Abstract
The adsorption of paracetamol and non-steroidal anti-inflammatory drugs (ibuprofen and naproxen) on ordered mesoporous carbons (OMC) and, for comparison, on commercial activated carbon, were investigated in this work. OMC adsorbents were obtained by the soft-templating method and were characterized by low-temperature nitrogen adsorption and scanning electron microscopy (SEM). The effects of contact time and initial concentration of organic adsorbates on the adsorption were studied. The contact time to reach equilibrium for maximum adsorption was 360 min for all the studied adsorbates. The adsorption mechanism was found to fit pseudo-second-order and intra particle-diffusion models. Freundlich, Langmuir and Langmuir-Freundlich isotherm models were used to analyze equilibrium adsorption data. Based on the obtained experimental data, the adsorption isotherm in the applied concentration range for all the studied adsorbates was well represented by the Freundlich-Langmuir model. The adsorption ability of ordered mesoporous carbon materials was much higher for paracetamol and naproxen in comparison to commercial activated carbon. The removal efficiency for ibuprofen was significantly lower than for other studied pharmaceuticals and comparable for all adsorbents. Theoretical calculations made it possible to obtain optimized chemical structures of (S)-naproxen, ibuprofen, and paracetamol molecules. Knowledge of charge distributions of these adsorbate molecules can be helpful to explain why paracetamol and naproxen can react more strongly with the surface of adsorbents with a large numbers of acidic groups compared to ibuprofen facilitating more efficient adsorption of these pharmaceuticals on ordered mesoporous carbons.
Highlights
Pharmaceuticals belong to the most significant groups of emerging pollutants to have been recognized in water resources
The results show that new mesoporous carbon materials respectively, i.e., for adsorption on adsorbents activated by CO2
Comparable adsorption efficiency on synthesis activation of mesoporous carbon (ST-A-P) and WG-15 adsorbents for ibuprofen suggests that the adsorption mechanism is influenced by other factors (Figure 5)
Summary
Pharmaceuticals belong to the most significant groups of emerging pollutants to have been recognized in water resources. Among the methods applied for the treatment of NSAIDs pollutants, adsorption is a low-cost process showing very high removal efficiency [2]. Surface functionality, pore structure, high surface area, and high adsorptive capacity is applied as an efficient adsorbent for water treatment, especially for water remediation with low pollutant concentration [2,5]. Baccar et al [9] investigated the adsorption of ibuprofen, ketoprofen, naproxen and diclofenac onto a low-cost activated carbon, prepared from olive-waste cakes. Chemically-activated carbon materials prepared from pine sawdust-Onopordum acanthium L. were studied for the removal of diclofenac and naproxen from aqueous solutions [25]. New ordered mesoporous carbon materials ST-A-P, ST-A-P-CO2 and, for comparison, commercial activated carbon WG-15, were studied for the removal of ibuprofen, paracetamol and naproxen from aqueous solutions. The analysis of kinetic and equilibrium adsorption data was performed for all the studied adsorbents
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