engleski

Functionalized carbon nanotubes as new sensor material for anionic surfactant sensing

Anionic surfactants (ASs) are commercially mostly used group of surfactants. In 2014 their annual production was 7686 KT [1]. ASs are used in detergent, pharmaceutical and cosmetic industry, biotechnology, etc. Considering their great consumption, it is necessary to monitor ASs concentrations in the environment, as well as in quality control of commercial products. Standard methods for their determination are two-phase titration [2] (for samples with high concentration of ASs) and Methylene Blue Active Substances method [3] (MBAS, for samples with low concentration of ASs). These methods have many disadvantages so there is necessity to find alternatives. Potentiometric determination of ASs using ASs selective electrodes is increasingly replacing standard methods [4]. Incorporating nanomaterials as membrane component improves ASs selective electrodes characteristic [5]. The new sensor material for ASs sensing was prepared by noncovalent functionalization of multiwalled carbon nanotubes (MWCNT) with tetraoctadecylammonium ion. As plasticizer, o-nitrophenyl octyl ether was used. The sensing membrane was incorporated in Philips electrode body IS-561. New sensor material was characterized and tested as a sensor for ASs detection using cetylpyridinium chloride (CPC) as titrant. Response characteristics were examined for dodecyl sulfate and dodecylbenzenesulfonate ions and both showed sub-Nernstian response. The new sensor material exhibited excellent selectivity for dodecyl sulfate over anions usually presented in commercial products.

functionalized carbon nanotubes ; anionic surfactant ; potentiometry

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