Porous Aluminum-Based Metal–Organic Framework–Aminoclay\nNanocomposite: Sustainable Synthesis and Ultrahigh Sorption of Cephalosporin\nAntibiotics

Abstract

A novel\nsorbent was synthesized based on MIL-53­(Al) MOF grown over\nan aminoclay (AC) platform, called MIL-53­(Al)@AC nanocomposite, via\na green and facile hydrothermal method. The nanocomposite was characterized\nusing FT-IR, PXRD, BET, TEM, FESEM, EDS, XPS, TGA, DLS, and zeta potential\nanalyses. BET analysis represented the porous nature and great surface\narea of MIL-53­(Al)@AC. The high crystalline structure for the synthesized\nnanocomposite was verified using the PXRD pattern. FESEM, EDS, TEM,\nand XPS analysis proved the successful decoration of MIL-53­(Al) over\nthe AC platform. Cephalosporin antibiotics cefixime (CFX) and cephalexin\n(CPX), which are often present in wastewaters, were utilized to examine\nthe sorption capacity of the nanocomposite. The significant influential\nfactors such as pH, temperature, sorbent amount, ionic strength, and\nimpurity were discussed. At an initial pH of 7.0 ± 0.1, the highest\nsorption capacities of CFX and CPX on MIL-53­(Al)@AC were 784.14 and\n747.91 mg g^–1 (<i>T</i> = 298 K, and sorbent\namount = 0.1 g L^–1), which were 1.43 and 1.47 times\ngreater compared to that of MIL-53­(Al), respectively. The evaluation\nof experimental results was implemented through the Langmuir and Freundlich\nisotherm equations. The isothermal data were described nobly by the\nFreundlich isotherm, which confirmed multilayer adsorption on heterogeneous\nsurfaces (<i>R</i>² > 0.970). A kinetic study\nindicated that the nanocomposite could adsorb the majority of cephalosporin\nantibiotics within 30 min. In addition, the experimental data were\nevaluated via pseudo-first-order, pseudo-second-order, and intraparticle\ndiffusion models. The results indicated that the pseudo-second-order\nequation agreed more closely with the kinetic data (<i>R</i>² > 0.990). Furthermore, the processes of adsorption\nwere\nexothermic and spontaneous. The electrostatic attraction, hydrophobic\ninteraction, π–π electron donor–acceptor\neffect, H-bond, and π–π stacking constituted the\nmain sorption mechanisms. Finally, MIL-53­(Al)@AC presented an excellent\nregeneration performance. Thus, the results revealed the potential\napplication of the MIL-53­(Al)@AC nanocomposite for water remediation.