In response to the escalating levels of heavy metal pollution, considerable efforts have been directed towards advancing electrochemical sensors. Polymer materials, known for their ability to sequester heavy metal ions, emerge as promising modifiers to augment sensitivity and selectivity in sensor design. This study focuses on the colloid and interface chemistry of a screen-printed electrode (SPE) by employing diverse polymer materials, such as cellulose acetate, chitosan, nylon 6, and Nafion, as modifiers. Anodic stripping voltammetry is employed to evaluate the modified SPE's sensing interface for detecting lead ions, considering both morphological characteristics and electrochemical perspectives. The impact of polymer concentration (1 - 5 wt.%) on the SPE surface is comprehensively investigated to discern its influence on lead ion detection. Results indicate that the enhanced sensitivity of the SPE is predominantly attributed to metal-attracting SO32- functional ligands and negatively charged electrode surfaces, prominently observed in Nafion-modified SPE (Naf/SPE). The proposed Naf/SPE (1 wt.%) attains a remarkable detection limit of 8.4 ppb, adhering to the WHO standards for drinking water (0.01 ppm). Conversely, higher polymer concentration (5 wt.%) results in reduced sensitivity of SPE sensors, primarily due to heightened electrochemical resistance introduced by the denser polymer layer, impeding the mass transfer of the target analyte near the electrode surface. This work provides profound insights into the synergistic contributions of metal-attractive functional groups, morphological structure, and charged surfaces of polymer-modified layers on SPE for efficient heavy metal detection.
Keywords: Heavy metal ions; Screen-printed electrode; Stripping voltammetry; Polymer; Nafion

Dr. Low Siew Chun is an Associate Professor in the School of Chemical Engineering at Universiti Sains Malaysia. Her research focuses on the development of membrane-based separation system. She has particular interest on understanding the fundamental transport phenomena across the thin film membrane and utilises the porous thin film to control the environmental pollution issues. Thus far, she has published 10 book chapters, more than 140peer-reviewed journals papers with h-index of 27, i10-index of79 and received more than 3150 cumulative citations according to Google Scholar. She has also attended more than 30 conference proceedings, including 5 keynoteand 5 invited lectures. As regards to academic responsibility, she served asa journal reviewer for leading publishers such as Springer, ACS, RSC, Elsevier and Taylor & Francis. Dr. Low is the section editor, editorial board member and guest editor for 9 WoS- and Scopus-indexed journals.