New Phenol–Glycol Cross-Linked Polymers for Efficient Removal of Mercury from Aqueous Solutions

The study reports the synthesis and characterization of phenol–glycol cross-linked polymers for the removal of mercury ions from aqueous solutions at low pH. The cross-linked polymers were synthesized by one pot in-situ polycondensation reaction of phenol, different glycols and paraformaldehyde used as a linker. The cross-linked polymers were characterized by different spectroscopic techniques (13\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{13}$$\end{document}C-NMR, FT-IR). Thermal properties were investigated by thermogravimetric analysis and differential scanning calorimetry. The most efficient cross-linked polymer Ph-TETA was investigated under different controlled conditions (pH, initial concentration, time and temperature). The experimental data were subjected to Langmuir and Freundlich isotherm models and found to fit the Freundlich model with a regression value of R2=0.9971\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R^{2}=0.9971$$\end{document}. The experimental kinetic data were investigated in pseudo-first-order, second-order and Intraparticle diffusion kinetic models. Thermodynamic parameters revealed that the adsorption is endothermic in nature and spontaneous at low pH values. The outcomes of this study reveal the possible use of Ph-TETA as an adsorbent for mercury ion removal from aqueous solutions.