The Use of Covalent Organic Framework Nanoparticles as a Sensing Material for the Fabrication of Silver Voltammetric Sensor: Optimization of Experimental Conditions With the Half Fraction Central Composite Design

Abstract

In this research, a benzothiadiazole-based covalent organic framework (BT-COF) has been prepared through imine linkage and acid-catalyzed Schiff-base reaction, which has high crystallinity and chemical stability. The construction and application of a modified carbon paste electrode (CPE) with BT-COF nanoparticles as a voltammetric sensor (BT-COF/CPE) to measure silver ion is the basis of this research work. The obtained experimental data were properly fitted in a quadratic model obtained from the half fraction central composite design (HF-CCD) method. The main role of BT-COF in this voltammetric sensor can be related to the presence of multiple binding sites in its structure to form a complex with silver, large surface area and high volume of BT-COF pores which is known to weaken the steric hindrance when forming a complex between silver and COF binding sites, and also make it easier for silver to reach the functional groups inside COF channels, and in addition, they create a large space for the deposition of a large amount of silver. Regression at a significance level of 5% and in the range of 0.1-100 nM led to a linear equation between the stripping current and the silver ion concentration in the pre-concentration solution. The detection limit was 0.06 nM. The impact of interferences on the performance of the proposed sensor was investigated. Electrochemical and SEM/EDS/MAP methods were used to check the performance principles of the resulting voltammetric sensor. The ability of the prepared sensor to determine the amount of silver in real samples was investigated.

Keywords

• covalent organic framework
• benzothiadiazole
• carbon paste electrode
• voltammetric sensor
• silver ion