ABSTRACT
Objective To prepare 4-sulfonylcalix[6]arene-modified cotton fibers for adsorption and removal of uranium based on the specific complexation of calix[6]arene with uranium (VI). Methods Chemical grafting was used for the modification of cotton, which reacted with α-bromoisobutyryl bromide, glycidyl methacrylate, and 4-sulfonylcalix[6]arene. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (FTIR) were used to characterize the structure of 4-sulfonylcalix[6]arene-modified cotton (Cotton S-C[6]a). A Franz diffusion cell was used to simulate uranium-contaminated skin. Laser fluorimetry was used to determine the uranium content. Results SEM, XPS, and FTIR showed that cotton fibers were successfully grafted with 4-sulfonylcalix[6]arene. The optimal conditions of Cotton S-C[6]a for the adsorption of uranium (VI) was pH 4.0, duration of 20 min, and 20 mg of adsorbent. The adsorption process fitted well with pseudo-secondary-order kinetics. The uranium removal efficiency of Cotton S-C[6]a was up to 78.46% in aqueous solution and 81.72% on skin. Conclusion The synthesized Cotton S-C[6]a is highly efficient in the removal of uranium (VI) in solution and on contaminated skin.
ABSTRACT
A necessidade de monitorar populações expostas à radiação ionizante tem apresentado demanda crescente no Brasil. O presente trabalho tem por objetivo construir um instrumento de estudo que permita realizar a avaliação deste impacto. A metodologia usada foi o da construção do protocolo a partir da revisão sistemática da literatura com o descritor radiação ionizante nas bases de dados Medline e Lilacs, no período de 1998-2008, com filtros específicos. O universo foi de 57 artigos que foram avaliados pelo desenho epidemiológico, população alvo, país de publicação e relação com a radiação ionizante. Os resultados mostraram que 84,2% das publicações apresentam relação positiva com a radiação ionizante. A partir dos resultados conclui-se que os estudos epidemiológicos caso-controle, transversais e de coorte são fundamentais nessa avaliação. As populações expostas ambientalmente ou ocupacionalmente são indicadas para estudos, principalmente a população adulta. Câncer e aberrações cromossomiais são marcadores apropriados para essa avaliação e, por fim, esses resultados apontam para a construção do protocolo que contemple o diagnóstico do sistema de saúde local, avaliação da percepção de risco da população, monitoramento da concentração de urânio ambiental, avaliação dos padrões de morbi-mortalidade, biomarcadores de efeitos em populações com exposição aumentada e avaliação dos indivíduos com biomarcadores alterados.
There is a growing demand to monitor populations exposed to ionizing radiation in Brazil. This work aims to create a research tool to enable the impact assessment. The adopted methodology was the systematic research in the Medline and Lilacs database within the period from 1998 to 2008 for the ionizing radiation descriptor using specific filters. There were a total of 57 used articles that have been evaluated by the epidemiological characteristics, population, country of publication and relation to ionizing radiation. The results showed that 84.2% of the publications have positive relationship with the ionizing radiation. From the results it is concluded that epidemiological studies, case-control, cross-sectional and cohort are fundamental in the evaluation. Populations exposed occupationally or environmentally are suitable for studies, especially the adult population. Chromosome aberrations and cancer are appropriate markers for this assessment and, finally, the results point to the creation of a protocol that addresses the diagnosis of local health system, assessment of populations risk perception, monitoring of the environmental uranion concentration, evaluation of the morbi-mortality patterns, effect biomarkers in populations with increased exposure and evaluation of individuals with altered biomarkers.