Effects of thiol functionalization of a waste-derived activated carbon on the adsorption of sulfamethoxazole from water: Kinetic, equilibrium and thermodynamic studies
authors Jaria, G; Calisto, V; Gil, MV; Ferreira, P; Santos, SM; Otero, M; Esteves, VI
nationality International
author keywords Organosilane grafting; Adsorptive wastewater treatment; Biowastes valorization; Emerging contaminants; Pharmaceuticals
abstract An activated carbon was produced from paper mill sludge (AC-P) and functionalized with thiol groups (AC-MPTMS) for the adsorptive removal of the antibiotic sulfamethoxazole (SMX) from buffered solutions prepared in ultrapure water (pH 8) and real wastewater samples. The physicochemical properties of the two materials (AC-P and AC-MPTMS) showed differences mainly in specific surface area (S-BET), in the type of oxygen functional groups and in the relative percentage of sulphur groups. The adsorption results showed a decrease in the Langmuir adsorption capacity (q(m)) upon an increase on temperature (15, 25 and 35 degrees C), varying between 113 +/- 7 and 42.5 = 0.6 mg g(-1) for AC-P and between 140 +/- 20 and 28.0 +/- 1.5 mg g(-1) for AC-MPTMS. Pseudo-second order model presented the best fit for the kinetic studies, with rate constants (k(2)) increasing with temperature and varying from 0.005 +/- 0.002 to 0.013 +/- 0.004 g mg(-1) min(-1) for AC-P and from 0.006 +/- 0.002 to 0.03 +/- 0.01 g mg(-1) min(-1) for AC-MPTMS. Both adsorbents showed very similar thermodynamic parameters, with the adsorption process being spontaneous (-26 kJ mol(-1) <= Delta G degrees <= -40 kJ mol(-1)), endothermic (69 kJ mol(-1)<= Delta H degrees 78 kJ mol(-1)), and entropically favorable (356 <= Delta S degrees <= 365 J mol(-1) K-1). The performance of AC-MPTMS in the removal of SMX was tested in wastewater, where the material displayed lower SMX adsorption velocity and capacity than in buffered aqueous solution (pH 8) due to competitive matrix effects. (C) 2020 Elsevier B.V. All rights reserved.
publisher ELSEVIER
issn 0167-7322
isbn 1873-3166
year published 2021
volume 323
digital object identifier (doi) 10.1016/j.molliq.2020.115003
web of science category 10
subject category Chemistry, Physical; Physics, Atomic, Molecular & Chemical
unique article identifier WOS:000610844800082
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