A new methodology to determine the effect of the adsorbate-adsorbent interactions on the analgesic adsorption onto activ
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RESEARCH ARTICLE
A new methodology to determine the effect of the adsorbate-adsorbent interactions on the analgesic adsorption onto activated carbon using kinetic and calorimetry data Valentina Bernal 1 & Liliana Giraldo 2 & Juan Carlos Moreno-Piraján 2 Received: 10 February 2020 / Accepted: 12 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This work proposes a new methodology to determine the adsorption mechanism for salicylic acid and paracetamol on activated carbon based on the physicochemical characteristics of adsorbent and adsorbates. The methodology is divided into two parts: the determination of adsorption kinetics (order and mechanism) and the study of the chemical interactions (adsorbate-adsorbent and solvent-adsorbent) using calorimetry tests. Then, the results obtained in both techniques were correlated with the amount of drug adsorbed. The adsorption kinetics of salicylic acid and paracetamol on activated carbons with different oxygen contents could be described with widely kinetic models such as intraparticle, pseudo-first-order, pseudo-second-order, Avrami, and Elovich models; different information about the adsorption mechanism are offered by each of them. The results indicated that the pseudo-first-order rate constant decreases with the molecular size of analgesics and the carboxylic acid groups on the adsorbent surface; the rate constant values are between 0.12 and 2.31 h−1. The adsorbed amount of analgesics and the adsorption rate are greatest on activated carbons with basic characteristics (QRAC 0.45 > 0.24 > 0.21 mmol g−1 for phenol, salicylic acid, and paracetamol, respectively). The enthalpy changes follow the same trend in all activated carbons; for RAC, the results were ΔHimmPHEN = − 33.4 J g−1, ΔHimmSA = − 35.9 J g−1, and ΔHimmPAR = − 45.4 J g−1. The analgesic diffusion rate in the boundary layer increases with the formation of adsorbate-adsorbent interactions (exothermic process). Keywords Activated carbon . Adsorption . Enthalpy . Interactions . Kinetic . Paracetamol . Salicylic acid
Introduction The pain is defined as an emotional and physical experience associated with a potential tissue damage. It is estimated that 10–55% of people around the world suffer from chronic pain. For example, 19% and 30% of the population in Europe and the USA lives with nociceptive or neuropathic pain such as musculoskeletal pain, fibromyalgia, tension-type headache, and osteoarthritis (Naranjo-Hernández et al. 2020). Additionally, it
Responsible Editor: Tito Roberto Cadaval Jr * Juan Carlos Moreno-Piraján [email protected] 1
Departamento de Química, Universidad de los Andes, Cra. 1a No. 18A-12, Bogotá, D.C., Colombia
2
Departamento de Química, Universidad Nacional de Colombia, Cra. 30 No. 45-03, Bogotá, D.C., Colombia
is a major cause of disability and generates a high impact in the economy to the countries because treatment costs are greater than $635 billion of US dollars per year (Axon et al. 2019). The use of analgesics or painkillers is necessary to tre
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