State-of-the-art dense composite membranes: An innovative step towards separation of organic liquid–liquid mixtures

• Separation of styrene : aniline was conducted using Eg-C 3 N 4 -PVDF membranes. • Foremost ever molecular sieving property on basis of organic liquids’ polarity. • Eg-C 3 N 4 -PVDF membranes exhibited a selective separation of aniline over styrene . • Rejection rate exceeding 85 % for styrene and a separation factor of 12.66. • Separation of aniline: nitrobenzene was conducted using Eg-C 3 N 4 -PVDF membranes. Current study investigated the novel separation of styrene- aniline and aniline- nitrobenzene mixture using dense composite membrane. These mixtures in particular was selected for membrane-based separation as they are coupled redox reaction products and partake individual industrial implications. The composite membranes were fabricated with 0.5, 1 and 1.5 wt% of Eg-C 3 N 4 . The membrane with 1 wt% of Eg-C 3 N 4 (GM 2 ) demonstrated styrene rejection of 87.03 ± 1.89 %, with a proficient aniline permeance of 2.98 ± 0.01 LMH/bar, separation factor of 12.66 for aniline over styrene mixture. For aniline- nitrobenzene membrane GM 2 , aniline rejection of 69.13 ± 0.61 % with a permeance of 3.38 ± 0.02 LMH/bar was achieved. Along with which the membrane shows high selectivity towards other polar organic solvents such as methyl benzoate with high styrene rejection of 73.53 ± 0.15 % and a permeance of 1.74 ± 0.10 LMH/bar during separation of methyl benzoate: styrene. Furthermore, for a mixture of anisole: styrene, styrene rejection of 70.53 ± 1.74 % and permeance of 1.78 ± 0.02 LMH/bar was procured. These outcomes demonstrate the polarity-based separation of Eg-C 3 N 4 -PVDF dense membrane irrespective of the feed concentration, highlighting the study’s novelty. The obtained results were further supported and corelated by Hansen Solubility Parameter studies with remarkable solvent resistance over a period of several days under ambient conditions.