VALORISATION VIA NANOFILTRATION OF THE ANTIOXIDANT RESIDUAL WATER FROM INDUSTRIAL HYDRODISTILLATION OF ROSA DAMASCENA MILL. PETALS

Abstract

The essential oil produced from R. damascena petals is one of the most valuable and important base materials in the flavour and fragrance industry. For each ton of processed rose flowers, less than 0.5 kg of essential oil and about 4 tons of residual water is generated. Due to the presence of polyphenolic compounds in the latter, its uncontrolled disposal has an adverse effect on the ecological balance. Moreover, valuable substances with biological activity are lost. The possibility to recover by nanofiltration a refined polyphenolic fraction, composed primarily of flavonoids, their glycosides and polyphenolic acids, contained in the waste residual water was demonstrated in the present work. The nanofiltrations were carried out with DL (Veolia) and NP030 (Mycrodin Nadir) commercial nanofiltration membranes. The DL membrane was proposed for process design due to its lower susceptibility to fouling by the target solutes. The experimentally determined membrane permeance for the DL membrane ranged from 1.8 to 0.5 LMH bar-1 during batch concentration at an operating pressure of 10 bar and degree of feed volume reduction in the range from 1 to 2. Since the target compounds are well known antioxidants, their concentrations in the studied materials were evaluated in terms of global antioxidant activity. The retentates were up to 2.00 times more potent antioxidants compared to the feed solutions. The experimentally determined membrane rejection coefficients for both membranes with respect to global antioxidant activity were in agreement with theoretically predicted values reported in a previous study, indicating efficient membrane fractionation.