Synthesis, characterisation and application of imidazolium based ionic liquid modified montmorillonite sorbents for the removal of amaranth dye

Abstract

The removal of amaranth dye using montmorillonite modified with an ionic liquid (IL) wasinvestigated. An ionic liquid (1-methyl, 3-decahexyl imidazolium) was synthesised, and characterised by nuclear magnetic resonance ( 1 H and 13 C NMR), fourier transform infrared (FT-IR) spectroscopy, high resolution mass spectroscopy (HR-MS) as well as thermal gravimetric analysis and differential thermal (TGA/DCS) analysis. The ionic liquid was thereafter used to modify sodium montmorillonite (Na+-Mt) to form a hydrophobic montmorillonite that has a positively charged surface, by adding IL in excess of the cation exchange capacity (CEC) of Na+-Mt. Energy dispersive X-ray analyser (EDX) was used to determine the chemical composition of Na+-Mt. Modified montmorillonite (Mt-IL) and Na+-Mt was characterised using FT-IR, scanning electron microscopy (SEM), x-ray diffraction (XRD) and Brunauer−Emmett−Teller (BET) method, and used in the adsorption study of an anionic amaranth dye. A higher CEC of the Mt-IL (112 meq/100 g) than Na+-Mt (89 meq/100 g) was observed. The effects of sorbent dosage, dye concentration, solution pH and contact time were investigated in order to determine optimal experimental conditions. Optimum adsorption was obtained at pH 2 and adsorption data was better described by the pseudo-second-order kinetics and Langmuir adsorption isotherm. A maximum adsorption capacity of 263.2 mg/g was calculated. The thermodynamic parameters ∆G°, ∆H° and ∆S° were also investigated at temperatures of 313, 303 and 293 K. Column studies were performed on the modified material and the data generated was applied to the Thomas model where high column adsorption capacities of 393.7, 580.9 and 603.6 mg/g at different concentrations were obtained.

Sorption mechansim of pharmaceuticals from aqueous medium on ionic liquid modified biomass

“…This showed that modifying KP with IL has significantly increased it sorption capacity. Similar outcomes have been reported by other researchers …”

“…) show the decomposition of KP. KP is rich in H and O contents, and the peaks in the region 3000–3690 cm −1 were assigned to –OH and ‐NH groups; intense peaks at 2915 and 2850 cm −1 on KP‐IL were assigned to symmetric and asymmetric stretching vibrations of the methylene groups in the ionic liquid showing the modification of the biomass with ionic liquid molecules . These peaks were not as pronounced in the unmodified plant material.…”

“…Ketoprofen (CAS no 22071‐15‐4), diclofenac sodium salt (CAS number 15307‐79‐6), ibuprofen (CAS number 15687‐27‐1) and ampicillin (CAS number 69‐53‐4) were purchased from Aldrich. 1‐methyl, 3‐decahexyl imidazolium was synthesized in our laboratory and the synthesis and characterization was reported in a previous paper . Double distilled deionized water was used throughout the study.…”

“…In addition, many researchers have reported various biomass modifications by different surfactants for the adsorption of organic and inorganic pollutants . Ionic liquid has recently been considered as an alternative surfactant for modification of materials for the purpose of adsorption of pollutants from aqueous solutions …”

Fixed‐Bed and Batch Adsorption of Pharmaceuticals from Aqueous Solutions on Ionic Liquid‐Modified Montmorillonite

“…Among adsorbents, montmorillonite proved to be a suitable material for water remediation. The hydrophilic properties of the montmorillonite surface are changed to hydrophobic ones through modification by surfactants to form organo‐montmorillonite , , for the purpose of adsorbing organic pollutants. When introduced at low concentration into a system, surfactants are able to adsorb onto the surfaces or interfaces of the system, thereby altering to a certain degree the surface or interfacial free energies of such surfaces or interfaces .…”