Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons

Abstract

Paracetamol adsorption in acidic, neutral and basic media on three activated carbons with different chemistry surfaces was studied. A granular activated carbon (GAC) was prepared from coconut shell; starting from this sample, an oxidized activated carbon (GACo) was obtained by treating the GAC with a boiling solution of 6 M nitric acid, so to generate a greater number of oxygenated surface groups. In addition, a reduced activated carbon (GACr) was obtained by heating the GAC at 1173 K, to remove the oxygenated surface groups. Paracetamol adsorption was higher for GACr due to the lower presence of oxygenated surface functional groups. Moreover, adsorption was highest at neutral pH. The magnitude of the interactions between paracetamol molecules and activated carbons was studied by measuring the immersion enthalpies of activated carbons in solution of paracetamol at different concentrations and pH values and by calculating the interaction enthalpy. The highest value was obtained for GACr in a paracetamol solution of 1000 mg L−1 at pH 7, confirming that paracetamol adsorption is favoured on basic activated carbons at pH values near to neutrality. Finally, the Gibbs energy changes confirmed the latter result, allowing explaining the different magnitudes of the interactions between paracetamol and activated carbons, as a function of solution pH.

Ordered Mesoporous Carbons for Adsorption of Paracetamol and Non-Steroidal Anti-Inflammatory Drugs: Ibuprofen and Naproxen from Aqueous Solutions

“…The molecules of adsorbates occur mainly in neutral forms under used experimental conditions during our research. According to literature data [52], three different mechanisms of adsorption of aromatic compounds on carbonaceous materials are possible: dispersive interactions by π electrons, donor-acceptor electron complexes, and hydrogen bond formation. The mechanism of paracetamol adsorption on the surface of activated carbon containing mainly oxygen functional groups occurs through π electron interactions because the possibility of forming Lewis acid-base complexes or hydrogen bonds [52].…”

“…According to literature data [52], three different mechanisms of adsorption of aromatic compounds on carbonaceous materials are possible: dispersive interactions by π electrons, donor-acceptor electron complexes, and hydrogen bond formation. The mechanism of paracetamol adsorption on the surface of activated carbon containing mainly oxygen functional groups occurs through π electron interactions because the possibility of forming Lewis acid-base complexes or hydrogen bonds [52]. Acidic groups containing oxygen atoms are predominant on the surface of ST-A-P and ST-A-P-CO 2 adsorbents, so one can expect that the interactions between paracetamol and naproxen molecules with the surface of these adsorbents can be similar.…”

Removal of monoethylene glycol from wastewater by using Zr-metal organic frameworks

“…It is important to investigate the effect of acidity on the adsorption of MEG on the surface of modified UiO-66 and UiO-66-2OH. The distribution of acidic or basic molecules in pollutants is strongly dependent on acidity of the aqueous solution, and consequently their interaction with the surface of an adsorbent through adsorption processes [42]. When the solution is an acidic medium, the attractive force toward the surface of the adsorbent is enhanced.…”

Acetaminophen adsorption using a low‐cost adsorbent prepared from modified residues of Moringa oleifera Lam. seed husks

“…In many countries this pharmaceutical is accessible without any prescription . Such easy access to this analgesic is considered a public health problem due to the excessive consumption by the population . Significant concentrations of acetaminophen are detected in water bodies because of this high consumption, inducing risks to the environment, animal and human health .…”

“…4 Such easy access to this analgesic is considered a public health problem due to the excessive consumption by the population. 5 Significant concentrations of acetaminophen are detected in water bodies because of this high consumption, inducing risks to the environment, animal and human health. 6 Quesada et al 7 stated that in surface waters there are traces of acetaminophen in concentrations ranging from 0.03 to 9822 ng L −1 , the highest concentration of 18 common pharmaceuticals surveyed.…”