Hierarchical multi-porous carbonaceous beads prepared with nano-CaCO₃ in-situ encapsulated hydrogels for efficient batch and column removal of antibiotics from water

Novel hierarchical multi-porous carbonaceous beads were prepared by a simple process derived from nano-CaCO3 in-situ encapsulated hydrogels for the efficient batch and column removal of antibiotics from water. The obtained material (CCx-CB) was characterized by several techniques and methodologies such as, SEM, TEM, XRD, Raman, BET, MIP and FTIR. To evaluate the feasibility of CCx-CB carbonaceous beads as a potential adsorbent for antibiotic removal, batch adsorption experiments and fixed bed column experiments were conducted using tetracycline as the model antibiotic. The results showed that CCx-CB carbonaceous beads were effective in removing tetracycline with no significant change at pH (3.0-7.0). The adsorption of TC onto CCx-CB carbonaceous beads better fitted the pseudo-second-order kinetics model, and the maximum adsorption capacity calculated from Langmuir isotherm model was 279.3 mg/g at pH 7.0. In the fixed bed column experiments, lower influent TC concentration and lower flow rate lead to favorable adsorption of TC on CCx-CB carbonaceous beads. The Adams-Bohart and Thomas models were applied to the experimental data to predict the breakthrough curves using non-linear regression. More significantly, the carbonaceous beads also exhibit excellent regeneration ability over the adsorption-desorption process. The obtained results suggested that the CCx-CB exhibit a promising candidate for tetracycline removal because of their highly effective TC adsorption capacity, low cost and good regenerability.