Highly Effective Removal of Tetracycline from Water by Hierarchical Porous Carbon: Batch and Column Adsorption

To improve the removal efficiency of pharmaceutical antibiotics from water by adsorption technologies, it is vital to optimize the porous geometrical structure of carbonaceous adsorbents. In this study, a hierarchical porous carbon that possesses micro/meso bimodal pores (MMC) is synthesized and is employed in the adsorption of tetracycline in both batch mode and column mode. In comparison, microporous carbon, mesoporous carbon, and commercial activated carbon (AC) are induced as carbonaceous adsorbents. In batch mode adsorption, the maximum adsorbed amount of tetracycline on MMC reaches 701.31 mg/g, which is twice as much as that on AC. While in the column adsorption process, the treatment capacity and the total adsorbed amount of MMC toward tetracycline are found 10 times greater than those of AC. The porous geometrical structure of the adsorbent is revealed to play an important role in determining the adsorption efficiency in the column adsorption process with a limited contact time. The surface utilizations of MMC in the column process keep similar to that in batch adsorption, which is totally different from the remarkable decreases in other studied adsorbents. The specific bimodal porous structure of MMC benefits the full play of its adsorption potential in column operation. The channel-like mesopores of MMC are helpful in providing a low resistance for the rapid transport of tetracycline molecules, and the micropores further enhance the accessibility and availability of adsorption sites.