Molecularly imprinted polymer-based nanoporous carbon nanocomposite for effective adsorption of Hg(II) ions from aqueous suspensions

Due to the release of hazardous heavy metals from various industries, water pollution has become one of the biggest challenges for environmental scientists today. Mercury Hg(II) is regarded as one of the most toxic heavy metals due to its ability to cause cancer and other health issues. In this study, a tailor-made modern eco-friendly molecularly imprinted polymer (MIP)/nanoporous carbon (NC) nanocomposite was synthesized and examined for the uptake of Hg(II) using an aqueous solution. The fabrication of the MIP/NC nanocomposite occurred via bulk polymerization involving the complexation of the template, followed by polymerization and, finally, template removal. Thus, the formed nanocomposite underwent characterizations that included morphological, thermal degradation, functional, and surface area analyses. The MIP/NC nanocomposite, with a high specific surface area of 884.9 m2/g, was evaluated for its efficacy towards the adsorptive elimination of Hg(II) against the pH solution changes, the dosage of adsorbent, initial concentration, and interaction time. The analysis showed that a maximum Hg(II) adsorption effectiveness of 116 mg/g was attained at pH 4, while the Freundlich model fitted the equilibrium sorption result and was aligned with pseudo-second-order kinetics. Likewise, thermodynamic parameters like enthalpy, entropy, and Gibbs free energy indicated that the adsorption was consistent with spontaneous, favorable, and endothermic reactions. Furthermore, the adsorption efficiency of MIP/NC was also evaluated against a real sample of condensate from the oil and gas industry, showing an 87.4 recovery of Hg(II). Finally, the synthesized MIP/NC showed promise as a selective adsorbent of Hg(II) in polluted environments, suggesting that a variety of combined absorbents of different precursors is recommended to evaluate heavy metal and pharmaceutical removals

Development of electrochemical sensor based on silica and silica/gold nanoparticle electrode for detection of arsenic (III)

Electrochemical sensor for the detection of arsenic(III) has been successfully developed based on nanoparticles modified screen printed carbon electrode (SPCE). In this research, silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs) were used as a modifier to enhance the performance of disposable screen printed carbon electrode. The electrocatalytic responses of the SiNPs and SiNPs/AuNPs modified electrode for the detection of As(III) were measured using cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV). The screen printed carbon electrode was modified by drop casting the nanoparticles onto the working electrode. There are two types of modified electrode were developed for detection and quantification of As(III) ions. Firstly, SiNPs/SPCE electrode was prepared by casting the SiNPs onto the SPCE surface. Meanwhile, AuNPs/SiNPs/SPCE electrode was prepared by casting the SiNPs onto the working electrode, and then layered with 3- mercaptopropionic acid (MPA) followed by attachment of AuNPs. Both modified electrode, SiNPs/SPCE and AuNPs/SiNPs/SPCE were then applied for As(III) detection. Electrochemical studies using LSASV performed with SiNPs/SPCE and AuNPs/SiNPs/SPCE were found to give a better response through the optimization of numerous analytical parameters. The detection of As(III) using SiNPs/SPCE showed a linear response towards different concentration of As(III) and linear calibration curve with R2 = 0.9702 was obtained. The detection limit of 5.64 µg L-1 was achieved by applying deposition potential of - 0.5 V and deposition time of 120 s. Meanwhile, the detection of As(III) using AuNPs/SiNPs/SPCE gave a linear response towards different concentration of As(III) and linear calibration curve with R2 = 0.9975 was obtained. The detection limit of 1.4 µg L-1 was achieved by applying deposition potential of - 0.4 V and deposition time of 120 s. The modified SPCE was characterized using Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), and Energy Dispersive X-ray (EDX) respectively. The proposed methods showed good selectivity of target analyte even in the presence of some foreign ions. Furthermore, the developed sensors; SiNPs/SPCE and AuNPs/SiNPs/SPCE showed good reproducibility for six measurements where the RSD values of 5.72 % and 4.52 % were obtained, respectively

Development of electrochemical sensor based on silica/gold nanoparticles modified electrode for detection of arsenite

Arsenic is an extremely poison element in earth crust and its contamination in environment is a global hazard. In this study, an efficient electrochemical detection of arsenite [As(III)] has been developed using linear sweep anodic stripping voltammetry (LSASV), based on adsorption of arsenic on the surface of screen printed carbon electrode modified silica/gold nanoparticles (SiNPs/AuNPs/SPCE). The surface property of modified electrode was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR). The morphology studies using FESEM showed that the distribution of SiNPs/AuNPs composite is not homogenous therefore resulting in some areas with aggregation on the working electrode surface. Several optimum voltammetric parameters were established such as supporting electrolyte, 1 M HCl; deposition potential, -0.4 V and deposition time, 300 s. Under optimum condition, a linear correlation was obtained in the range of 10 - 100 ppb with limit of detection 5.6 ppb. A variety of common coexistence ions such as Pb 2+ , Ni 2+ , Zn 2+ , Hg 2+ and Cu 2+ in water samples showed no interferences in arsenite detection. The proposed method showed high sensitivity and good reproducibility with a relative standard deviation of 4.52 %, providing potential application of arsenite detection in environment

Electrochemical detection of arsenite using a silica nanoparticles- modified screen-printed carbon electrode

Arsenic poisoning in the environment can cause severe effects on human health, hence detection is crucial. An electrochemical-based portable assessment of arsenic contamination is the ability to identify arsenite (As(III)). To achieve this, a low-cost electroanalytical assay for the detection of As(III) utilizing a silica nanoparticles (SiNPs)-modified screen-printed carbon electrode (SPCE) was developed. The morphological and elemental analysis of functionalized SiNPs and a SiNPs/SPCE-modified sensor was studied using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The electrochemical responses towards arsenic detection were measured using the cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) techniques. Under optimized conditions, the anodic peak current was proportional to the As(III) concentration over a wide linear range of 5 to 30 µg/L, with a detection limit of 6.2 µg/L. The suggested approach was effectively valid for the testing of As(III) found within the real water samples with good reproducibility and stability

Functional nano molecularly imprinted polymer for the detection of Penicillin G in pharmaceutical samples

In the present study, we demonstrated the synthesis of nanosized molecularly imprinted polymer (nanoMIP) particles via a miniemulsion polymerization strategy for the selective recognition of Penicillin G element, a β-lactam antibiotic (PenG-nanoMIP). The PenG-nanoMIP probe was developed by the mixture of functional monomer, methacrylic acid (MAA) and crosslinking agent, ethylene glycol dimethacrylate (EGDMA). The pre-polymerization of monomer-template mixture was emulsified into miniemulsion via sonication where the PenG-nanoMIP particles were obtained with an average diameter of 60–70 nm. Also, various MIPs were formed by taking different combinations of monomer to crosslinker and among all, the MIP formed with a ratio of 6:24 was chosen as the optimum formulation. In addition, the PenG-nanoMIP probe has been characterized thoroughly for the surface functionality (FTIR), morphological changes (FESEM-EDX), and particles diameter. Finally, the batch rebinding tests via UV–Vis were conducted to investigate that the PenG-nanoMIP 2 has the greatest binding capacity with 4.37 mg/g as compared to PenG-nanoMIP 1 and PenG-nanoMIP 3 having the binding capacities of 3.33 mg/g and 3.62 mg/g respectively. Based on the analysis, it can be suggested that PenG-nanoMIP 2 has offered the highest binding and selectivity for PenG

Surface-enhanced Carboxyphenyl diazonium functionalized screen-printed carbon electrode for the screening of tuberculosis in sputum samples

Curbing tuberculosis (TB) requires a combination of good strategies, including a proper prevention measure, diagnosis, and treatment. This study proposes an improvised tuberculosis diagnosis based on an amperometry approach for the sensitive detection of MPT64 antigen in clinical samples. An MPT64 aptamer specific to the target antigen was covalently attached to the carboxyphenyl diazonium-functionalized carbon electrode via carbodiimide chemistry. The electrochemical detection assay was adapted from a sandwich assay format to trap the antigen between the immobilized aptamer and horseradish peroxidase (HRP) tagged polyclonal anti-MPT64 antibody. The amperometric current was measured from the catalytic reaction response between HRP, hydrogen peroxide, and hydroquinone, which is used as an electron mediator. From the analysis, the detection limit in the measurement buffer was 1.11 ng mL-1. Additionally, the developed aptasensor exhibited a linear relationship between the current signal and the MPT64 antigen-spiked serum concentration ranging from 10 to 150 ng mL-1 with a 1.38 ng mL-1 detection limit. Finally, an evaluation using the clinical sputum samples from both TB (+) and TB (-) individuals revealed a sensitivity and specificity of 88% and 100%, respectively. Based on the analysis, the developed aptasensor was found to be simple in its fabrication, sensitive, and allowed for the efficient detection and diagnosis of TB in sputum samples