Emerging Contaminants (Dec 2023)
Efficient and simultaneous removal of four antibiotics with silicone polymer adsorbent from aqueous solution
Abstract
The extensive utilization of pharmaceuticals in developing nations, notably antibiotics, has resulted in the occurrence of these substances in water and wastewater, widely accepted as emerging pollutants. The focus of this study was to devise a strategy that can efficiently and concurrently eliminate multiple antibiotics from an aqueous medium. A silicone-based polymer–polydimethylsiloxane (PDMS) adsorbent was prepared to remove antibiotics from aqueous solution. Characterization of PDMS was carried out using different techniques, and the adsorption capacity of the adsorbent was determined in batch experiments. Kinetics and Isotherms fittings were employed to better understand the mechanism for the removal of antibiotics. The PDMS was prepared without the addition of any chemicals. The experiments were performed in batch mode for two weeks and the operating parameters include pH 7 and temperature 25 °C. The antibiotics analysis was performed on HPLC-DAD at 280 nm. The adsorbent (PDMS) showed maximum removal efficiency of 99.71% for ofloxacin followed by oxytetracycline, ciprofloxacin, and sulfamethoxazole i.e., 99.58%, 96.01%, and 93.90%, respectively. The adsorption capacity had a similar trend with the maximum value for ofloxacin (8.79 mg/g), followed by oxytetracycline (8.76 mg/g), ciprofloxacin (8.41 mg/g), and sulfamethoxazole (8.27 mg/g). The fitting of data into isotherm models confirmed that the Langmuir model was the governing mechanism for ofloxacin and sulfamethoxazole having R2 = 0.9663 and 0.9681, respectively. Whereas, for oxytetracycline and ciprofloxacin, the Freundlich model was the best fitted (R2 = 0.9970 and 0.9328, respectively). Adsorption studies showed that all four antibiotics followed the pseudo-second-order kinetics with R2 values 0.9549, 0.9893, 0.9692, and 0.9994 for ciprofloxacin, ofloxacin, sulfamethoxazole, and oxytetracycline, respectively. The encouraging results of regeneration studies further confirmed the potential of PDMS as a promising adsorbent showing ≥74% removal efficiencies for all the antibiotics in the fourth cycle. In general, it can be concluded from the results that PDMS has great potential to serve as an effective and efficient adsorbent for the removal of antibiotics without using chemicals and thus not adding further to environmental contamination.
