Ionic liquid modification of zeolite and its removal of chromate from water

Abstract

2014) Ionic liquid modification of zeolite and its removal of chromate from water, Green Chemistry Letters and Reviews, 7:2,[191][192][193][194][195][196][197][198] This study focused on using imidazolium of different chain lengths to modify the negatively charged zeolite. The modification involves a cation exchange process of the organic cations of ionic liquids (ILs) for the alkali and alkaline earth elements on zeolite surfaces. X-ray diffraction analyses revealed that the uptake of ILs was on the external surfaces. Fourier transform infrared analyses showed that different mechanisms were attributed to IL uptake on zeolite at below and above the external cation exchange capacity. After modification, the zeolite reversed its surface charge to positive, thus enhancing adsorptive removal of anionic contaminants such as chromate from water. At the same time, the modified zeolite increased their total organic carbon content, and thus could promote better adsorptive removal of hydrophobic organic contaminants from water, too. These features enable IL-modified zeolite to be used as inexpensive sorbents for the removal of multi-types of contaminants from water simultaneously.

Ionic-liquid-crafted zeolite for the removal of anionic dye methyl orange

“…The MO sorption on ILCZ modified to 1.0 and 2.0 ECEC followed the Langmuir type isotherm [35], similar to MO sorption on HDTMAmodified zeolites [24] and chromate sorption on the same type of ILCZ [36] (Fig. 2):…”

“…Similarly, the uptake of chromate on the same type of ILCZ was also attributed to surface anion exchange [36]. Due to the negative charges of MO, the sorption of MO by ILCZ would conceivably follow the same mechanism.…”

“…The MO sorption on ILCZ modified to 1. ILCZ modified to 2.0 ECEC was much higher than 70 mmol/kg for its sorption on HDTMA-modified zeolites [24] and 25 mmol/kg for chromate sorption on the same ILCZ [36]. In comparison to ILCZ, MO sorption capacity was up to 196 mg/g, or 600 mmol/kg on HDTMAmodified MMT to 200% of the CEC value, but the value decreased to 50 mg/g, or 150 mmol/kg when the HDTMA loading was equivalent to 100% of the CEC [37].…”

“…The maximum MO sorption on ILCZ modified to 2.0 ECEC was much higher than that by ILCZ modified to 1.0 ECEC because of a better IL bilayer formation when IL modification reached 2.0 ECEC. And the MO sorption capacity on ILCZ was about the same as the ECEC of the zeolite and about the same as the amount of pre-sorbed counterion chloride [36].…”

Dual functionality of amphiphilic 1-alkyl-3-methylimidazolium hydrogen sulfate ionic liquids: surfactants with catalytic function

“…23 The surface active properties of ILs were used for the modication of the zeolite surface to enhance the adsorptive removal of anionic contaminants such as chromate from water. 24 Pino et al proposed the application of the 1-hexadecyl-3-methylimidazolium bromide micellar solution for the extraction of the polycyclic aromatic hydrocarbons from sediments. 25 It was revealed that ILs cannot be considered as only common cationic surfactants.…”