Synthesis and application of silver nanorods for the colorimetric detection of sulfate in water

Improved selectivity of electrochemical aniline sensing using one-dimensional silver nanorods with high aspect ratio synthesized by ascorbic acid assisted method

BACKGROUND

Aniline serves as a pivotal precursor in many industries such as pesticides, pharmaceuticals, and chemicals. However, its ingestion can lead to severe health consequences, including the potential to induce cancer, respiratory tract irritation, and adverse effects on the nervous and digestive systems in the human body. The widespread use of aniline in industrial processes, coupled with inadequate wastewater management that allows for the direct release of aniline into the environment, leads to surface and groundwater contamination. Therefore, it becomes crucial to devise a reliable electrochemical sensor capable of detecting even trace amounts of aniline.

RESULTS

This study presents a modified polyol synthesis method for producing silver nanorods (AgNRs, length: 861-1345 nm, diameter: 66-107 nm) with preferential growth along the (111) crystal plane. Immobilizing AgNRs on a glassy carbon (GC) electrode with Nafion as a binder decreases its charge transfer resistance from 3040 to 129 kΩ and increases its electroactive area from 0.034 to 0.101 cm2. AgNRs/GC electrode exhibited an aniline detection limit of 0.032 μM and sensitivity of 1.4841 μA.M-1cm-2 within a linear range of 0-10 μM using square wave voltammetry (SWV). The reaction rate constant of aniline sensing was determined to be 0.08697 s-1. Chlorobenzene, acephate, and chlorpyrifos could not interfere aniline detection, and 26 % decrease in peak response was observed after the 10th cycle of aniline sensing. The sensor demonstrated ∼100 % recovery for aniline, comparable to the performance of high-performance liquid chromatography when applied to real-world samples like tap and river water.

SIGNIFICANCE

The electrochemical sensing of aniline is notably efficient in tap and river water within the acceptable limit, by utilizing one dimensional AgNRs functionalized GC electrode. Importantly, the presence of interferents does not compromise the sensitivity of the sensor. Therefore, one dimensional AgNRs synthesized via a modified polyol route emerge as a promising electrocatalyst for the in-situ detection and determination of aniline.

Adaptive neuro fuzzy selection of important factors for prediction of plasmons in silver nanorods

The major goal of this study was to find predictors of plasmon positions in silver nanorod (NR) optical absorption spectra. The goal of this study is to use an adaptive neural fuzzy inference system to identify the various input parameters for longitudinal surface plasmon resonance (LSPR) and transverse surface plasmon resonance (TSP). A seed strategy has been used for preparation of the silver NRs. During the preparation, the seed particles are synthesized in the presence of cetyltrimethylammonium bromide (CTAB). To produce the silver NRs, metal salt (AgNO₃) has been added, as well as ascorbic acid (AA) and CTAB. Skillful prediction could play a pivotal role in the plasmon NR production management. The combination of CTAB and the seeds has the largest influence on the TSPR. The combination of CTAB and AA has the largest influence on the LSPR. The study considering different input parameters simultaneously, to the best of our knowledge, is the first on a small scale and should attract great general interest.

Direct-determination of high-concentration sulfate by serial differential spectrophotometry with multiple optical pathlengths

Direct-determination is a fast and free of contamination method for analysis of substances in water samples. However, direct-determination of SO₄^2- with high concentration in environmental systems is still challenging due to deviation from Beer-Lambert law is generally observed when a substance with high concentration is directly determined, resulting in poor accuracy, sensitivity, and narrow linear range. In this study, a simple and rapid method for the direct-determination of SO₄^2- with high concentration was proposed. Serial high-absorbance differential spectrophotometry was applied to incrementally widen the determination range under different optical pathlengths. In this process, the effects of optical pathlength and reference concentration on sensitivity were further investigated. The results showed that SO₄^2- could be accurately quantified within a concentration range of 0-4.10 g/L, and the determination range by this method was 10-fold and 19.5-fold wider than those by conventional differential spectrophotometry and conventional spectrophotometry, respectively. And the applicable ranges of sensitivity were obtained at various optical pathlengths by adjusting the reference solution concentration. This approach exhibited several advantages over conventional methods, including high accuracy, excellent precision, low cost, less time consumption, and easy operation. This method is promising and can provide accurate and reliable data support for environmental monitoring and pollution control.

Statistically Optimized Production of Saccharides Stabilized Silver Nanoparticles Using Liquid-Plasma Reduction Approach for Antibacterial Treatment of Water

Various conventional approaches have been reported for the synthesis of nanomaterials without optimizing the role of synthesis parameters. The unoptimized studies not only raise the process cost but also complicate the physicochemical characteristics of the nanostructures. The liquid-plasma reduction with optimized synthesis parameters is an environmentally friendly and low-cost technique for the synthesis of a range of nanomaterials. This work is focused on the statistically optimized production of silver nanoparticles (AgNPs) by using a liquid-plasma reduction process sustained with an argon plasma jet. A simplex centroid design (SCD) was made in Minitab statistical package to optimize the combined effect of stabilizers on the structural growth and UV absorbance of AgNPs. Different combinations of glucose, fructose, sucrose and lactose stabilizers were tested at five different levels (-2, -1, 0, 1, 2) in SCD. The effect of individual and mixed stabilizers on AgNPs growth parameters was assumed significant when p-value in SCD is less than 0.05. A surface plasmon resonance band was fixed at 302 nm after SCD optimization of UV results. A bond stretching at 1633 cm-1 in FTIR spectra was assigned to C=O, which slightly shifts towards a larger wavelength in the presence of saccharides in the solution. The presence of FCC structured AgNPs with an average size of 15 nm was confirmed from XRD and EDX spectra under optimized conditions. The antibacterial activity of these nanoparticles was checked against Staphylococcus aureus and Escherichia coli strains by adopting the shake flask method. The antibacterial study revealed the slightly better performance of AgNPs against Staph. aureus strain than Escherichia coli.