The Preparation And Application Of Magnetic Graphene-based Molecular Bottlebrush Adsorbent

Magnetic solid-phase extraction(MSPE)is the most widely used method in sample preparation techniques,which has some advantage of simplicity,quick and excellent efficiency.The adsorbent has an important role in MSPE procedure,which not only affects extraction efficiency,but also determines the sensitivity of the method.Therefore,it is necessary to develop a kind of adsorbent with high adsorption capacity and selectivity.Molecular bottlebrush polymers were grafted from the surface of polydopamine coated magnetic grapheme(mag GO@PDA)via surface initiated-atom transfer radical polymerization(SI-ATRP),to obtain a high adsorption capacity and high selectivity adsorbent.The process as follows:(1)Firstly,poly(2-hydroxyethyl methacrylate)(PHEMA)were grafted from the surface of mag GO@PDA via the SI-ATRP polymerization to produce the main chain of the molecular bottlebrush,followed by grafting polystyrene(PSt)from the main chain via the second SI-ATRP polymerization to produce the molecular bottlebrush grafted adsorbent(mag GO@bottlebrush).In the process of adsorption,multivalent interactions,such as hydrophobic effect,?-? stacking and H-bnding,can improve the adsorption capacity and selectivity.The results indicate that the adsorbent had a better selective adsorption for non-planar and non-linear compounds.The adsorbent was successfully used to pre-concentrate bisphenol A(BPA)and polychlorinated biphenyls(PCBs)in real water samples.(2)Firstly,the PHEMA were grafted from the surface of mag GO@PDA to produce main chain of the molecular bottlebrush,and then,3-acrylaminophenylboronic(AAPBA)were grafted from the main chains to obtain boronate affinity adsorbent(mag GO@AAPBA)via SI-ATRP method.The adsorption capacities and selectivity were improved via tuning the ligand densities and lengths by changing the ATRP conditions.The adsorbent was characterized by Fourier-transform infrared spectrometer(FT-IR),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).The adsorption capacity for ovalbumin(OVA)was 375.9 mg/g,which was much higher than that for non-glycoproteins.This result indicates that the adsorbent had better selectivity for OVA.