Forward osmosis: Principles, applications, and recent developments

Cath, Tzahi Y.; Childress, Amy E.; Elimelech, Menachem

doi:10.1016/j.memsci.2006.05.048

Cited by 2,263 publications

(1,621 citation statements)

References 49 publications

Supporting

Mentioning

1,594

Contrasting

Unclassified

Order By: Relevance

“…GO laminates soaked in liquid water showed d ≈ 13.7 ± 0.3 Å. All these values agree with previous reports, where the changes in d were attributed to successive incorporation of water molecules into various sites between GO sheets 31 . Individual GO strips with desirable d were then encapsulated and stacked together using Stycast epoxy as shown in Figs.…”

supporting

confidence: 91%

“…To further understand the liquid water flux and salt rejection properties of GO-Gr membranes, we have performed forward osmosis (FO) 31,32 experiments. FO is relatively a new alternative technology to the conventional pressure-driven reverse osmosis (RO) membrane process, where hydraulic pressure is not required for its operation 31,32 .…”

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

“…FO is relatively a new alternative technology to the conventional pressure-driven reverse osmosis (RO) membrane process, where hydraulic pressure is not required for its operation 31,32 . In FO, a concentrated solution of a salt or other molecules (draw solution) is used to generate high osmotic pressure, which pulls the water molecules across a semi-permeable membrane from the low-concentration salt solution (feed solution), effectively filtering the feed water.…”

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

See 2 more Smart Citations

Tunable sieving of ions using graphene oxide membranes

et al. 2017

View full text Add to dashboard Cite

Graphene oxide membranes show exceptional molecular permeation properties, with a promise for many applications. However, their use in ion sieving and desalination technologies is limited by a permeation cutoff of 9 Å, which is larger than hydrated ion diameters for common salts. The cutoff is determined by the interlayer spacing d 13.5 Å, typical for graphene oxide laminates that swell in water. Achieving smaller d for the laminates immersed in water has proved to be a challenge. Here we describe how to control d by physical confinement and achieve accurate and tuneable ion sieving. Membranes with d from  9.8 Å to 6.4 Å are demonstrated, providing the sieve size smaller than typical ions' hydrated diameters. In this regime, ion permeation is found to be thermally activated with energy barriers of 10-100 kJ/mol depending on d. Importantly, permeation rates decrease exponentially with decreasing the sieve size but water transport is weakly affected (by a factor of <2). The latter is attributed to a low barrier for water molecules entry and large slip lengths inside graphene capillaries. Building on these findings, we demonstrate a simple scalable method to obtain graphene-based membranes with limited swelling, which exhibit 97% rejection for NaCl.Selectively permeable membranes with sub-nm pores attract strong interest due to analogies with biological membranes and potential applications in water filtration, molecular separation and desalination [1][2][3][4][5][6][7][8] . Nanopores with sizes comparable to, or smaller than, the diameter D of hydrated ions are predicted to show enhanced ion selectivity 7,9-12 because of dehydration required to pass through such atomic-scale sieves. Despite extensive research on ion dehydration effects 3,7,9-13 , experimental investigation of the ion sieving controlled by dehydration has been limited because of difficulties in fabricating uniform membranes with well-defined sub-nm pores. The realisation of membranes with dehydration-assisted selectivity would be a significant step forward. So far, research into novel membranes has mostly focused on improving the water flux rather than ion selectivity. On the other hand, modelling of practically relevant filtration processes shows that an increase in water permeation rates above the rates currently achieved (2-3 L/m 2 ×h×bar) would not contribute greatly to the overall efficiency of desalination 8,14,15 . Alternative approaches based on higher water-ion selectivity may open new possibilities for improving filtration technologies, as the performance of state-of-the-art membranes is currently limited by the solution-diffusion mechanism, in which water molecules dissolve in the membrane material and then diffuses across the membrane 8 . Recently, carbon nanomaterials including carbon nanotubes (CNT)

show abstract

supporting

confidence: 91%

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

Section: Swelling-controlled Graphene Oxide-graphene (Go-gr)membranesmentioning

confidence: 99%

See 1 more Smart Citation

Tunable sieving of ions using graphene oxide membranes

et al. 2017

View full text Add to dashboard Cite

show abstract

“…NaCl) (Cath et al, 2006). FO can directly pre-66 concentrate wastewater without significant external energy input (Alturki et …”

Section: Introduction 32mentioning

confidence: 99%

Factors governing the pre-concentration of wastewater using forward osmosis for subsequent resource recovery

Ansari

Hai

Guo

et al. 2016

Science of The Total Environment

View full text Add to dashboard Cite

This study demonstrated a technique using forward osmosis (FO) to pre-concentrate the organic matter in raw wastewater, thereby transforming low strength wastewater into an anaerobically digestible solution. The chemical oxygen demand (COD) of raw wastewater was concentrated up to approximately eightfold at a water recovery of 90%. Thus, even low strength wastewater could be pre-concentrated by FO to the range suitable for biogas production via anaerobic treatment. Excessive salinity accumulation in pre-concentrated wastewater was successfully mitigated by adopting ionic organic draw solutes, namely, sodium acetate, and EDTA-2Na. These two draw solutes are also expected to benefit the digestibility of the pre-concentrated wastewater compared to the commonly used draw solute sodium chloride. Significant membrane fouling was observed when operating at 90% water recovery using raw wastewater. Nevertheless, membrane fouling was reversible and was effectively controlled by optimising the hydrodynamic conditions of the cross-flow FO system. Thus, even low strength wastewater could be pre-concentrated using FO to the range suitable 21 for biogas production via anaerobic treatment. Excessive salinity accumulation in pre-22 concentrated wastewater was successfully mitigated by adopting ionic organic draw solutes, 23 namely, sodium acetate and EDTA-2Na. These two draw solutes are also expected to benefit 24 the digestibility of the pre-concentrated wastewater compared to sodium chloride. Significant 25 membrane fouling was observed when operating at 90% water recovery using raw 26 wastewater. Nevertheless, membrane fouling was reversible and was effectively controlled by 27 optimising the hydrodynamic conditions of the cross-flow FO system. 28Keywords: forward osmosis (FO); wastewater; pre-concentration; ionic organic draw 29 solution; anaerobic digestion; membrane fouling. 30 31 3

show abstract

“…In a FO process, water transports across a selectively permeable membrane spontaneously from a region of higher water chemical potential (feed solution) to a region of lower water chemical potential (draw solution) (Qin et al, 2012). This results in the concentration of the feed solution and dilution of the draw solution (Cath et al, 2006). It is traditionally believed that the FO process has the advantages of no or low pressure operation, higher water flux and recovery rate, less fouling propensity and easy cleaning (Chung et al, 2012;Duong and Chung, 2014).…”

Section: Introductionmentioning

confidence: 99%