**4. Conclusions**

In this study, activated-carbon-coated glass bead adsorbents were developed and applied for phenol removal from synthetic wastewater. Batch adsorption studies indicated a maximum phenol removal of 80% for the optimal operational conditions of an adsorbent dosage 2.5 g, contact time 3 h and temperature 30 ◦C. Reusability studies of the adsorbent beads using a 5% (*v*/*v*) ethanol solution showed a good regeneration percentage of 56%, which were associated with the activated-carbon beads for phenol removal studies. To further enhance the performance of the phenol-removal process using the as-developed activated-carbon beads, a column study was performed in an LSCFB. A very high phenol-removal efficiency of 98% was achieved in the LSCFB with an enhanced regeneration efficiency of 64% for the adsorbent beads, within a shorter duration of 20 min (as compared to batch adsorption results). The results analyzed from the batch and column study indicated that the Langmuir and Adam-Bohart models provided the best fit, respectively. This elucidated the monolayer deposition of the phenol on the adsorbent beads through a quasi-chemical reaction phenomenon. Furthermore, the morphological analysis of the adsorbent beads at various stages of adsorption and regeneration studies exhibited their intact structural stability. Furthermore, surface chemistry studies of the adsorbent using the FTIR technique showed that the chemical functionality of the adsorbent was well maintained, and that successful phenol adsorption/desorption occurred on the surface of the activated-carbon glass beads. The results highlighted that the continuous mode of phenol removal and adsorbent regeneration using the LSCFB was more advantageous and significant than the batch mode. Thus, phenol removal using activated-carbon-coated glass beads in an LSCFB is reported as a novel approach for effective treatment of phenol-polluted wastewater streams. The promising results of the study indicate the possible industrial potential of the presented technique, especially towards toxic phenol contaminant elimination from aqueous solutions.

**Author Contributions:** Conceptualization, N.G. and R.K.; methodology, N.S., S.B. and S.S.; software, N.G. and R.K.; data curation, N.S., S.B. and S.S.; data validation, N.G., R.K. and P.L.S.; writing—original draft, N.S., S.B., S.S. and R.K.; writing—review and editing, N.G., M.T., F.A. and H.A.; project administration, N.G., M.T. and R.K.; funding acquisition, N.G. and H.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors are grateful to the Vellore Institute of Technology, Vellore, for providing SEED money and an efficient infrastructure facility to carry out the present study, as well as for providing a scanning electron microscopy analysis facility aided by DST-FIST-SBST-VIT (SEM EVO 18, CARL ZEISS).

**Conflicts of Interest:** The authors declare no conflict of interest.
