Adsorption of salicylic acid from ethanol solutions onto activated carbon: Kinetics and equilibrium studies
Year: 2025
Type: article
Abstract: This work examines the removal of salicylic acid (SA) from ethanol solutions by activated carbon (AC). Batch adsorption experiments were conducted to determine adsorption kinetics and equilibrium. The adsorption capacity q e was calculated from concentration changes, and kinetics were analyzed using pseudo-first-order and pseudo-second-order models. Equilibrium data were fitted to Langmuir and Freundlich isotherms. Results showed rapid uptake of SA: over 90 % adsorption occurred within 60 min, reaching equilibrium by ∼180 min. The pseudo-second-order model fitted the kinetic data exceptionally well (R 2 ~ 0.995), whereas the pseudo-first-order model was poorer (R 2 ~ 0.86), indicating that chemisorption controls the adsorption rate. Equilibrium behavior followed the Langmuir isotherm (R 2 ~ 0.993), yielding a high monolayer capacity (∼85 mg g −1 ). The Freundlich model was less suited (R 2 ~ 0.89), suggesting relatively uniform binding sites on the carbon. A Weber–Morris diffusion plot showed a two-stage uptake (initial film diffusion and slower intraparticle diffusion). These findings demonstrate that activated carbon effectively adsorbs SA from ethanol, with kinetics and capacity comparable to aqueous systems. • Activated carbon effectively adsorbs salicylic acid from ethanol solutions. • Kinetic data fit the pseudo-second-order model (R 2 > 0.99), indicating chemisorption. • Equilibrium adsorption follows the Langmuir isotherm (monolayer capacity). • High maximum capacity (∼85 mg g −1 ) demonstrates strong affinity of AC for SA. • Intraparticle diffusion analysis reveals a two-stage adsorption process.
Source: Results in Materials
Institution: Uzhhorod National University
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,530
Funder: European Commission
OpenAlex ID: W4417279447