Highly sensitive UO22+ ion preconcentration method based on flow sorbent extraction using multiwall carbon nanotubes

Author(s)

do Lago, Ayla C. ^[1] ; Lima, Giovana de F. ^[2] ; Segatelli, Mariana G. ^[3] ; Tarley, Cesar R. T. ^{[2, 3, 1]}

Affiliation

^[1] Univ Fed Alfenas, Programa Pros Grad Quim, BR-37130000 Alfenas, MG - Brazil

^[2] Univ Fed Uberlandia, Inst Quim, BR-38400902 Uberlandia, MG - Brazil

^[3] Univ Estadual Londrina, Dept Quim, BR-86051990 Londrina, PR - Brazil

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY; v. 92, n. 7, p. 767-782, 2012.
• Web of Science Citations: 7

Abstract

In this work a solid phase on-line uranium ion preconcentration system coupled with spectrophotometry has been developed. The method is based on uranyl ion preconcentration at pH 3.75 onto multiwall carbon nanotubes treated with HNO3. After preconcentration, the uranyl ions are eluted with 0.32 mol L-1 HCl followed by reaction with 3,6-bis{[}(2-arsonophenyl)-azo]-4,5-dihydroxy-2, 7-naphthalendisulfonic acid 0.08%{[}w/v] (Arsenazo III), which had maximum monitored absorbance of 650 nm. Effects of the pertinent experimental parameters on the system were investigated by means of 2(6-2) fractional factorial design, while optimization was carried out using the Doehlert matrix. Under optimized conditions, detection and quantification limits were found to be 0.21 and 0.7 mu gL(-1), respectively. The analytical curve ranged from 5 to 150 mu gL(-1) (r = 0.998), while the relative standard deviations (RSD) were 3.27 and 2.56% for the respective uranium concentrations of 10 and 100 mgL(-1) (n = 10). The features obtained for the on-line preconcentration system were: preconcentration factor of 228, concentration efficiency of 57 min(-1), consumption index of 0.13mL and sample throughput of 15 h(-1). In order to assess the accuracy of the proposed method, addition and recovery studies were carried out on spring water samples from different sources and synthetic seawater with satisfactory results ranging from 94.85 up to 103.65%. (AU)