Enhanced adsorption performance for selected pharmaceutical compounds by sonicated Ti₃C₂T_X MXene

This paper is aimed at evaluating the feasibility of selected pharmaceutical compounds’ adsorption on Ti₃C₂T_X MXene (termed ‘MXene’ in this study) as the first attempt. For adsorption mechanism analysis, amitriptyline (AMT), verapamil, carbamazepine, 17 α-ethinyl estradiol, ibuprofen, and diclofenac were the selected pharmaceutical compounds and experiments were conducted in three different pH conditions (3.5, 7, and 10.5). Due to electrostatic attraction between negatively charged MXene and positively charged AMT, the adsorption capacity for AMT showed the highest value (58.7 mg/g) at pH 7. In addition, for enhanced adsorption performance, MXene sonicated at different frequencies (0, 28, and 580 kHz) was applied for AMT adsorption. The maximum adsorption capacity was observed in the following order: 28 kHz (214 mg/g) > 580 kHz (172 mg/g) > 0 kHz (138 mg/g). This is because cavitation bubbles by sonication can make well-dispersed MXene and more forming oxygenated functional groups on MXene. In particular, by generating larger cavitation bubbles, the highest performance was shown at lower frequencies. Furthermore, because there are a lot of ions in real aquatic environments, the effect of various ions on adsorption performance on pharmaceutical compounds was evaluated using sonicated MXene. Although background inorganics negatively affect adsorption performance, natural organic matter as background organics increased the adsorption performance. However, cetylpyridinium chloride (CPC), a major cationic surfactant of the pharmaceutical industry, had a negative effect on adsorption performance by exhibiting a competition effect between CPC and pharmaceutical compounds. Finally, a comparison between sonicated MXene and commercial powdered activated carbon and recyclability performances indicated that sonicated MXene could be an alternative adsorbent for pharmaceutical compounds removal due to its high adsorption capacity, selectivity, and reusability.