Metal-organic frameworks for the adsorptive removal of pharmaceutically active compounds (PhACs): Comparison to activated carbon

During the past few years, there has been growing concern about the presence of various pharmaceutically active compounds (PhACs) in water systems. Although their concentrations could be considered relatively low, their long-term negative impacts on the aquatic ecosystem and human beings cannot be neglected. Therefore, significant efforts have been directed towards finding an effective water treatment method that can completely remove PhACs from water systems. Among the available strategies, adsorption could be considered the most feasible because of a number of advantages, such as high effectiveness and low cost. Until now, activated carbon (AC) has been widely used as the main adsorbent to accomplish this task. However, over the last two decades, there has been growing interest in the development of metal–organic frameworks (MOFs). As a relatively new class of porous material, MOFs could be deployed as an effective adsorbent to remove PhACs from water. However, after more than 20 years of research and development of MOFs, the main question remains: could MOF outperform AC as the most-widely used adsorbent to accomplish this task? This article then tries to answer this question by conducting an extensive comparative study of the recent adsorption performances of MOF and AC towards various PhACs. Through this comparison, a clear difference in adsorption performance between the two adsorbents could be established. In addition, this article also discusses the adsorption mechanisms and various factors that could affect the adsorption performance in each adsorbent. Lastly, some future perspectives are also given which could be used as a guideline in the future studies. This comprehensive analysis could then be expected to guide the selection of either AC or MOF as an effective adsorbent to remove PhACs from water systems.