Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.

/pdf/advanced-oxidation-processes-for-organic-contaminant-546ow329vb.pdf

Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry

Decontamination and disinfection of water by solar photocatalysis: Recent overview and trends

Fundamental principles and application of heterogeneous photocatalytic degradation of dyes in solution

Synthesis and photocatalytic activity of ferrites under visible light: A review

Dissolved organic matter (DOM) is defined as the organic matter fraction in solution that passes through a 0.45 μm filter. Although DOM is ubiquitous in terrestrial and aquatic ecosystems, it represents only a small proportion of the total organic matter in soil. However, DOM, being the most mobile and actively cycling organic matter fraction, influences a spectrum of biogeochemical processes in the aquatic and terrestrial environments. Biological fixation of atmospheric CO 2 during photosynthesis by higher plants is the primary driver of global carbon cycle. A major portion of the carbon in organic matter in the aquatic environment is derived from the transport of carbon produced in the terrestrial environment. However, much of the terrestrially produced DOM is consumed by microbes, photo degraded, or adsorbed in soils and sediments as it passes to the ocean. The majority of DOM in terrestrial and aquatic environments is ultimately returned to atmosphere as CO 2 through microbial respiration, thereby renewing the atmospheric CO 2 reserve for photosynthesis. Dissolved organic matter plays a significant role in influencing the dynamics and interactions of nutrients and contaminants in soils and microbial functions, thereby serving as a sensitive indicator of shifts in ecological processes. This chapter aims to highlight knowledge on the production of DOM in soils under different management regimes, identify its sources and sinks, and integrate its dynamics with various soil processes. Understanding the significance of DOM in soil processes can enhance development of strategies to mitigate DOM-induced environmental impacts. This review encourages greater interactions between terrestrial and aquatic biogeochemists and ecologists, which is essential for unraveling the fundamental biogeochemical processes involved in the synthesis of DOM in terrestrial ecosystem, its subsequent transport to aquatic ecosystem, and its role in environmental sustainability, buffering of nutrients and pollutants (metal(loid)s and organics), and the net effect on the global carbon cycle.

Dissolved Organic Matter: Biogeochemistry, Dynamics, and Environmental Significance in Soils

Neural network based approach for optimization of industrial chemical processes

Photo-Fenton degradation of wastewater containing organic compounds in solar reactors

The degradation of polyvinyl alcohol (PVA) by the photo-Fenton process was studied in laboratory scale, with aim of investigating the effect of process conditions on the polymer degradation rate. The experiments were based on a complete factorial design for the amounts of Fe(II) and H 2 O 2 added to water solutions of PVA of different concentrations. The degradation rate of the organic compounds was monitored along the time in discontinuous experiments by analyzing the dissolved organic carbon concentration (DOC) in the solutions. Under adequate conditions more than 90% of the DOC could be degraded in the process. Depending on the initial DOC concentration and the amounts of Fe(II) and H 2 O 2 added an insoluble phase is formed, which can be separated by mechanical methods, thus favoring the removal of organic contaminants in the treatment of industrial wastewaters containing PVA. The interpretation of the experimental results was based on the fitting of neural network models for predicting solid phase formation, and DOC concentration along the reaction time.

Study on the photo-Fenton degradation of polyvinyl alcohol in aqueous solution

Crude petroleum oils are complex mixtures of different compounds (mainly organic), which are obtained from an extensive range of different geological sources. The fluorescence of crude petroleum oils derives largely from the aromatic hydrocarbon fraction, and this fluorescence emission is strongly influenced by the chemical composition (e.g., fluorophore and quencher concentrations) and physical characteristics (e.g., viscosity and optical density) of the oil. The fluorescence spectroscopy (FS) is increasingly used in petroleum technology due the availability of better optical detection techniques, because FS offers high sensitivity, good diagnostic potential, and relatively simple instrumentation. In this work we analyzed crude petroleum at different dilution in Nujol, a transparent mineral oil. The main objective of this work was to verify the possibility to measure crude oil emission spectroscopic without use of volatile solvents. The mixtures of nujol with different -crude oil concentrations were measured with a 10 mm optical path cuvette thus simplifying the fluorescence spectroscopy signal detection. The emission spectra were obtained by exciting the samples with a 400 W Xenon lamp at 350 nm, 450 nm and 532 nm. The emissions of the samples were collected perpendicularly with the excitation axis.

/pdf/application-of-fluorescence-to-the-study-of-crude-petroleum-3c9fvbpfax.pdf

Application of Fluorescence to the Study of Crude Petroleum

We have investigated the kinetics of the degradation of 2,4-dimethyl aniline (2,4-xylidine), chosen as a model pollutant, by the photochemically enhanced Fenton reaction. This process, which may be efficiently applied to the treatment of industrial waste waters, involves a series of complex reactions leading eventually to the mineralization of the organic pollutant. A model based on artificial neural networks has been developed for fitting the experimental data obtained in a laboratory batch reactor. The model can describe the evolution of the pollutant concentration during irradiation time under various conditions. It has been used for simulating the behavior of the reaction system in sensitivity studies aimed at optimizing the amounts of reactants employed in the process — an iron(II) salt and hydrogen peroxide. The results show that the process is much more sensitive to the iron(II) salt concentration than to the hydrogen peroxide concentration, a favorable condition in terms of economic feasibility.

Roberto Guardani

Papers

Neural network based approach for optimization of industrial chemical processes

Photo-Fenton degradation of wastewater containing organic compounds in solar reactors

Study on the photo-Fenton degradation of polyvinyl alcohol in aqueous solution

Application of Fluorescence to the Study of Crude Petroleum

Modeling the kinetics of a photochemical water treatment process by means of artificial neural networks