Pervaporation recovery of aromatic compounds from lemon oil wastewater using a uniform zeolitic imidazolate framework/polydimethylsiloxane composite membrane

The application of pervaporation technology in the recovery of aromatic compounds from water faces the challenge of low performance. In this paper, a uniform zeolitic imidazolate framework/polydimethyl-siloxane (ZIF-8/PDMS) composite membrane was fabricated by means of contra-diffusion crystallization and a casting method in sequence. The diffusion time was optimized to be 24 h. ZIF-8/PDMS showed improving performance to pure PDMS. The permeation flux of linalool, neral, and geranial in ZIF-8/PDMS increased by 73.3%, 110.9%, and 106.0%, respectively; and the separation factors were also improved. The separation effect of neral (cis-citral) was much better than that of geranial (trans-citral), suggesting the potential enantioselectivity. In ternary model system, the separation of citral (neral and geranial) was competitively restrained by the presence of linalool. ZIF-8/PDMS also showed good performance in real lemon oil. After treatment for 9 h, the recovery rates of linalool, neral and geranial were 97.20%, 96.15%, and 92.56%, respectively.