Graphene films were prepared on a glassy carbon electrode for amperometric determination of promethazine hydrochloride in pharmaceutical products. This modified sensor was prepared by chemical oxidation of graphite powder followed by product exfoliation in ultrapure water using an ultrasonic bath. Then, the resultant graphene oxide was electrochemically reduced in 0.10 mol L À1 acetic acid-sodium acetate (pH = 5.0) on a glassy carbon electrode surface. The proposed sensor exhibited reproducible amperometric responses in a wide linear range from 1.99 Â 10 À6 to 1.03 Â 10 À3 mol L À1 at +0.78 V (vs. Ag/AgCl).Low detection and quantification limits (1.99 Â 10 À7 mol L À1 and 6.63 Â 10 À7 mol L À1 , respectively) were achieved. This method was applied to the analyses of commercial tablet samples and all results were in good agreement with those obtained using spectrophotometry and high-performance liquid chromatography.
The management of health, safety, and environmental (HSE) aspects during production, manipulation, storage, incorporation, and disposal of carbon nanomaterials is the key factor for the development of a safe-by-design work based on nanotechnology. The almost endless possibility of functionalization, chemical interaction, and addition of nanomaterials into new products implies a new management approach of HSE. Low amount of reliable toxicity and ecotoxicity data of nanomaterials and nanomaterial composites is available. As complete exposure/ release assessments are a challenging task, recommendation for control measurements is still based on the precautionary point of view. There is an incomplete understanding of environmental fate-and time-related exposure, and of consumer-and worker-related risks and hazards. Control banding and risk evaluation matrix tools can be used to mitigate labor and environment impacts of carbon nanomaterials. This chapter presents new tools and methodologies for exposure assessment and risk evaluation of hazards used on HSE management system of carbon nanomaterials.
Mortar bond covering systems are multilayered and applied to a base, composed of render mortars (stucco, plaster) followed by some decorative element for a finishing touches (paint, ceramic plate, ornamental stones, etc.). In order to homogenize the characteristics of the base material and to increase the bond with the render mortar, it is a common practice to apply some type of preparation, either an even, smooth solution such as wetting the walls, or roughened solution utilizing roughcast. Studies have shown that the presence of calcium ions in ceramic bases results in the formation of a more dense crystalline structure at the interface, which culminates with higher mechanical bond strength. In this light, the present study presents an experimental investigation, the purpose of which is to evaluate, in a comparative way, the direct tensile strength of bond of a mortar coating applied to the same base, preceded in its application by five different preparation techniques. It can be concluded from this study that the preparation of the mortar base is of fundamental importance for bonding strength and, therefore, the addition of a lime solution to the roughcast is economically feasible and a satisfactory alternative in order to obtain positive results in environments where bond strength is critical.
RESUMO -O objetivo desse trabalho foi verificar a capacidade de partição dos ácidos húmicos por extração líquido-líquido em um sistema formado a partir de n-propanol, NaOH e água, e a influência da temperatura no processo de separação. A construção da curva binodal pela metodologia proposta por Merchuk, permitiu escolher concentrações para a formação do sistema bifásico. O menor coeficiente de partição obtido foi de 0,013 e a maior recuperação de 99,282%. INTRODUÇÃOAs substâncias húmicas (SH) são complexantes de origem natural resultantes da decomposição da matéria orgânica presente no solo mediante ação de intempéries físicos, químicos e biológicos. Tais substâncias são classificadas em três grupos com base na solubilidade: ácidos fúlvicos (AFs), solúveis em meio ácido e alcalino, ácidos húmicos (AHs) solúveis em meio alcalino, parcialmente solúveis em água e insolúveis em meio ácido e huminas, insolúveis em qualquer faixa de pH (Cooper, 1999).AHs são moléculas anfifílicas com grande quantidade de grupos funcionais fenólicos e carboxílicos, que compõem as suas porções hidrofílica e hidrofóbica (Terashima et al., 2004). Esses grupos são responsáveis por várias propriedades farmacológicas tais como antifúngica, antioxidante, anti-inflamatória, dentre outras, que tornam os AHs de grande interesse para aplicações farmacêuticas (Junek et al., 2009).Atualmente os AHs comerciais são extraídos principalmente de fontes não renováveis de carbono, como a turfa e o carvão mineral. A obtenção de AH a partir de fontes renováveis de carbono foi estudada por Motta e Santana (2014) a partir da fermentação submersa ou em estado sólido utilizando linhagens de Trichoderma reesei ou viridiae, e o fruto vazio da palma, um resíduo agroindustrial abundante no Brasil e em países produtores do óleo de palma, como substrato.A recuperação dos AHs das várias fontes é normalmente feita por extração, que utiliza diferenças de pH e reagentes químicos que podem alterar a sua estrutura e consequentemente a sua funcionalidade nas aplicações (Saito e Seckler, 2014).
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