Application of Electrochemical Degradation of Wastewater Composed of Mixtures of Phenol-Formaldehyde

The industrial wastewater from resin production plants contains as major components phenol and formaldehyde, which are traditionally treated by biological methods. As a possible alternative method, electrochemical treatment was tested using solutions containing a mixture of phenol and formaldehyde simulating an industrial effluent. The anode used was a dimensionally stable anode (DSAA (R)) of nominal composition Ti/Ru0.3Ti0.7O2, and the solution composition during the degradation process was analyzed by liquid chromatography and the removal of total organic carbon. From cyclic voltammetry, it is observed that for formaldehyde, a small offset of the beginning of the oxygen evolution reaction occurs, but for phenol, the reaction is inhibited and the current density decreases. From the electrochemical degradations, it was determined that 40 mA cm(-2) is the most efficient current density and the comparison of different supporting electrolytes (Na2SO4, NaNO3, and NaCl) indicated a higher removal of total organic carbon in NaCl medium.

Composites from a forest biorefinery byproduct and agrofibers: Lignosulfonate-phenolic type matrices reinforced with sisal fibers

The replacement of phenol with sodium lignosulfonate and formaldehyde with glutaraldehyde in the preparation of resins resulted in a new resol-type phenolic resin, sodium lignosulfonate-glutaraldehyde resin, in addition to sodium lignosulfonate-formaldehyde and phenol-formaldehyde resins. These resins were then used to prepare thermosets and composites reinforced with sisal fibers. Different techniques were used to characterize raw materials and/or thermosets and composites, including inverse gas chromatography, thermogravimetric analysis, and mechanical impact and flexural tests. The substitution of phenol by sodium lignosulfonate in the formulation of the composite matrices increased the impact strength of the respective composites from approximately 400 Jm(-1) to 800 J m(-1) and 1000 J m(-1), showing a considerable enhancement from the replacement of phenol with sodium lignosulfonate. The wettability of the sisal fibers increased when the resins were prepared from sodium lignosulfonate, generating composites in which the adhesion at the fiber-matrix interface was stronger and favored the transference of load from the matrix to the fiber during impact. Results suggested that the composites experienced a different mechanism of load transfer from the matrix to the fiber when a bending load was applied, compared to that experienced during impact. The thermogravimetric analysis results demonstrated that the thermal stability of the composites was not affected by the use of sodium lignosulfonate as a phenolic-type reagent during the preparation of the matrices.

Tannin-phenolic resins: Synthesis, characterization, and application as matrix in biobased composites reinforced with sisal fibers

A tannin-phenolic resin (40 wt% of tannin, characterized by H-1 nuclear magnetic resonance (NMR) and C-13 NMR, Fourier transform infrared, thermogravimetry, differential scanning calorimetry) was used to prepare composites reinforced with sisal fibers (30-70 wt%). Inverse gas chromatography results showed that the sisal fibers and the tannin-phenolic thermoset have close values of the dispersive component and also have predominance of acid sites (acid character) at the surface, confirming the favoring of interaction between the sisal fibers and the tannin-phenolic matrix at the interface. The Izod impact strength increased up to 50 wt% of sisal fibers. This composite also showed high storage modulus, and the lower loss modulus, confirming its good fiber/matrix interface, also observed by SEM images. A composite with good properties was prepared from high content of raw material obtained from renewable sources (40 wt% of tannin substituted the phenol in the preparation of the matrix and 50 wt% of matrix was replaced by sisal fibers). (C) 2012 Elsevier Ltd. All rights reserved.

Purification of coagulation factor VIII using chromatographic methods. Direct chromatography of plasma in anion exchange resins

Coagulation factor VIII (FVIII) concentrates are used in the treatment of patients with Hemophilia A. Human FVIII was purified directly from plasma using anion exchange chromatography followed by gel filtration. Three Q-Sepharose resins were tested, resulting in 40% recovery of FVIII activity using Q-Sepharose XL resin, about 80% using Q-Sepharose Fast Flow and 70% using the Q-Sepharose Big Beads. The vitamin K-dependent coagulation factors co-eluted with FVIII from the anion exchange columns. In the second step of purification, when Sepharose 6FF was used, 70% of FVIII activity was recovered free from vitamin K-dependent factors.

Kinetic and Thermodynamic Studies on the Adsorption of Reactive Red 239 by Carra Sawdust Treated with Formaldehyde

In this study, carra sawdust pre-treated with formaldehyde was used to adsorb reactive red 239 (RR239). The effects of several experimental conditions, including the concentration of dye, sorbent dosage, temperature, ionic strength, stirring speed and solution pH, on the kinetics of the adsorption process have been studied, and the experimental data were fitted to pseudo-second-order model. A study of the intra-particle diffusion model indicates that the mechanism of dye adsorption using carra sawdust is rather complex and is most likely a combination of external mass transfer and intra-particle diffusion. The experimental data obtained at equilibrium were analyzed using the Langmuir and Freundlich isotherm models, and the results indicated that at this concentration range, both models can be applied for obtaining the equilibrium parameters. The maximum dye uptake obtained at 298 K was found to be 15.1 mg g(-1). In contrast to the usual systems, the reactive dye studied in the present work is strongly attached to the sawdust even after several washes with water, allowing it to be discarded as a solid waste.

Polymerization kinetics and reactivity of alternative initiators systems for use in light-activated dental resins

Objectives. The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems. Methods. A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1 mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV-Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R-p(max)) profile of the model resin. Results. In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ + EDAB exhibited higher DC and R-p(max) values. In formulations that contained ternary initiator systems, the group CQ + QTX + EDAB was the only one of the investigated experimental groups that exhibited an R-p(max) value greater than that of CQ + EDAB. The groups QTX + EDAB + DPIHFP and QTX + DPIHFP + SULF exhibited values similar to those of CQ + EDAB with respect to the final DC; however, they also exhibited lower reactivity. Significance. Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Anti-Atherogenic Effects of a Phenol-Rich Fraction from Brazilian Red Wine (Vitis labrusca L.) in Hypercholesterolemic Low-Density Lipoprotein Receptor Knockout Mice

Moderate wine intake (i.e., 1-2 glasses of wine a day) is associated with a reduced risk of morbidity and mortality from cardiovascular disease. The aim of this study was to evaluate the anti-atherosclerotic effects of a nonalcoholic ethyl acetate fraction (EAF) from a South Brazilian red wine obtained from Vitis labrusca grapes. Experiments were carried out on low-density lipoprotein (LDL) receptor knockout (LDLr-/-) mice, which were subjected to a hypercholesterolemic diet and treated with doses of EAF (3, 10, and 30 mg/kg) for 12 weeks. At the end of the treatment, the level of plasma lipids, the vascular reactivity, and the atherosclerotic lesions were evaluated. Our results demonstrated that the treatment with EAF at 3 mg/kg significantly decreased total cholesterol, triglycerides, and LDL plus very low-density lipoprotein levels compared with control hypercholesterolemic mice. The treatment of mice with EAF at 3 mg/kg also preserved the vasodilatation induced by acetylcholine on isolated thoracic aorta from hypercholesterolemic LDLr-/- mice. This result is in agreement with the degree of lipid deposit on arteries. Taken together, the results show for the first time that the lowest concentration of an EAF obtained from a red wine produced in southern Brazil significantly reduced the progression of atherosclerosis in mice.

Phenol degradation in an anaerobic fluidized bed reactor packed with low density support materials

The objective of this research was to study phenol degradation in anaerobic fluidized bed reactors (AFBR) packed with polymeric particulate supports (polystyrene - PS, polyethylene terephthalate - PET, and polyvinyl chloride - PVC). The reactors were operated with a hydraulic retention time (HRT) of 24 h. The influent phenol concentration in the AFBR varied from 100 to 400 mg L-1, resulting in phenol removal efficiencies of similar to 100%. The formation of extracellular polymeric substances yielded better results with the PVC particles; however, deformations in these particles proved detrimental to reactor operation. PS was found to be the best support for biomass attachment in an AFBR for phenol removal. The AFBR loaded with PS was operated to analyze the performance and stability for phenol removal at feed concentrations ranging from 50 to 500 mg L-1. The phenol removal efficiency ranged from 90-100%.

The filler content of the dental composite resins and their influence on different properties

The purpose of this study was to compare the inorganic content and morphology of one nanofilled and one nanohybrid composite with one universal microhybrid composite. The Vickers hardness, degree of conversion and scanning electron microscope of the materials light-cured using LED unit were also investigated. One nanofilled (Filtek (TM) Supreme XT), one nanohybrid (TPH (R) 3) and one universal microhybrid (Filtek (TM) Z-250) composite resins at color A2 were used in this study. The samples were made in a metallic mould (4 mm in diameter and 2 mm in thickness). Their filler weight content was measured by thermogravimetric analysis (TG). The morphology of the filler particles was determined using scanning electron microscope equipped with a field emission gun (SEM-FEG). Vickers hardness and degree of conversion using FT-IR spectroscopy were measured. Filtek (TM) Z-250 (microhybrid) composite resin shows higher degree of conversion and hardness than those of Filtek (TM) Supreme XT (nanofilled) and TPH (R) 3 (nanohybrid) composites, respectively. The TPH3 (R) (nanohybrid) composite exhibits by far the lowest mechanical property. Nanofilled composite resins show mechanical properties at least as good as those of universal hybrids and could thus be used for the same clinical indications as well as for anterior restorations due to their high aesthetic properties. Microsc. Res. Tech. 75:758765, 2012. (C) 2011 Wiley Periodicals, Inc

Interference of inorganic ions on phenol degradation by the Fenton reaction

The addition of Cu2+ ions to the classical Fenton reaction (Fe2+ plus H2O2 at pH 3) is found to accelerate the degradation of organic compounds. This synergic effect causes an approximately 15 % additional reduction of the total organic carbon (TOC), representing an overall improvement of the efficiency of the mineralization of phenol. Although Fe2+ exhibits a high initial rate of degradation, the degradation is not complete due to the formation of compounds refractory to the hydroxyl radical. The interference of copper ions on the degradation of phenol by the Fenton reaction was investigated. In the presence of Cu2+, the degradation is slower, but results in a greater reduction of TOC at the end of the reaction (t = 120 min). In the final stages of the reaction, when the Fe3+ in the solution is complexed in the form of ferrioxalate, the copper ions assume the role of the main catalyst of the degradation.

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 Fe2+ ([Fe2+](0)) from 1.0 up to 2.5 mM, the rate in mmol of H2O2 fed into the system (F-H2O2,F-in) from 3.67 up to 7.33 mmol of H2O2/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. (C) 2012 Elsevier Ltd. All rights reserved.

Degree of conversion of nanofilled and microhybrid composite resins photo-activated by different generations of LEDs

Objective: This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs). Material and methods: Filtek (TM) Z350 nanofilled composite resins and Amelogen (R) Plus, Vit-l-escence (TM) and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free Light (TM) 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm(-1)) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1). Results: The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (p<0.001). The Tukey's test showed that the nanofilled resin (Filtek (TM) Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (Filtek (TM) Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free Light (TM) 2). Conclusions: The nanofilled resin showed the lowest DC, and the Vit-l-escence (TM) microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second-generation LED Radii-cal provided the lowest DC.

Mechanistic Implications of Zinc(II) Ions on the Degradation of Phenol by the Fenton Reaction

A study of the interference of Zn2+ ions on phenol degradation by Fenton reaction (Fe2+/Fe3(+) + H2O2) is reported. One of the first intermediates formed in the reaction, catechol, can reduce Fe3+ to Fe2+ and, in the presence of H2O2 initiates an efficient catalytic redox cycle. In the initial stages of the reaction, this catechol-mediated cycle becomes the principal route of thermal degradation of phenol and its oxidation products. The Zn2+ ion addition enhances the persistence time of catechol, probably by stabilization of the corresponding semiquinone radical via complexation.

Evaluation of the flexural strength and elastic modulus of resins used for temporary restorations reinforced with particulate glass fibre

Objective: The flexural strength and the elastic modulus of acrylic resins, Dencor, Duralay and Trim Plus II, were evaluated with and without the addition of silanised glass fibre. Materials and methods: To evaluate the flexural strength and elastic modulus, 60 test specimens were fabricated with the addition of 10% ground silanised glass fibres for the experimental group, and 60 without the incorporation of fibres, for the control group, with 20 test specimens being made of each commercial brand of resin (Dencor, Duralay and Trim Plus II) for the control group and experimental group. After the test specimens had been completed, the flexural strength and elastic modulus tests were performed in a universal testing device, using the three-point bending test. For the specimens without fibres the One-Way Analysis of Variance and the complementary Tukey test were used, and for those with fibres it was not normal, so that the non-parametric Mann-Whitney test was applied. Results: For the flexural strength test, there was no statistical difference (p > 0.05) between each commercial brand of resin without fibres [Duralay 84.32(+/- 8.54), Trim plus 85.39(+/- 6.74), Dencor 96.70(+/- 6.52)] and with fibres (Duralay 87.18, Trim plus 88.33, Dencor 98.10). However, for the elastic modulus, there was statistical difference (p > 0.01) between each commercial brand of resin without fibres [Duralay 2380.64 (+/- 168.60), Trim plus 2740.37(+/- 311.74), Dencor 2595.42(+/- 261.22)] and with fibres (Duralay 3750.42, Trim plus 3188.80, Dencor 3400.75). Conclusion: The result showed that the incorporation of fibre did not interfere in the flexural strength values, but it increased the values for the elastic modulus.

Phenol biodegradation by a microbial consortium: application of artificial neural network (ANN) modelling

In this study, an effective microbial consortium for the biodegradation of phenol was grown under different operational conditions, and the effects of phosphate concentration (1.4 g L-1, 2.8 g L-1, 4.2 g L-1), temperature (25 degrees C, 30 degrees C, 35 degrees C), agitation (150 rpm, 200 rpm, 250 rpm) and pH (6, 7, 8) on phenol degradation were investigated, whereupon an artificial neural network (ANN) model was developed in order to predict degradation. The learning, recall and generalization characteristics of neural networks were studied using data from the phenol degradation system. The efficiency of the model generated by the ANN was then tested and compared with the experimental results obtained. In both cases, the results corroborate the idea that aeration and temperature are crucial to increasing the efficiency of biodegradation.