Maria das Graças da Silva Valenzuela
University of São Paulo
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TMS Annual Meeting & Exhibition | 2018
Adriana Cutrim; Margarita Bobadilla; Kleberson Ricardo de Oliveira Pereira; Fabio Jose Esper; Guillermo Ruperto Martin Cortes; Maria das Graças da Silva Valenzuela; Francisco Rolando Valenzuela-Díaz
Bentonites are an important kind of industrial clays with more than a hundred different uses. In the oil and gas industries they are used as thixotropic additives for drilling fluids and also as sorbents for purification of flows and effluents. Due to the mechanical and thermal properties that they exhibit, bentonites will become in a near future important fillers in clay/polymer nanocomposites which could be used in the oil and gas industry for replacement of various metal components. In this paper a chocolate color bentonite from the state of Paraiba in Brazil was characterized by diverse techniques such as XRD, DSC/TGA, surface area, and cation exchange capacity and it was studied its potential use as thixotropic additive for oil and gas drilling fluids and as sorbents of oils. The bentonite showed good potential for use in those applications.
Characterization of Minerals, Metals, and Materials | 2015
C. G. Bastos Andrade; V. F. Justo; Danilo Marin Fermino; Maria das Graças da Silva Valenzuela; C. Volzone; Francisco Rolando Valenzuela-Díaz
The present paper presents the study of light green smectite clay, from Paraiba, Brazil, submitted to mild acid attack under moderated conditions. Usually, clays are subjected to treatment with strong inorganic acids at temperatures near the boiling point and at high acid concentrations and then, widely used as bleaching agents. The treatment occurred under bellow boiling temperature and at short times of reaction (90°C, reaction times of 1, 6, 12, 18 and 24 hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, clay/acid solution ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities providing color, with minimal change in the clay minerals structure, aiming at use in products of high value such as cosmetics and polymer/clay nanocomposites. The raw clay and the attacked samples were characterized by X-ray diffraction (XRD), cation exchange capacity (CEC), stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray detector (EDS).
Characterization of Minerals, Metals, and Materials | 2015
Guillermo Ruperto Martín-Cortés; Fabio José Esper; Antonio J. Santana de Araujo; Wildor Theodoro Hennies; Maria das Graças da Silva Valenzuela; Francisco Rolando Valenzuela-Díaz
Seeking to replace carbon-black as filler of rubber in the production of vulcanized goods, researchers from University of Sao Paulo have studied different materials types as minerals, vegetal or wastes agricultural and industry. Results of rubber composites filled with MA1 a waste of mineral treatment provided by Esper Industries are presented. MA1 was characterized through X-ray diffraction; Thermal analysis; Scanning Electronic Microscopy; and others laboratory methods. The composite and shaped masses were evaluated by these methods plus their mechanical properties such as tensile strength, elongation at break and hardness. Exceptional results were obtained in the mechanical properties evaluated, better than those obtained with the traditional carbon-black. Seeing the kind of material used as filler, it can conclude that the environmental benefit is present, as well as economic development, giving credibility to the use of these alternative material in replacement carbonblack.
Characterization of Minerals, Metals, and Materials | 2015
C. G. Bastos Andrade; V. F. Justo; Camila Martini Matos; Maria das Graças da Silva Valenzuela; C. Volzone; Francisco Rolando Valenzuela-Díaz
For industrial use, the smectite clays are usually treated with inorganic acid of high concentration at temperatures under boiling point, which provide the bentonite´s bleaching power. In the present paper, a sample of brown smectite from Paraiba, Brazil, was submitted to treatment under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5M, clay/acid solution ratio of 1g/10mL), aiming to reduce impurities, responsible for the color of the clay, without causing significant changes in their structure. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray detector (EDS), stereomicroscopy, Cation Exchange Capacity (CEC), Thermal Analysis (TG/DTA), and X-ray diffraction (XRD). It was observed a bleaching in samples with time of 12h to 18h. With the DRX was possible to monitor the peak intensity of the clay structure and the sample with 12 hours of treatment was not significantly altered its crystalline structure, maintaining the peak clay at d(001). The most pronounced changes in the bleaching occurred within the first 12 hours of acid treatment. Thus, clay can be used in products with high added value.
Applied Clay Science | 2013
Liaqat Ali Shah; Maria das Graças da Silva Valenzuela; Abdul Mannan Ehsan; Francisco Rolando Valenzuela Díaz; Nazir Shah Khattak
Materials Research-ibero-american Journal of Materials | 2007
Ana Carolina Vale Campos Lisbôa; Maria das Graças da Silva Valenzuela; Gisella Grazioli; Francisco Rolando Valenzuela Díaz; Mari Cleide Sogayar
Characterization of Minerals, Metals, and Materials | 2014
Danilo Marin Fermino; Maria das Graças da Silva Valenzuela; Esperidiana A. B. Moura; Duclerc Fernandes Parra; Francisco Rolando Valenzuela Díaz
Archive | 2017
F. García; Amanda R. Porrua; Giselle F. Colls; Esperidiana A. B. Moura; Maria das Graças da Silva Valenzuela; Tania R. Moliner; José Luís Valín Rivera; Francisco Rolando Valenzuela Díaz; th Brazilian Mrs Meeting
Archive | 2017
Jesús Eduardo González Ruiz; Lais Ronconi; Lourdes Y. Lazaro; Rene C. Carceller; Maria das Graças da Silva Valenzuela; Esperidiana A. B. Moura; José Luis Valin Rivera; Tania R. Moliner; Francisco Rolando Valenzuela Díaz; th Brazilian Mrs Meeting
Characterization of Minerals, Metals, and Materials | 2014
Messias dos Santos Machado; Hélio Wiebeck; Francisco Rolando Valenzuela-Díaz; Maria das Graças da Silva Valenzuela; V. F. Justo