An electrochemical sequential injection method to investigate the adsorption of selenite on Fe(III) polyhydroxy cations intercalated vermiculite

Author(s)

do Nascimento, Fernando H. ; Masini, Jorge Cesar

• Document type: Journal article
• Source: WATER SCIENCE AND TECHNOLOGY; v. N/A, n. 1, p. 10-pg., 2018-04-01.

Abstract

A sequential injection - square wave anodic stripping voltammetry (SI-SWASV) method for determination of Se(IV) at a gold working electrode was developed to investigate the adsorption of Se(IV) onto vermiculite intercalated with Fe(III) polyhydroxy cations. The limits of detection and quantification were 0.060 and 0.20 mu mol L-1, respectively (4.7 and 15.7 mu g L-1). The linearity was up to 1.0 mu mol L-1, and the sampling throughput was 18 analyses h(-1). The proposed approach is a low-cost alternative to more expensive spectrometric methods. Adsorption onto vermiculite intercalated with Fe(III) polyhydroxy cations removed 93% of Se(IV) from a 1.0 mu mol L-1 solution (250 mL) after 5 min of contact time with 625 mg of adsorbent. Adsorption isotherms (25.0 +/- 0.5 degrees C) were fitted by the Freundlich equation resulting in 1/n = 0.51 +/- 0.03 and K-f = (1.584 +/- 0.002) x 10(3) mu mol(1-1/n) g(-1) L-1/n (r(2) = 0.995). Fitting by the Langmuir equation resulted in an adsorption constant of 0.026 +/- 0.008 L g(-1) and adsorption capacity of 47 +/- 5 mu mol g(-1) (3.7 +/- 0.4 mg g(-1)) (r(2) = 0.97). This capacity was higher than that found for several other iron oxides, but lower than that obtained for oxide/hydroxide-based Fe(III) nanoparticles. (AU)

• FAPESP's process: 12/08065-1 - Development and Validation of flow methods with electrochemical detection for application in studies of interactions of Hg (II), As (III) and Se (IV) with naturally occurring heterogeneous ligands
• Grantee: Fernando Henrique Do Nascimento
• Support Opportunities: Scholarships in Brazil - Doctorate