Multiwalled Carbon Nanotube (MWCNT) Based Electrochemical Paper-Based Analytical Device (ePAD) for the Determination of Catechol in Wastewater

Abstract

A novel platform for the phenolics in wastewater based on an electrochemical multiwalled carbon nanotube paper-based analytical device (MWCNT-ePAD) has been developed. Phenolics such as catechol are widely used in industrial processes. Catechol has a strong aroma and is a possible human carcinogen. Therefore, this work focused on the determination of catechol in wastewater. The ePAD was fabricated on chromatography paper. Graphite ink was used as the working electrode and counter electrode, while Ag/AgCl ink was employed as a pseudo reference electrode. The sensitivity of the MWCNT-ePAD biosensor toward phenolics was improved using a multiwall carbon nanotube modified working electrode. The determination of phenolics as the enzyme-catalyzed reaction product using laccase was performed by chronoamperometry. The MWCNT-ePAD biosensor was used for the determination of catechol from 0.8 to 3.0 mg/L with a detection limit of 0.25 mg/L. The reproducibility of the MWCNT-ePAD biosensor was less than 4.95%, and the lifetime of the device was more than 30 days. Additionally, the developed biosensor was applied to determine catechol in wastewater with consistent results compared to a Folin-Ciocalteu assay. The MWCNT-ePAD biosensor was rapid (15 s), cost-effective (0.7 $), and required low reagent consumption (15 µL) with accurate phenolic determination in wastewater by the combination of a paper-based device, an electrochemical biosensor, and a nanomaterial technology.