Ultrasensitive and selective detection of Congo Red in textile wastewater using Ag-molecular imprinted polymers as surface-enhanced Raman scattering active substrate

The discharge of textile wastewater into the water environment caused continuous pollution and poses a potential threat to public health. It is meaningful to develop an inexpensive, effective and pollution-free method for the ultrasensitive detection of residual Congo red (CR) in textile wastewater. Ag particles were prepared using ascorbic acid reduction method with glutamine as the guiding agent. Then, Ag particles were modified with 3-aminopropyltriethoxysilane to bring -NH 2 onto the surface of the Ag particles. Surface imprinting polymerization method for coating imprinted layer on Ag-NH 2 surface using CR as the template molecule (Ag@MIPs). The morphological characteristics of Ag@MIPs was performed on Scanning Electron Microscopy equipped with Energy Dispersive Spectrometer, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, etc. The enhancement effect of CR was researched when using Ag@MIPs as SERS substrate. Examining the SERS substrate for detecting different concentrations of CR, it was found that the minimum concentrations of Ag and Ag@MIPs were 1.0 × 10 –7 mol l -1 and 1.0 × 10 –9 mol l -1 , respectively. Besides, Ag@MIPs shown satisfactory selectivity and sensitivity to CR instead of methylene blue due to the imprinted holes that match template molecules. This method provides an ultrasensitive method for the qualitative and semi-quantitative detection of CR in textile wastewater.