Porous Aluminum-Based Metal-Organic Framework-Aminoclay Nanocomposite: Sustainable Synthesis and Ultrahigh Sorption of Cephalosporin Antibiotics.

Abstract

A novel sorbent was synthesized based on MIL-53(Al) MOF grown over an aminoclay (AC) platform, called MIL-53(Al)@AC nanocomposite, via a green and facile hydrothermal method. The nanocomposite was characterized using FT-IR, PXRD, BET, TEM, FESEM, EDS, XPS, TGA, DLS, and zeta potential analyses. BET analysis represented the porous nature and great surface area of MIL-53(Al)@AC. The high crystalline structure for the synthesized nanocomposite was verified using the PXRD pattern. FESEM, EDS, TEM, and XPS analysis proved the successful decoration of MIL-53(Al) over the AC platform. Cephalosporin antibiotics cefixime (CFX) and cephalexin (CPX), which are often present in wastewaters, were utilized to examine the sorption capacity of the nanocomposite. The significant influential factors such as pH, temperature, sorbent amount, ionic strength, and impurity were discussed. At an initial pH of 7.0 ± 0.1, the highest sorption capacities of CFX and CPX on MIL-53(Al)@AC were 784.14 and 747.91 mg g-1 (T = 298 K, and sorbent amount = 0.1 g L-1), which were 1.43 and 1.47 times greater compared to that of MIL-53(Al), respectively. The evaluation of experimental results was implemented through the Langmuir and Freundlich isotherm equations. The isothermal data were described nobly by the Freundlich isotherm, which confirmed multilayer adsorption on heterogeneous surfaces (R2 > 0.970). A kinetic study indicated that the nanocomposite could adsorb the majority of cephalosporin antibiotics within 30 min. In addition, the experimental data were evaluated via pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The results indicated that the pseudo-second-order equation agreed more closely with the kinetic data (R2 > 0.990). Furthermore, the processes of adsorption were exothermic and spontaneous. The electrostatic attraction, hydrophobic interaction, π-π electron donor-acceptor effect, H-bond, and π-π stacking constituted the main sorption mechanisms. Finally, MIL-53(Al)@AC presented an excellent regeneration performance. Thus, the results revealed the potential application of the MIL-53(Al)@AC nanocomposite for water remediation.