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

Valentina Bernal,Liliana Giraldo,Juan Moreno-Piraján,Alessandro Erto

doi:10.3390/molecules22071032

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.

Highlights

Paracetamol, or 4-hydroxyacetanilide, is a widely used drug due to its analgesic and antipyretic properties
Results and Discussion indicate that the decrease of surface area and micropore volume for GACo can be related to the oxygenated groups the edges of the pore openings, which limits the accessibility of
Properties and to investigate their influence on the adsorption of paracetamol, Boehm analysis were indicate that the decrease of surface area and micropore volume for GACo can be related to the carried out on all the activated carbon sample (Table 2)

Summary

Introduction

Paracetamol, or 4-hydroxyacetanilide, is a widely used drug due to its analgesic and antipyretic properties. It is available by prescription and as an over-the-counter medicine; the U.S Food and Drug. Easy access to pain medication is considered a public health problem due to the high consumption of drugs, such as paracetamol, by the population. This drug is considered safe in the United. 51% of acute liver failures that occurred between 1998 and 2003 were due to the consumption of paracetamol in high amounts [2,3].

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