Membrane fouling during the fractionation of phytosterols isolated from orange juice

The aim of this study is to isolate phytosterol compounds from orange juice using ultrafiltration (UF) flat sheet membranes (supplied by Alfa Laval) with molecular weight cut-off (MWCO) values of 10 kDa fabricated from regenerated cellulose, polyethersulphone and fluoropolymer. A cross-flow filtration rig operated at a transmembrane pressure (TMP) of 0.5–2 bar, and a cross-flow velocity (CFV) of 0.5–1.5 m s−1. Membrane rejection towards total phytosterols, proteins, sugars were determined along with antioxidant activity. The regenerated cellulose membrane displayed the highest permeate flux (a pseudo steady-state value of 22 L m−2 h−1), with a higher fouling index (75%) and a good separation efficiency of phytosterols (32% rejection towards phytosterols) from orange juice. Although the yield of phytosterols was relatively low (40 mg/L), there is a great potential to optimise the filtration process to produce commercially relevant amount of phytosterols. All membranes investigated displayed cleaning efficiencies of &gt;95%.</p

Orange juice ultrafiltration:Characterisation of deposit layers and membrane surfaces after fouling and cleaning

The influence of feed condition and membrane cleaning during the ultrafiltration (UF) of orange juice for phytosterol separation was investigated. UF was performed using regenerated cellulose acetate (RCA) membranes at different molecular weight cut-off (MWCO) values with a 336 cm2 membrane area and a range of temperatures (10-40 °C) and different feed volumes (3-9 L). Fluid dynamic gauging (FDG) was applied to assess the fouling and cleaning behaviours of RCA membranes fouled by orange juice and cleaned using P3-Ultrasil 11 over two complete cycles. During the FDG testing, fouling layers were removed by fluid shear stress caused by suction flow. The cleanability was characterised by using ImageJ software analysis. A Liebermann-Buchard-based method was used to quantify the phytosterol content. The results show that RCA 10 kDa filters exhibited the best separation of phytosterols from protein in orange juice at 20 °C using 3 L feed with a selectivity factor of 17. Membranes that were fouled after two cycles showed higher surface coverage compared to one fouling cycle. The surface coverage decreased with increasing fluid shear stress from 0 to 3.9 Pa. FDG achieved 80-95% removal at 3.9 Pa for all RCA membranes. Chemical cleaning using P3-Ultrasil 11 altered both the membrane surface hydrophobicity and roughness. These results show that the fouling layer on RCA membranes can be removed by fluid shear stress without affecting the membrane surface modification caused by chemical cleaning.</p

Membrane fouling during the fractionation of phytosterols isolated from orange juice

The aim of this study is to isolate phytosterol compounds from orange juice using ultrafiltration (UF) flat sheet membranes (supplied by Alfa Laval) with molecular weight cut-off (MWCO) values of 10 kDa fabricated from regenerated cellulose, polyethersulphone and fluoropolymer. A cross-flow filtration rig operated at a transmembrane pressure (TMP) of 0.5–2 bar, and a cross-flow velocity (CFV) of 0.5–1.5 m s−1. Membrane rejection towards total phytosterols, proteins, sugars were determined along with antioxidant activity. The regenerated cellulose membrane displayed the highest permeate flux (a pseudo steady-state value of 22 L m−2 h−1), with a higher fouling index (75%) and a good separation efficiency of phytosterols (32% rejection towards phytosterols) from orange juice. Although the yield of phytosterols was relatively low (40 mg/L), there is a great potential to optimise the filtration process to produce commercially relevant amount of phytosterols. All membranes investigated displayed cleaning efficiencies of &gt;95%.</p

The influence of membrane charge and porosity upon fouling and cleaning during the ultrafiltration of orange juice

The ultrafiltration of orange juice has been performed to separate phytosterols from proteins. Commercial regenerated cellulose acetate (RCA) ultrafiltration membranes of different molecular weight cut offs (MWCOs) of 10 kDa, 30 kDa and 100 kDa were fouled with orange juice and cleaned with Ultrasil 11 over two operational cycles. Fouling and cleaning mechanisms were investigated by using surface zeta potential, Brunauer-Emmet-Teller (BET) analysis and Fourier transform infrared (FTIR) analysis. The RCA conditioned membranes displayed zeta potential values of −0.2 to −31.5 mV. Fouling caused RCA membranes to have a greater magnitude of negative surface charge and cleaning restored the membrane surface charges close to its pristine state. Fouling increased both the total surface area and the total pore volume of all membranes. The total surface area and total pore volume for RCA 100 kDa after fouling increased by 102% and 185%, respectively. Pore area and volume distributions revealed that the porosities were returned close to the original level after cleaning. The recovery flux ratios of RCA 10, RCA 30 and RCA 100 decreased after fouling by 27%, 6% and 10% respectively; and changes were 25%, 9% and 1% respectively after cleaning. The charge of membrane surfaces after two operational cycles and the IR intensity of RCA membrane deposits, varied with MWCO such that RCA 30 &gt; RCA 100 &gt; RCA 10. Ultrafiltration using RCA 10 kDa membrane displayed the best separation efficiency, with 32 ± 4% rejection of phytosterols. and 96 ± 1% rejection of proteins. Changes in membrane surface charge and porosity have been found to affect the RCA membrane performance due to fouling and cleaning during the isolation of phytosterols from orange juice.</p

Improved efficiency of tocotrienol extraction from fresh and processed latex

Vitamin E, mainly in the form of tocotrienols, was extracted from Hevea brasiliensis latex with organic solvents. The content of tocotrienols and a small amount of tocopherols recovered from the latex was determined using high performance liquid chromatoghraphy (HPLC). Gas chromatoghraphy-mass spectrometry (GC-MS) confirmed the identities of the tocotrienols and tocopherols forms that were present. Gamma-tocotrienol was the most abundant form of vitamin E in Hevea latex. The yield of tocotrienols (339 ug/g of latex) was significantly increased by the use of the detergant Triton X-100 in the extraction procedure. This method improves the extraction efficiency by 83%. Through drying of the organic fraction using anhydrous magnesium sulphate following phase separation was also advantageous in the extraction procedure. On the other hand, the presence of ammonia in latex suspension reduced extraction efficiency. Vitamin E was also found in the waste serum generated from the processing of deproteinised natural rubber (DPNR). Although the yield vitamin from this source was relatively low, there is a potential to modify the processing procedure another value added end product i.e. latex vitamin E in addition to DPNR

Preparation and benchmarking of highly hydrophilic polyaniline poly(2-acrylamido-2-methyl-1-propanesulfonic acid) PANI PAMPSA membranes in the separation of sterols and proteins from fruit juice

A straightforward approach is presented to prepare highly hydrophilic ultrafiltration polyaniline poly(2-acrylamido-2-methyl-1-propanesulfonic acid (PANI PAMPSA) membranes. Their application in the fractionation of phytosterols and proteins from fruit juice is described. Poly(2-acrylamido-2-methyl-1-propanesulfonic (PAMPSA) is added to aniline during the polymer synthesis and the membrane is prepared via phase inversion forming a highly hydrophilic and mechanically stable ultrafiltration membrane of 200 µm thickness and pure water flux of 126 LMH at 1 bar. The membrane so produced is benchmarked against a hydrophilic commercial regenerated cellulose acetate membrane (RCA) for the separation of phytosterols and proteins from orange juice. Cross-flow filtration experiments show comparable protein separation efficiency of the membranes, but better rejection of phytosterols for the commercial RCA membrane. Both commercial and lab prepared membranes are subject to fouling, with the PANI PAMPSA membrane showing higher irreversible fouling. Nevertheless, the PANI PAMPSA membrane showed a good cleaning efficiency of 74% after three fouling-cleaning cycles. Overall, this work has demonstrated the possibility of use PANI PAMPSA for ultrafiltration application and provided a better understanding of its fouling ability when compared to a commercial membrane in a multicomponent system.</p

Fouling Analysis and the Recovery of Phytosterols from Orange Juice Using Regenerated Cellulose Ultrafiltration Membranes

This study describes the use of regenerated cellulose (RCA) membranes with molecular weight cut-off (MWCO) values of 10, 30, and 100 kDa, respectively, to separate phytosterols from orange juice for possible nutraceutical production. A desirable membrane separation rejects protein whilst transmitting phytosterols and other low molecular mass compounds such as sugars. The ultrafiltration was performed in a cross-flow membrane system with a total filtration area of 336 cm2. Total phytosterol analysis was carried out by using a Liebermann-Buchard-based method. Protein concentration was quantified by the Bradford method. The effects of three different membranes upon the rejection of total phytosterol content, proteins, sugar, and antioxidant activity were studied. Of the membranes tested, the 10-kDa membrane displayed the highest concentration of phytosterols in the permeate. The 30-kDa and 100-kDa membranes gave comparatively higher phytosterol rejection. The membrane surface roughness and corresponding pure water flux values varied as a function of MWCO such that RCA30 &gt; RCA100 &gt; RCA10. Membranes with rougher surfaces displayed higher fouling than those with smoother surfaces. Hydrophobicity and surface roughness both influenced filtration performance, by controlling the development of the protein-based foulant which modified membrane selectivity

Preparation and benchmarking of highly hydrophilic polyaniline poly(2-acrylamido-2-methyl-1-propanesulfonic acid) PANI PAMPSA membranes in the separation of sterols and proteins from fruit juice

A straightforward approach is presented to prepare highly hydrophilic ultrafiltration polyaniline poly(2-acrylamido-2-methyl-1-propanesulfonic acid (PANI PAMPSA) membranes. Their application in the fractionation of phytosterols and proteins from fruit juice is described. Poly(2-acrylamido-2-methyl-1-propanesulfonic (PAMPSA) is added to aniline during the polymer synthesis and the membrane is prepared via phase inversion forming a highly hydrophilic and mechanically stable ultrafiltration membrane of 200 µm thickness and pure water flux of 126 LMH at 1 bar. The membrane so produced is benchmarked against a hydrophilic commercial regenerated cellulose acetate membrane (RCA) for the separation of phytosterols and proteins from orange juice. Cross-flow filtration experiments show comparable protein separation efficiency of the membranes, but better rejection of phytosterols for the commercial RCA membrane. Both commercial and lab prepared membranes are subject to fouling, with the PANI PAMPSA membrane showing higher irreversible fouling. Nevertheless, the PANI PAMPSA membrane showed a good cleaning efficiency of 74% after three fouling-cleaning cycles. Overall, this work has demonstrated the possibility of use PANI PAMPSA for ultrafiltration application and provided a better understanding of its fouling ability when compared to a commercial membrane in a multicomponent system.</p