Carmen Pazos

Design and construction of a modular pilot plant for the treatment of oil-containing wastewaters☆

A modular pilot size plant involving coagulation/flocculation, centrifugation, ultrafiltration and sorption processes has been designed and constructed. The pilot plant can be used for the treatment of different water-based coolants and oily wastewaters, generated in metalworking processes and steel cold rolling operations. Different treatments are considered depending on the nature of the oily waste emulsion. The main advantage of the plant is its versatility, allowing the combination of several of the aforementioned treatments. It is a feasible waste management alternative with potential savings as a result of a better control of the elimination of oily wastes and water reuse, with the result of environmental and economic benefits.

Nanodesign of olein vesicles for the topical delivery of the antioxidant resveratrol

The ex‐vivo percutaneous absorption of the natural antioxidant resveratrol in liposomes and niosomes was investigated. The influence of vesicle composition on their physicochemical properties and stability was evaluated. Liposomes containing resveratrol were formulated using soy phosphatidylcholine (Phospholipon90G). Innovative niosomes were formulated using mono‐ or diglycerides: glycerol monooleate (Peceol) and polyglyceryl‐3 dioleate (Plurol OleiqueCC), respectively, two suitable skin‐compatible oleins used in pharmaceutical formulations as penetration enhancers.

Ultrafiltration of a Waste Emulsified Cutting Oil using Organic Membranes

The influence of operating conditions on permeate flux was investigated using organic ultrafiltration membranes to treat a synthetic cutting-oil emulsion containing 0.05 to 0.8 wt. % oil. A commercial cutting oil, Alba-Kool, and four organic ultrafiltration membranes, two made of polysulfone (PM10 and PM30) and the other two of regenerated cellulose (YM10 andYM30), with cut-off sizes of 10 000 or 30 000 Dalton, were used.All experiments were performed in a commercially available stirred ultrafiltration cell. Within the range of operating conditions studied, it was found that the highest fluxes wereobtained at the following conditions: crossflow velocity (rotation speed) of 375 rpm, temperature of 40 °C andtransmembrane pressure of 0.1–0.15 MPa. Oil rejections between99 and 99.9% were obtained. Complete membrane regeneration wasachieved with a 2 vol. % aqueous solution of a commercial cleaning agent (Derquim+, Panreac).

Liquid-liquid extraction of lactic acid with Alamine 336

The extraction of lactic acid from aqueous solutions by Alamine 336 dissolved in toluene was studied. Experiments were performed in the temperature range of 25-60°C and for two amine concentrations of 20 and 40% (v/v) in toluene. The extent to which the organic phase (amine+toluene) may be loaded with lactic acid is expressed as a loading ratio, Z. Z values are independent of the amine concentration and, hence, the extracted complex contains only one molecule of amine. Z decreases with increasing temperature. Experimental results indicate that the system presents overloading, i.e. Z>1. The extraction equilibrium may be interpreted as a result of consecutive formation of three acid-amine species with stoichiometries of 1:1, 2:1 and 3:1.

Treatment of a waste oil-in-water emulsion from a copper-rolling process by ultrafiltration and vacuum evaporation.

A process is proposed for the treatment of a waste oil-in-water (O/W) emulsion generated in an industrial copper-rolling operation. The use of demulsifier agents improves the subsequent treatment by techniques such as ultrafiltration (UF) or evaporation. The effluent COD is reduced up to 50% when the O/W emulsion is treated by UF using a flat 30 nm TiO(2) ceramic membrane (ΔP = 0.1 MPa) and up to 70% when it is treated by vacuum evaporation, after an emulsion destabilization pretreatment in both cases. Increases in the UF permeate flux and in the evaporation rate are observed when a chemical demulsifier is used in the pretreatment step. A combined process consisting of destabilization/settling, UF, and vacuum evaporation can yield a very high-quality aqueous effluent that could be used for process cooling or emulsion reformulation.

Recovery of Gallium From Coal Fly Ash By a Dual Reactive Extraction Process

The extraction of gallium from coal fly ash by leaching and extraction with commercial extractants Amberlite LA-2 and LIX 54N dissolved in kerosene was studied. Leaching of gallium and other metals from the fly ash was carried out with 6 M hydrochloric acid. The leaching liquor is first contacted with Amberlite LA-2 which extracts the gallium and iron. The iron is then precipitated with sodium hydroxide, while gallium remains in solution. Gallium is extracted selectively from the base solution with LIX 54; the resulting stripped solution contains 83% of the gallium present in the leaching liquor. A flow diagram for this dual-extraction process is proposed.

Resveratrol entrapped niosomes as yoghurt additive

Nanodesign of niosomes containing resveratrol (RSV) was carried out using food-grade surfactants with dodecanol to stabilise the membrane. Niosomes were prepared using a modified thin film hydration method. A factorial design analysis was carried out to reduce the number of experiments. The response factors were: mean size, polydispersity index (PDI) and entrapment efficiency (EE). Agitation speed and surfactant to dodecanol weight ratio were selected as key parameters for niosomes preparation. Parameter contribution was determined using a statistical analysis of variance (ANOVA). Niosomes formulated with Span 60 or Maisine 35-1 as surfactants, and dodecanol as stabiliser, were able to incorporate RSV. These niosomes exhibited a small mean size, narrow size distribution, high RSV entrapment efficiency and good stability. RSV addition did not involve changes in the textural properties of regular yoghurt demonstrating that RSV entrapped niosomes are suitable additives in these dairy products.

Influence of Coagulant Salt Addition on the Treatment of Oil‐in‐Water Emulsions by Centrifugation, Ultrafiltration, and Vacuum Evaporation

Abstract Droplet size is a key factor in the treatment of oil‐in‐water (O/W) emulsions, because of its influence on emulsion properties. The addition of a coagulant salt generally causes emulsion destabilization, increasing the droplet size, and enhancing coalescence between oil droplets, which helps its further treatment. The influence of CaCl2 addition on droplet size distribution of a commercial O/W emulsion used in machining processes was studied in order to facilitate oil removal and to improve its further treatment by centrifugation, ultrafiltration (UF) and vacuum evaporation. The critical coagulation concentration (CCC) was observed at a CaCl2 concentration of 0.05 M. The quality of the final aqueous effluent, expressed as its chemical oxygen demand (COD) value, was compared for all treatments. The highest COD values were obtained for centrifugation, while the COD of the UF permeate was approximately constant for all UF trials. The best effluent quality was obtained by vacuum evaporation. A combination of these techniques should be appropriate for most industrial treatments of O/W emulsions, depending on the subsequent use of the resulting aqueous effluent.

Formulation of resveratrol entrapped niosomes for topical use.

A new approach to the formulation of resveratrol (RSV) entrapped niosomes for topical use is proposed in this work. Niosomes were formulated with Gelot 64 (G64) as surfactant, and two skin-compatible unsaturated fatty acids (oleic and linoleic acids), commonly used in pharmaceutical formulations, as penetration enhancers. Niosomes were prepared by two different methods: a thin film hydration method with minor modifications followed by a sonication stage (TFH-S), and an ethanol injection modified method (EIM). Niosomes prepared with the EIM method were in the range of 299-402 nm, while the TFH-S method produced larger niosomes in the range of 293-496 nm. Moreover, niosomes with higher RSV entrapment efficiency (EE) and better stability were generated by the EIM method. Ex vivo transdermal experiments, carried out in Franz diffusion cells on newborn pig skin, indicated that niosomes prepared by the EIM method were more effective for RSV penetration in epidermis and dermis (EDD), with values up to 21% for both penetration enhancers tested. The EIM method, which yielded the best RSV-entrapped niosomes, seems to be the most suitable for scaling up.

ZETA POTENTIALS OF CUTTING-OIL WATER EMULSIONS: INFLUENCE OF INORGANIC SALTS

ABSTRACT Electrophoretic light scattering (ELS) is used to determine the zeta potential of O/W emulsions of five commercial cutting oils. AlCl3, MgCl2, CaCl2 and NaCl were added as electrolytes to the emulsions at concentrations varying from 10−4 mol/dm3 to 10−1 mol/dm3 in order to study the influence of electrolyte concentration and cation charge on the zeta potential of the emulsions and to explain their stability. A decrease of the absolute value of the zeta potential was observed when the electrolytes were added to the emulsions, except for low NaCl concentrations where the zeta potential increased due to the adsorption of the Cl− ions on the droplet surface while AlCl3 cancelled the zeta potential of the droplets at very low concentrations. The effect of added electrolytes agrees well with the Schulze-Hardy rule. The tendency of the dispersed oils to coagulate is discussed using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.