Analysis of the Toxicity of Phenol Solutions Treated with H₂O₂/UV and H₂O₂/Fe Oxidative Systems

Abstract

This study investigates the environmental quality of water treatments by evaluating the effectiveness of advanced oxidation technologies, such as H2O2/Fe(II) and H2O2/UV, in treating phenol-contaminated effluents. Toxicity measurements complement the chemical analyses used to evaluate the environmental quality of a treated effluent and are an additional method for interpreting the effects of chemicals not directly measured. This study proposes an estimation model for toxicity based on the Microtox test that is adaptable to the contaminant concentration of each case. The model allows for analysis of the contribution of the different components of the treated effluent: hydrogen peroxide, phenolics, colored compounds, and others. In the second part of this work, a study was conducted of the toxicity of samples treated with the aforementioned oxidative systems. In the Fenton system, the sample after oxidation was analyzed, and it was observed that the toxicity was due to intermediate oxidation compounds, such as carboxylic acids, which rejects the influence of compounds of color and other phenolics. The H2O2/UV system tracks the progress of toxicity. This parameter quickly reaches minimum values (within about 15 min) from the start of the reaction and is a representation of the final values of primary degradation. Therefore, it is not recommended to extend the oxidation beyond this point to minimize the toxicity.

Heterogeneous catalytic oxidation of phenol by in situ generated hydrogen peroxide applying novel catalytic membrane reactors

“…A comparison of these values suggests that about 10-15% of the generated peroxide is directly involved in the organic oxidation. The results therefore are not very far from the recommended conditions for the Fenton reaction where usually an oxidant excess of about 3-5 times with respect to the organic matter is considered [7]. The efficiency is calculated as…”

“…This chemical remediation technique uses hydrogen peroxide and ferrous ions (Fe 2+ ) which catalyze the generation of OH Å . This technology is available commercially but possesses some drawbacks: it works under acid conditions (range of pH 2.5-3.5), require from 5 to 10 time the stoichiometric amount of H 2 O 2 , and the catalyst recovery requires several steps that increase the operational costs [6,7]. Different approaches have been developed to turn the homogeneous Fenton reaction to heterogeneous one, known as Fenton-like processes [8,9].…”

A complete phenol oxidation pathway obtained during electro-Fenton treatment and validated by a kinetic model study

“…classical Fenton process [9][10][11][12][13][14][15][16], Fenton-like treatment [17][18][19] and photo-Fenton process [20][21][22]. However, only two papers refer to electro-Fenton process [23,24].…”

Influence of substituent type and position on photooxidation of phenolic compounds: Response surface methodology approach

“…According to U.S. EPA [3] and European Commission [4] phenols, chloro-and nitro-substituted phenols are characterized as the priority pollutants. They are hardly biodegradable and difficult to remove from the environment, and moreover highly toxic, mutagenic and carcinogenic [3][4][5][6][7][8].…”

“…Among various types and combinations of AOTs, photochemical processes based on usage of strong oxidants, e.g. H 2 O 2 , are shown to be suitable for the degradation of various phenols and other aromatic pollutants [5,6,[11][12][13][14].…”