Highly effective removal of Cu(II) by a novel 3-aminopropyltriethoxysilane functionalized polyethyleneimine/sodium alginate porous membrane adsorbent

• Adsorption capacity of the PEI/SA was 7 times more than that of pristine SA membrane.
• The PEI/SA showed excellent adsorption selectivity for Cu(II) ions.
• The adsorption rate was very fast, and adsorption equilibrium time was 60 min.
• Reusability of the PEI/SA was excellent.
• The PEI/SA is an easy operation and efficient adsorbent for removal Cu(II) ions.

In the present paper, we prepared a novel porous membrane adsorbent (PEI/SA) by immobilizing polyethyleneimine (PEI) with sodium alginate (SA), then further functionalized PEI/SA with 3-aminopropyltriethoxysilane and tested its adsorption performance for removing Cu(II). To investigate the adsorption kinetics of Cu(II) onto this newly developed PEI/SA, we performed a series of batch experiments under various conditions: solution pH, adsorbent dose, initial Cu(II) concentration, adsorption temperature, and contact time. The results show that the maximum adsorption capacity of Cu(II) onto the PEI/SA is approximate 329.8 mg/g, which is 7 times more than that of pristine SA porous membrane. We also examined the Lagergren pseudo-first-order and pseudo-second-order kinetic models, the intra-particular diffusion model, and the Crank model to study the mechanism of adsorption process. Kinetics experiments indicate that the pseudo-second-order model displays the best correlation with adsorption kinetics data. The Crank model shows that the intra-particle solute diffusion is the main rate-controlling step. Furthermore, our adsorption equilibrium data could be better described by the Freundlich equation. Effect of ionic strength on adsorption process is weakly. Co-existing Cd(II), Ni(II) and Cr(VI) ions hardly affect the adsorption capacity of PEI/SA towards Cu(II). The reusability experiments show that the PEI/SA has excellent adsorption–desorption efficiencies. The results indicate that the prepared PEI/SA is promising for Cu(II) removal, from the viewpoints of low cost and easy operation.