Adsorption of ciprofloxacin on surface functionalized superparamagnetic porous silicas

Abstract

The effect of surface functional groups 3-aminopropyltriethoxy- and 4-(triethoxysilyl)-butyronitrile-, 3-mercaptopropyltriethoxy-, phenyltrimethoxy-, and n-octyl-dimethoxychloro- grafted superparamagnetic particles coated with hexagonal mesoporous silicas (HMS-SPs) on the adsorption of ciprofloxacin (CIP) was evaluated. CIP adsorption followed the pseudo-second-order kinetic model, and intraparticle diffusion was suggested to be the rate-controlling step. Higher CIP adsorption capacities revealed on the hydrophobicity of the adsorbents, however, the phenyltrimethoxy group had the highest adsorption capacity due to the interaction of electron-donor acceptors. The adsorption capacities strongly depended on an electrostatic interaction, with the exception of the phenytrimethoxy group. The presence of tannic acid (TA) could increase the adsorption capacity of CIP on adsorbent surfaces by multilayer adsorption between a positively charged amine group of CIP and negatively charged TA.

Keywords:

• Superparamagnetic hexagonal mesoporous silica
• Adsorption
• Ciprofloxacin
• Surface functional group
• Tannic acid

Acknowledgments

The authors are grateful for the financial support from the 90th Anniversary of Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund). This work is conducted under the research cluster “Control of Emerging Micropollutants in Aquacultural and Feedstock Industry” granted by Center of Excellence for Environmental and Hazardous Waste Management (EHWM) and Special Task Force for Activating Research (STAR) program of Chulalongkorn University. The authors are also grateful for support from the Research, Development and Engineering (RD&E) fund through The National Nanotechnology Center (NANOTEC), The National Science and Technology Development Agency (NSTDA), Thailand (Project No. P-11-00985) of Chulalongkorn University. This research was also supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission (FW1017A). The authors wish to express their gratitude to Hitachi Scholarship Foundation for full support via the Hitachi Research Fellowship 2011. The technical support from Department of Environmental Engineering, Faculty of Engineering and the Center for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University are also acknowledged.