Isabel Villaescusa - Academia.edu (original) (raw)

Papers by Isabel Villaescusa

Resum Partint de que els alumnes que arriben a l'Escola Politècnica Superior ja han assolit l... more Resum Partint de que els alumnes que arriben a l'Escola Politècnica Superior ja han assolit la decisió prèvia de seguir estudis tècnics, i porten un semestre després d'haver iniciat el curs, els proposem una reflexió sobre els seus estudis i la possibilitat d'exposar les seves il·lusions i els seus desencisos respecte al que n'esperaven de la universitat. Aprofitem per a remarcar-los-hi la disponibilitat dels recursos que proporciona el Centre per facilitar-los-hi la integració a la Universitat, a l'Escola i concretament al seu estudi. Aquesta part del procés s'inicia amb l'oportunitat de respondre una enquesta preparada per fer el seguiment de la seva inserció universitària amb preguntes de resposta oberta que al mateix temps d'ajudar a la verificació del funcionament de les diferents activitats de suport que els dóna l'escola, serveixen d'invitació a la reflexió tant per als alumnes matriculats per primera vegada com per als professors i equ...

The possibility of using biosorption as alternative technology for metal ions removal in wastewat... more The possibility of using biosorption as alternative technology for metal ions removal in wastewaters and contaminated sites is well known since many years as documented by several articles and compilations [Eccles et al., 1986;]. Among the possible low cost biomaterials which can be used in the metal sorption process, alginic acid, a copolymer of 1,4 linked -D-mannuronic (M) and α-L-guluronic (G) acid residues (the main component of brown algae) and pectin, a galacturonic acid based polysaccharide usually extracted from apple pulp and peel of citrus fruits, have been considered in this work. All these sorbent materials were used as calcium compounds gel beads and their sorption capacity, in terms of kinetics ( ) and equilibrium study toward mercury(II) ion, was also evaluated considering the amount of calcium exchanged by the mercury(II) ion. 0 50 100 150 200 250 300 0 5 10 15 20 25 30 35 CA PGA Pect mg of Hg 2+ per g of gel Time / min Figure 1. Dependence of Lagergren pseudo second order equation q t parameter (mg of Hg 2+ / g of dry biosorbent) on contact time for different gel beads at pH = 3.6, T = 25 ± 0.1°C.

Journal of Environmental Chemical Engineering, 2013

Reactive and Functional Polymers, 2013

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Enterprise internships stand nowadays as one of the key educational activities carried out outsid... more Enterprise internships stand nowadays as one of the key educational activities carried out outside the classroom. While internships help students in their curriculum development, the increase of student placements due to the Bologna process raises a number of issues such as: (a) the establishment of adequate protocols to guarantee enough high-quality industrial internships for all our students; (b) lack of adequate management tools to efficiently organize and monitor internships. In this paper we present a transversal enterprise internships programme, which targets quality improvement, academic control and satisfaction of collaborating enterprises. The fundamental infrastructure of this programme combines a web-based intranet platform with a protocol of procedures and tasks that are observed and followed at all internship stages.

Coordination Chemistry Reviews, Sep 1, 2010

After an overview of environmental pollution and the environmental threat posed by metals, this p... more After an overview of environmental pollution and the environmental threat posed by metals, this paper focuses on a literature survey of the different analytical methodologies and techniques used to investigate the functional groups involved in metal sorption onto biomass derived from agricultural waste. The recent literature has mainly focused on identifying the binding groups on the biomass surface through the

Journal of Hazardous Materials, Mar 15, 2010

Grape stalk Effect of pH Effect of temperature Box plots a b s t r a c t In this work, the effect... more Grape stalk Effect of pH Effect of temperature Box plots a b s t r a c t In this work, the effect of pH control on kinetics of Cr(VI) sorption onto grape stalks has been studied. A set of experiments were performed at a constant pH 3 ± 0.1 which was assured by means of a Programmable Logic Controller (PLC). In a second set of experiments the initial pH was adjusted to pH 3 and then pH was allowed to freely evolve during the sorption process. Both sets of experiments were carried out at different temperatures within the range 5-50 • C. Constant temperature was assured by water recirculation from a thermostatic bath. Results demonstrated that pH has high influence on kinetics only at the lowest temperatures studied. A model based on a complex reaction sequence which takes into account Cr(VI) sorption, reduction of Cr(VI) to Cr(III), sorption of the formed Cr(III) which includes the pH variation during the sorption process has been proposed to model Cr(VI) kinetics sorption onto grape stalk waste. Furthermore, the robustness of the model has been tested.

The Science of the total environment, Jan 19, 2015

In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using s... more In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)-Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been develo...

The increasing application and the immutable nature of heavy metals has made of this kind of poll... more The increasing application and the immutable nature of heavy metals has made of this kind of pollution one of the most serious environmental problems nowadays. As they are no degradable, they can accumulate in the components of the environment where their toxicity is expressed. Due to the special concern of heavy metal pollution in waters, there is an increasing interest towards the development of sustainable, environmentally friendly and cheap technologies for water treatment. Among the different materials that can be used for the detoxification of heavy metal polluted effluents, grape stalks (GS) has demonstrated an excellent performance. GS are the branches that connect the grape grains in the compact structure of the bunch. The material, mainly composed by cellulose and lignin, is an industrial by-product of wine elaboration industries that is generated in huge amounts in several countries worldwide. The management of these wastes, in many cases, involves an important extra cost...

Science of The Total Environment

The most frequently encountered forms of organic arsenic, namely, dimethylarsinic acid, monomethy... more The most frequently encountered forms of organic arsenic, namely, dimethylarsinic acid, monomethylarsonic acid, arsenobetaine, arsenocholine and Roxarsone (4-hydroxy-3-nitrobenzene arsonic acid) were tested for toxicity either by using the Microtox bioassay, based on the rapid (within 15 min) fading of luminescence emitted by Vibrio fischeri marine bacteria, or by monitoring growth rate of the same bacteria for 3 days. Organic arsenic was generally found to be less toxic to these biological models than inorganic arsenic. In many cases, EC50 values for DMA, MMA or HNAA when using luminescence or growth inhibition assays could not be determined because of the low toxicity of the compounds. Nevertheless, results from the luminescence inhibition assay, which was found to be more sensitive than the growth inhibition assay, allowed to rank toxicity as follows: arsenate at pH 8>HNAA at pH 5>arsenate at pH 5>MMA at pH 5>HNAA at pH 8>DMA at pH 5. Arsenobetaine and monomethylar...

Reviews in Environmental Science and Bio/Technology

Because dramatic cases of arsenic contamination of water resources, soils, vegetables, humans and... more Because dramatic cases of arsenic contamination of water resources, soils, vegetables, humans and animals increase, this review has focussed on the fate and behaviour of this element and what kind of health impacts are related with its release in surface or ground waters. In a first part, we point out how the primary minerals can lead to As mobilization and exportation by surface waters and suspended matter. We also emphasize the particular key role for As retention through both adsorption onto natural Fe(III) (hydr)oxides, Mn oxides and/or precipitation as Fe(III) arsenates. Nowadays, numerous and efficient systems for arsenic removal from any natural resources are available to produce good quality drinking water (with <10μg/l As); however it is not within the scope of the present review. In a second part we focus on recent knowledge about the human toxicity of the various arsenic species. Chronic exposure to As in drinking water lead to many health diseases and, although the me...

International Journal of Biological Macromolecules, 2015

Selected biosorbents, brewers draff and grape waste, have been encapsulated in calcium alginate b... more Selected biosorbents, brewers draff and grape waste, have been encapsulated in calcium alginate beads and used for the removal of Cr(VI) from aqueous solutions. The effects of encapsulation variables, including the type of waste, the percentage of waste in the beads and the curing time of the beads in CaCl2, on the diameters of the beads and Cr(VI) sorption kinetics have been evaluated. In total, 21 different types of beads were produced. The diameters of the beads increased with increasing amounts of encapsulated biomaterial. Beads that contained grape waste were larger than those containing brewers draff. The most efficient beads for Cr(VI) removal were beads that contained 4% w/w of grape waste. No significant differences in the kinetics of Cr(VI) sorption were found with respect to the curing time variable in the case of grape waste calcium alginate beads. Statistical analysis confirmed that the type and percentage of waste are the critical parameters influencing the diameters of the beads and Cr(VI) removal. It was proven that the sorption efficiencies of the beads containing draff and grape waste encapsulated under the optimum conditions were much higher than the efficiencies obtained when using both wastes in their native states.

The Science of the total environment, Jan 7, 2015

Understanding the role of biomacromolecules and their interactions with pollutants is a key for e... more Understanding the role of biomacromolecules and their interactions with pollutants is a key for elucidating the sorption mechanisms and making an accurate assessment of the environmental fate of pollutants. The knowledge of the sorption properties of the different constituents of these biomacromolecules may furnish a significant contribution to this purpose. Suberin is a very abundant biopolymer in higher plants. In this study, suberin monomers isolated from cork were analyzed by thermally-assisted methylation with tetramethylammonium hydroxide (TMAH) in a pyrolysis unit coupled to gas chromatography-mass spectrometry (GC/MS). The isolated monomer mixture was used to study the sorption of three pesticides (isoproturon, methomyl and oxamyl). The modes of pesticide-sorbent interactions were analyzed by means of two modeling calculations, the first one representing only the mixture of suberin monomers used in the sorption study, and the second one including glycerol to the mixture of s...

Biomass - Detection, Production and Usage, 2011

Comptes Rendus Chimie, 2015

ABSTRACT The performance of a microporous activated carbon prepared chemically from olive stones ... more ABSTRACT The performance of a microporous activated carbon prepared chemically from olive stones for removing Cu(II), Cd(II) and Pb(II) from single and binary aqueous solutions was investigated via the batch technique. The activated carbon sample was characterized using N2 adsorption-desorption isotherms, SEM, XRD, FTIR, and Boehm titration. The effect of initial pH and contact time were studied. Adsorption kinetic rates were found to be fast and kinetic experimental data fitted very well the pseudo-second-order equation. The adsorption isotherms fit the Redlich-Peterson model very well and maximum adsorption amounts of single metal ions solutions follow the trend Pb(II) > Cd(II) > Cu(II). The adsorption behavior of binary solution systems shows a relatively high affinity to Cu(II) at the activated carbon surface of the mixture with Cd(II) or Pb(II). An antagonistic competitive adsorption phenomenon was observed. Desorption experiments indicated that about 59.5% of Cu(II) and 23% of Cd(II) were desorbed using a diluted sulfuric acid solution.

International Journal of Chemical Engineering and Applications, 2012

The sorption of heavy metals (Cd2+, Ni2+) on activated carbons produced from olive stones (OSAC) ... more The sorption of heavy metals (Cd2+, Ni2+) on activated carbons produced from olive stones (OSAC) was studied by using a batch technique. OSAC was prepared by tow processes using phosphoric acid as chemical agent. The physicochemical proprieties of these carbon materials were investigated in the term of N2 adsorptions, pHpzc and SEM-EDX. Cd(NO3)2,4H2O and Ni(NO3)2,3H2O were used as heavy metal samples. The effects of equilibrium time, initial concentration and initial pH were investigated. The adsorption isotherms of heavy metals from aqueous solution were determined. These isotherms were seen to be consistent with Langmuir adsorption isotherm. The adsorption constant rate was determined for obtained kinetics curves suitable for second degree of rate kinetics. Chemical and combined activated carbons were compared according to their percent of removal of heavy metals.

Chemical Speciation and Bioavailability, 2004

The removal of hexavalent chromium from aqueous solution using grape stalks wastes encapsulated i... more The removal of hexavalent chromium from aqueous solution using grape stalks wastes encapsulated in calcium alginate (GS-CA) beads was investigated. Cr(VI) sorption kinetics were evaluated as a function of chromium initial concentration and grape stalks (GS) content in the calcium alginate (CA) beads. The process follows pseudo second-order kinetics. Transport properties of hexavalent chromium on GS-CA beads was characterised by calculating chromium diffusion coefficient using the Linear Absorption Model (LAM). Langmuir isotherms, at pH 3.0 were used to describe sorption equilibrium data as a function of GS percentage in the CA beads. Maximum uptake obtained was 86.42 mmol of Cr(VI) per L of wet sorbent volume. Results indicated that both kinetic and equilibrium models describe adequately the adsorption process.

Arabian Journal of Chemistry, 2013

Sorption of Cr(III) and Cr(VI) ions onto 2% grape stalk (GS) powder entrapped in a biopolymeric g... more Sorption of Cr(III) and Cr(VI) ions onto 2% grape stalk (GS) powder entrapped in a biopolymeric gel matrix of calcium alginate (CA) has been investigated and a mechanism for the retention of both, Cr(VI) and Cr(III) is proposed. Protons were found to be consumed in Cr(VI) sorption/reduction and to compete with Cr(III) for the sorbent active sites. Isotherm equilibrium was modelled according to Langmuir equation: maximum capacity was found to be 6.4 and 3.6 mg g À1 for Cr(III) and Cr(VI), respectively. The important Ca 2+ release observed when Cr(III) is sorbed indicates that ion exchange is the main mechanism involved at concentrations lower than 200 mg L À1 while other mechanisms such as microprecipitation or coordination might take place for higher initial concentrations. In the case of Cr(VI), the sorption mechanism is based on the reduction to Cr(III) promoted by both protons and the functional groups on the GS surface; this reduction-formed Cr(III) is retained by the alginate gel matrix and by microprecipitation onto the surface of GS particles. ESR and SEM-EDX were used to identify chromium species sorbed on the solid phase. Results from this study suggest that GS entrapped in CA gel beads is an effective sorbent for both, Cr(III) and Cr(VI) removal from aqueous solutions. ª 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University.

Fresenius Journal of Analytical Chemistry, 1998

ABSTRACT The toxicity of nickel and lead compounds has been evaluated in NaCl and NaClO4 solution... more ABSTRACT The toxicity of nickel and lead compounds has been evaluated in NaCl and NaClO4 solutions by using the MicrotoxR bioassay. The aim of this work was to assess the toxicity of the different species in solution when varying the concentration of the medium. A modified Microtox protocol which enables the pH to be constant in all the cuvettes during analysis has been used. The positively charged species (Ni2+, Pb2+, PbCl+) were found to contribute more to the toxicity of Ni and Pb in NaCl while in NaClO4 solutions free metal was the responsible species. In all media studied, Pb compounds were the most toxic and provoked a quick response of the bacteria.