Tapered optical fiber sensor coated with carbon nanotubes containing functional groups or Fe nanoparticles for sensing applications

Abstract

Anthraquinone dyes are the second largest group of synthetic dyes that are widely used for dyeing textiles. As an anthraquinone dye, Alizarin Red S (ARS) has been widely used in the textile industry; however, it is extremely resistant to standard degradation due to its structural peculiarities and it can cause a serious threat to aquatic ecosystems and human health. Previous studies on theoretical calculations of single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) demonstrated that SWCNTs and MWCNTs can serve as adsorbents, with their highly active sites and large specific surface area, and they exhibit great performance. In the present work, the detection of ARS by the SMF28e single-mode fiber optic-based sensor was investigated. For detection of ARS, multiwall carbon nanotubes with -COOH and -OH functional groups and Fe nanoparticles were applied on the optical fiber. The effects of contact time, adsorbent dose, pH and temperature on the adsorption were studied. The study evaluated the feasibility of detecting and removing ARS from aqueous solutions using MWCNTs with the -COOH and -OH functional groups and Fe nanoparticles.