Silver-coated polyethene terephthalate membrane for detection of pharmaceuticals using surface-enhanced Raman spectroscopy
Ndilowe, George Michael
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Surface-enhanced Raman spectroscopy (SERS) has emerged as one of the analytical tools for detection of micro pollutants in the aquatic environment. The SERS technique is touted to have fingerprinting capability, specificity, ease of operation and single-molecule sensitivity. Therefore SERS can be used for detection of trace level organic pollutants in water. Trace level aquatic micro pollutants such as pharmaceuticals, have been detected in effluents from water treatment plants. Pharmaceuticals, due to the intended therapeutic use, may have adverse effects on living organisms, even in trace-level concentrations. Furthermore, the growing interest to reuse wastewater to augment conventional water supplies has resulted in a growing demand to explore sensitive and rapid analytical techniques such as SERS. In addition the use of track-etched polymer membranes in the filtration process has attracted considerable attention due to their flexibility in providing shape, durability and pore size control versatility. In this work, a silver-coated track-etched polyethene terephthalate (PET) membrane was developed as a platform to detect acetaminophen and had its surface-enhance Raman properties evaluated. The silver-coated track-etched PET membrane was fabricated by modifying the surface of the PET membrane with diethylenetriamine (DETA) via solid-liquid interface reaction known as aminolysis. The characterisation techniques used to ascertain the surface modification of track-etched PET membrane are Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS). Silver nanoparticles were immobilised on the amine-modified surface of track-etched polyethene terephthalate membrane by immersing an amine-modified track-etched PET membrane in a 102 mL mixture of 1 mM of silver nitrate and 1% trisodium citrate heated at 90 oC for 30 minutes. The immobilised silver nanoparticles were of varying sizes with an average size of 62 nm and mostly of spherical shape. The successful immobilisation of silver nanoparticles on modified track-etched PET membrane was further characterised by ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).