Use Of Fenton's Reagent Research Articles

Comparison of two excilamps and two reactor configurations in the UV-H2O2 removal process of amaranth

Nowadays dyes are used in many industrial activities and their presence in wastewater is quite common and involves different environmental and health problems. In addition, dyes are usually recalcitrant compounds and conventional treatment are not appropriate for their removal. So there is great interest in finding alternative removal processes, as the one based on excimer lamp technology for the removal of amaranth dye described in the present work. Two excilamps and two reactor configurations have been tested: a batch reactor with KrCl or XeBr excilamp and a KrCl flow-through photoreactor. After comparing the results for both lamps in the batch reactor, the KrCl excilamp has proven to be more efficient both in terms of conversions achieved and energy consumption and, by this, it has been selected to be used in the flow-through photoreactor. For both reactor configurations, several experimental series were done to analyze the influence of the different operational variables on the photoprocess and the optimal mass ratio between hydrogen peroxide and dye has been established. Also, it has been proven that the use of Fenton reagent improves the process efficiency, particularly in the case of the XeBr lamp.In addition, a kinetic model, based on a previous one developed by the authors for a flow-through photoreactor and slightly modified to can also apply it to batch reactors, has been applied. The model has been validated with an excellent fitting of the experimental data for all series and both reactor configurations.

Preliminary studies on the use of Fenton reagent to reduce pollution from wastewater from the production of household chemicals

Abstract Industrial sewage from the production of household chemicals contain large amounts of impurities in the form of ionic and non-ionic surfactants, detergents, active extenders, enzymes. The mixture of these components means that the reduction of pollutants from this type of waste-water is very burdensome. The article presents the results of preliminary laboratory tests of the possibility of using Fenton reaction in the reduction of pollution in wastewater from the household chemistry industry. The reduction of impurities was determined by the concentration of COD. The tests were carried out on samples of wastewater taken from an industrial wastewater treatment plant from the production of household chemistry. A pollution reduction of 24.7–32.3% was achieved. On the basis of the preliminary tests carried out, the need to better match the doses of reagents to carry out pollution reduction was determined. Despite obtaining values exceeding the limit values for introducing this type of sewage into the sewage system and into the environment, the conducted tests can be considered as prognostic. To compare the process carried out on industrial waste-water, a reduction of impurities was carried out using the Fenton reagent in the standard phenol solution.

Depolymerization of microcrystalline cellulose by the combination of ultrasound and Fenton reagent

In this study, the combined use of Fenton reagent and ultrasound to the pretreatment of microcrystalline cellulose (MCC) for subsequent enzyme hydrolysis was investigated. The morphological analysis showed that the aspect ratio of MCC was greatly reduced after pretreatment. The X-ray diffraction (XRD) and degree of polymerization (DP) analyses showed that Fenton reagent was more efficient in decreasing the crystallinity of MCC while ultrasound was more efficient in decreasing the DP of MCC. The combination of Fenton reaction and ultrasound, which produced the lowest crystallinity (84.8±0.2%) and DP (124.7±0.6) of MCC and the highest yield of reducing sugar (22.9±0.3g/100g), provides a promising pretreatment process for MCC depolymerization.

Use of Fenton reagent combined with humic acids for the removal of PFOA from contaminated water

Perfluorinated compounds (PFCs) are receiving significant attention due to its global distribution, high persistence, and bioaccumulation properties. Among them, perfluorooctanoic acid (PFOA) is one of the most commonly found in the environment. The strong bond C–F in PFOA is extremely difficult to degrade, therefore advanced oxidation processes (AOPs) at room temperature and pressure are not able to oxidize them, as was noticed here using Fenton like reagent (FR) or persulfate (PS) at 25°C. On the contrary, by using persulfate activated by heat (100mM and T=70°C) a complete defluorination of PFOA 0.1mM was noticed after 18h, with a sequential degradation mechanism of losing one CF2 unit from PFOA and its intermediates (perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPA) and perfluorobutanoic acid (PFBA)).Since this thermal treatment is not usually desirable from an economical point of view, alternative process has been tested. For this scope, a hybrid process is proposed in this work, by adding humic acid, HA, (600mgL−1) and FR, (165mM in H2O2 and 3mM in Fe3+) to the 0.1mM PFOA solution. It was found that the HA was oxidized by FR. PFOA was entrapped quantitatively and irreversibly during HA oxidation, resulting PFOA non-available to the aqueous phase. Oxidized HA with PFOA entrapped precipitates. Both, the leftover Fe(III) acting as a coagulant and neutral pH enhance the separation of this solid phase. The precipitation noticed by adding HA to the PFOA solution in absence of FR was negligible.

Removal of Refractory Pollutants from Landfill Leachate Using Two‐Phase System

The study focused on the problem of removing refractory substances from leachate treated by means of activated sludge method and advanced oxidation process. Biological treatment was conducted in sequencing batch biofilm reactor. Biologically treated leachate was subject to further chemical treatment with the use of Fenton reagent. The permanent dosage of H2O2 amounting to 2 mg x L(-1) was applied. Fe(II):H2O2 ratio was 1:10, 1:5 and 1:3. Biological treatment allowed for removing 97% of benzene and only 20% of ethylbenzene. There was a 25% decrease in the concentration of volatile organochlorine compounds. The concentration of benzene in chemically treated leachate increased in comparison with the value found in biologically treated leachate and the growth coincided with the decreasing Fe(II):H2O2 ratio. An analysis of polycyclic aromatic hydrocarbons showed that leachate subjected to advanced oxidation contained the sum of polycyclic aromatic hydrocarbons that was lower than in biologically treated leachate, irrespective of Fe(II):H2O2 ratio.

Using central composite experimental design to optimize the degradation of real dye wastewater by Fenton and photo-Fenton reactions

This work focuses on the use of Fenton reagent and UV-irradiation, in a lab-scale experiment, for the treatment of real dye wastewater coming from a Spanish textile manufacturer.Response surface methodology and a 23 factorial design were used to evaluate the effects of the three independent variables considered for the optimization of the oxidative process: temperature, Fe (II) and H2O2 concentrations, for a textile wastewater generated during a dyeing process with chemical oxygen demand of 1705 mg L−1 O2 at pH = 3. Wastewater degradation was followed in terms of chemical oxygen demand reduction.In the optimization, the correlation coefficients for the model (R2) were 0.985 and 0.990 for Fenton and photo-Fenton treatments respectively. Optimum reaction conditions at pH = 3 and temperature = 298 K were [H2O2] = 73.5 mM and [Fe(II)] = 1.79 mM.The combination of Fenton, Fenton-like and photon-Fenton reactions has been proved to be highly effective for the treatment of such a type of wastewaters, and several advantages for this technique arise from the study. Under optimum conditions, 120 min of treatment resulted in a 62.9% and 76.3% reduction in chemical oxygen demand after Fenton and photo-Fenton treatments respectively.

Fenton and photo-Fenton oxidation of textile effluents

The simultaneous use of Fenton reagent and irradiation for the treatment of textile wastewaters generated during a hydrogen peroxide bleaching process is investigated. The experimental conditions tested during this study provide the simultaneous occurrence of Fenton, Fenton-like and photo-Fenton reactions. The batch experimental results are assessed in terms of total organic carbon reduction. Identification of some of the chemical constituents of the effluent was performed by means of GC–MS. Other pollution related features of the initial effluent-like COD and color were also measured. The main parameters that govern the complex reactive system, i.e., light intensity, temperature, pH, Fe(II) and H 2O 2 initial concentrations have been studied. Concentrations of Fe(II) between 0 and 400 ppm, and H 2O 2 between 0 and 10,000 ppm were used. Temperatures above 25°C and up to 70°C show a beneficial effect on organic load reduction. A set of experiments was conducted under different light sources with the aim to ensure the efficiency of using solar light irradiation. The combination of Fenton, Fenton-like and photon-Fenton reactions has been proved to be highly effective for the treatment of such a type of wastewaters, and several advantages for the technique application arise from the study.

Use of fenton reagent to improve organic chemical biodegradability

Fenton reagent has been used to test the degradation of different organic compounds (formic acid, phenol, 4-chlorophenol, 2,4-dichlorophenol and nitrobenzene) in aqueous solution. A stoichiometric coefficient for the Fenton reaction was found to be 0.5 mol of organic compound/mol of hydrogen peroxide, except for the formic acid where a value of approximately one was obtained (due to the direct formation of carbon dioxide). The treatment eliminates the toxic substances and increases the biodegradability of the treated water (measured as the ratio BOD 5/COD). Biodegradability is attained when the initial compound is removed.