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The aim of this investigation was to evaluate the modification of physicochemical properties (viscosity and density) of four vegetable oils (grapeseed, sunflower, avocado, and olive) during ozonation, and to relate such variation with the ozonation kinetics, the ozonation degree, and the ozonation by-products distribution. During ozonation, the monitorization of the double bonds' decomposition and accumulation of ozonation by-products yields defined the relationship between the ozonation degree and the physicochemical properties of the ozonated oils. The ozonated oils were characterized by FT-IR and 1H NMR. The ozonation degree was determined by the measurement of the total unsaturation (TU); this method quantified the substrate reactive with ozone contained in oils. During the ozonation, the variation of viscosity, density, and ozonation by-products exhibited differences among the studied oils, which was effectively correlated to the corresponding ozonation degree. These were characterized by the observed reaction rate constants obtained by a parametric algorithm based on the application of a nonlinear least mean square method. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an adaptive state estimator with discontinuous parameter adjustment law for the catalytic ozonation system. A nonlinear transformation defined an equivalent system presented in chain-of-integrators form with uncertain structure in the dynamics of the last state. A step-by-step state estimator using a sequence of super-twisting algorithms (STAs) estimated the unmeasured states of the uncertain system. A class of differential neural network (DNN) with discontinuous learning law served to estimate the uncertain section of the catalytic process. The learning method was developed by implementing a strong lower-semi-continuous Lyapunov function. The method used to generate the laws that adjusted the weights, also yields the estimation of the parameters included in the catalytic ozonation system. A set of numerical simulations demonstrated the application of the DNN-based state observer to solve the estimation of the non-measurable information in the catalytic ozonation system. The available output signal was the concentration of the ozone gas at the output of the reactor. This was the only information used by the observer. The state estimator with discontinuous learning laws was also evaluated with experimental information obtained by a catalytic ozonation system using NiO as catalyst and phtalic acid as model contaminant. The effect of aggregating the DNN in the observer structure was compared with the observer using only the sequence of STA. The superior performance of the observer developed in this study was confirmed by evaluating the mean square error of the identification error. [ABSTRACT FROM AUTHOR]

This article describes the study of the treatment of tequila industry vinasses based on the sequential application of coagulation-flocculation and heterogeneous catalytic ozonation. Coagulation-flocculation treatment used biopolymers to reduce the nondissolved organic matter and to reduce the degree of color units in effluent. Among six different substances, chitosan was the most efficient biopolymer to remove the highest chemical organic demand (COD) concentration (84.0%). The response surface technique was used to obtain the best attainable operation conditions of coagulation-flocculation process. The initial organic matter concentration, the reaction period and biopolymer concentration were selected as the independent variables. Two levels of analysis were performed: optimally and sensibility. The best reaction conditions were 3.23 × 104mg L−1of initial COD, 125.4 mg L−1of chitosan concentration, and 60.0 min of reaction. Ozonation process was performed on the effluent of coagulation-flocculation treatment. A batch reaction with 30 mg L−1of ozone in gaseous phase and a flow of 0.1 L min−1was implemented. Nickel oxide (100 mg L−1) was used as the catalyst of the ozonation reaction. Twice larger COD concentration removal was obtained when the catalyst participated in the reaction compared to the so-called conventional ozonation (12.00% in conventional case vs 26.70% in catalyst presence). An ultraviolet-visible (UV-Vis) spectroscopy study was conducted to obtain a preliminary evaluation of organic compounds removal by effect of the sequential method proposed in this study. A significant total organics removal from the tequila industry wastewater (measured as the integral of UV-Vis spectrum) of 398.6 conditional units was obtained when the conventional ozonation was used after coagulation-flocculation, but that value was increased up to 1609.12 conditional units when the catalyst was inserted into the reaction. [ABSTRACT FROM PUBLISHER]

A dynamic neural network is applied to estimate the state of the “phenol-water-ozone” chemical system. A new method based on dynamic neural observers with sliding mode (signum) term is used to estimate the dynamics of decomposition of phenols by ozone and to identify their kinetic parameters without the use of any process model. Decomposition of phenols and their mixtures by ozone in a semi-batch reactor is regarded as a dynamic process with an uncertain model (“black box”). Only the content of gaseous ozone is measured at the reactor output during ozonization. Variations of this variable are used to construct a total characteristic curve of the ozonization process. A dynamic state observer is used to estimate the phenol ozonization constant at different pH values from 2 to 12. Experimental data on decomposition dynamics are in good agreement with their estimates. Our method is helpful in on-line monitoring of water purification process without the use of special chemical sensors. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]

Abstract: 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 70,000mg/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 25min 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. [Copyright &y& Elsevier]

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 SiO 2 , specific density of 1701.38 kg/m 3 , a true density of 2492.50 kg/m 3 , 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/m 3 , a true density of 2673.55 kg/m 3 , surface area of 34.92 m 2 /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. [ABSTRACT FROM AUTHOR]

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. • The type of soil affected significantly the DMP elimination using ozone. • DEP ozonation obtained 70% TOC removal on calcinated agricultural soil. • The ozonation generated less toxic by-products than DMP. [ABSTRACT FROM AUTHOR]