Exploration of two novel highly efficient polymer composite materials based on 3-chloropropyltriethoxysilane-grafted waste para-aramid functionalized by organo-phosphonic acid/L-proline and their excellent adsorption performance for gold ions

Two novel highly efficient polymer composite adsorbents based on 3-chloropropyltriethoxysilane-grafted waste para-aramid (PPTA-CP-AT and PPTA-CP-L, PPTA=poly-p-phenylene terephthamide; CP = 3-chloropropyltriethoxysilane; AT=amino trimethylene phosphonic acid; L=L-proline) have been successfully prepared and characterized. The new adsorbents were synthesized by functionalizing 3-chloropropyltriethoxysilane-grafted waste para-aramid with amino trimethylene phosphonic acid and L-proline, respectively. They have been employed to adsorb gold ions from aqueous solution, and the relevant adsorption behaviors have been investigated in detail. The adsorption isotherms of PPTA-CP-AT and PPTA-CP-L were consistent with the Langmuir isotherm model, and the corresponding kinetics could be best described by the pseudo-second-order kinetic model. In particular, the adsorption capacity of PPTA-CP-L was much higher than the values reported in the literature. In addition, the effect of pH on the gold ions adsorption and the thermodynamic parameters of the adsorption procedure were assessed. The research results indicated that PPTA-CP-AT and PPTA-CP-L are two novel adsorbents with high efficiency in wastewater treatment and recovery of precious gold. In particular PPTA-CP-L, which was obtained through facile esterification synthesis at low temperature, showed an excellent adsorption performance and could be used as potentially excellent adsorbent for gold uptake.