Supported Ionic Liquids for the Efficient Removal of Acetylsalicylic Acid from Aqueous Solutions

Abstract

Acetylsalicylic acid, commercially available as aspirin, is one of the most used drugs in the world, being detected in several environmental compartments, including drinking water supplies. Given its environmental impact, the development of a cost-effective technology capable of removing this pharmaceutical from water samples is of high relevance, for which materials based on silica chemically modified with ionic liquids (SILs) can be foreseen as a promising alternative. In this work, four SILs (with the chloride anion and imidazolium or tetraalkylammonium cations of different alkyl side chain length) were synthesized and characterized, and their potential for the adsorption of acetylsalicylic acid appraised by adsorption kinetics and isotherms. Envisioning their use to treat drinking water, the toxicity of all SILs towards the liver cell line Hep2G was determined.The best identified SIL, comprising the dimethylbutylammonium cation, displays a maximum adsorption capacity of 0.08 mmol/g, being 1 g of this material sufficient to treat ca. 14,500 L of water containing 1 μg/L of acetylsalicylic acid (under ideal conditions). Furthermore, this material has a negligible toxicity towards the liver cell line Hep2G. The results obtained reinforce the potential of SILs as alternative adsorbents to effectively remove acetylsalicylic acid from aqueous solutions, and may be envisioned as a promising strategy for the treatment of wastewater and drinking water.

Efficient Isolation of Bacterial RNAs Using Silica-Based Materials Modified with Ionic Liquids

“…According to Table 1 , the carbon and nitrogen contents on the IL-functionalized silica supports range from 6.34 to 8.21 wt% and from 0.06 to 2.50 wt%, respectively. These values are in good agreement with those previously reported for some of the SILs addressed in this work [ 30 ]. Moreover, based on the nitrogen content provided by the elemental analysis, the ligand density was determined for each modified support [ 35 ], being given in Table 1 .…”

“…SEM images of starting silica and SILs are given in the Supplementary Material ( Figure S2 ). As reported by Bernardo and co-workers [ 30 ], no significant differences in the materials morphology were observed between the prepared SILs and the non-functionalized silica. Thus, these findings indicate that the silica functionalization with ILs and required reaction steps do not change the material morphology.…”

“…Previously, our research group prepared SILs comprising ILs with distinct chemical structures by the immobilization of the IL cationic moieties in silica for the efficient removal of acetylsalicylic acid from aqueous solutions [ 30 ]. In the current work, similar and new SILs were investigated as stationary phases for the separation of nucleic acids, while addressing the type of interactions (assessed using different chromatographic buffers) that are established, as well as their binding capacity towards RNA.…”

“…The preparation of the chromatographic supports was achieved by the chemical modification of silica with each IL and in accordance with procedures previously reported by our research team [ 28 , 29 , 30 ]. Briefly, 5 g of silica were initially immersed in hydrochloric acid (37%) for 24 h, and then washed with double distilled water and dried under vacuum at 105 °C to ensure its activation.…”

“…Herein, we report the chemical modification of silica-based stationary phases with different ILs, namely with 1-methyl-3-propylimidazolium chloride, triethylpropylammonium chloride, dimethylbutylpropylammonium chloride, and trioctylpropylammonium chloride. Although the synthesis process using amorphous silica was previously reported [ 28 , 29 , 30 ], their application as chromatographic matrices for the separation of nucleic acids is addressed here for the first time. The scope of SILs towards the separation of nucleic acids is extended here, both by the preparation of SILs with distinct chemical structures and by the study of distinct chromatographic conditions, allowing for inferring the role that the IL chemical structure plays in the nucleic acids interaction and purification.…”