Determination of Pb2+ by Colorimetric Method Based on Catalytic Amplification of Ag Nanoparticles Supported by Covalent Organic Frameworks

Abstract

In this paper, covalent organic frameworks (COFs) are prepared by solvothermal synthesis using 1,3,5-benzenetricarboxaldehyde and benzidine as ligands. Then, using COFs as a template, AgCOFs with high catalytic activity is prepared by in situ loading silver nanoparticles (AgNC) on the surface of COFs by sodium borohydride reduction method. AgCOFs are characterized by TEM, SEM, FTIR and XRD. At the same time, the catalytic ability of AgCOFs for trisodium citrate-AgNO3 nanosilver reaction is studied. The results show that AgCOFs can catalyze the reaction of trisodium citrate-AgNO3 to generate silver nanoparticles (AgNPs). The solution color of the system gradually changes from colorless to yellow, and the absorbance value increases. Based on the catalytic reaction of AgCOFs and the regulation effect of nucleic acid aptamer reaction on AgCOFs, a new “on–off–on” colorimetric analysis platform is constructed and applied to the detection of trace Pb2+ in water samples. This analytical platform is simple, sensitive and selective. Finally, the catalytic mechanism of the system is discussed to verify the feasibility of constructing a colorimetric analysis platform.

An optical and electrochemical sensor based on l-arginine functionalized reduced graphene oxide

“…Several spectroscopic methods have been utilized to detect and measure small amounts of heavy metals, most of which suffer from expensive instruments, huge arrangements, and highly skilled operators. While optical approaches are fast and facile for determining heavy metals 4 , 5 , electrochemical techniques have some advantages and benefit from remarkable sensitivity 6 – 16 . In addition, the inconvenience of storing and moving samples is eliminated using existing portable tools.…”

Efficient Adsorption and Removal of Congo Red from Aqueous Solution Using Magnetic Covalent Organic Framework Nanocomposites

“…The C 1s spectrum in Figure 3B shows that the main peak generated at 284.4 eV is assigned to the C=C bond, while the peaks at 287.5 eV is assigned to the C=O bond [36] . The O 1s spectrum in Figure 3C shows that the main peak generated at 531.7 eV is assigned to C=O bonds, and the peak generated at 536.1 eV is assigned to O−H bonds [37] . The XPS spectrum of N 1s element has two peaks in Figure 3D, the peak at 398.7 eV is attributed to the C−N, and the peak at 400.7 eV is belonged to the C−H bond [38] .…”