Farid B. Cortés

Adsorptive removal of oil spill from oil-in-fresh water emulsions by hydrophobic alumina nanoparticles functionalized with petroleum vacuum residue

Oil spills on fresh water can cause serious environmental and economic impacts onshore activities affecting those who exploit freshwater resources and grassland. Alumina nanoparticles functionalized with vacuum residue (VR) were used as a low-cost and high hydrophobic nanosorbents. The nanomaterial resulting showed high adsorption affinity and capacity of oil from oil-in-freshwater emulsion. The effects of the following variables on oil removal were investigated, namely: contact times, solution pH, initial oil concentrations, temperature, VR loadings and salinity. Kinetic studies showed that adsorption was fast and equilibrium was achieved in less than 30 min. The amount adsorbed of oil was higher for neutral system compared to acidic or basic medium. Increasing the VR loading on nanoparticle surface favored the adsorption. Results of this study showed that oil removal for all systems evaluated had better performance at pH value of 7 using nano-alumina functionalized with 4 wt% VR. Adsorption equilibrium and kinetics were evaluated using the Polanyi theory-based Dubinin-Ashtakhov (DA) model, and pseudo-first and pseudo-second order-models, respectively.

Removal of oil from oil-in-saltwater emulsions by adsorption onto nano-alumina functionalized with petroleum vacuum residue

Formation water from oilfields is one of the major environmental issues related to the oil industry. This research investigated oil adsorption onto nanoparticles of hydrophobic alumina and alumina nanoparticles functionalized with a petroleum vacuum residue (VR) at 2 and 4wt% to reduce the amount of oil in oil-saltwater emulsions at different pH values (5, 7 and 9). The initial concentration of crude oil in water ranged from 100 to 500mg/L. The change in oil concentration after adsorption was determined using a UV-vis spectrophotometer. The results indicated that all of the systems performed more effectively at a pH of 7 and using Al/4VR material. The oil adsorption was higher for neutral and acid systems compared with basic ones, and it was improved by increasing the amount of VR on the surface of the alumina. Additionally, the amount of NaCl adsorbed onto nanoparticles was estimated for different mixtures. The adsorption equilibrium and kinetics were evaluated using the Dubinin-Astakhov model, the Brunauer-Emmet-Teller model, and pseudo-first- and pseudo-second-order models, with a better fitting to the Brunauer-Emmet-Teller model and pseudo-second-order model.

Water Remediation Based on Oil Adsorption Using Nanosilicates Functionalized with a Petroleum Vacuum Residue

Discharging water from oilfields has become one of the major environmental issues related to the oil industry. This work presents a study on the adsorption of oil onto nanoparticles of hydrophobic silica and silica nanoparticles functionalized with a petroleum vacuum residue (VR) at 2 and 4 wt% to reduce the amount of oil in oil–brine and oil–water emulsions at different pH values (5, 7 and 9). The initial concentration of crude oil in water ranged from 500 to 1500 mg/l. The change in oil concentration after adsorption was determined using a UV–VIS spectrophotometer. Experimental data on the adsorption kinetics were fitted to pseudo-first-order and pseudo-second-order models, with better results being obtained for the latter. Results of the study showed 100% oil removal for all the systems studied and a better performance was achieved for oil-saltwater emulsions than the experiments performed using oil-saltwater emulsions. In addition, the adsorption equilibrium was achieved faster for the oil–water emulsion using the salty medium. Adsorption velocity was higher for neutral and basic systems compared with acid ones, and it was improved by increasing the amount of VR on silica surface.

A rapid and novel approach for predicting water sorption isotherms and isosteric heats of different meat types

A rapid and novel approach for predicting sorption isotherms based on the Polanyi theory is proposed. This approach allows the prediction of the sorption isotherms at different temperatures from one experimental isotherm. The theoretical predictions of isotherms and isosteric heats were validated successfully using data from the literature for different meat types. This method allows total experimental time and operation costs to be reduced.

Effect of Relative Humidity on the Antioxidant Activity of Spray-Dried Banana Passion Fruit (Passiflora Mollisima Baley)-Coated Pulp: Measurement of the Thermodynamic Properties of Sorption

The antioxidant activity of the spray-dried banana passion fruit-coated pulp with maltodextrin10 DE was evaluated throughout 30 days of storage at a temperature of 25°C for different relative humidity values It was influenced by the relative humidity throughout the 30 days of storage. In addition, the sorption equilibria of water for spray-dried banana passion fruit-coated pulp with maltodextrin 10 DE at 25, 35, 45, and 55°C, over a range of relative humidity levels from 0.113 to 0.843, was determined using a gravimetric static method. The isosteric heat and Gibbs free energy were calculated from the sorption equilibrium. The Guggenheim-Anderson-Boer (GAB) and Brunauer-Emmett-Teller (BET) models were tested to fit the experimental data. The GAB model was found to be the most suitable for describing the sorption curves, exhibiting an error smaller than 10% and an r greater than 0.99. The monolayer moisture content values for the sorption at different temperatures that were calculated using the GAB model ranged between 0.05315 to 0.05716 g water/g dry matter. The sorption curves exhibited a Type III behavior. The isosteric heat decreased with increasing moisture content while the Gibbs free energy increased.

Effect of temperature on antioxidant capacity during drying process of mortiño (Vaccinium meridionale Swartz)

ABSTRACT The mortiño fruit (Vaccinium meridionale Swartz) has been recognized as an excellent source of antioxidants, phenolic compounds, and anthocyanins. Drying conditions, particularly temperature, often lead to food quality degradation. The present study investigated the influence of drying temperature (40, 50, and 60°C) on antioxidant activity, anthocyanin, and phenol content of mortiño. Four different thin layer drying models of drying kinetics (Modified page, Newton, Henderson & Pabis and, two-terms) were fitted to the experimental data. For antioxidant capacity determination, oxygen radical absorbance capacity and ferric ion reducing antioxidant power assays were used. The results showed that antioxidant capacity, and phenolic and anthocyanin content all decreased with increasing temperature and drying time. It was observed that phenols and anthocyanins were conserved in greater amounts at 60°C with 34% (5.85 mg gallic acid/g dm) and 32% (2.36 mg Cyanidin-3-glucoside/g dm) preservation of initial content, respectively. Drying kinetics models were compared based on their R2 and root mean square error values between the experimental and predicted moisture ratios. The two-terms model was found to satisfactorily describe the drying curves for all temperatures evaluated, with a determination coefficient (R2) above 0.9987 and root mean square error lower than 0.0201.

Effects of resin I on the catalytic oxidation of n-C7 asphaltenes in the presence of silica-based nanoparticles

This study aims to evaluate the effects of resin I on the n-C7 asphaltene thermal decomposition under an oxidative atmosphere in the presence of hybrid nanoparticles (SNi1Pd1) of NiO and PdO supported over fumed silica nanoparticles. Resin I and n-C7 asphaltenes were characterized by elemental analyses, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The adsorption of resin I and n-C7 asphaltenes was evaluated using heavy oil model solutions through a combined method of thermogravimetric analysis and softening point measurements. Adsorption isotherms were measured for individual resin I and n-C7 asphaltene samples as well as for different n-C7 asphaltene to resin I ratios of 7 : 3, 1 : 1 and 7 : 3. For the first time, competitive adsorption of n-C7 asphaltene and resin I on functionalized nanoparticles with NiO and PdO is assessed. The oxidation tests were carried out in an air atmosphere for a specific n-C7 asphaltene loading in each sample (ca. 0.20 ± 0.02 mg m−2). In this order, for samples adsorbed from different A : R ratios of 7 : 3, 1 : 1 and 3 : 7, the amounts of resin I adsorbed were 0.06, 0.10 and 0.20 ± 0.01 mg m−2, respectively. Hence, the A : R ratios in the adsorbed phase were 10 : 3, 2 : 1 and 1 : 1. The catalytic effect was measured through thermogravimetric analysis coupled to Fourier transform infrared spectroscopy, which evaluated the effluent gases of the catalytic oxidation process. The adsorption isotherms were modeled using the solid-liquid-equilibrium (SLE) model, and the effective activation energies for the oxidation process of the adsorbate were calculated through the non-linear integral method of Vyazovkin (NLN). As a result, it was observed that the temperature of n-C7 asphaltene decomposition did not vary significantly with the inclusion of resin I in the system. Rate of mass loss curves showed that the main peak temperatures of n-C7 asphaltenes and resin I decreased drastically from approximately 500 °C to 250, 260 and 270 °C for resin I loadings over SNi1Pd1 nanoparticles of 0.20, 0.10 and 0.06 mg m−2, respectively. However, the catalytic effect of the nanoparticles was indeed affected, as revealed by the increase in the estimated effective activation energy as the amount of resin I in the system increased. It is expected that this work opens a better outlook about the use of catalytic nanoparticles in the oil and gas industry, mainly in improved (IOR) or enhanced oil recovery (EOR) processes for heavy and extra-heavy oil upgrading.

A New Model for Predicting Sorption Isotherm of Water in Foods

A new model for predicting sorption isotherms of type II and III based on the Polanyi theory is proposed. This model allows the prediction of the sorption isotherms at different temperatures from one experimental isotherm. The theoretical predictions of isotherms and isosteric heat were validated successfully using data from literature for twenty one foods. This method allows total experimental time and operation costs to be reduced.

Effects of glycerol on the minimization of water readsorption on sub-bituminous coal

ABSTRACT The presence of water in coal presents a technological challenge for its industrial use in energetic processes. Water tends to negatively affect the coal quality and its net heating value (NHV), in addition to affecting its transportation costs. Therefore, this study aims to investigate the effects of glycerol and temperature on water adsorption onto systematically modified coals. A Colombian bituminous coal sample was used as support for being modified with glycerol. The virgin coal and modified coal were characterized by nitrogen adsorption at 77 K (SBET), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (C–H–N elemental), and thermogravimetric analysis (TGA). The results showed that the water uptake decreased as the amount of glycerol on the coal surface increased. The optimum concentration of 8 wt% of glycerol impregnated on the coal minimized water adsorption. Over a range of water activity evaluations, this amount of glycerol (C8) reduced water adsorption by approximately 60% compared with nonimpregnated coal (C0). As expected, water uptake decreased with increasing temperature. These results are reflected in the NHV with an increase of 17% for the C8 sample compared with the other samples evaluated. The Talu and Meunier model was used to fit the experimental adsorption isotherms, and the mean square root error (MSRE%) was lower than 10%. The isosteric heat of sorption (IHS) for coal tends to decrease as the amount of adsorbed water increases. In addition, the value of IHS decreases as the concentration of glycerol increases due to the blocking of polar adsorption sites present on the coal surface, which are the main regions of low uptake of adsorbed water. Additionally, the Gibbs free energy was found to have negative values, which corroborates the spontaneous adsorption process.

Polifenoles y Actividad Antioxidante del Fruto de Guayaba Agria (Psidium araca)

The content of polyphenol compounds such as total phenols, total flavonoids, condensed tannins and phenolic acids of the sour guava fruits (Psidium araca) was determined. These compounds determine the antioxidant capacity, property that expresses the facility for scavenging reactive oxygen species as nutraceutical value of the specie. The antioxidant activity of sour guava was determined by different methods such as DPPH, ABTS, FRAP and ORAC. The results are comparable with those found for common guava (Psidium guajava) and higher than those reported for common fruits such as pineapple, watermelon, passion fruit and melon. In conclusion, sour guava is a fruit with antioxidant potential, which can be handled by various technological methods to get high added-value products.