Hydrophilic triazine-based dendron for copper and lead adsorption in aqueous systems: Performance and mechanism

In this study, a triazine-based dendron produced by the reaction of cyanuric chloride and diamine was synthesized successfully and applied in the adsorption of copper and lead ions in aqueous systems. The effects of pH, contact time, adsorbent dosage, solution temperature, initial concentration, coexisting substances and desorption were systematically performed in the case of adsorption operations. The adsorption of the both heavy metal ions followed the pseudo-second-order kinetic model best, with the equilibrium adsorption time at 120 min. The adsorption isotherms were well-described by the Langmuir model and the calculated maximum adsorption capacity of Cu²⁺ and Pb²⁺ was 103.68 and 133.47 mg g^{− 1} at 25 °C, respectively. Based on the Dubinin-Radushkevich (D-R) isotherm model and calculation of adsorption free energy, the sorption processes for Cu²⁺ and Pb²⁺ were both chemisorption. Desorption and reuse experiments demonstrated that without significant loss in its original performance that could be reused in five cycles. The high density of terminal hydroxyl groups on the dendron was believed to participate in the chemical sorption process of Cu²⁺ and Pb²⁺ due to electrostatic attraction and surface complexation in the binding process. These results suggested the triazine-based dendron can be used as an efficient adsorbent for metal ions removal from wastewater.