Departamento de Química, Universidad Nacional de Colombia, Cra 30 No. 45-03, Bogotá D.C. 110231, Colombia.
Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università di Napoli Federico II, P. Le Tecchio 80, 80125 Napoli, Italy.
Molecules. 2017 Jun 22;22(7):1032. doi: 10.3390/molecules22071032.
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 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.
研究了三种具有不同化学表面的活性炭在酸性、中性和碱性介质中对扑热息痛的吸附。一种颗粒状活性炭（GAC）是由椰子壳制备的；从这个样品开始，通过用沸腾的 6M 硝酸溶液处理 GAC，得到氧化的活性炭（GACo），从而生成更多的含氧表面基团。此外，通过在 1173K 下加热 GAC，得到还原的活性炭（GACr），以去除含氧表面基团。由于含氧表面官能团的存在较少，GACr 对扑热息痛的吸附更高。此外，吸附在中性 pH 时最高。通过测量活性炭在不同浓度和 pH 值的扑热息痛溶液中的浸出焓，并计算相互作用焓，研究了扑热息痛分子与活性炭之间相互作用的大小。在 pH 为 7 的 1000mg/L 扑热息痛溶液中，GACr 的值最高，证实扑热息痛吸附在接近中性 pH 值的碱性活性炭上更有利。最后，吉布斯能量变化证实了这一结果，允许解释作为溶液 pH 函数的扑热息痛与活性炭之间相互作用的不同幅度。
