Tunable aryl alkyl pyrazolium tetrafluoroborate ionic liquids/salts: synthesis, characterization, and applications for removal of methyl orange from aqueous solution

Abstract

In this work, new tunable aryl alkyl pyrazolium tetrafluoroborate ionic liquids/salts, 2-ethyl-1-(p-X-phenyl)-3,5-dimethylpyrazolium tetrafluoroborate [X: -Br (4a), -OCH3 (4b), -NO2 (4c)] and 2-butyl-1-(p-X-phenyl)-3,5-dimethylpyrazolium tetrafluoroborate [X: -Br (5a), -OCH3 (5b), -NO2 (5c)], were synthesized by following halide-free synthetic route. Their chemical structures were identified through NMR ( 1 H, 13 C, 19 F), IR, elemental analysis, and HRMS data. The synthesized 4a-4c and 5a-5c salts over 90 %. Accordingly, a time-efficient, simple, and highly effective method has been presented to remove methyl orange dye from aqueous solutions.