scholarly journals A Rational Analysis on Key Parameters Ruling Zerovalent Iron-Based Treatment Trains: Towards the Separation of Reductive from Oxidative Phases

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2948
Author(s):  
Iván Sciscenko ◽  
Antonio Arques ◽  
Carlos Escudero-Oñate ◽  
Melina Roccamante ◽  
Ana Ruiz-Delgado ◽  
...  
Keyword(s):  
Fenton Oxidation ◽  
Zerovalent Iron ◽  
Aminobenzoic Acid ◽  
Pollutant Degradation ◽  
Rational Analysis ◽  
Initial Amount ◽  
Nitrobenzoic Acid ◽  
Initial Ph ◽  
Iron Based ◽  
Pre Treatment

The development of treatment trains for pollutant degradation employing zerovalent iron has been attracting a lot of interest in the last few years. This approach consists of pre-treatment only with zerovalent iron, followed by a Fenton oxidation taking advantage of the iron ions released in the first step. In this work, the advantages/disadvantages of this strategy were studied employing commercial zerovalent iron microparticles (mZVI). The effect of the initial amount of mZVI, H2O2, pH, conductivity, anions and dissolved oxygen were analysed using p-nitrobenzoic acid (PNBA) as model pollutant. 83% reduction of PNBA 6 µM into p-aminobenzoic acid (PABA) was achieved in natural water at an initial pH 3.0 and 1.4 g/L of mZVI, under aerobic conditions, in 2 h. An evaluation of the convenience of removing mZVI after the reductive phase before the Fenton oxidation was investigated together with mZVI reusability. The Fenton step against the more reactive PABA required 50 mg/L of H2O2 to achieve more than 96% removal in 15 min at pH 7.5 (final pH from the reductive step). At least one complete reuse cycle (reduction/oxidation) was achieved with the separated mZVI. This approach might be interesting to treat wastewater containing pollutants initially resistant to hydroxyl radicals.

scholarly journals UVA-LED Technology’s Treatment Efficiency and Cost in a Competitive Trial Applied to the Photo-Fenton Treatment of Landfill Leachate

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1026
Author(s):  
Javier Tejera ◽  
Antonio Gascó ◽  
Daphne Hermosilla ◽  
Víctor Alonso-Gomez ◽  
Carlos Negro ◽  
...  
Keyword(s):  
Landfill Leachate ◽  
Mercury Vapor ◽  
Cod Removal ◽  
Treatment Efficiency ◽  
Alternative Source ◽  
Effluent Quality ◽  
Radiation Sources ◽  
Initial Ph ◽  
Pre Treatment ◽  
Set Up

The objective of this trial was to assess the application of UVA-LED technology as an alternative source of irradiation for photo-Fenton processes, aiming to reduce treatment costs and provide a feasible treatment for landfill leachate. An optimized combination of coagulation with ferric chloride followed by photo-Fenton treatment of landfill leachate was optimized. Three different radiation sources were tested, namely, two conventional high-pressure mercury-vapor immersion lamps (100 W and 450 W) and a custom-designed 8 W 365 nm UVA-LED lamp. The proposed treatment combination resulted in very efficient degradation of landfill leachate (COD removal = 90%). The coagulation pre-treatment removed about 70% of the COD and provided the necessary amount of iron for the subsequent photo-Fenton treatment, and it further favored this process by acidifying the solution to an optimum initial pH of 2.8. The 90% removal of color improved the penetration of radiation into the medium and by extension improved treatment efficiency. The faster the Fenton reactions were, as determined by the stoichiometric optimum set-up reaction condition of [H2O2]0/COD0 = 2.125, the better were the treatment results in terms of COD removal and biodegradability enhancement because the chances to scavenge oxidant agents were limited. The 100 W lamp was the least efficient one in terms of final effluent quality and operational cost figures. UVA-LED technology, assessed as the application of an 8 W 365 nm lamp, provided competitive results in terms of COD removal, biodegradability enhancement, and operational costs (35–55%) when compared to the performance of the 450 W conventional lamp.

Characteristics of p-chlorophenol degradation by Photo Fenton oxidation

2000 ◽  
Vol 42 (3-4) ◽  
pp. 219-224 ◽  
Author(s):  
J. Yoon ◽  
S. Kim ◽  
D.S. Lee ◽  
J. Huh
Keyword(s):  
Degradation Kinetics ◽  
Decomposition Kinetics ◽  
Fenton Oxidation ◽  
Oh Radical ◽  
Mercury Lamp ◽  
Batch Mode ◽  
Specific Objective ◽  
Initial Ph

This study investigated the characteristics of Photo Fenton oxidation in comparison with Fenton oxidation in dark environments. The specific objective was to provide an in-depth understanding as to how the presence of UV would effect the reaction and its efficiency as compared to the Dark Fenton Oxidation. All reactions were carried out in batch mode at an initial pH of 3.5, with H2O2 in excess and iron in catalytic concentrations. The medium pressure mercury lamp (320-400 nm) was used as a UV source. The role of UV in Photo Fenton Oxidation of p-chlorophenol was found to be manyfold as compared to Dark Fenton Oxidation. It included the expedition of ferric ion reduction and the photolysis of H2O2, which exerted a direct impact on the p-chlorophenol degradation kinetics by enhancing the production of OH radical. Also included in the role was alteration of the quantity (and potentially quality) of intermediates, which would lead to a change in the decomposition kinetics in an indirect manner. Therefore, it was concluded that the performance of Photo Fenton Oxidation as compared to Dark Fenton Oxidation could vary in complicated ways depending upon the characteristics of target compounds and their intermediates.

scholarly journals Degradation of Diallyl Phthalate (DAP) by Fenton Oxidation: Mechanistic and Kinetic Studies

2018 ◽  
Vol 9 (1) ◽  
pp. 23
Author(s):  
Sondos Dbira ◽  
Nasr Bensalah ◽  
Moustafa Zagho ◽  
Ahmed Bedoui
Keyword(s):  
High Performance ◽  
Hplc Analysis ◽  
Degradation Mechanism ◽  
Kinetic Studies ◽  
Cost Effective ◽  
Fenton Oxidation ◽  
Fenton’S Reaction ◽  
Toc Removal ◽  
Initial Ph ◽  
Diallyl Phthalate

In this work, the degradation and mineralization of Diallyl Phthalate (DAP) in water by Fenton oxidation was investigated. The effects of different experimental parameters including the initial pH, the hydrogen peroxide (H2O2) dose, the catalyst (Fe2+) dose, the iron source, and the DAP concentration on the rate and the yield of DAP degradation by Fenton oxidation were evaluated. DAP and its intermediates were quantified by high performance liquid chromatography (HPLC) analysis and the measurement of total organic carbon (TOC) during Fenton oxidation. The results obtained confirmed that hydroxyl radicals (HO•) generated from Fenton’s reaction were capable of completely eliminating DAP from water. Fenton oxidation of 100 mg/L DAP aqueous solution at pH = 3.2 required 1000 mg/L H2O2 and 50 mg/L Fe2+. Under these conditions, more than TOC removal exceeded 95% after 300 min Fenton oxidation. The competition kinetics method was used to determine an absolute rate constant of 7.26.109 M−1 s−1 for the reaction between DAP and HO• radicals. HPLC analysis showed that phthalic acid, 1,2-dihydroxybenzene, 1,2,4-trihydroxybenzene, maleic acid, formic acid and oxalic acid were the main intermediates formed during DAP degradation. Accordingly, a simple DAP degradation mechanism by the Fenton reaction was proposed. These promising results proved the potential of Fenton oxidation as a cost-effective method for the decontamination of wastewaters containing phthalates.

Fenton oxidation and chromium recovery from tannery wastewater by means of iron-based coated biomass as heterogeneous catalyst in fixed-bed columns

2018 ◽  
Vol 351 ◽  
pp. 1-11 ◽  
Author(s):  
Giorgio Vilardi ◽  
Javier Miguel Ochando-Pulido ◽  
Marco Stoller ◽  
Nicola Verdone ◽  
Luca Di Palma
Keyword(s):  
Heterogeneous Catalyst ◽  
Fixed Bed ◽  
Fenton Oxidation ◽  
Tannery Wastewater ◽  
Iron Based ◽  
Chromium Recovery

Heterogeneous Fenton oxidation of 2,4-dichlorophenol using iron-based nanoparticles and persulfate system

2015 ◽  
Vol 264 ◽  
pp. 587-594 ◽  
Author(s):  
Renchao Li ◽  
Xiaoying Jin ◽  
Mallavarapu Megharaj ◽  
Ravendra Naidu ◽  
Zuliang Chen
Keyword(s):  
Fenton Oxidation ◽  
Heterogeneous Fenton ◽  
Iron Based ◽  
Heterogeneous Fenton Oxidation

Analysis of a complex produced in the Fenton oxidation process

2014 ◽  
Vol 69 (5) ◽  
pp. 1115-1119 ◽  
Author(s):  
Chang Wang ◽  
Siyue Zhang ◽  
Sakai Yuji ◽  
Zongpeng Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Complex Formation ◽  
Hydroxyl Radical ◽  
Fenton Reaction ◽  
Oxidation Process ◽  
Fenton Oxidation ◽  
Radical Theory ◽  
Uv Visible ◽  
Iron Based ◽  
Fenton Oxidation Process

The absorbances of different concentrations of Fe2+, Fe3+ and H2O2 were investigated by UV-visible spectrophotometry without separating the substances. The law of complex formation was studied by considering changes in the UV-vis spectra of mixtures of these three substances. The results show that upon eliminating the influence of the substrate, an iron-based complex was present in the Fenton reaction, which exhibited substantial absorbance from 190 to 500 nm. Therefore, the presence of an unknown complex in the Fenton oxidation process was verified and its concentration varied with a change in the concentration of hydrogen peroxide. This study provides a strong foundation for further studies into the mechanism of traditional hydroxyl radical theory of the Fenton reaction.

Influence of some commercial proteases and enzymatic associations on the hydrolytic solubilization of deboned poultry meat proteins Influencia de algunas proteasas comerciales y preparados enzimáticos en la solubilización hidrolitica de las proteínas de la carne de pollo separada mecánicamente

2000 ◽  
Vol 6 (4) ◽  
pp. 301-306 ◽  
Author(s):  
L.H. de Barros Soares ◽  
D. Ney Marques ◽  
P. Melchionna Albuquerque ◽  
M.A. Záchia Ayub
Keyword(s):  
Soluble Protein ◽  
Proteolytic Enzymes ◽  
Poultry Meat ◽  
Initial Amount ◽  
Maximum Value ◽  
Initial Ph ◽  
Basic Source ◽  
Proteolytic Activities ◽  
Fungal Protease ◽  
Hydrolysis Of

Mechanically deboned poultry meat (MDPM) was used as a basic source of protein to assess the efficiency of seven proteolytic enzymes and some enzymatic associations over the hydrolysis of that protein. As a main parameter, the evolution of protein solubilization during 4 h of proteolysis was evaluated. The enzymes alcalase, esperase, flavourzyme, fungal protease, HT-proteolytic, papain, proteopex, and combinations of alcalase + flavourzyme, esperase + flavourzyme, HT-proteolytic + flavourzyme, and proteopex + flavourzyme were applied at concentrations of 0.60% and 1.20% of commercial product as a function of total protein. The initial pH was adjusted to 7.0 or 8.0 and the temperature was maintained at 50 °C or 60 °C according to optimal conditions for each enzyme. The proteolytic activities of the enzymes were also compared with azocasein. The hydrolysis index (HI), i.e., the rate between the maximum value and the initial amount of soluble protein was formulated to allow the comparison among treatments. Results showed that the temperature did not influence the proteolysis in the tested model. The association of alcalase + flavourzyme was shown to be more efficient than all other treatments, obtaining more than 70% of soluble protein. Fungal protease pre sented the lowest results.

scholarly journals Application Of Seeding Crystallization as a Pre-Treatment Stage for The Reduction of Scaling Tendency of Seawater Feed to Thermal Desalination Units

2021 ◽  
Vol 15 (1) ◽  
pp. 10-17
Author(s):  
Mazen N. Al-Amaireh
Keyword(s):  
Kinetic Parameters ◽  
Growth Kinetic ◽  
Growth Process ◽  
Ph Value ◽  
Operating Conditions ◽  
Integration Step ◽  
Surface Integration ◽  
Thermal Desalination ◽  
Initial Ph ◽  
Pre Treatment

Objective: The fouling inhibition in seawater desalination and scale control using crystallization with calcite seeds is evaluated experimentally in this study. Methods: The growth kinetic parameters are determined experimentally, correlated and discussed at different operating conditions. Supersaturation levels represent driving force behind the growth of crystals, which is influenced directly by seawater pH values and temperatures. Results: Results indicate that the initial pH value of seawater must be controlled to be in the range (8-9) and calcite seeds will not have the potential to start the growth process in seawater at the normal pH (7.36). The growth kinetic parameters are determined from the measured desupersaturation curves. Conclusion: It is found that the growth process of calcite is controlled by the surface integration step. The growth rate of calcite increases with increasing temperature and seeding ratio (up to 1 g/L), while it decreases with increasing the salinity of seawater.

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