Osvaldo Chiavone-Filho

Determination of the solubility of extracts from vegetable raw material in pressurized CO2: a pseudo-ternary mixture formed by cellulosic structure+solute+solvent

This paper discusses the application of the dynamic method to measure the solubility in pseudo-ternary systems formed by vegetable raw materials (cellulosic structure+solute) and CO2. For aromatic, medicinal, and spice plants, the soluble portion of the solid is formed of essential oils, oleoresins, pigments, and various substances from several other classes of organic compounds. The experimental data were measured in two independent laboratories, using three experimental set-ups, and three vegetable species: clove buds, eucalyptus, and ginger. The solubility for the system clove buds/CO2 varied from 0.220 to 0.277 kg-extract/kg-CO2 for the isotherm of 288.15 K. The ginger extract solubility varied from 2.01×10−3 to 7.20×10−3 kg-extract/kg-CO2 for pressures of 100–300 bar, and temperatures of 298.15–313.15 K. The eucalyptus solubility for the isobar of 66.7 bar varied from 3.95×10−3 to 4.07×10−3 kg-extract/kg-CO2.

Experimental results for the extraction of essential oil from Lippia sidoides cham. using pressurized carbon dioxide

The odoriferous species Lippia sidoides Cham. is abundant in the Brazilian Northeast. Its essential oil possesses antiseptic activity due to the presence of thymol. In this work, thermodynamic and kinetic data were experimentally determined for the CO2 + L. sidoides system. Solubility was determined using the dynamic method at pressures of 66.7 and 78.5 bar and temperatures of 283.15, 288.15, 293.15, 295.15, and 298.15 K. SFE kinetic data were obtained at 288.15 K and 66.7 bar. The composition of the multicomponent solute mixture was determined by GC-MS and compared to the composition of both the volatile oil obtained by steam distillation and the oleoresin obtained using ethanol. The SFE process yield was higher than the yield of either the steam distillation or the ethanol extraction. The solubilities were correlated using the Peng- Robinson equation of state with one binary interaction parameter for the attractive term, considering the essential oil as a pseudo-component. Sovovas model quantitatively described the overall extraction curve.

Oil removal from produced water by conjugation of flotation and photo-Fenton processes

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal.

Photo-Fenton oxidation of phenol and organochlorides (2,4-DCP and 2,4-D) in aqueous alkaline medium with high chloride concentration

A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe(2+) ([Fe(2+)](0)) from 1.0 up to 2.5 mM, the rate in mmol of H(2)O(2) fed into the system (FH(2)O(2);in) from 3.67 up to 7.33 mmol of H(2)O(2)/min during 120 min of reaction time, and the initial pH (pH(0)) from 3.0 up to 9.0 in the presence and absence of NaCl (60.0 g/L). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes.

Effects of Solvent Diols on the Synthesis of ZnFe2O4 Particles and Their Use as Heterogeneous Photo-Fenton Catalysts

A solvothermal method was used to prepare zinc ferrite spinel oxide (ZnFe2O4) using ethylene glycol and 1,4 butanediol as solvent diols, and the influence of diols on the physical properties of ZnFe2O4 particles was investigated. The produced particles were characterized by X-ray powder diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption isotherms, and the catalytic activity for the organic pollutant decomposition by heterogeneous photo-Fenton reaction was investigated. Both solvents produced particles with cubic spinel structure. Microporous and mesoporous structures were obtained when ethylene glycol and 1,4 butanediol were used as diols, respectively. A higher pore volume and surface area, as well as a higher catalytic activity for the pollutant degradation were found when 1,4 butanediol was used as solvent.

Industrial Wastewater Treatment by Photochemical Processes Based on Solar Energy

Background: The solar photo-Fenton process has enormous potential for becoming a viable alternative to conventional processes for the treatment of industrial wastewater. However the costs associated with the use of artificial irradiation have hindered many times industrial application of these processes. Method of Approach: In this work, the photo-Fenton remediation of various industrial wastewaters (containing silicones, pesticides, phenol and hydrocarbons, model, and real) in aqueous systems has been studied using Fe(II), H 2 O 2 , and UV-visible sunlight. Experiments were carried out using a concentrating parabolic trough reactor (PTR) and a nonconcentrating falling-film reactor. Results: In general, at low contaminant concentration, more than 90% of the total organic carbon content could be converted to inorganic carbon within about 2-3 h, using sunlight, in reactors of different geometry. Conclusions: Solar light can be used either as an effective complementary or alternative source of photons to the photo-Fenton degradation process of a diversity of chemical pollutants.

Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene.

Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min(-1) for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H(2)O(2) concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

Adsorption Equilibria of C8 Aromatic Liquid Mixtures on Y Zeolites Using Headspace Chromatography

Abstract Liquid phase adsorptive separations are found in several industrial applications such as the recovery of p‐xylene from its isomers. In this study, the headspace experimental technique was used to measure pure and multicomponent adsorption equilibria of liquid xylenes in Y zeolite. Data for pure‐component equilibrium were determined at temperatures between 80 and 120°C and correlated using the Extended Langmuir model. The parameters for pure components estimated from the correlated data showed good agreement with data reported in previous studies and relatively low deviations when compared to the experimental data dispersion. Using the pure‐component data, two models were tested for multicomponent (binary and quaternary) equilibrium correlation: Ideal Adsorbed Solution (IAS) model and Extended Langmuir Multicomponent model. The results from the IAS model did not conform well to the experimental results, indicating the existence of significant nonidealities in the system. The Extended Langmuir model predicted values generally in good agreement with the binary and quaternary experimental data measured using the Headspace technique.

Photo-Fenton degradation of phenol, 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenol mixture in saline solution using a falling-film solar reactor

In this work, a saline aqueous solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a falling-film solar reactor. The influence of the parameters such as initial pH (5–7), initial concentration of Fe2+ (1–2.5 mM) and rate of H2O2 addition (1.87–3.74 mmol min−1) was investigated. The efficiency of photodegradation was determined from the removal of dissolved organic carbon (DOC), described by the species degradation of phenol, 2,4-D and 2,4-DCP. Response surface methodology was employed to assess the effects of the variables investigated, i.e. [Fe2+], [H2O2] and pH, in the photo-Fenton process with solar irradiation. The results reveal that the variables’ initial concentration of Fe2+ and H2O2 presents predominant effect on pollutants’ degradation in terms of DOC removal, while pH showed no influence. Under the most adequate experimental conditions, about 85% DOC removal was obtained in 180 min by using a reaction system employed here, and total removal of phenol, 2,4- and 2,4-DCP mixture in about 30 min.

CuO/ZnO coupled oxide films obtained by the electrodeposition technique and their photocatalytic activity in phenol degradation under solar irradiation.

CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photocatalysts in degradation of phenol molecules in aqueous solution under sunlight. The obtained films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the photocatalytic activity of films was significant, especially to coupled oxide film with a CuO/ZnO ratio equal to 0.697, which presented about 70% degradation of the aromatic molecules and 42% of total organic carbon (TOC) removal at 300 min under solar irradiation. Therefore, this work highlights the potential application of CuO/ZnO coupled oxide films obtained by electrodeposition onto aluminum substrate in the field of photocatalysis.