title: Highly Sensitive Detection and Removal of Lead Ions in Water Using Cysteine-Functionalized Graphene Oxide/Polypyrrole Nanocomposite Film Electrode.
abstract: We synthesized cysteine-functionalized graphene oxide (sGO) using carbonyldiimidazole as a cross-linker via amide and carbamate linkages. The sGO/polypyrrole (PPy) nanocomposite film was grown on the working electrode surface of a screen-printed electrode (SPE) via controlled one-step electrochemical deposition. The sGO/PPy-SPE was used to detect lead ions (Pb(2+)) in water by first depositing Pb(2+) on the working electrode surface for 10 min at -1.2 V, and then anodic stripping by differential pulse voltammetry (DPV). The DPV signals were linear in the ranges of 1.4-28 ppb (R(2) = 0.994), 28-280 ppb (R(2) = 0.997), and 280-14 000 ppb (R(2) = 0.990) Pb(2+). The measurable detection limit of the sensor is 0.07 ppb (S/N = 3), which is more than 2 orders of magnitude below the 10 ppb threshold for drinking water set by the World Health Organization. The average removal efficiency of Pb(2+) deposited on the electrode was 99.2% (S/N = 3), with relative standard deviation (RSD) of 3.8%. Our results indicate good affinity of sGO/PPy nanocomposite to Pb(2+), which can be used to effectively adsorb and remove Pb(2+) in water samples. Therefore, sGO/PPy nanocomposite we synthesized is useful for highly sensitive on-site and real-time monitoring of heavy metal ions and water treatment.
authors.affiliation: †Department of Biological Systems Engineering, University of Wisconsin-Madison, 460 Henry Mall, Madison, Wisconsin 53706, United States.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Seenivasan
authors.affiliation: ‡Department of Mechanical Engineering, University of Wisconsin-Milwaukee, 3200 North Cramer Street, Milwaukee, Wisconsin 53211, United States.
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Chang
authors.affiliation: †Department of Biological Systems Engineering, University of Wisconsin-Madison, 460 Henry Mall, Madison, Wisconsin 53706, United States.
authors.forename: Sundaram
authors.initials: S
authors.lastname: Gunasekaran
keywords: cysteine-functionalized graphene oxide; differential pulse anodic stripping voltammetry; heavy metal; lead ions; water treatment