High-density amine-functionalized MCM-41 derived from pumice: facile synthesis and antibiotic adsorption

The MCM-41 adsorbent was derived from Iranian natural pumice as source of silica for the first time and highly grafted with APTES for anchoring cephalexin (CEX) molecules. The parent MCM-41 had a specific surface of 913 m 2 /g while the value decreased to 819 m 2 /g after grafting with 6.52 μmol APTES per square meter of adsorbent surface. Batch adsorption data were best fitted onto various kinetic and isotherm model with higher correlation coefficient and lower residual sum of squares for pseudo-first-order kinetic model and Langmuir isotherm model. In this regard, amine-grafted MCM-41 (N-MCM-41) showed an excellent adsorption capacity of 56.31 mg/g according to Langmuir model. Removal efficiency was decreased by 50% in the presence of coexisting ions. Nonlinear Thomas model best fitted onto breakthrough curves at various experimental condition. For synthetic solution and at moderate condition, about 41.53 mg/g of CEX was adsorbed in continues experiment. For simulated samples, 19.74 mg/g adsorption capacity was achieved under dynamic condition. Thermal destruction method was used to recover the spent adsorbent and after six cycle adsorption–desorption, adsorption capacity decreased from 41.53 to 8.72 mg/g. Overall, the present study proposed N-MCM-41 prepared from natural pumice for effective adsorption–desorption of CEX, which could be a guidance for antibiotics adsorption.