Adsorption performance of an amine-functionalized MCM–41 mesoporous silica nanoparticle system for ciprofloxacin removal

Abstract

Abstract Antibiotic pollutants discharged from pharmaceutical industries are often present in the aquatic environment due to ineffective treatment of pharmaceutical wastewater and are hazardous to human and aquatic life. Therefore, effective treatment of antibiotic-containing wastewater is of utmost importance in the field of environmental protection. This study aims to evaluate the adsorption performance of an amine-functionalized MCM–41 mesoporous silica nanoparticles system (MCM–41–NH2) as an adsorbent for the removal of ciprofloxacin (CIP) antibiotic from aqueous solution. Surface and structural characteristics of MCM–41–NH2 were examined using scanning electron microscopy, X-ray diffraction, N2 adsorption–desorption analysis, Fourier transform infrared spectroscopy, and point of zero charge analysis. In addition, thermal stability was investigated by thermogravimetric analysis. Via the proposed treatment, 99.25% CIP removal was achieved under the following conditions: pH\xa0=\xa07; MCM–41–NH2 dose\xa0=\xa00.8\xa0g/L; CIP concentration\xa0=\xa010\xa0mg/L; adsorption time\xa0=\xa0120\xa0min; and shaking speed\xa0=\xa0200\xa0rpm. Isotherm study showed that the experimental data fitted well with the Langmuir equation. Moreover, the maximum adsorption capacity of MCM–41–NH2 for CIP was 164.3\xa0mg/g. Thermodynamic parameters showed that the adsorption process of CIP on MCM–41–NH2 was endothermic and spontaneous. Additionally, the increase in solution temperature had a positive impact on the removal of CIP. The kinetic data obtained at different CIP concentrations (10, 25, 50, and 100\xa0mg/L) were consistent with the pseudo-second-order model. MCM–41–NH2 could be recycled eight times in the proposed adsorption process, with a slight loss in its adsorption capacity. Compared with other adsorbents, MCM–41–NH2 was more effective for CIP removal.