Thermodynamic properties, i.e., DGo, DHo, and DSo showed that adsorption of
Pb(II) and Ni(II) onto PPH was endothermic, spontaneous and feasible in the temperature range of 293–
313 K. The PPH powder can be used as an effective, low cost, and eco-friendly green adsorbent for the
removal of selected metal ions from aqueous solution.