APSUSC 349-2015-485

New insight into electrochemical-induced synthesis of NiAl2O4/Al2O3:Synergistic effect of surface hydroxyl groups and magnetism forenhanced adsorptivity of Pd(II)

A new promising adsorbent, Ni supported on -Al2O3was prepared in a simple electrolysis system(Ni/Al2O3-E) in minutes and was compared with the sample prepared by a physical mixing method(Ni/Al2O3-PM). The adsorbents were characterized by XRD, TEM, FTIR,27Al MAS NMR, XPS, and VSM.The results showed that besides NiO nanoparticles, a NiAl2O4spinel was also formed in Ni/Al2O3-E dur-ing the electrolysis via the dealumination and isomorphous substitution of Ni2+ions. In contrast, onlyagglomerated NiO was found in the Ni/Al2O3-PM. Adsorption test on removal of Pd2+ions from aqueoussolution showed that the Pd2+ions were exchanged with the hydrogen atoms of the surface–OH groups ofboth adsorbents. Significantly, the Ni/Al2O3-E demonstrated a higher adsorption towards Pd2+ions thanNi/Al2O3-PM due to its remarkably higher degree of magnetism, which came from the NiAl2O4. The use of0.1 g L−1Ni/Al2O3-E gave the maximum monolayer adsorption capacity (qm) of 40.3 mg g−1at 303 K andpH 5. The Ni/Al2O3-E showed high potential for simultaneous removal of various noble and transitionmetal ions and could be also used repetitively without affecting the high adsorptivity for Pd2+ions. Thiswork may provide promising adsorbents for recovery of various metals as well as other materials forsuch related applications.