Separation of bio‐based chemicals using pervaporation

Abstract

The increasing demand of raw materials and the ever‐present risk of fossil resource depletion are effective motivators for the development of new bio‐based routes for the synthesis of chemicals. The use of non‐renewable natural resources, such as fossil fuels, and the generation of greenhouse gases have led to severe environmental problems. However, one of the challenges of using renewable biomass resources to produce building block molecules is achieving an efficient and economically viable purification step. The complexity of the mixture involves generally high separation costs. Separation processes, such as distillation and liquid–liquid extraction, have been proposed to purify target bio‐based compounds. However, the high energetic cost associated with such processes is pushing the current research towards the development of alternative solutions. In this context, membrane technology, such as pervaporation, is an interesting solution for minimizing the energy consumption of the process. This review highlights the main parameters and factors that impact the performance of pervaporation in the separation of complex bio‐based chemical mixtures. Coupling effects, which are among the critical issues in pervaporation, are discussed in detail. Hybrid processes, in which both reaction and distillation are performed during the pervaporation process, are also addressed. © 2020 Society of Chemical Industry

Pervaporation performance of poly(vinyl alcohol)‐graft‐poly(N‐hydroxymethyl acrylamide) membranes for dehydration of isopropyl alcohol‐water mixture

“…As illustrated in Figure 8, the total flux and partial fluxes decreased almost linearly with the increase in membrane thickness, which is due to the increased mass transfer resistance and the decreased diffusion rate, confirming the Fick's Law 45,46 . In the pervaporation, the flux of a membrane is inversely proportional to its thickness according to the Fick's Law and solution‐diffusion model 45 . Figure 9a displays the linear correlation between the flux and the reciprocal of the membrane thickness, indicating fitting of PVA‐g‐PNHMA 6 membrane with Fick's Law.…”

“…In order to explore the influence of membrane thickness on the flux and separation factor, PVA‐g‐PNHMA 6 membranes with different thicknesses in a range of 48 and 80 μm were used for the separation of 60% IPA feed concentration and the results obtained are depicted in Figure 8. As illustrated in Figure 8, the total flux and partial fluxes decreased almost linearly with the increase in membrane thickness, which is due to the increased mass transfer resistance and the decreased diffusion rate, confirming the Fick's Law 45,46 . In the pervaporation, the flux of a membrane is inversely proportional to its thickness according to the Fick's Law and solution‐diffusion model 45 .…”

“…Membrane thickness is a critical parameter in optimizing the performance of membrane separation of binary mixture via the pervaporation process 45 . In order to explore the influence of membrane thickness on the flux and separation factor, PVA‐g‐PNHMA 6 membranes with different thicknesses in a range of 48 and 80 μm were used for the separation of 60% IPA feed concentration and the results obtained are depicted in Figure 8.…”

Pervaporation via silicon‐based membranes: Correlation and prediction of performance in pervaporation and gas permeation

“…By contrast to the performance of RO (flux and selectivity), which in principle is restrained via osmotic pressure, with PV, such a negative effect is not a consideration to achieve a high level of separation performance. Due to these advantages, many types of polymeric membranes such as poly(vinyl alcohol) (PVA), polyimide (PI), and amorphous perfluoropolymer (APFP) have been developed for PV 1‐4 . Furthermore, to avoid the swelling and low stability of conventional polymeric membranes, in the past several decades we have witnessed the development of inorganic sub‐nanoporous membranes using materials such as zeolite and amorphous silica 4‐6 …”

Separation and Semi-Empiric Modeling of Ethanol–Water Solutions by Pervaporation Using PDMS Membrane

“…When both the membrane and feed are in contact, some molecules can be recovered from the feed due to its higher affinity and quicker diffusivity in the membrane [ 4 ], which can be carried out applying a differential pressure between the membrane walls through a vacuum pump or a carrier gas [ 5 ]. The main advantage of pervaporation is the low energy consumption compared with traditional processes such as distillation and liquid-liquid extraction [ 6 , 7 , 8 ], but also the possibility to work at moderate temperature can be an advantage for the separation of temperature sensitive products, be an environmentally friendly process [ 9 ], reduces the cost of production, generates products free from solvent contamination and can be adapted to both continuous and batch processes [ 10 ]. Initially, pervaporation was intended for the selective separation of azeotropic mixtures.…”