Improvement of zeolite adsorption capacity for cephalexin by coating with magnetic Fe3O4 nanoparticles

Abstract

The removal of cephalexin (CEX) from aqueous solution by natural zeolite (NZ) and magnetic Fe3O4 nanoparticles prepared and coated onto natural zeolite (CZ) was investigated. Magnetic Fe3O4 nanoparticles were synthesized by chemical precipitation of a Fe2+ and Fe3+ salts from aqueous solution by ammonia hydroxide solution. SEM images, XRD patterns, XRF spectroscopy, and FTIR spectroscopy were used to characterize the adsorbents. The maximum CEX removal efficiency was 28% and 93% for NZ and CZ, respectively, at optimized condition (pH7, an amount of adsorbent of 0.6g/L, a concentration of CEX of 40mg/L, contact time of 2h, and a temperature of 20°C). The isotherm adsorption of CEX onto both adsorbents was best fitted with Langmuir isotherm equation and the maximum adsorption capacity was 16.1 and 24.9mg/g for NZ and CZ, respectively. The kinetics followed is second order in nature and the intraparticle diffusion was the dominating mechanism. Thermodynamic parameters (∆G°>0 and ∆H°<0) showed the non-spontaneity and exothermic in nature of adsorption process. However, the results showed that the increasing of nitrate, carbonate, and hardness ions decreased the CEX removal efficiency by different trends but their effect can be ranked as nitrate<carbonate<hardness.