Aminated Sorbents Preparation And Adsorption For Heavy Metals And PFCs

Preparation of highly efficient adsorbent is very important in sorption research andsurface modification can increase the sorption capacity of adsorbents significantly. Twoaminated adsorbents, aminated resin and aminated rice husk (RH), were prepared viaATRP and subsequent amination reaction on the surfaces of Merrifieldchloromethylated resin and RH. Preparation conditions of aminated adsorbentsincluding ATRP time and aminization time were optimized, and the materialcharacterization was conducted. The aminated resin and aminated RH were applied toremove heavy metal and PFCs from aqueous solution respectively, and the sorptionproperties and mechanisms were studied.The optimum ATRP and aminization time of aminated resin were100min and10h, respectively. SEM, FTIR and XPS analysises proved that amine groups were graftedon the resin surface and inner pores successfully. The maximum sorption capacities ofCu(II), Pb(II), Cr(VI) and As(V) on the aminated resin at pH5were2.6,0.97,3.0, and2.2mmol g-1, respectively; sorption capacities of cationic Cu(II) and Pb(II) increasedwith the increase of solution pH, while the sorption capacities of the anionic Cr(VI) andAs(V) decreased with increasing solution pH. XPS spectra confirmed that amine groupson the aminated resin surface were responsible for cation removal via chelation, whilethe electrostatic interaction between protonated amine groups and anionic speciesdominated the sorption of anions.The optimum ATRP and aminization time of aminated RH were2.5h and12h,respectively. SEM, FTIR and zeta analysises proved amine groups were successfullygrafted on RH surface, and the zero of zeta potential increased from2.73to8.54afterthe amination of RH. The maximum sorption capacities of PFBA, PFOA and PFOS onaminated RH at pH5were1.70,2.49and2.65mmol g-1, respectively; sorptionequilibrium can be achieved within8h, which is faster than traditional porousadsorbents distinctly. Sorption behavior and XPS analysis indicted the electrostaticinteraction and hydrophobic interaction occurred between aminated RH and PFCs.