Pre-concentration and determination of trace uranium (VI) in environments using ion-imprinted chitosan resin via solid phase extraction

Abstract

Foram preparadas resinas quitosana de ligação cruzada com impressão molecular de uranil e sem impressão, possuindo grupamentos quinolin-8-ol. Em todos os casos um efeito de impressão significativo foi observado na comparação do percentual de extração de urânio (VI). A resina com impressão molecular foi usada para pré-concentração extrativa de urânio (VI) em fase sólida antes de determinação espectrofotométrica. Variáveis experimentais que influenciam a extração quantitativa de urânio (VI) foram otimizadas em método estático e em extração com coluna. A capacidade de retenção de urânio (VI) foi de 218 mg por g de resina, que é maior que a resina sem impressão molecular correspondente ou outra fase sólida adsorvente que possua grupamento quinolin-8-ol. O intervalo de pH ótimo encontrado foi 4,5-7,0. O urânio adsorvido foi fácil e quantitativamente eluido com HCl 1 mol L -1 (10 mL) sob uma vazão de 2 mL min . A exatidão do método foi testada com material padrão de referência de rocha de urânio. Além disso, o método foi aplicado para a determinação de urânio em amostras de solo contaminado e sedimento.The uranyl-ion-imprinted and non-imprinted cross-linked chitosan resins possessing quinoline-8-ol moiety have been prepared. In all the cases, a significant imprinting effect was noticed on comparing percent extraction of uranium (VI). The resulting ion-imprinted resin was used for solid phase extractive preconcentration of uranium (VI) prior to its determination by spectrophotometry. Experimental variables that influence the quantitative extraction of uranium (VI) were optimized by both static and column methods. The retention capacity found for uranium (VI) was 218 mg g -1 of resin which is higher than the corresponding non-imprinted resins and other solid phase extraction sorbents possessing quinoline-8-ol moiety. The optimum pH range was 4.5-7.0. Uranium adsorbed was easily and quantitatively eluted with 1 mol L -1 HCl (10 mL) at a flow rate of 2 mL min -1 . Interference studies showed a high tolerance of diverse ions and electrolyte species. The limit of detection was 2 µg L -1 and the dynamic linear range was 5-100 µg L -1. The accuracy of the developed method was tested with one uranium ore standard reference material. Furthermore, the proposed method was successfully applied for the determination of uranium in contaminated soil and sediment samples.

Production and physicochemical characterization of chitosan for the harvesting of wild microalgae consortia

“…For N and N, the values were similar to the 44.02 % C and 7.96 % of N reported by Hussein et al [ 30 ] in samples of chitosan obtained from shrimp shell by the chemical method. Liu et al [ 31 ] reported values of % C = 44.63 and % N = 8.71 in commercial chitosan. Gupta et al [ 32 ] mentioned that the results of elemental analysis change according to the deacetylation degree of chitosan, due to the loss of acetyl groups and reported ranges of 5.13–8.03% for N and 28.56–48.36% for C. In this sense, the chitosan obtained in the present work is of good quality and within the ranges previously reported.…”

Application of solvent-assisted dispersive solid phase extraction combined with flame atomic absorption spectroscopy for the determination of trace amounts of Cadmium

“…Thus, in order to the determination of heavy metals, several pre-concentration procedures have been developed (8). Several methods have been used for these purposes such as dispersive liquid-liquid microextraction (DLLME) (10-13), co-precipitation (14)(15)(16), electrochemical methods (17)(18)(19)(20)(21) and solid phase extraction (SPE) (22)(23)(24)(25)(26)(27)(28) Although, disadvantages such as large amounts of sample and/or organic solvents, significant chemical additives and high time consumption, limit the application of these techniques (29). Recently, a novel extraction technique as a high performance and powerful preconcentration method termed as SA-DSPE was demonstrated by Jamali et al (2013).…”