Cellulose mini-membranes modified with TiO2 for separation, determination, and speciation of arsenates and selenites

Beata Zawisza,Rafal Sitko,Anna Gagor,Ignasi Queralt,Eva Margui

doi:10.1007/s00604-020-04387-4

Abstract

Sorptive and selective mini-membranes based on TiO2 directly synthesized onto cellulose filters (TiO2@cellulose) have been developed. The in situ synthesis of TiO2@cellulose applied is simple and economically advantageous. The obtained membranes can be useful for (1) separating arsenic(V) and selenium(IV) from other ions and organic matter, (2) speciation of arsenic and selenium, and (3) determining ulratraces of these ions in water samples. The membranes exhibit good stability and high maximum adsorption capacities for Se(IV) (71 mg g−1) and As(V) (41 mg g−1). A monolayer chemical adsorption of analytes on the membranes was confirmed. The structure of membranes was examined with scanning electron microscopy, x-ray diffractometry, and micro energy-dispersive x-ray fluorescence spectrometry (μ-EDXRF). The membranes were characterized by homogenous distribution of TiO2 onto cellulose. The TiO2@cellulose was used as a new sorbent in micro-solid phase extraction for determination of Se(IV) and As(V) by EDXRF. Using direct analysis of mini-membranes after sorption of analytes avoids the elution step. Thus, the proposed procedure is an attractive and solvent-free option for quantitative monitoring of Se(IV) and As(V) in different materials. Both analytes were quantitatively and simultaneously separated/determined from samples at pH 2 with very good recovery (close to 100%), precision (4.5%), and detection limits (0.4 ng mL−1 Se and 0.25 ng mL−1 As). TiO2@cellulose membranes were applied to water analysis.Graphical-abstractEffective method for determination of ultra trace arsenates and selenites using cellulose-based sorbent

Highlights

Many sorbents included nanosorbents are mainly oriented towards cationic species of metal but the sorption of Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users. 430 Page 2 of 9Microchim Acta (2020) 187: 430 used for the quantification of As and Se at ultra-trace level in different samples
The proposed in situ method for developing new cellulosebased sorbents is a simpler method in comparison with the ex situ procedures, in which the metal oxide particles must be synthesized separately and incorporated in cellulose matrix
In the in situ methods, metal particles are synthesized on the cellulose matrix directly

Summary

Introduction

The cellulose filters were pipetted with Ti(OC3H7) and immersed in ammonia to coat/impregnate cellulose surface with TiO2. TiO2@cellulose was applied as a solid adsorbent in μSPE for preconcentration of metalloid species from an aqueous solution. The filters were directly analyzed by an energy-dispersive x-ray fluorescence spectrometry (EDXRF) for determination of preconcentrated trace amount of selenium and arsenic. Experiments aimed at determining adsorption isotherms and developing a preconcentration procedure were preceded by determination of the optimal pH for sorption of analytes. For this purpose, 25 mL single-element aqueous solutions were prepared. After this procedure, dried mini-filters at 60 °C were analyzed by EDXRF, and remaining solutions were analyzed by ICP-OES

Results and discussion

TMA-Cb

Conclusion

Compliance with ethical standards