Multistage recovery process of seaweed pigments: Investigation of ultrasound assisted extraction and ultra-filtration performances

The objectives of this study were first to evaluate the performance of seaweed pigments' recovery through ultrasound assisted extraction (UAE) and ultra-filtration (UF), and second to investigate the membrane fouling mechanism and evidence the threshold flux during filtration. The pigments' recovery from the extract was performed using 5 kDa and 10 kDa ultra-filtration membranes. Results showed that increasing the extraction temperature in the range of 40-60 degrees C was proportional to chlorophyll extraction efficiency, while the maximal carotenoid yield was achieved at 50 degrees C. Ultrasonic power (from 100W to 300W) facilitated the extraction of both chlorophylls and carotenoids. Results from ultra-filtration showed that most pigments (>90%) were available in permeate through 101rDa membrane, while 5 kDa membrane partially retained the pigments. Filtration resistance was quantified with resistance-in-series' model, showing that the cake layer was the most important fouling resistance during filtration. Threshold flux at different rotation speeds (200 and 600 rpm) was determined by trans-membrane pressure stepping tests, which were around 10 and 14.5 L/m(2) h, respectively. Results from this study demonstrated the efficiency of the multistage process involving UAE and UF to enhance the recovery of pigments from brown seaweeds. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.