Effect of the type of soil on dimethyl phthalate degradation by ozone.

In the present study, ozone was applied for the removal of dimethyl phthalate (DMP) from soil. The effect of several experimental parameters was investigated considering, the initial DMP concentration, ozone flow, the type of soil (sand and agricultural soil) and the presence of α-FeOOH as a potential catalyst in the reaction system with sand. The elimination of DMP using ozone is significantly affected by the type of soil. In the case of sand, conventional ozonation was capable to degrade 74% of the initial DMP concentration (0.5 mg g-1) after 8 h of the reaction, however, the mineralization degree was below 50%. Under the same experimental conditions, the complete elimination of DMP was achieved when calcined agricultural soil was present reaching a 70% of mineralization. The presence of metal oxides in calcined agricultural soil combined with ozone produced oxidants species which were responsible of incrementing the mineralization degree (around 20% in comparison with the sand). The toxicity tests on lettuce seed demonstrated lower toxicity of DMP byproducts after ozonation. The DMP high removal efficiencies and the lower toxicity of generated byproducts in soil prove the applicability of ozone treatment for soil remediation.

Effect of additives on ozone-based decomposition of Reactive Black 5 and Direct Red 28 dyes.

In this research, ozonation of Reactive Black 5 (RB5) and Direct Red 28 (DR28) under the presence of Na2SO4 and Na2CO3 used as textile additives was investigated. The effect of these salts on discoloration, degradation dynamics, and the composition of the final compounds were studied. Different systems were evaluated; such as RB5-Na2SO4 (100 g/L), RB5-Na2CO3 (30 g/L), RB5-Na2SO4/Na2CO3 (100 g/ L/30 g/L), and DR28-Na2SO4 (10 g/L, 40 g/L, and 80 g/L) with dye concentrations of 50, 150, and 250 mg/L without pH adjustment. Discoloration of RB5 and DR28 with and without additives was determined by visible and UV (UV-Vis) spectroscopy. Decomposition of the dyes and the dynamics of intermediates and final byproducts were followed by high performance liquid chromatography. The presence of additives accelerated discoloration and decomposition for both dyes (more than 50%). The accumulation of oxalic and formic acids was observed. Possible mechanism schemes of ozonation for both dyes are proposed.

BTEX decomposition by ozone in gaseous phase.

Environment management is turning its efforts to control the air pollution. Nowadays, gas phase contaminants coming from different sources are becoming into the main cause of serious human illness. Particularly, benzene, toluene, ethylbenzene and xylene (BTEX) are getting more and more attention from the scientific community due the high level of volatilization showed by these compounds and their toxicity. Decomposition of these compounds using different treatments is requiring lots of new strategies based on novel options. In the present work the use of ozone was proposed as possible alternative treatment in the gaseous phase of VOC's liberated from water by stripping. This study deals with the decomposition by ozone in gaseous phase of model mixtures of BTEX stripped from water. The experiments were realized in a tubular reactor with fixed length (1.5 m length and diameter of 2.5 cm). The experiments were conducted in two stages: in the first one, organics was ventilated by oxygen flow to liberate BTEX to the gaseous phase; second stage deals with the liberated BTEX decomposition by ozone in the tubular reactor. Ozonation efficiency was determined measuring the VOC's concentration at the output of the tubular reactor. This concentration was compared to the concentration obtained at the input of the reactor. The obtained results confirm the possibility to use of ozone for the VOC's decomposition in gaseous phase. Also, the dynamic relationship between degradation and liberation was studied and characterized.

Phenanthrene degradation in soil by ozonation: Effect of morphological and physicochemical properties.

The aim of this study was to characterize the ozone reaction with phenanthrene adsorbed in two types of soils (sand and agricultural). The effect of soil physicochemical properties (texture, bulk density, particle density, porosity, elemental composition, permeability, surface area and pore volume) on the phenanthrene decomposition was evaluated. Commercial sand has a uniform morphology (spherical) with a particle size range between 0.178 and 0.150 mm in diameter, regular elemental composition SiO2, specific density of 1701.38 kg/m3, a true density of 2492.50 kg/m3, with an effective porosity of 31%. On the other hand, the agricultural soil had heterogeneous morphology, particle size between 0.1779 and 0.05 mm in diameter, elemental composition was montmorrillonite silicon oxide, apparent density of 999.52 kg/m3, a true density of 2673.55 kg/m3, surface area of 34.92 m2/g and porosity of 57%. The percentage of phenanthrene decomposition in the sand was 79% after 2 h of treatment. On the other hand, the phenanthrene degradation in the agricultural soil was 95% during the same reaction time. The pore volume of soil limited the crystal size of phenanthrene and increased the contact surface with ozone confirming the direct impact of physicochemical properties of soils on the decomposition kinetics of phenanthrene. In the case of agricultural soil, the effect of organic matter on phenanthrene decomposition efficiency was also investigated. A faster decomposition of initial contaminant and byproducts formed in ozonation was obtained in natural agricultural soil compared to the sand. The partial identification of intermediates and final accumulated products produced by phenanthrene decomposition in ozonation was developed. Among others, phenanthroquinone, hydroquinone, phenanthrol, catechol as well as phthalic, diphenic, maleic and oxalic acids were identified.

Application of a neural observer to phenols ozonation in water: simulation and kinetic parameters identification.

Presented in this study, a dynamic neural network (DNN) is employed to estimate the states dynamics of the phenols-ozone-water system. A new technique based on the dynamic neural network observer (DNNO) with relay (signum) term is applied to estimate the decomposition dynamics of phenols and to identify their kinetic parameters without any mathematical model usage. The decomposition of phenols (phenol (PH), 4-chlorophenol (4-CPH) and 2,4-dichlorophenol (2,4-DCPH)) and their mixture by ozone, realized in a semi-batch reactor, is considered as a process with uncertain model ("black-box"). Only one parameter monitoring, namely, the ozone concentration in gas phase in the reactor outlet, is measured during ozonation. The variation of this variable is used to obtain the summary characteristic curve for the phenols ozonation. Then, using the experimental decomposition dynamics of phenols and of their mixture, obtained by HPLC method, the proposed DNNO is applied to estimate the ozonation constants of phenols at the different pH 2-12. A good correspondence between the decomposition dynamics and the estimated ones by DNNO is obtained.

Distribution of the total unsaturation in lipid components of plasma as a new differential diagnostic method in clinical analysis.

Using ozonization and thin-layer chromatographic methods we determined the qualitative and quantitative correlation of unsaturation distribution (UD) in individual fractions of blood plasma lipids in children suffering from insulin-dependent diabetes mellitus (IDDM). The research was aimed at elucidation of biochemical criterion of the degree of metabolic disorders in children with IDDM and at development of methods for quantitative assessment of such disorders. Twenty children were examined during the compensation stage (group 1), and twelve during decompensation with ketoacidosis (group 2). The present investigation shows that in the case of insulin-dependent diabetes mellitus in children the total unsaturation distribution (TUD) in plasma lipid fractions were found to be decreased significantly compared to healthy controls. The pattern of TUD in plasma lipid fractions may serve as a new biochemical criterion for metabolic disorders and decompensation in IDDM.

Switching robust control for ozone generators using the attractive ellipsoid method.

This paper deals with a switching robust tracking feedback design for a corona-effect ozone generator. The generator is considered as a switched systems in the presence of bounded model uncertainties as well as external perturbations. Three nonlinear dynamic models under arbitrary switching mechanisms are considered assuming that a sample-switching times are known. The stabilization issue is achieved in the sense of a practical stability. We apply the newly elaborated (extended) version of the conventional attractive ellipsoid method (AEM) for this purpose. The same analysis was efficient to obtain the minimal size of region where the tracking error between the trajectories of the ozone generator and reference states converges. The numerically implementable sufficient conditions for the practical stability of systems are derived based on bilinear matrix inequalities (BMIs).

Remediation of lignin and its derivatives from pulp and paper industry wastewater by the combination of chemical precipitation and ozonation.

In the present work the degradation of the lignin and its derivatives in the residual water of a paper industry by simple ozonation was investigated. The remediation of lignin was realized using the combination of the pre-treatment with chemical precipitation, using concentrated sulfuric acid (97.1%) at the pH 1 and 3, and of the simple ozonation of the filtered residual water at the pH 1, 3, 8 and 12. Since the high residues content (the initial chemical oxygen demand (COD) is 70,000 mg/L) in the experiments the diluted samples (1:10) were used. The previous precipitation has showed a significant effect on the reduction of the COD (77%) and color (96.1%). The sludge precipitated contents sulfolignin, which in the reaction with sulfuric acid was formed. In ozonation of the filtered residual water during 25 min at the pH 1, 3, 8 and 12 the follows by-products were formed: fumaric, maleic, malonic and formic acids. The biodegradability of the treated water in ozonation increases up 0.067-0.29. The effect of the precipitation and the ozonation conditions on the decolorization kinetics was evaluated.

Estimation of unsaturated hydrocarbon pollutants in air based on selective gas chromatography with ozone.

Regular monitoring of toxic organic pollutants in air is a very important issue in environmental pollution control. Among these, unsaturated hydrocarbon pollutants (UHP) such as ethylene and beta-propylene and another 18 olefins are of prime importance. A very fast method for the individual identification of UHPs in air is proposed. This method is based on gas-chromatographic separation with selective detection of unsaturated organic compounds (UOC) and on the chemical reaction of UOC with ozone in the gas phase. In view of the mathematical model derived for this ozonation process, a comparison of FID-chromatogram and ozonogram can be carried out for identification of the contaminants. This identification can be performed without preliminary separation in the presence of the main components. The method provides a high sensitivity (< 0.005 to 0.72 mass %) and selectivity.

Chromium toxic effect monitoring using ozonation method.

The hexavalent chromium toxicity (in vitro) to plasma, erythrocytes, and semen lipids was evaluated. The ozonation technique is suggested to realize the rapid measurements of the lipid peroxidation (LPO) by means of the double bond indexes (DB-index and DB(cell)-index) calculation. The obtained experimental results permit to conclude that it is possible to detect the chromium effect on LPO by ozonation. The DB-index and DB(cell)-index determination in the plasma, erythrocytes, and sperm can be considered as a measure of this effect. Ozonation, suggested in this work, can provide the useful preliminary information for specialists and is a quantitative, fast, inexpensive, and simple method. In view of these comments, we conclude that the suggested ozonation method can be considered as the acceptable modern technique for the chromium toxic effect monitoring in vitro.