Leveraging conventional and natural solvents: physical extraction of 4-hydroxybenzoic acid

The demand of 4-hydroxybenzoic acid (4-HBA) has increased due to their promising properties in the various industries such as pharmaceutical, cosmetic, and plastic sectors. Mostly 0.005 to 0.035 mol/liter of 4-HBA was observed in the waste stream or fermentation broth. Hence, this work presents a schematic study of 4-HBA separation from the aqueous phase by physical extraction method using conventional and natural solvents (CANS). The harmless and eco-friendly green solvents such as alsi (flaxseed) oil, castor oil, and conventional solvents such as diethyl carbonate, diethyl succinate, and xylene are employed in the extraction experiments. Several parameters, such as the K_DHBA, %E_HBA, P_HBA, and the D_HBA, were examined. The parameters were examined to evaluate the equilibrium for this physical extraction experiment. The obtained results showed the following trend of K_DHBA and %E_HBA, respectively, diethyl carbonate (0.951, 48.75%) > alsi oil (0.565, 36.12%) > diethyl succinate (0.504, 33.51%) > castor oil (0.457, 31.35%). > xylene (0.283, 22.06%).