Theoretical and experimental adsorption studies of sulfamethoxazole and ketoprofen on synthesized ionic liquids modified CNTs

Isiaka A Lawal; Monsurat M Lawal; Samson O Akpotu; Mayowa A Azeez; Patrick Ndungu; Brenda Moodley

doi:10.1016/j.ecoenv.2018.06.019

Theoretical and experimental adsorption studies of sulfamethoxazole and ketoprofen on synthesized ionic liquids modified CNTs

Ecotoxicol Environ Saf. 2018 Oct:161:542-552. doi: 10.1016/j.ecoenv.2018.06.019. Epub 2018 Jun 18.

Authors

Isiaka A Lawal¹, Monsurat M Lawal², Samson O Akpotu³, Mayowa A Azeez⁴, Patrick Ndungu³, Brenda Moodley⁵

Affiliations

¹ Energy, Sensors and Multifunctional Nanomaterials Research Group, Department of Applied chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028 Johannesburg, South Africa; School of Chemistry and Physics, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, P/Bag X45001, Westville Campus, Durban 4000, South Africa. Electronic address: ilawal@uj.ac.za.
² Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa.
³ Energy, Sensors and Multifunctional Nanomaterials Research Group, Department of Applied chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028 Johannesburg, South Africa.
⁴ Department of Chemistry, Ekiti State University, P.M.B 5363 Ado Ekiti, Nigeria.
⁵ School of Chemistry and Physics, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, P/Bag X45001, Westville Campus, Durban 4000, South Africa. Electronic address: moodleyb3@ukza.ac.za.

PMID: 29929130
DOI: 10.1016/j.ecoenv.2018.06.019

Abstract

The adsorption of sulfamethoxazole (SMZ) and ketoprofen (KET) using carbon nanotubes (CNTs) and CNTs modified with ionic liquids (ILs) was investigated. Two ionic liquids (1-benzyl, 3-hexyl imidazolium, IL1 and 1-benzyl, 3-decahexyl imidazolium, IL2) were synthesized, and characterized by nuclear magnetic resonance (¹H and ¹³C NMR) and high resolution-mass spectrometry (HR-MS). CNTs and modified CNTs were characterized using FT-IR, X-ray diffraction (XRD), surface area and porosity analysis, thermal gravimetric analysis (TGA), Zeta potential, Raman and scanning electron microscopy (SEM). Kinetics, isotherm and computational studies were carried out to determine the efficiency and adsorption mechanism of SMZ and KET on modified CNTs. A density functional theory (DFT) method was applied to shed more light on the interactions between the pharmaceutical compounds and the adsorbents at the molecular level. The effects of adsorbent dosage, concentration, solution pH, energetics and contact time of SMZ and KET on the adsorption process were investigated. The adsorption of SMZ and KET on CNTs and modified CNTs were pH dependent, and adsorption was best described by pseudo-second-order kinetics and the Freundlich adsorption isotherm. Ionic liquid modified CNTs showed improved adsorption capacities compared to the unmodified ones for both SMZ and KET, which is in line with the computational results showing performance order; CNT+KET/SMZ < CNT-ILs+SMZ < CNT-ILs+KET.

Keywords: Adsorption; Carbon nanotubes; Density Functional Theorem (DFT); Ionic liquid; Ketoprofen; Sulfamethoxazole.

MeSH terms

Adsorption
Ionic Liquids / chemistry*
Ketoprofen / analysis*
Kinetics
Nanotubes, Carbon / chemistry*
Porosity
Sulfamethoxazole / analysis*
Surface Properties
Water Pollutants, Chemical / analysis*
Water Purification / methods*

Substances

Ionic Liquids
Nanotubes, Carbon
Water Pollutants, Chemical
Ketoprofen
Sulfamethoxazole