A Novel Bismuth-Chitosan Nanocomposite Sensor for Simultaneous Detection of Pb(II), Cd(II) and Zn(II) in Wastewater

Abstract

A novel bismuth (Bi)-biopolymer (chitosan) nanocomposite screen-printed carbon electrode was developed using a Bi and chitosan co-electrodepositing technique for detecting multiple heavy metal ions. The developed sensor was fabricated with environmentally benign materials and processes. In real wastewater, heavy metal detection was evaluated by the developed sensor using square wave anodic stripping voltammetry (SWASV). The nanocomposite sensor showed the detection limit of 0.1 ppb Zn2+, 0.1 ppb Cd2+ and 0.2 ppb Pb2+ in stock solutions. The improved sensitivity of the Bi-chitosan nanocomposite sensor over previously reported Bi nanocomposite sensors was attributed to the role of chitosan. When used for real wastewater samples collected from a mining site and soil leachate, similar detection limit values with 0.4 ppb Cd2+ and 0.3 ppb Pb2+ were obtained with relative standard deviations (RSD) ranging from 1.3% to 5.6% (n = 8). Temperature changes (4 and 23 °C) showed no significant impact on sensor performance. Although Zn2+ in stock solutions was well measured by the sensor, the interference observed while detecting Zn2+ in the presence of Cu2+ was possibly due to the presence of Cu-Zn intermetallic species in mining wastewater. Overall, the developed sensor has the capability of monitoring multiple heavy metals in contaminated water samples without the need for complicated sample preparation or transportation of samples to a laboratory.

One-Step Fabrication of Stimuli-Responsive Chitosan-Platinum Brushes for Listeria monocytogenes Detection

“…XPS spectrum of the CHI/Pt brushes ( Figure 2 ) shows the effective co-deposition of both chitosan and platinum-based on the presence of C 1s, O 1s, N 1s, and Pt 4f and Pt 4d peaks. C 1s peaks between 285 eV and 286.5 eV are assigned to CH 2 alkyl chain backbone, C–NH 2 , and C–O species [ 17 , 21 ]. The N 1s binding energy between 399 eV and 401 eV are consistent with that of C-N species of the amine group at 399 eV and protonated amine group at 401 eV [ 10 , 21 ].…”

“…The N 1s binding energy between 399 eV and 401 eV are consistent with that of C-N species of the amine group at 399 eV and protonated amine group at 401 eV [ 10 , 21 ]. Hwang et al [ 17 ] assigned a peak at 399.3 eV to the amino group involved in the hydrogen bond and a peak at 401.7 eV to the chelation between the amino group and bismuth metal. From the platinum co-deposition, the Pt 4f spectrum shows a characteristic doublet with binding energies of 71.5 eV and 74.8 eV ( Figure 2 inset).…”

“…Hills et al [ 15 ] presented ESA about six times lower (0.048 ± 0.017 cm 2 ) than the present work with chitosan being electrodeposited onto a reduced graphene oxide/nano-platinum coated electrode. The improved ESA results obtained here with the simultaneous electrodeposition of chitosan and platinum might be attributed to the properties of chitosan related to the formation of stable chelates with many transition metal ions due to the presence of hydroxyl and amino groups, which provide enhanced affinity to metal ions and improved detection sensitivity [ 17 , 32 ].…”

“…Thiolation (conjugation of a thiol group) is one of the most versatile tagging methods and is highly useful in electrochemical sensing due to the coupling with noble metal(s), such as gold and platinum, on the sensor surface. Previous studies have co-electrodeposited chitosan with metal ions [ 17 , 18 , 19 ]. However, no work has been done on simultaneous electrodeposition of chitosan and platinum to fabricate stimuli-responsive nanostructures, nor its use to detect bacteria in food products.…”

Recent Developments of PFAS-Detecting Sensors and Future Direction: A Review

“…Various classes of electrochemical sensors exist and are categorized based on their electrical magnitude of detection: potentiometric measures changes in the ion-selective membrane potential (mV), conductometric measures changes in the conductance (G, Ω −1 ), impedimetric measures changes in the impedance (Z) over a range of frequencies (Hz), and voltammetric measures the change in current (pA) that occurs as a result of the initial electrochemical reaction caused by an applied voltage (mV). Various types of electrochemical sensors have been used to detect chemical and biological compounds, such as heavy metal ions [ 86 , 87 , 88 , 89 , 90 , 91 ], nitrite [ 92 ], pH [ 93 , 94 ], dissolved oxygen (DO) [ 95 , 96 ], phosphate [ 96 , 97 , 98 , 99 ], and free chlorine (or monochloramine) [ 94 , 100 , 101 , 102 , 103 ]; the technology used ranges from microelectrodes to screen-printed electrodes and can be applied to natural and engineered water systems and environmental samples (e.g., biofilms, metals, and plants). Voltammetric and potentiometric sensors are the most common types of electrochemical sensors used for PFAS detection.…”