Studies on adsorption mechanism and thertmodynamics of chelating adsorption material PAO/SiO_2 with composite-type for heavy metal ions

Acrylonitrile(AN) was graft-polymerized on micron-sized silicon particles,resulting in grafted particles PAN/SiO2.Subsequently,the grafted PAN was converted to poly(amidoxime) via amidoximation reaction,and composite-type chelating adsorption partucles PAO/SiO2 were obtained.In this work,the chelating adsorption behaviours of PAO/SiO2 towards several heavy metal ions were examined,the adsorption mechanism and adsorption thermodynamics were mainly studied.The experimental results show that the composite-type chelating adsorption material PAO/SiO2 has strong chelating adsorption ability for heavy metal ions by right of the synergy of electronic interaction and coordination chelation between amidoxime groups of PAO/SiO2 and heavy metal ions.In a pH range in which the hydrolysis of heavy metal ions can be inhibited,to increase pH value of the medium will strengthen the chelation adsorption ability of the composite-type chelating adsorption material PAO/SiO2 towards heavy ions.For the different metal ions,PAO/SiO2 exhibits different adsorption abilities,and the order of the adsorption capacity is Cu2+Ni2+Pb2+Cd2+.