One-pot polycondensation and characterization of melamine-based polymer for mercury and sodium hypochlorite sensing

Abstract

A porous, low-cost, organic, amorphous and carbon-nitride functionalized polymer was synthesized using melamine and 5-bromo-2-thiophenecarboxaldehyde. One-pot polycondensation method was opted, to yield hyper-crosslinked polyaminal network which was used for the detection of NaOCl and Hg2+. Reaction proceeds in single step without addition of any catalyst and gives promising yield. The authenticity of the synthesized polymer MB was established using X-Ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and Energy-dispersive spectroscopy (EDS). However, the morphology and thermal stability of MB was studied using X-Ray diffraction (XRD) & Scanning electron microscopy (SEM) and Thermogravimetric analysis (TGA) & Differential thermal analysis (DTA) respectively. BET studies were carried out to analyze the porous structure of MB. The pore diameter is centred at 6.2851 nm with specific surface area of 24.348 m2 g–1 and pore volume of 0.038258 cm3 g–1. The TGA curve showed that it has a good thermal stability (250°C). The synthesized compound was checked for its sensing behaviour with different analytes (metal ions: Cu2+, Cr2+, Mg2+, Cd2+, Mn2+, Zn2+, Pb2+, Hg2+; acids: HCl, H2SO4, HNO3 and ROS: t-BuOOH, KO2, NaOCl) in deionized water and was found to show significant change in intensity with NaOCl and Hg2+. The change in absorption spectra was observed at varied concentrations of NaOCl and Hg2+ solutions in deionized water using UV-Vis. Spectrophotometer.