Master's Theses

Date of Award

2016

Document Type

Thesis

Department

Earth and Atmospheric Sciences

First Advisor

Pengfei Zhang

Second Advisor

Karin Block

Third Advisor

Urs Jans

Keywords

vermiculite, antibiotics, adsorption

Abstract

The occurrence of residual antibiotics in the environment has been a worldwide issue and warrants the development of inexpensive yet effective methods for antibiotics removal from contaminated water. In this thesis work, the adsorption of four antibiotics, namely chlorotetracycline (CTC), oxytetracycline (OTC), ofloxacin (OFL), and enrofloxacin (ENR), onto natural vermiculite has been studied using batch (static) and column (dynamic) adsorption techniques. The Langmuir and Freundlich isotherm models were initially used to explain the adsorption processes. The separation factor (RL) values derived from the Langmuir model and the 1/n values derived from Freundlich model in the present investigation were less than one, indicating that the adsorption of the antibiotics onto vermiculite is favorable. A slightly more sophisticated Langmuir-Freundlich was also used to obtain the maximum adsorption capacity since the Langmuir model significantly underestimated the capacity. The maximum adsorption capacities obtained from the column experiments for CTC, OTC, OFL and ENR are approximately 0.79, 1.2, 1.9 and 1.0 mg/g respectively, 10-20% of those obtained from the batch equilibrium experiments (8.1, 7.1, 10.3, and 6.6 mg/g for CTC, OTC, OFL and ENR respectively). This difference could be attributed to the kinetic limitations during column experiments. Results indicate that the low-cost adsorbent vermiculite can be used as an economically viable adsorbent for the removal of selected antibiotics (CTC, OTC OFL and ENR) from contaminated water.

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