Optimizing the removal of pharmaceutical drugs Carbamazepine and Dorzolamide from aqueous solutions using mesoporous activated carbons and multi-walled carbon nanotubes

Several experiments were carried out to study the efficiency of mesoporous activated carbons (Meso-AC) and as-synthetized multi-walled carbon nanotubes (intermittently MWCNTs or CNTs) to remove two pharmaceutically active compounds (PhACs), Carbamazepine (CZ) and Dorzolamide (DA), from artificially contaminated waters. In order to optimize the removal efficiency of the tested carbonaceous materials, the influence of varying key parameters was evaluated, including exposure time (up to 30 h), temperature (15–45 °C), solution pH (2 − 10), as well as the application of ultrasonication (0–120 min). The efficiency of the adsorption process was linked to the porous structure of the materials (pore volumes of 0.438, 0.062 and 0.423 cm³/g, respectively for Meso-AC 1 and 2, and CNT). Optimum removal capacities were recorded at pH between 6 and 8 for both adsorbents and PhACs. The application of ultrasound helped enhancing the removal capacities of CZ and DA for the case of MWCNTs (21 and 30% improvement). However, the impact on the activated carbons was unfavorable. The Brouers-Sotolongo equation was the best fitting isotherm model (99.5–99.9% correlation coefficients). The highest removal capacities were registered using MWCNT (224.6 mg/g for CZ and 78.8 mg/g for DA), which are highly efficient performances, when compared with other adsorbents reported in the literature.