Open AccessInsight into the Effect of Sulfonation Techniques on the Adsorption Properties of −SO3H Surface-Functionalized Coal as Adsorbent for Malachite Green Dye: Steric and Energetic Investigation
Author(s) -
Ali A. AlHammadi,
Rania Nasser,
Mohamed Shaban,
Sarah I. Othman,
Jong Seong Khim,
Jamaan S. Ajarem,
Ahmed A. Allam,
Mostafa R. Abukhadra
Publication year - 2022
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.2c04985
Subject(s) - adsorption , physisorption , chemistry , steric effects , van der waals force , hydrogen bond , molecule , malachite green , monolayer , sonication , nuclear chemistry , organic chemistry , chromatography , biochemistry
Natural coal (N.C) was sulfonated with sulfuric acid by normal stirring (MS.C) and sonication waves (SS.C) to obtain -SO 3 H functionalized coal as enhanced adsorbents of malachite green dye (MG). The sulfonated products exhibit enhanced surface area (MS.C (27.2 m 2 /g) and SS.C (45.8 m 2 /g)) as compared to N.C. SS.C achieved higher acid density (14.2 mmol/g) and sulfur content (13.2 wt. %) as compared to MS.C. The impact of the sulfonation processes on the adsorption of MG was assessed based on the monolayer isotherm model of one energy. The MG Q sat of N.C (121.3 mg/g), MS.C (226.3 mg/g), and SS.C (296.4 mg/g) validate the significant effect of the sulfonation processes by the sonication waves. This is in agreement with the active site densities that reflect the saturation of SS.C by more active sites (180.74 mg/g) than MS.C (120.38 mg/g) and N.C (70.84 mg/g). The MS.C and SS.C can adsorb three MG molecules as compared to two molecules per site of N.C. The Gaussian energy (<8 kJ/mol) and adsorption energy (<40 kJ/mol)) reflects the physisorption of MG involving van der Waals forces, hydrogen bonding, and dipole bonding forces. The thermodynamic functions demonstrate the uptake of MG by exothermic, spontaneous, feasible reactions.