Investigation of nicotinic acid recovery from aqueous solutions by green liquid membranes

Nicotinic acid (niacin) is a valuable carboxylic acid that is widely used in various industries such as pharmaceuticals, food, cosmetics, and biotechnology. Due to its broad range of applications, significant amounts of nicotinic acid can enter wastewater streams during its production and processing. When these industrial effluents are discharged directly into the environment, they can reduce water quality, pose a threat to aquatic life, and cause excessive organic loading in wastewater treatment systems. Therefore, effective separation and purification technologies are needed to both reduce environmental impacts and recover this valuable compound economically. Liquid membrane technology offers an innovative and sustainable approach for the selective and efficient separation of nicotinic acid from aqueous media. Liquid membranes consist of a thin liquid layer positioned between two phases (feed and stripping), which enables the transport of the target compound. This system offers several advantages, including high selectivity, low energy consumption, reusability of the carrier, and operational simplicity. In this study, the use of bulk ionic liquid membrane (BILM) was investigated for the separation of nicotinic acid from aqueous medium. 1-Butyl-3-Methyl Imidazolium Hexafluorophosphate [BMIM][PF6], 1-Butyl-3-Methyl Imidazolium Bis(trifluoromethylsulfonyl)imide [BMIM][Tf2N], 1-Hexyl-3-Methyl Imidazolium Hexafluorophosphate [HMIM][PF6] and 1-Hexyl-3-Methyl Imidazolium Bis(trifluoromethylsulfonyl)imide [HMIM][Tf2N] ionic liquids were used as green solvents. Tributylphosphate (TBP) was used as the carrier in the membrane phase. Using the Box-Behnken experimental design, the effects of initial acid concentration (0.02-0.1 mol/L NA), carrier concentration in the membrane phase (0-2 mol/L TBP) and stripper phase type and concentration (water and 0.1-0.2 N NaOH) on the separation efficiency were revealed, and optimum conditions were determined. The optimum condition was determined as 0.02 mol/L initial NA acid concentration in the feed phase, 2 mol/L TBP in the membrane phase, and 0.2 mol/L NaOH as the stripper phase. The results obtained showed that ionic liquids can be used as alternative membrane solvents in the separation of nicotinic acid from aqueous solutions.