Ofloxacin adsorption by activated carbon derived from luffa sponge: Kinetic, isotherm, and thermodynamic analyses

Ofloxacin (OFL) removal from aqueous solution by carbon activated made from luffa sponge was studied. Scanning electron microscopy showed that the activated carbon (AC) surface was rough. The AC surface area was 834.008 m2/g and the average pore diameter was 5.35 nm. AC adsorbed 96% of OFL at a concentration of 30 mg/L, and the maximum amount of OFL adsorbed was about 132 mg/g. The AC adsorption kinetic data fitted a pseudo-second-order model (R2 = 0.9997) well, indicating chemisorption control. The experimental data at 308 K best fitted the Freundlich isotherm equation (R2 = 0.9912), indicating multilayer adsorption. A thermodynamic simulation showed that adsorption was spontaneous and exothermic. The optimal conditions for OFL adsorption were pH 6, initial OFL concentration 30 mg/L, temperature 293 K, and AC dosage 0.5 g/L. Fourier-transform infrared spectroscopy showed that phosphorus-containing functional groups, and CO, COC, and CC bonds were present on the AC surface.