Speciation of metal oxyanions from water on magnetic amino-functionalized polymer

U ovom radu je suspenzionom kopolimerizacijom in situ u prisustvu nanočestica magnetita obloţenih (3-aminopropil)trimetoksisilanom (APTMS) sintetisan magnetični polimerni nanokompozit glicidilmetakrilata (GMA) i etilenglikoldimetakrilata (EGDMA) (10MAGSi-SGE-60) i funkcionalizovan dietilentriaminom (deta). Amino-funkcionalizovani uzorak (10MAGSi-SGE-60-deta) je okarakterisan infracrvenom spektroskopijom sa Furijevom transformacijom (ATR-FTIR), ţivinom porozimetrijom, termogravimetrijskom analizom (TGA), rendgenskom difrakcionom analizom (XRD), skenirajućom elektronskom mikroskopijom sa energetski disperzivnom spektrometrijom (SEM-EDS), transmisionom elektronskom mikroskopijom (TEM) i magnetometrijom (SQUID). Uzorak 10MAGSi-SGE-60-deta je ispitivan kao sorbens Cr(VI), Mo(VI), Re(VII), V(V), W(VI), As(V) i Se(VI) oksianjona iz vodenih rastvora. Ispitan je uticaj pH vrednosti rastvora, vremena kontakta, temperature i početne koncentracije jona na efikasnost i kapacitet sorpcije. Kinetika sorpcije je analizirana primenom modela pseudo-prvog i pseudo-drugog reda, Jelovičevog i modela unutarčestične difuzije (IPD). Ravnoteţni podaci analizirani su Lengmirovim, Frojndlihovim i Temkinovim modelima izotermi. Priroda vezivanja oksianjona za aktivna mesta sorbensa analizirana je teorijskim modelovanjem, primenom kvantno-hemijskih metoda: Teorije funkcionala gustine (DFT), statističke analize struktura na osnovu Kembričke baze podataka (CSD) i implicitnim solvatacionim modelom (SMD). UtvrĎeno je da je proces sorpcije spontan i egzoterman, kao i da Frojndlihov model pokazuje najbolje slaganje sa ravnoteţnim podacima. Aktivna mesta na sorbensu su amino grupe (iz dietilentriamina i APTMS) koje elektrostatičkim interakcijama vezuju oksianjone iz vodenih rastvora.In this study, the magnetic polymer nanocomposite of glycidylmethacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA), (10MAGSi-SGE-60) was synthesized by suspension copolymerization in situ in the presence of magnetite nanoparticles coated with (3-aminopropyl)trimethoxysilane (APTMS), and functionalized with diethylenetriamine (deta). Amino-functionalized 10MAGSi-SGE-60-deta was characterized by using Fourier Transform infrared spectroscopy (FTIR), mercury porosimetry, thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM) and magnetometry (SQUID). The sample 10MAGSi-SGE-60-deta was tested as sorbent of Cr(VI), Mo(VI), Re(VII), V(V), W(VI), As(V) and Se(VI) oxyanions from aqueous solution. The effect of pH, contact time, temperature and initial concentration on the sorption capacity and efficiency were studied. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD) models were used to analyze the kinetic data. The equilibrium sorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The nature of oxyanion binding to the active sites of sorbents was analyzed by theoretical modeling, using quantum-chemical methods: Density Functional Theory (DFT), statistic analysis of the crystal structure extracted from Cambridge Structural Database (CSD) and by implicit solvation model (SMD). It was found that the process is spontaneous and exothermic. Also, the Freundlich isotherm best fits the experimental data. The active sites of sorbents are amino groups (of diethylenetriamine and APTMS) which form electrostatic interactions with oxyanions in aqueous solution