Solution‐Diffusion Processes

Verliefde, Arne; Meeren, Paul Van der; Bruggen, Bart Van der

doi:10.1002/9781118522318.emst017

Cited by 14 publications

(12 citation statements)

References 73 publications

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“…Although the effect of changing permeate flux on salt rejection is clearly observable (49% decline in rejection when the flux was reduced by 22%), the effect is almost insignificant on the rejection of caffeine as a decline of only 5% was measured (at similar flux decline value). Rejection of solutes is expected to increase with increasing flux (or pressure) as the increasing flux has a dilution effect (Verliefde et al, 2013). Figure 2 shows the membrane surface charges (with varying pH) before and after fouling with alginate and latex without the addition of Ca 2+ .…”

Section: Resultsmentioning

confidence: 98%

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Rejection of pharmaceuticals by nanofiltration (NF) membranes: Effect of fouling on rejection behaviour

Mahlangu

Msagati

Hoek

et al. 2014

Physics and Chemistry of the Earth, Parts A/B/C

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Section: Resultsmentioning

confidence: 98%

“…Based on the solution diffusion model, rejection of solutes is a function of flux (Verliefde et al, 2013). However, other factors also play a role in solute rejection in addition to flux.…”

Section: Relation Between Flux Decline and Solute Rejectionmentioning

confidence: 99%

Rejection of pharmaceuticals by nanofiltration (NF) membranes: Effect of fouling on rejection behaviour

Mahlangu

Msagati

Hoek

et al. 2014

Physics and Chemistry of the Earth, Parts A/B/C

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“…However, it is not clear whether the role of CECP is substantial for NF membranes that poorly reject salts. According to the solution–diffusion model, flux through a membrane increases linearly with applied pressure and solute permeability does not change in dense membranes [ 34 ]. However, solute permeability is independent of the applied pressure and solute concentration.…”

Section: Resultsmentioning

confidence: 99%

Interdependence of Contributing Factors Governing Dead-End Fouling of Nanofiltration Membranes

Mahlangu

Mamba

2021

Membranes

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Cake-enhanced concentration polarization (CECP) has been ascribed as the main cause of flux decline in dead-end filtration. An unfamiliar approach was used to investigate the role of CECP effects in the fouling of a nanofiltration membrane (NF-270) that poorly reject salts. Membrane–foulant affinity interaction energies were calculated from measured contact angles of foulants and membrane coupons based on the van der Waals/acid–base approach, and linked to resistance due to adsorption (Ra). In addition, other fouling mechanisms and resistance parameters were investigated using model organic and colloidal foulants. After selection, the foulants and membranes were characterized for various properties, and fouling experiments were conducted under controlled conditions. The fouled membranes were further characterized to gain more understanding of the fouling layer properties and flux decline mechanisms. Sodium alginate and latex greatly reduced membrane permeate flux as the flux declined by 86% and 59%, respectively, while there was minor flux decline when aluminum oxide was used as model foulant (<15% flux decline). More flux decline was noted when fouling was conducted with a combination of organic and colloidal foulants. Contrary to other studies, the addition of calcium did not seem to influence individual and combined fouling trends. Foulants adsorbed more on the membrane surface as the membrane–foulant affinity interactions became more attractive and pore blocking by the foulants was not important for these experiments. Hydraulic resistance due to cake formation (Rc) had a higher contributing effect on flux decline, while CECP effects were not substantial.

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“…It was demonstrated that hydrophobic compounds may be adsorbed on the hydrophobic membrane surface. However, high rejections due to adsorption are typically only a temporarily effect, until membrane saturation occurs [ 233 ]; then adsorbed molecules may be transported to a higher extent due to their higher partition coefficient [ 234 ]. Reversely, D’haese demonstrated that small hydrophilic organics (such as alcohols) may show negative rejection (up to 4–5 times concentration in the permeate), their transfer being promoted by salting out [ 220 ].…”

Section: Tuning Fo Process To Tackle Current Limitations For Optimmentioning

confidence: 99%

Forward Osmosis as Concentration Process: Review of Opportunities and Challenges

et al. 2020

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In the past few years, osmotic membrane systems, such as forward osmosis (FO), have gained popularity as “soft” concentration processes. FO has unique properties by combining high rejection rate and low fouling propensity and can be operated without significant pressure or temperature gradient, and therefore can be considered as a potential candidate for a broad range of concentration applications where current technologies still suffer from critical limitations. This review extensively compiles and critically assesses recent considerations of FO as a concentration process for applications, including food and beverages, organics value added compounds, water reuse and nutrients recovery, treatment of waste streams and brine management. Specific requirements for the concentration process regarding the evaluation of concentration factor, modules and design and process operation, draw selection and fouling aspects are also described. Encouraging potential is demonstrated to concentrate streams more than 20-fold with high rejection rate of most compounds and preservation of added value products. For applications dealing with highly concentrated or complex streams, FO still features lower propensity to fouling compared to other membranes technologies along with good versatility and robustness. However, further assessments on lab and pilot scales are expected to better define the achievable concentration factor, rejection and effective concentration of valuable compounds and to clearly demonstrate process limitations (such as fouling or clogging) when reaching high concentration rate. Another important consideration is the draw solution selection and its recovery that should be in line with application needs (i.e., food compatible draw for food and beverage applications, high osmotic pressure for brine management, etc.) and be economically competitive.

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Solution‐Diffusion Processes

Cited by 14 publications

References 73 publications

Rejection of pharmaceuticals by nanofiltration (NF) membranes: Effect of fouling on rejection behaviour

Rejection of pharmaceuticals by nanofiltration (NF) membranes: Effect of fouling on rejection behaviour

Interdependence of Contributing Factors Governing Dead-End Fouling of Nanofiltration Membranes

Forward Osmosis as Concentration Process: Review of Opportunities and Challenges

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