Magnetic Graphene Oxide Grafted Dendrimers For The Adsorption Of Heavy Metal Ions

The water pollut ion by heavy meta l ions has become the ser ious t hreat to the huma n healt h,living resources,ecologica l systems and the sustainable developme nt of socia l economy.How to effective ly remo ve the hea vy meta ls in aqueous so lu t ion has been attracted great attent ion b y researchers and t he gover nments around the word.In this work,us ing graphe ne oxide loaded Fe₃O₄ nanopartic les as carriers,magnet ic graphene oxide gra fted different hydrophobic cha in le ngth a nd end groups dendr imers used for adsorption of hea vy metal ions in aqueous solut io n were fabricated by diver gent method and magnet ic separatio n techno logy.（1）First ly,the hexa met hyle nedia mine（HMD）modified ma gnet ic graphene oxide（HMGO-N H₂）was prepared by solvother ma l method,then us ing HMGO-N H₂ as carr ier,hexa methyle nedia min and met hyl acrylate（MA）as funct ion mono mers,magnet ic graphene oxide grafted longer hydrophobic chain lengt h low-generat ion hexa methylened ia mine t ype polyamidoa mine dendr imer（HMGO-PAMAM-G1.0）was fabricated by divergent met hod and magnet ic separation technolo gy.The morpholo gy,structure and compos it ion o f the sa mp les were characterized by trans miss ion e lectron microscope（TEM）,X-ray diffract ion（X RD）,Fourier trans for m infrar ed spectrometer（FT-IR）,N₂ adsorption/desorption isother m,thermo gravimetr ic analyzer（TG A）,vibrating samp le magnetometer（VSM）and X-ray photoelectron spectrometer（XPS）.The adsorpt ion propert ies of MGO-PAMAM-G1.0 and HMGO-PAMAM-G1.0 for Pb（II）and Hg（II）in s ingle s ystem were studied by batch experime nts.The adsorption experiment data of MGO-PAMAM-G1.0 and HMGO-PAMAM-G1.0 for Pb（II）and Hg（II）were obtained by us ing k inet ic models and isother m models.The results showed that the superparamagnet ic HMGO-PAMAM-G1.0 was successfully prepared.The specific saturat ion magnet izat io n of HMGO-PAMAM-G1.0 was 25.9 emu·g^-1,which can be quick ly separated fro m aqueous solut ion under externa l magnet ic fie ld.Compared w ith MGO-PAMAM-G1.0,HMGO-PAMAM-G1.0 had a lar ger average poresize and a sma ller BET specific sur face area,higher adsorptio n rate and lower adsorption capacit ies for Pb（II）and Hg（II）.The adsorptio n processes of MGO-PAMAM-G1.0 and HMGO-PAMAM-G1.0 for Pb（II）and Hg（II）could be described by the pseudo-first-order kinet ic model and Langmuir isother m model.The analys is of XPS indicated that vale nce state of Pb（II）didn’t change,Hg（II）was part ially reduced to Hg（I）in the adsorptio n process.（2）The terminal groups of a series of magnet ic graphene oxide grafted polya midoamine dendrimers（MGO-PAMAM）were mod ified w ith chlorohydrin to fabricate magnet ic graphene oxide grafted hydroxyl-terminated polya midoamine dendr imers（MGO-PAMAM-O H）.MGO-PAMAM-O H for the adsorption of Hg（II）in aqueous solut ion was characterized by transmiss ion e lectron microscope（TEM）,X-ray diffractio n（XRD）,Four ier transfor m infrared spectrometer（FT-IR）,ele menta l analys is,ther mogra vimetr ic ana lyzer（TG A）,vibrat ing sa mple ma gneto meter（VSM）and X-ray photoelectron spectrometer（XPS）.The results s howed that ma gnet ic graphene oxide gra fted 3.0 generatio n hydroxyl-terminated polya midoamine dendr imers（MGO-PAMAM-O H-G3.0）had better adsorpt ion property,and the maximum adsorptio n capacit y was 129.98 mg·g^-1.The adsorptio n process of MGO-PAMAM-O H-G3.0 for H g（II）could be better described by the pseudo–first-order kinet ic model and Langmuir isother ma l adsorptio n model,whic h indicated the adsorption was s ingle la yer che mical adsorptio n on homo geneous surface.