Search

The decomposition of naphthalene in the presence of TiO2 dispersions irradiated with simulated solar light has been investigated in water and in aqueous Brij 35 solutions, used to wash soil samples containing the adsorbed pollutant. The monitoring of the reaction system performed during the treatment showed the formation of various aromatic intermediates, in turn degraded, which were identified using suitable analytical techniques. Fast and complete mineralization of naphthalene to CO2 was achieved when working in the absence of additives, whereas a neat inhibition of the degradation was observed in the presence of amphiphiles and other organic components coming from soil. Experimental conditions under which surfactant-containing washes can be treated were investigated and defined.

The degradation of Methyl Orange (C(14)H(14)N(3)SO(3)Na), chosen as a model sulfonated azo dye, was investigated in aqueous solutions containing suspended polycrystalline TiO(2) particles under irradiation with simulated sunlight. The dye disappearance and the formation of the mineralization end products were monitored; the formation of the main transient intermediates was also examined in detail. Particular attention was devoted to the identification and to the evolution of fragments retaining the chromophoric group. The comparison of data coming from various analytical techniques led to a possible reaction mechanism for the degradation process, giving insight into an aspect of the treatment which has not been considered in previous studies.

The photocatalytic degradation of carbaryl in aqueous TiO2 dispersions irradiated with simulated solar light was investigated. Complete mineralization of the pesticide to CO2 was observed, with the formation of nitrate and ammonium ions as nitrogen-containing end products. Various aromatic intermediates, detected during the process, were identified using HPLC and GC−MS techniques, and their kinetic evolution was also investigated. The formation of the transient compound 1,3-indandione, more persistent than carbaryl, was observed. From obtained analytical and kinetic data, a possible reaction scheme was proposed.

Food wastes are shown as a cost-effective source of added-value products for a wide number of uses. For soluble substances isolated from municipal biowastes, the present chapter reviews work performed in the last 7 years investigating the chemical nature, the physical-chemical properties, and the performance in chemical and environmental technologies, in material chemistry and in agriculture. Very recent unpublished data are also reported to show that ongoing research is a worthwhile effort to realise the full potential of the above refuse-derived biobased products. The available data allow a viable situation to be envisioned where urban waste-treatment plant are turned into biorefinery for the production of energy, chemicals and consumer products with friendly environmental impact. The perspectives for this scenario to become real are discussed.

Soluble bio-organic substances (SBO) isolated from urban biorefuses have been investigated in photocatalytic processes for wastewater treatment using a cationic dye, namely crystal violet (CV) as target compound. The SBO have been found to enhance the photobleaching of CV solutions with an optimal SBO concentration of ca. 20 mg L⁻¹. Mechanistic investigation based on chemical probes and changes in the absorption spectrum of CV in the presence of SBO seems to indicate that a complex formed between sensitizer and substrate plays a major role in the process. SBO have also been tested for the implementation of photo-Fenton processes at circumneutral media: the observed pseudo first order rate constants for CV decoloration was higher for UV/SBO/Fe(II)/H₂O₂ (5.5 × 10⁻³ min⁻¹) than for UV/Fe(II)/H₂O₂ (1.5 × 10⁻³ min⁻¹). A modified mechanism, in which HO· are less relevant that at the acidic medium, is in agreement with results of experiments carried out with chemical probes., Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

Soluble bio-based substances (SBO) have been isolated from urban waste. Their structural similarity with natural organic matter suggested exploring their activity in the photodegradation of organic substrates. In this work, they are shown to promote the photodegradation of monochlorophenols. Experiments performed with 1.0 × 10−4 M substrate solutions irradiated by simulated solar light in the presence of SBO showed the progressive degradation of all the probe substrates. The experimental data were fitted to a pseudo-first-order kinetics, and the rate constant was found to decrease in the following order: 2-chlorophenol > 3- chlorophenol > 4-chlorophenol. The effect of pH and SBO concentration on chlorophenols degradation was assessed. Experiments performed in the presence of selective scavengers along with EPR measurements supported the main role of singlet oxygen in the substrate photodegradation mechanism. Toxicity assays showed that the photodegradation of chlorophenols in the presence of SBO is accompanied with a progressive up to complete detoxification of the system. Moreover, no significant contribution of SBO to the whole system toxicity was observed. The results show how urban wastes can be a resource of photosensitizing bio-based substances to be explored in wastewater treatments., This work has been partially supported with Italian Ministero delle Politiche Agricole e Forestali funds for the Agrienergia project. The authors are also grateful to 7thFP, IRSES-2010-269128-EnvironBos Marie Curie Action, to Acea Pinerolese Industriale in Pinerolo, TO (Italy), for supplying the sourcing UBW material, and to Studio Chiono and Associati in Rivarolo Canavese, TO (Italy), for making available the pilot equipment for SBO production.

The aim of this paper (presented in Rome, Italy, at the 2nd Congress of Probiotics, Prebiotics, and New Food, September 7-9, 2003) was to provide an objective view of the regulatory trends at the European level specifically referring to probiotics, because until now they have never been directly mentioned nor officially or expressly regulated per food and/or dietary applications, excluding their use as "active principles" in pharmaceutical products. Such a report presented during a scientific congress could represent a potential link between the world of research and the world of industry, both of presently deeply engaged and attracted by the potentiality raised until now, as per the application of probiotics under different points of view.

Surfactant-based separation techniques largely exploit the solubilization power of micelles and other amphiphilic aggregates towards a great variety of hydrophilic and hydrophobic solutes. Micellar extraction, based on the cloud-point phenomenon, and micellar ultrafiltration have been succesfilly applied for preconcentration and removal of organic and inorganic analytes of environmental concern from aqueous media. In particular, the recent development of chelating surfactant aggregates allows to perform very selective demetallation treatments. The factors which control the separation efficiencies of these methods are examined and discussed.

A bio-organic substances (BOS) was isolated from urban bio-refuse undergoing aerobic biodegradation. The isolated BOS was characterized for chemical composition and performance as sensitizers for the photodegradation of azo-dyes in solution. Three commercial sulphonated azo-dyes, i.e., ethylorange (EO), Orange I (OI) and Orange II (OII), were selected as probe molecules. For these molecules high abatement rates (60–100%) were obtained within few hours of irradiation in the presence of BOS, whereas almost no abatement was observed in the absence of BOS. A delay in the color bleaching was observed, in comparison to the dyes degradation; coloured intermediates were identified. Acute toxicity tests showed a low toxicity for the samples at the end of the degradation process.

The versatility and efficiency of the VUV photolysis of water as an “Advanced Oxidation Procedure” for the light-induced oxidative degradation of atrazine as a pollutant of surface and ground waters is evaluated. The oxidation of atrazine using TiO2 as a photocatalyst has been reported to produce almost stoichiometric amounts of cyanuric acid. Mineralization to CO2, water and inorganic nitrogen containing ions occurred to a very low extent implying that cyanuric acid is resistant to further degradation under the chosen experimental conditions. Our present results show that in oxygen saturated solutions 50% of the initial atrazine is converted to cyanuric acid, whereas only 10% of the initial atrazine is isolated as cyanuric acid in argon saturated solutions. The results indicate that mineralization is more efficient in not strictly oxidative reaction media.

Surfactant-assisted soil washing and photocatalysis are well-known remediation processes of environmental concern. The application of photocatalysis to treat soil washing extracts containing 4-methylphenol, 4-ethylphenol and 4-tert-butylphenol in the presence of nonionic (C(12)E(8) and C(12)E(23)) and anionic (SDS) surfactants and some of their binary mixtures was investigated in this work by studying the pollutants degradation in the presence of TiO(2) dispersions irradiated with simulated solar light.Clean soil samples were spiked with the investigated alkylphenols. Aqueous solutions of the chosen surfactants were placed in contact for some hours with the spiked soil samples in a rotatory mixer. The pollutants recoveries were evaluated via HPLC analysis. Photocatalytic experiments were performed in solarbox on aqueous solutions and on aqueous surfactant solutions containing the pollutants.The pollutants removal from the soil was proven effective using the examined surfactant solutions. The photocatalytic treatment of the wastes was faster using Brij 35, but also SDS and C(12)E(8)-SDS mixtures can be applied. After 2-5 h the complete pollutants abatement was obtained, depending on the surfactant chosen and on the amount of TiO(2) employed. On the contrary, the treatment of wastes containing C(12)E(8) was an extremely slow process.The photocatalytic approach can be applied to remove the examined aromatic pollutants from the washing wastes, confirming the viable coupling between this advanced oxidation method and the surfactant-based soil remediation treatments. Surfactant adsorption onto TiO(2) and micelles concentration play a dominant role.

Urban waste-derived bioorganic substances (UW-BOS) have shown promise as chemical auxiliaries for a number of technological applications in the chemical industry and in environmental remediation. In this study, the application of these substances in the photodegradation of organic pollutants is addressed. The experimental work is specifically focused on the photolysis mechanism promoted by AC8, a UW-BOS isolated from a 2:1 w/w mixture of food and green residues, composted for 110 days, using 4-chlorophenol (4-CP) as probe molecule. The production of (⋅)OH and the ¹O₂ is monitored by EPR spectroscopy. The correlation between radical species evolution and photodegradation of 4-CP is investigated. The effect of ¹O₂ and (⋅)OH scavengers on the 4-CP degradation process is also checked. The results suggest that the role of these species in the photodegradation of 4-CP depends on AC8 concentration. AC8 is thereby proven to be a photosensitizer for applications in environmental remediation. The results on AC8 further support the use of urban bio-waste as a versatile source of chemical auxiliaries of biological origin for use in diversified applications.

Traces of aluminium were preconcentrated in water samples by forming a complex with lumogallion, and successfully accumulated in the micellar phase obtained from cationic or non-ionic surfactants and filtered through 10 000 molecular weight cut-off ultrafiltration membranes. Studies indicated that, at pH 5.9, with 1 X 10 −3 M lumogallion and 2 X 10 −2 M cetyltrimethylamonium bromide, quantitative retention of aluminium present at μg ml −1 concentration levels was achieved. A micellar-enhanced fluorimetric procedure was employed to analyse the permeate solutions, whereas nitrous oxide-acetylene flame atomic emission spectrometry was used to determine aluminium in the retentate. The experimental parameters that influence the micellar-enhanced ultrafiltration (MEUF) efficiency were investigated and the analytical procedures were optimized. the MEUF of trace levels of aluminium allows for either preconcentration of the analyte or enhancement of the emission signals.

The photocatalytic degradation of Monuron (3-(4-chlorophenyl)-1-1-dimethylurea) in aqueous TiO2 dispersions irradiated in the near-UV region has been investigated by using a Pyrex batch photoreactor. The Monuron and total organic carbon concentrations were determined; several reaction intermediates were also identified using HPLC. The influence on the degradation kinetics of the initial Monuron concentration, of the TiO2 concentration, and of the initial pH of dispersion was studied. A pseudo-first order kinetics of Langmuir-Hinshelwood type was found to satisfactorily describe the Monuron degradation. The mineralization of the pollutant was virtually complete in the 3–9 pH range while at pH = 1.0 and 11.0 only a partial mineralization was reached even after a long irradiation time. The quantum yield values of Monuron degradation were determined by measuring the photon flow transmitted by the dispersion and applying a macroscopic photon balance on the photoreactor. The quantum yields were found to increase by increasing the pH of the dispersion.

To promote bio-based products for the industry, six bio-organic substances (cHALi) isolated from yard trimmings (green) and food (humid) urban residues aged under aerobic digestion for 0–60 days were investigated for their potential to perform as sensitizers for azo-dyes photodegradation. Ethylorange (EO) was used as probe molecule at 5 mg L −1 starting concentration and irradiated in a closed Pyrex ® cell with a Xenon (1500 W) lamp and a cut-off filter for wavelengths below 340 nm or in a cylindrical photochemical reactor equipped with a 125 W medium pressure Hg lamp. The cHALi/EO ratio in the starting EO solution varied in the 0–200 (w/w) range. The % dye abatement was found a function of the irradiation time, of the type of cHALi substance and of the cHALi/EO ratio. The best results were achieved with cHALi isolated after 7 days biomass aerobic digestion. Total dye abatement was achieved within relatively short few hours. A progressive dye mineralization was observed under the same experimental conditions. On the contrary no significant degradation was evident for the cHALi substances within the same irradiation time. Several hydroxylated azo compounds were identified as likely responsible of residual color after total EO abatement. The results, coupled to the previously reported good performance of the same cHALi substances as auxiliaries for textile dyeing, augur well for the development of both efficient and environmentally friendly textile dyeing processes.

Quantitative removal of uranyl ions present in aqueous solutions at the μg ml −1 concentration level was achieved using the micellar-enhanced ultrafiltration technique. Suitable chelating micelles were formed by dissolving selective hydrophobic acyclic ligands in the usual amphiphilic aggregates. These ligand-doped miceles accumulate the uranyl ions through the formation of tightly bound chelates. The aggregates and their guest metal complexes were successively separated by ultrafiltration through hydrophilic membranes of suitable pore size. The efficiency of the process is related to the affinity of the ligands for the micelles. Non-ionic and cationic surfactants were investigated. Quantitative retention of the analyte in the surfactant-rich retente solution was achieved when working with cetyltrimethylammonium bromide micelles. The uranyl recovery was significantly increased by introducing trioctylphosphine oxide as an auxiliary ligand, which allowed for very efficient preconcentrations at lower pH.

The effect of simulated solar light on nitrobenzene degradation in Fe⁺³ /H₂ O₂ solutions was investigated under different experimental conditions. Consumption profiles of NBE and H₂ O₂ display an autocatalytic kinetic behavior for both dark and photo-assisted degradation experiments. The rates of the initial slow phase that precedes the catalytic phase are significantly enhanced by irradiation, although the effect of simulated solar light on the rates of the fast phase is negligible. The absolute rates of the slow phase increase with the concentrations of Fe⁺³ and H₂ O₂ , whereas the initial rate of the degree of conversion increase decreases with organic matter loading. The reaction progress was characterized by HPLC, GC–MS, IC, TOC (total organic carbon) and toxicity analyses. The main products detected were 4-nitrophenol, 3-nitrophenol, 2-nitrophenol, 1,3-dinitrobenzene, phenol, oxalic acid, formic acid, NO₂ − and NO₃ − . Product distribution profiles are discussed in connection with TOC and toxicity measurements. The results show that dark treatment is neither capable of lowering the organic content nor capable of reducing the effluent toxicity to acceptable levels. On the other hand, photo-assisted processes induced by simulated solar light can significantly enhance both mineralization and detoxification efficiencies., Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

High-performance liquid chromatography coupled to ultraviolet diode array detection and electrospray ionization mass spectrometry was applied to monitor the photocatalytic degradation mediated by TiO2 of three sulfonated monoazo dyes (Orange I, Orange II, and Ethylorange) present in aqueous solution. Photobleaching, organic carbon, nitrogen and sulfur evolution were also followed during the process. Delayed carbon mineralization was observed with respect to both dyes disappearance and photobleaching, due to the formation of transient intermediate compounds which were in turn completely degraded. Among the intermediates produced during the initial degradation steps the formation of several hydroxylated derivatives, mostly coloured, was evidenced. The MS(2) spectra allowed one to formulate hypothesis about the OH attack positions; a peculiar reactivity of the azo moiety was shown by Orange I and Orange II.

The possible application of two environmental remediation technologies – soil washing and photocatalysis – to remove and decompose various aromatic pollutants present in excavated soils of a contaminated industrial site has been investigated. Aqueous solutions containing the non-ionic surfactant Brij 35 were used to extract the contaminants from the soil samples. The photocatalytic treatment of the obtained washing wastes, performed in the presence of TiO2 suspensions irradiated with simulated sunlight, showed a slow abatement of the toxic compounds due to the relevant concentrations of organics in the waste. A neat improvement of the process performances, obtained by operating in the presence of added potassium peroxydisulfate, suggests a feasible treatment route.