Synthesis of 3D Sb2O3-based heterojunction reinforced by SPR effect and photo-Fenton mechanism for upgraded oxidation of metronidazole in water environments.

The traditional homogenous and heterogenous Fenton reactions have frequently been restrained by the lower production of Fe2+ ions, which significantly obstructs the generation of hydroxyl radicals from the decomposition of H2O2. Thus, we introduce novel photo-Fenton-assisted plasmonic heterojunctions by immobilizing Fe3O4 and Bi nanoparticles onto 3D Sb2O3 via co-precipitation and solvothermal approaches. The ternary Sb2O3/Fe3O4/Bi composites offered boosted photo-Fenton behavior with a metronidazole (MNZ) oxidation efficiency of 92% within 60 min. Among all composites, the Sb2O3/Fe3O4/Bi-5% hybrid exhibited an optimum photo-Fenton MNZ reaction constant of 0.03682 min- 1, which is 5.03 and 2.39 times higher than pure Sb2O3 and Sb2O3/Fe3O4, respectively. The upgraded oxidation activity was connected to the complementary outcomes between the photo-Fenton behavior of Sb2O3/Fe3O4 and the plasmonic effect of Bi NPs. The regular assembly of Fe3O4 and Bi NPs enhances the surface area and stability of Sb2O3/Fe3O4/Bi. Moreover, the limited absorption spectra of Sb2O3 were extended into solar radiation by the Fe3+ defect of Fe3O4 NPs and the surface plasmon resonance (SPR) effect of Bi NPs. The photo-Fenton mechanism suggests that the co-existence of Fe3O4/Bi NPs acts as electron acceptor/donor, respectively, which reduces recombination losses, prolongs the lifetime of photocarriers, and produces more reactive species, stimulating the overall photo-Fenton reactions. On the other hand, the photo-Fenton activity of MNZ antibiotics was optimized under different experimental conditions, including catalyst loading, solution pH, initial MNZ concentrations, anions, and real water environments. Besides, the trapping outcomes verified the vital participation of •OH, h+, and •O2- in the MNZ destruction over Sb2O3/Fe3O4/Bi-5%. In summary, this work excites novel perspectives in developing boosted photosystems through integrating the photocatalysis power with both Fenton reactions and the SPR effects of plasmonic materials.

Comparison of kinetics and costs of Fenton and photo-Fenton processes used for the treatment of a textile industry wastewater.

In this study, the treatment of textile industrial wastewater by Fenton and Photo-Fenton oxidation processes was investigated. For this purpose, the pH, Fe2+ and H2O2 concentrations with the best organic matter and color removal were determined in the Fenton process and comparison with Fenton was made by Photo-Fenton oxidation at the optimal Fe2+/H2O2 ratio. The influent COD and TOC values of the wastewater used in the study were 848 mg/L and 253 mg/L, respectively. With the Fenton process, the best organic matter and color removal was obtained at pH 3, at 200 mg/L Fe2+ and 300 mg/L H2O2 concentrations. Under these conditions, 88.9% COD, 84.2% TOC and over 97% color removal were obtained with Fenton oxidation, and 93.2% COD, 88.9% TOC and 98% color were obtained with Photo-Fenton oxidation. However, when Fe2+ and H2O2 amounts were reduced to 50 mg/L and 75 mg/L, both organic matter and color removal were reduced with Fenton process, while higher organic matter removal and color removal were achieved with Photo-Fenton process. The total cost was changed between 9.56-16.88 €/m3 and 13.46-20.13 €/m3 with Fenton and Photo-Fenton oxidation process for all Fe2+/H2O2 ratios, respectively. With the Photo-Fenton oxidation process, higher organic matter removal was obtained at optimum Fe2+ and H2O2 concentrations. In addition, less Fe2+ and H2O2 chemicals were used in Photo-Fenton oxidation process to achieve the same removal efficiency compared to the Fenton oxidation process.

Photo-degradation of sugar processing wastewater by copper doped bismuth oxyiodide: Assessment of treatment performance and kinetic studies.

In this study, photo-Fenton-like oxidation method was evaluated for synthetic sugar industry wastewater using visible-light driven Cu-BiOI photocatalyst. Reaction conditions including initial pH, catalyst loading, initial hydrogen peroxide (H2O2) concentration, and temperature, were optimized. At these optimized conditions, the total saccharide concentration (TSC) and total organic carbon (TOC) removals were 56.20% and 30.67%, respectively whereas the maximum TSC and TOC removal reached up to 93.35% and 74.72% respectively by decreasing initial sucrose concentration. The kinetic study showed that the reaction order for sucrose and TOC oxidation was determined as 2 for pseudo-homogeneous power law models with respect to sucrose concentration and TOC, respectively.For heterogeneous models, Langmuir-Hinshelwood model based on the mechanism of adsorbed pollutant and oxidant on different catalytic sites was the best fit for oxidation of sucrose and other organic intermediates. According to the catalyst characterization studies, incorporation of copper was successful and Cu-BiOI possesses high photocatalytic activity accomplished by acid-assisted synthesis method.

Facile introduction of coordinative Fe into oxygen-enriched graphite carbon nitride for efficient photo-Fenton degradation of tetracycline.

Tetracycline (TC) antibiotics have been widely used over the past decades, and their massive discharge led to serious water pollution. Photo-Fenton process has gained ever-increasing attention for its excellent oxidizing ability and friendly solar energy utilization ability in TC polluted water treatment. This work introduced coordinative Fe into oxygen-enriched graphite carbon nitride (OCN) to form FeOCN composites for efficient photo-Fenton process. Hemin was chosen as the source to provide the source of coordinative Fe-Nx groups. The degradation efficiency of TC reached 82.1 % within 40 min of irradiation, and remained 76.9 % after five runs of reaction. The degradation intermediates of TC were detected and the possible degradation pathways were gained. It was found that h+, OH, and O2- played major roles in TC degradation. Notably, the photo-Fenton performance of FeOCN was stable in highly saline water or strong acid/base environment (pH 3.0-9.0). Besides, H2O2 can be generated in-situ in this photo-Fenton process, which is favorable for practical application. It can be anticipated that the coordinative FeOCN composites will promote the application of photo-Fenton oxidation process in TC polluted water treatment.

Reclamation of real textile wastewater by sequential advanced oxidation and adsorption processes using corn-cob based materials.

Wastewater management has become crucial for sustaining biological life in the near future. One of the key aspects is integration of treatment processes aiming reuse of treated water for many purposes instead of water discharge. This study focused on combining two different methods, photo-Fenton-like oxidation, and adsorption, for treatment of real textile wastewater to improve water quality to be reused for irrigation. The real textile wastewater was collected from a local plant and subjected to photo-Fenton-like oxidation and adsorption as hybrid process. The operational parameters were optimized for each step by assessing the water quality according to the domestic regulations for irrigation water. The photo-Fenton-like oxidation itself was not successful to achieve the targeted water quality for reuse whereas adsorption as an additional step made the treated water reusable in terms of organic content. But the treated water still contained a certain amount of salinity due to extreme salt usage in textile processing. It was concluded that the treated water at the end of hybrid process could be used for salinity resistant plants such as sugar beet, barley, and cotton which demonstrates a promising contribution to the circular economy for biomass.

Application of Fe0.66Cu0.33@Al(OH)3 catalyst from fluidized-bed crystallizer by-product for RB5 azo dye treatment using visible light-assisted photo-Fenton technology.

This study aims to explore the reusability of wastewater treatment by-product for photo-Fenton process to treat an organic pollutant model. The optimal condition, reactive oxygen species (ROS), and kinetic approach in photo-Fenton process was discussed. The Metal oxide crystal pellets from are a by-product of the Fluidized-Bed Crystallization (FBC) process and can be used as a catalyst in the Photo-Fenton process. Electroplating wastewater containing iron and copper was treated via the FBC process using granulated Al(OH)3 as carrier seeds. The binary oxide of FeOOH and Cu2O on the Al(OH)3 surface (Fe0.66Cu0.33@Al(OH)3) was identified as the FBC by-product after characterization using FTIR and XPS analysis. In the photo-Fenton process, visible light from a fluorescence lamp with a wavelength of 400-610 nm was chosen as an irradiation source. Oxalic acid was added as chelating agent to form photosensitive iron oxalate species and hydrogen peroxide was applied as oxidant to generate active radical to decolorize and mineralize RB5 synthesized solution (100 mg/L). The operating conditions including the oxalic acid to pollutant ratio ([OA]0/[RB5]0) of 4.5-13.0, reaction pH (pHr) of 3-7 and initial to theoretical hydrogen peroxide molar ratio [H2O2]0/[ H2O2]theoretical of 35%-120% were optimized. Under the optimal conditions, pHr = 5.0; [H2O2]0/[RB5]0 at 75% stoichiometric and [OA]0/[RB5]0 = 9, the RB5 is almost completely decolorized after 210 min of operation and the mineralization efficiency is 58%. The contribution of •OH, O2•-, and O21 to the Photo-Fenton system was determined using ESR analysis with the addition of DMPO and TEMP as spin trap agents. The kinetic analysis reveals the observed rate constants kRB5, kOA and kR from fitting are 0.0120, 0.0054 and 0.0001 M-1s-1, respectively.

Inhibitory effect of fungoid chitosan in the generation of aldehydes relevant to photooxidative decay in a sulphite-free white wine.

The reaction pathways were investigated by which a fungoid chitosan (CsG) may protect against photooxidative decay of model solutions and a sulphite-free white wine. Samples containing CsG were dark incubated for 2 days before exposure to fluorescent lighting for up to 21 days in the presence of wine like (+)-catechin and/or iron doses. In both systems CsG at winemaking doses significantly reduced the photoproduction of acetaldehyde and, to a better extent, glyoxylic acid, two key reactive aldehydes implicated in wine oxidative spoilage. After 21 days, CsG was two-fold more effective than sulphur dioxide in preventing glyoxylic acid formation and minimizing the browning of white wine. Among the antioxidant mechanisms involved in CsG protective effect, iron chelation, and hydrogen peroxide quenching were demonstrated. Besides, the previously unreported tartrate displacement from the [iron(III)-tartrate] complex was revealed as an additional inhibitory mechanism of CsG under photo-Fenton oxidation conditions.

Removal of p-aminobenzenesulfanilamide from water solutions by catalytic photo-oxidation over Fe-pillared clay.

The catalytic photo-oxidation of p-aminobenzenesulfanilnamide (ABS) with hydrogen peroxide in the presence of Fe-pillared clay as heterogeneous catalyst has been investigated under UV-irradiation (λmax = 254 nm). Fe-pillared clay was synthesized by intercalating the iron polyhydroxycomplexes into the interlayer space of a natural layered aluminosilicate - montmorillonite and a subsequent heat treatment at 500 °C. The catalyst was characterized by chemical analysis, low temperature nitrogen adsorption and XRD. The kinetics of photocatalytic oxidative degradation of ABS in aqueous solutions under various experimental conditions was studied. The dependence of the photo-oxidation rate on such experimental factors as pH, hydrogen peroxide concentration and catalyst content was established. The conversion of ABS was 100% and the mineralization efficiency was 52.3% at optimal conditions. The intermediate products of ABS photo-oxidation identified by HPLC were a sulfanilic acid, benzenesulfonamide, benzenesulfonic acid, hydroquinone, pyrocatechol, benzoquinone and aliphatic acids. Fe-pillared clay remained highly active in three consecutive catalytic cycles without regeneration. The results of the study suggested that the heterogeneous photo-system «Fe-pillared clay/H2O2/UV¼ was effective in the oxidative degradation of aminobenzenesulfanilnamide. This system may be of interest for use in organic wastewater treatment processes.

Epoxy graphene oxide from a simple photo-Fenton reaction and its hybrid with phytic acid for enhancing U(VI) capture.

A novel approach to synthesize phytic acid (PA) functionalized graphene oxide (P-pFGO-7) treated by the photo-Fenton reaction has been designed, which has been used as an adsorbent for efficient capture of U(VI) from aqueous solution. The structure and morphology of P-pFGO-7 were characterized well. The adsorption property for P-pFGO-7 was comprehensively assessed by batch experiments, showing the high adsorption capacity (266.7 mg/g, at pH = 4.0, T = 298 K), fast adsorption kinetics (~10 min), good selectivity for U(VI) and Ln-An ions in various coexisting ions and excellent regeneration capacity. With the assistance of various characterization techniques and batch adsorption results, it is found that PA makes the most contribution to coordinate U(VI) heavily depending on the PO moiety. P-pFGO-7 could be regenerated by 0.1 mol/L Na2CO3 with ~95% desorption efficiency and reused well after five recycles. This present work provides a feasible route to modify graphene oxide and extend PA for potentially practical application in the removal of U(VI) from radioactive wastewater.

Step by step procedures: Degradation of polycyclic aromatic hydrocarbons in potable water using photo-Fenton oxidation process.

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds, composed of two or more fused benzene rings and abundantly found in mixed-use areas. Mixed-use areas consist of dense population, urbanization, industrial and agricultural activities. River pollution are common in mixed-use areas and 98% of Malaysia's fresh water supply originates from surface water. The biological degradation, adsorption and advanced oxidation process were documented as the available PAHs treatment for water. To date, the application of the photo-Fenton oxidation process has been reported for the treatment of PAHs from contaminated soil (review paper), landfill leachate, municipal solid waste leachate, sanitary landfill leachate, aniline wastewater, ammunition wastewater and saline aqueous solutions. As for potable water, the application of Fenton reagent was aided with photo treatment or electrolysis not focusing on PAHs removal. •The presented MethodsX was conducted for PAHs degradation analysis in potable water samples using photo-Fenton oxidation process.•The designed reactor for batch experiment is presented.•The batch experiment consists of parameters like concentration of 17 USEPA-PAHs in the prepared aqueous solution (fixed variable), reaction time, pH and molarity ratio of hydrogen peroxide (H2O2): ferrous sulfate (FeSO4).

Visible-light photo-Fenton oxidation of phenol with rGO-α-FeOOH supported on Al-doped mesoporous silica (MCM-41) at neutral pH: Performance and optimization of the catalyst.

In this study, α-FeOOH on reduced graphene oxide (rGO-α-FeOOH) supported on an Al-doped MCM-41 catalyst (RFAM) was optimized for the visible-light photo-Fenton oxidation of phenol at neutral pH. The stability of the catalysts, effect of bubbling aeration, and degradation intermediates were investigated. Results indicated that RFAM with a large Brunauer-Emmett-Teller (BET) area and mesoporous structure displayed excellent catalytic activity for the visible-light-driven (VLD) photo-Fenton process. Phenol degradation was well described by a pseudo-first-order reaction kinetics model. Raman analysis demonstrated that an rGO-α-FeOOH (RF) composite is formed during the ferrous-ion-induced self-assembly process. Al-MCM-41 could uniformly disperse RF nanosheets and promote the mobility and diffusion of matter. The activity of the main catalyst α-FeOOH was enhanced after the incorporation of rGO nanosheets. The α-FeOOH crystal in RFAM showed catalytic activity superior to those of Fe3O4 and Fe2O3. The RFAM catalyst, with an optimal GO-Fe2+mass ratio of 2.33, exhibited a larger BET area, pore size, and pore volume, and thus exhibited high performance and energy utilization efficiency in the VLD photo-Fenton reaction with remarkable stability. Bubbling N2 inhibited catalytic performance, while bubbling O2 or air only slightly accelerated the phenol degradation. Visible light played an important role in accelerating the formation of reactive oxygen species (·OH) for the highly efficient phenol degradation. Analysis of degradation intermediates indicated a high phenol mineralization level and the formation of low-molecular-weight organic acids. This work would be helpful in providing an insight into a new type of catalyst assembly and a possible route to a promising heterogeneous catalyst applicable in the visible light photo-Fenton process for effective wastewater remediation at neutral pH.

Treatment efficiency and economic feasibility of biological oxidation, membrane filtration and separation processes, and advanced oxidation for the purification and valorization of olive mill wastewater.

Olive mill wastewater (OMW) is a major waste stream resulting from numerous operations that occur during the production stages of olive oil. The resulting effluent contains various organic and inorganic contaminants and its environmental impact can be notable. The present work aims at investigating the efficiency of (i) jet-loop reactor with ultrafiltration (UF) membrane system (Jacto.MBR), (ii) solar photo-Fenton oxidation after coagulation/flocculation pre-treatment and (iii) integrated membrane filtration processes (i.e. UF/nanofiltration (NF)) used for the treatment of OMW. According to the results, the efficiency of the biological treatment was high, equal to 90% COD and 80% total phenolic compounds (TPh) removal. A COD removal higher than 94% was achieved by applying the solar photo-Fenton oxidation process as post-treatment of coagulation/flocculation of OMW, while the phenolic fraction was completely eliminated. The combined UF/NF process resulted in very high conductivity and COD removal, up to 90% and 95%, respectively, while TPh were concentrated in the NF concentrate stream (i.e. 93% concentration). Quite important is the fact that the NF concentrate, a valuable and polyphenol rich stream, can be further valorized in various industries (e.g. food, pharmaceutical, etc.). The above treatment processes were found also to be able to reduce the initial OMW phytotoxicity at greenhouse experiments; with the effluent stream of solar photo-Fenton process to be the least phytotoxic compared to the other treated effluents. A SWOT (Strength, Weakness, Opportunities, Threats) analysis was performed, in order to determine both the strengths of each technology, as well as the possible obstacles that need to overcome for achieving the desired levels of treatment. Finally, an economic evaluation of the tested technologies was performed in an effort to measure the applicability and viability of these systems at real scale; highlighting that the cost cannot be regarded as a 'cut off criterion', since the most cost-effective option in not always the optimum one.