/cm2, 32.0% with 2 mg/L H2O2, and 57.9% with 2 mg/L O3. Next, we investigated using the combined UV/H2O2/O3 advanced oxidation process to treat water containing DCBQ. A Box–Behnken design was used to optimize the parameters of the UV/H2O2/O3 process, which gave the following optimum DCBQ removal conditions: UV dose of 180 mJ/cm2, O3 concentration of 0.51 mg/L, and H2O2 concentration of 1.76 mg/L. The DCBQ removal rate under the optimum conditions was 94.3%. We also found that lower humic acid concentrations promoted DCBQ degradation, while higher humic acid concentrations inhibited DCBQ degradation.

Molybdenum phosphide (MoP) with dual active sites for the degradation of diclofenac in Fenton-like system

The leaching and non-recoverability of mental ions have always limited the practical application of Fenton-like processes. For the first time, we synthesized molybdenum phosphide (MoP) with dual active sites for the degradation of diclofenac (DCF) in the Fenton-like process. The DCF degradation rate constant (k) of MoP + H2O2 process was calculated to be 0.13 min-1 within 40 min, indicating a highly efficient catalytic ability of MoP. In addition, this catalyst exhibits a stable structure and good activity, which could apply in a broad pH range, different ions solution and real wastewater condition. Accordingly, this efficient catalytic capability may be attributed to the presence of the metal sites Moδ+ and the electron-rich sites Pδ− in MoP, which could induce the generation of hydroxyl radical (•OH) and superoxide radical (•O2−) through electron transfer, resulting in the effective removal of DCF. This study provides an idea for the optimization of Fenton-like technologies and environmental remediation.

H2O2: From Sustainable Synthesis to Fenton Assisted Environmental Application of Wastewater Treatment

Hydrogen peroxide (H2O2) has great application prospects in the wastewater treatment environmental field due to its clean degradation product of merely H2O. While the green synthesis and highly efficient purification are also challengeable but significant. Thus, we intended to overview the H2O2 preparation methods, which are environmentally friendly, producing efficiently and economically. Here, we first discussed the most widely used H2O2 producing method of anthraquinone autoxidation synthesis method and put forward the main drawback. Six ideal substitute methods were next put forward which are oxidation of alcohols, photocatalysis, synthesis from CO/O2/H2O mixtures, direct synthesis method, fuel cell method, and direct electrosynthesis method. We then analyzed the traditional homogeneous Fenton process and summarized the promising substitute application of H2O2 in water treatment through heterogeneous Fenton processes from three main points. They are advanced heterogeneous iron oxychloride, heterogeneous electro Fenton catalytic assistance, and heterogeneous photo-Fenton catalytic assistance. Finally, a new sequential process of H2O2 applied in the environment as a form of water treatment was envisaged and named as One-stop Sequential H2O2 Process combining each way from the source and terminal. Additionally, in all the methods mentioned, we restated mechanisms and redrawn them more concisely and clearly to make them easier to understand.

The Coupling Use of Weak Magnetic Field and Fe0/H2O2 Process for Bisphenol a Abatement: Influence of Reaction Conditions and Mechanisms

The coupling use of the heterogeneous Fenton-like process (zero-valent iron (Fe0)/H2O2) and weak magnetic field (MWF) for bisphenol A (BPA) abatement was systematically investigated in this study. Though both the Fe0/H2O2 and WMF-Fe0/H2O2 processes are sensitive to pH, WMF remarkably enhanced BPA removal under the pH range of 3.0–6.0 by 0.5–9.5 times. The characterization of Fe0 confirmed the role of WMF in promoting the corrosion of Fe0. Radicals, rather than Fe intermediates, were responsible for BPA degradation. Due to the presence of Cl– as the background ions and its reactivity towards HO•, reactive chlorine species (RCS, i.e., Cl• and Cl2•−) were produced and considerably contributed to BPA degradation. In addition, ~37% and 54% of degraded BPA was ascribed to RCS in the presence of 2 and 100 mM of Cl−, respectively. However, 1.9 mg/L of ClO3− was detected in the presence of 2 mM of Cl− in the WMF- Fe0/H2O2 process. HCO3− could diminish ClO3− generation significantly through transforming RCS. The concentration of ClO3− decreased by 74% and 82% with dosing 1 and 10 mM HCO3−, respectively. The results of this study suggest that the WMF-Fe0/H2O2 process is a promising approach for BPA removal.

A novel signal amplification label based on AuPt alloy nanoparticles supported by high-active carbon for the electrochemical detection of circulating tumor DNA

The detection of circulating tumor DNA (ctDNA) has increasingly received a great deal of attention considering its significance in cancer diagnosis. And the signal amplification plays an important role in the development of sensitive ctDNA biosensors. Herein, the nanocomposites (denoted as HAC-AuPt), integrating from high-active carbon (HAC) and AuPt alloy nanoparticles, were synthesized and subsequently used as a signal amplification label to fabricate a sandwich-type ctDNA electrochemical biosensor. Characterizations demonstrated that HAC presents uniform size distribution and AuPt alloy nanoparticles were successfully loaded on HAC. The current response could be amplified to a great extent by the resultant HAC-AuPt due to its excellent electrochemical property. The nanocomposites were further bounded with DNA signal probes (SPs) via Au-S or Pt-S assembly to form SPs-label. After the capture probes (CPs) were immobilized on the electrode surface, the target DNA (tDNA) and SPs-label were stepwise incubated on the CPs-modified electrode, thus forming a sandwich-type structure. By monitoring the catalytic signal of HAC-AuPt towards the reduction process of H2O2, this biosensor provided a wide linear range of 10−8 mol/L - 10−16 mol/L with a low detection limit of 3.6 × 10−17 mol/L (S/N = 3) for the detection of the tDNA. Furthermore, obvious differences in response signals among different DNAs were observed benefitting from the excellent selectivity of the biosensor. Besides, the long-term stability, reproducibility, and recovery rate were proved to be outstanding. These results indicate that the established biosensor holds a potential application in the clinical diagnosis of ctDNA.

Effectiveness of O3/Fe2+/H2O2 process for detoxification of heavy metals in municipal wastewater by using RSM

The intensification of wastewater treatment using combined ozonation and Fenton process (O3/Fe 2+/H2O2) for removal of toxic heavy metals such as Lead, Chromium (VI), Zinc, and Manganese in actual municipal wastewater was investigated. RSM was used to optimize process parameters viz. ozone concentration, initial pH, Fe (II), and H2O2 concentration. The high value of the coefficient of determination (R2 =0.9793 for Pb; 0.9824 for Zn; 0.9735 for Mn; 0.9724 for Cr (VI)) confirms that RSM effectively predicted the performance of the O3/Fe 2+/H2O2 process. The heavy metal removal efficiency of 98.66% for Pb, 99.22% for Zn, 95.11% for Mn, and 94.55% for Cr (VI) obtained at optimized conditions were comparable with RSM predicted efficiencies. The present intensification approach has enhanced the treatment efficiency and was found to be cost-effective than ozonation.

Optimization of opeation parameters for methylene blue degradation by UV/TiO2/H2O2 process in an annular reactor

In this study, the degradation of methylene blue (MB) by UV/TiO2/ H2O2 process was ivestigated in an annular reactor. The effects of the factors: TiO2 concentration, H2O2 dosage, UV density, and hydrodynamic conditions on the reaction rate constant were evaluated by the response surface methodology. The results showed that TiO2 concentration, H2O2 dosage and UV density had a great influence on the kapp, hydrodynamics had a lower influence. Design Expert V.11 software is used to optimize the reaction conditions, the optimal apparent reaction rate constant is 0.168 min-1 under the following conditions: TiO2 concentration of 0.2 g/l, H2O2 dosage is 0.063 mol/l, UV density of 287 W/m2 and Re number is 10000.