Insight into the effects of H2SO4 and HNO3 acidification processes on the properties of coal as an enhanced adsorbent for ciprofloxacin residuals: Steric and energetic studies

Ibrahim G Al-Labadi; Marwa H Shemy; Alaa Y Ghidan; Ahmed A Allam; Horváth M Kálmán; Jamaan S Ajarem; Jianmin Luo; Chuanyi Wang; Mostafa R Abukhadra

doi:10.3389/fchem.2023.1130682

Insight into the effects of H₂SO₄ and HNO₃ acidification processes on the properties of coal as an enhanced adsorbent for ciprofloxacin residuals: Steric and energetic studies

Front Chem. 2023 Mar 27:11:1130682. doi: 10.3389/fchem.2023.1130682. eCollection 2023.

Authors

Ibrahim G Al-Labadi¹, Marwa H Shemy^{2

3}, Alaa Y Ghidan⁴, Ahmed A Allam⁵, Horváth M Kálmán¹, Jamaan S Ajarem⁶, Jianmin Luo⁷, Chuanyi Wang⁸, Mostafa R Abukhadra^{2

9}

Affiliations

¹ Department of Environmental Analysis and Technologies, Institute of Environmental Sciences, Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary.
² Materials Technologies and Their Applications Lab, Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
³ Chemistry Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
⁴ Department of Biological Sciences, Faculty of Sciences, The University of Jordan, Amman, Jordan.
⁵ Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
⁶ Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
⁷ School of Chemistry and Civil Engineering, Shaoguan University, Shaoguan, China.
⁸ School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, China.
⁹ Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.

Abstract

A sub-bituminous natural coal sample (R.C) was treated with sulfuric acid (S.C) and nitric acid (N.C) as modified products and enhanced adsorbents for obtaining ciprofloxacin (CFX) antibiotic residuals from water. The characterization studied demonstrates enhancement in the surface area and the incorporation of new active oxygenated, sulfur-bearing, and nitrogen-bearing chemical groups into the structure of coal samples. This was reflected in the adsorption capacities that were enhanced from 164.08 mg/g (R.C) to 489.2 mg/g and 518.5 mg/g for N.C and S.C, respectively. The impact of the acid modification processes was evaluated based on the energetic and steric properties of their adsorption systems considering the parameters of the advanced monolayer equilibrium model with one energy site. The determined occupied active sites' density of R.C (46.32-61.44 mg/g), N.C (168.7-364.9 mg/g), and S.C (159.2-249.9 mg/g) reflects an increase in the quantities of active centers after the acid treatment processes, especially with HNO₃. The higher efficiencies of the active sites of S.C to adsorb more CFX molecules (n = 2.08-2.31) than N.C (n = 1.41-2.16) illustrate its higher adsorption capacity. The energetic investigation [adsorption (˂40 kJ/mol) and Gaussian (˂8 kJ/mol) energies] suggested adsorption of CFX by N.C and S.C mainly by physical processes such as van der Waals forces, hydrogen bonding, dipole bonding, and π-π interactions. Moreover, the determined thermodynamic functions including entropy, internal energy, and free enthalpy reflect the spontaneous and endothermic uptake of CFX on the surfaces of N.C and S.C.

Keywords: acid treatment; ciprofloxacin; coal; energetic; steric.