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Determination of fungicides in residual tanning floats using solid phase micro extraction

Tue, 05 Feb 2013 15:48:08 GMT

Title: Determination of fungicides in residual tanning floats using solid phase micro extraction Authors: Font Vallès, Joaquim; Reyes Reyes, Maria; Cuadros, Sara; Bacardit Dalmases, Anna; Ollé Otero, Lluís; Marsal Monge, Agustín Abstract: Solid-phase microextraction (SPME) was optimized for extraction of the leather preservative agents 2-(thiocyanomethylthio)-benzothiazole (TCMTB), 4-chloro-3-methylphenol (PCMC), 2-phenylphenol (OPP), 2-Octyl-3(2H)-isothiazolone (OIT), 2-mercaptobenzothiazol (MBT) and 3-iodo-2-propynyl-butylcarbamate (IPBC) in spent tanning floats. Determination was carried out by high performance liquid chromatography (HPLC) with photo diode array detection (PDA). The following parameters were studied to achieve the maximum efficiency in extraction: fiber type, adsorption conditions (extraction time, ionic strength, temperature) and desorption parameters (time, temperature and composition of the desorption solvent). Results indicate that SPME using a 60um polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber is appropriate for the extraction of these types of compounds. Recoveries ranged from 82% to 116% with RSDs between +-8% and +-12% and limits of detection below 1 mg/L except for IPBC. The optimized procedure was successfully applied for the determination of leather preservatives in eleven residual tanning floats taken from different companies. This method enables us to determine quantitatively the fungicides contained in th residual floats. Consequently, it will constitute a very useful tool to improve the preservative uptake in leather manufacturing processes

GREDIQ-RIMA: The evolution of a teaching project of experimentation in chemistry

Tue, 05 Feb 2013 15:33:21 GMT

Title: GREDIQ-RIMA: The evolution of a teaching project of experimentation in chemistry Authors: Grau Vilalta, Maria Dolors; Guaus Guerrero, Ester; Martínez Martínez, María del Rosario; Calvet Tarragona, Aureli; Farran Marsà, Adriana; Salán Ballesteros, Maria Núria; Álvarez del Castillo, María Dolores; Gorchs Altarriba, Roser; Almajano Pablos, María Pilar; Morillo Cazorla, Margarita; Garrido Soriano, Núria Abstract: Authors of this project belong to the Resources Chemistry Teaching Group (GReDiQ) involved in RIMA (Research and innovation in learning methodologies). The audiovisual and multimedia material productions realized have been grouped into three themes: Basic Techniques of Experimentation in Chemistry, Safety in Chemistry Laboratories and Advanced Techniques of Experimentation in Chemistry. This work has been awarded a prize of the Universitat Politècnica de Catalunya (UPC–BARCELONATECH), one of the Autonomous Region of Catalunya and another one of a State scope

Isocyanate toughened pCBT: reactive blending and tensile properties

Tue, 11 Dec 2012 15:45:30 GMT

Title: Isocyanate toughened pCBT: reactive blending and tensile properties Authors: Abt, Tobias Martin; Martínez de Ilarduya Sáez de Asteasu, Domingo Antxon; Bou Serra, Jordi; Sánchez Soto, Miguel Abstract: Cyclic butylene terephthalate oligomers (CBT) were reacted in a ring-opening polymerization with three types of isocyanates: a bifunctional aromatic type, a bifunctional aliphatic type and a polymeric aromatic isocyanate. All reactions took place in a batch mixer. The use of 0.5 to 1 wt% isocyanate led to a dramatic increase in elongation at break of polymerized cyclic butylene terephthalate (pCBT), from 8 to above 100%. The stiffness and strength of the modified pCBT, however, were found to slightly decrease. Proton nuclear magnetic resonance (NMR) analysis shows that the formation of thermally stable amide groups is the dominant chain extension reaction mechanism. Gel content measurements suggest a linear structure for samples containing bifunctional isocyanates while pCBT modified with polyfunctional isocyanate exhibited some gel formation at higher isocyanate content. Melting and crystallization temperatures as well as degree of crystallinity were found to decrease with increasing isocyanate content. No phase separation was detected by scanning electron microscopy (SEM) analysis. Moreover, a high degree of polymerization is deduced due to the absence of CBT oligomer crystals. Description: Electronic version of an article published as "Express polymer letters" vol. 7, nº. 2, February 2013, p. 172-185.

Determination of penetration and fixation curves of leather using humic derivatives

Tue, 26 Jun 2012 14:27:04 GMT

Title: Determination of penetration and fixation curves of leather using humic derivatives Authors: Bacardit Dalmases, Anna; Shendrik, Alexander; Morera Prat, Josep Maria; Bou Serra, Jordi; Ollé Otero, Lluís Abstract: This study examines the behavior of three different types of humic acids (natural humic acids, regenerated humic acids, and sulphited humic acids) with regard to their penetration and fixation to the leather. More specifically, through the tests carried out the curves of penetration and fixation were drawn, and from these the optimum pH intervals of penetration and fixation to the leather were determined. The data obtained is essential in view of the subsequent application of humic acids as tanning agents and/or retanning agents

Study of the effect of temperature, relative humidity and UV radiation on chrome-tanned leather ageing

Thu, 07 Jun 2012 15:37:22 GMT

Title: Study of the effect of temperature, relative humidity and UV radiation on chrome-tanned leather ageing Authors: Bacardit Dalmases, Anna; Jorba, Montse; Font Vallès, Joaquim; Ollé Otero, Lluís Abstract: Since leather is strongly affected by three main environmental parameters: temperature, relative humidity and UV radiation, this piece of research focuses on the effect that these three factors have on chrome-tanned leather ageing. Chrome tanned leathers were exposed to weathering effects in a climatic chamber in order to identify the most important variables affecting this weathering process and also to check for any possible interactions. Both a multilevel centralized factorial experimental design and an analysis of variance (ANOVA) were used as statistical tools for estimating the effects of the parameters

Humic acid derivatives as tanning and retanning agents

Thu, 26 Apr 2012 15:16:08 GMT

Title: Humic acid derivatives as tanning and retanning agents Authors: Bacardit Dalmases, Anna; Morera Prat, Josep Maria; Shendrik, Alexander; Jorge Sánchez, Juan; Ollé Otero, Lluís Abstract: This study examines the behaviour of three types of humic acids (natural humic acids, regenerated humic acids, and sulphited humic acids) with regard to their capacity to be used as tans and retans. The study makes use of conditions set out in a previous study (See Determination of penetration and fixation curves of leather using humic derivatives). Additionally, subsequent complementary tests were carried out using other retans that are commonly used in the tanning industry in order to compare and improve on the physical properties assessed here

Comparison of weathering variables on chrome-tanned and wet-white leather ageing

Tue, 21 Feb 2012 10:39:49 GMT

Title: Comparison of weathering variables on chrome-tanned and wet-white leather ageing Authors: Ollé Otero, Lluís; Jorba, Montse; Castell, Joan Carles; Font Vallès, Joaquim; Bacardit Dalmases, Anna Abstract: Leather is a natural material that can be used in different environments and often under aggressive environmental conditions that may cause premature ageing. The most important factors influencing the degradation of leather are temperature, relative humidity and UV radiation. Leathers with chrome tannage and wet-white leathers were exposed to weathering effects using a climatic chamber in order to identify the most important variables affecting this weathering process and to check for interactions. Both a multilevel centralized factorial experimental design and an analysis of variance (ANOVA) have been employed as statistical tools for estimating the effects of the parameters

Neuroprotective effects of white tea against oxidative

Wed, 25 Jan 2012 11:51:47 GMT

Title: Neuroprotective effects of white tea against oxidative Authors: Almajano Pablos, María Pilar; Vila, Ingrid; Ginés, Silvia Abstract: Tea is one of the most widely consumed beverages in the world and represents an important source of antioxidants mainly catechins that confer beneficial effects in reducing the risk of cardiovascular diseases, age-related disorders or cancer. In the central nervous system, oxidative stress caused by increased production of reactive oxygen and nitrogen species represents an important mechanism for neuronal dysfunction and cell loss in different neurodegenerative disorders. The neuroprotective effects of green-tea-derived polyphenols have extensively been demonstrated in different models of neurotoxicity. However, few data have been reported on the antioxidant activity of white tea extracts in the nervous system. In the present study, we demonstrate that white tea extracts protect striatal cell lines against oxidative stress-mediated cell death. The effects of white tea on protection of striatal cell cultures are likely associated with the antioxidant properties of white tea components since neuronal cell loss induced by nonoxidative insults such as D1 dopamine receptor activation cannot be prevented by pre-treatment with white tea. Altogether our results suggest that regular consumption of white tea may contribute to reduce oxidative stress associated with brain injury and be clinically useful for treating age-related and neurodegenerative disorders.

Synthesis of highly carboxylate acrylic resins for leather impregnation

Mon, 16 Jan 2012 11:06:52 GMT

Title: Synthesis of highly carboxylate acrylic resins for leather impregnation Authors: Ollé Otero, Lluís; Solé, M.M.; Shendrik, Alexander; Labastida, L.; Bacardit Dalmases, Anna Abstract: This work describes the synthesis of new leather finishing acrylic resins. Four resins ware synthesized varying the concentration of ethyl acrylate, and metracrylic acid. Sodium lauryl sulphate was used as emulsifying system. By means of an experimental design, an optimal resin for leather impregnation was defined. The results obtained indicated that the variation of the monomer concentration influences the resin properties, the hardness of the film, and the penetration into the leather. Most importantly, this new highly carboxylate acrylic resin enables leather impregnation without the use of surfactants or penetrating agents

Determination of functional groups of humic derivatives as tanning-retanning agents

Wed, 30 Nov 2011 08:14:31 GMT

Title: Determination of functional groups of humic derivatives as tanning-retanning agents Authors: Bacardit Dalmases, Anna; Shendryck, Alexander; Morera Prat, Josep Maria; Bou Serra, Jordi; Ollé Otero, Lluís Abstract: Three types of humic acids of different sources have been analysed in order to quantify the functional groups that may be liable to react with the proteins of leather. The quantification serves to determine the extent to which each of these acids can be used as tanning or retanning agents. The three types of humid acids have been compared mathematically according to their content within the aforementioned functional groups. Humic acids have structures similar to those of vegetable tannins.

Optimizing a Sustainable and Innovative Wet-White Process with Tara Tannins

Wed, 05 Oct 2011 13:53:52 GMT

Title: Optimizing a Sustainable and Innovative Wet-White Process with Tara Tannins Authors: Castell, Joan Carles; Fabregat, Cristina; Sorolla Casellas, Sílvia; Ollé Otero, Lluís; Bacardit Dalmases, Anna; Solano, D Abstract: This study considers the fruit of the tara tree (Caesalpinia spinosa) as a sustainable source for tanning agents and proposes alternatives to the commercial mineral salts and vegetable extracts to comply with an increasing demand that concers low carbon footprint raw materials and health safety. Although tara tannins have been used in the leather industry and its properties being well known, the experimental part of the work aims to optimize innovative formulations using tara as wet-white pre-tanning agent. Combinations with naphthalene sulphonic and phenol condensation syntans will be used for wet white. Experiments have been designed by Simplex with centroids statistical calculations to obtain an optimized formulation. Tests are evaluated determining shrinkage temperature, tensile strenght, elongation, tear resistance and light fastness.

Use of water-based carbonyl-functional polymers on a cross-linker-free highperformance leather finish

Mon, 26 Sep 2011 11:28:47 GMT

Title: Use of water-based carbonyl-functional polymers on a cross-linker-free highperformance leather finish Authors: Ollé Otero, Lluís; Urteaga, Eva; Font, Joaquim; Labastida, Luis; Bacardit Dalmases, Anna Abstract: The present paper aims to study a new high-performance coating formulation while avoiding the use of cross-linkers. By using acrylic polymers with carbonyl functional groups, the negative environmental effects of the finishing process can be minimized. These new polymers can give very good physical properties without losing the inherent properties of flexibility and elasticity needed in upholstery leather

Use of water-based carbonyl-functional polymers on a cross-linker-free high performance leather finishing

Wed, 07 Sep 2011 15:42:56 GMT

Title: Use of water-based carbonyl-functional polymers on a cross-linker-free high performance leather finishing Authors: Ollé Otero, Lluís; Urteaga, Eva; Font, Joaquim; Labastida, Luis; Bacardit Dalmases, Anna Abstract: The present paper aims to study a new high-performance coating formulation while avoiding the use of cross-linkers. By using acrylic polymers with carbonyl functional groups, the negative environmental effects of the finishing process can be minimized. These new polymers can give very good physical properties without losing the inherent properties of flexibility and elasticity needed in upholstery leather

Comparisonof the effect of the tropical test on both chrome-tanned and wet-white upholstery leather

Wed, 22 Jun 2011 11:49:21 GMT

Title: Comparisonof the effect of the tropical test on both chrome-tanned and wet-white upholstery leather Authors: Ollé Otero, Lluís; Jorba Rafart, Montse; Font Vallès, Joaquim; Bacardit Dalmases, Anna Abstract: Automotive upholstery leather can undergo extreme environmental conditions that may cause premature ageing. Leather is strongly affected by three main environmental parameters: temperature,relative humidity and UV radiation. UV radiation causes colour change, fading, surface erosion, loss of gloss, etc. Increasing the levels of UV radiation represents a primary accelerating factor for leather ageing. Temperature produces thermal oxidation degradations, subsequent reaction rates and acceleration of other weathering reactions. Relative humidity acts as a chemical reagent in many hydrolytic weathering reactions and as a physical stressor of leather. Additionally, when relative humidity is over 65% leather is susceptible to mould attack. The aim of this work is to compare the effect of the tropical environment exposure on both chrometanned and wet-white upholstery leather.

Biodegradation of wet-white leather

Wed, 22 Jun 2011 11:31:03 GMT

Title: Biodegradation of wet-white leather Authors: Ollé Otero, Lluís; Jorba Rafart, Montse; Font Vallès, Joaquim; Shendrik, Alexander; Bacardit Dalmases, Anna Abstract: This paper deals with the study of the physical, chemical and biological processes associated with the deterioration of wet-white leather. The samples of leather were exposed for eight months to outdoor weathering and then their properties were subsequently evaluated. The results indicate that resistance and dimensional stability of wet-white (THPS-syntan) leather is higher than that of chrometanned leather. The comparative work with chrome leather was described earlier.