Synergetic effects of oxidized carbon nanotubes and graphene oxide on fouling control and anti-fouling mechanism of polyvinylidene fluoride ultrafiltration membranes

Organic Fouling of Graphene Oxide Membranes and Its Implications for Membrane Fouling Control in Engineered Osmosis

This study provides experimental evidence to mechanistically understand some contradicting effects of the characteristic properties of graphene oxide (GO), such as the high hydrophilicity, negative charge, strong adsorption capability, and large surface area, on the antifouling properties of GO membranes. Furthermore, this study demonstrates the effectiveness of forming a dense GO barrier layer on the back (i.e., porous) side of an asymmetric membrane for fouling control in pressure-retarded osmosis (PRO), an emerging engineered osmosis process whose advancement has been much hindered due to the severe irreversible fouling that occurs as foulants accumulate inside the porous membrane support. In the membrane fouling experiments, protein and alginate were used as model organic foulants. When operated in forward osmosis mode, the GO membrane exhibited fouling performance comparable with that of a polyamide (PA) membrane. Analysis of the membrane adsorption capacity showed that, likely due to the presence of hydrophobic regions in the GO basal plane, the GO membrane has an affinity toward organic foulants 4 to 5 times higher than the PA membrane. Such a high adsorption capacity along with a large surface area, however, did not noticeably aggravate the fouling problem. Our explanation for this phenomenon is that organic foulants are adsorbed mainly on the basal plane of GO nanosheets, and water enters the GO membrane primarily around the oxidized edges of GO, making foulant adsorption not create much hindrance to water flux. When operated in PRO mode, the GO membrane exhibited much better antifouling performance than the PA membrane. This is because unlike the PA membrane for which foulants can be easily trapped inside the porous support and hence cause severe irreversible fouling, the GO membrane allows the foulants to accumulate primarily on its surface due to the sealing effect of the GO layer assembled on the porous side of the asymmetric membrane support. Results from the physical cleaning experiments further showed that the water flux of GO membranes operated in PRO mode can be sufficiently restored toward its initial prefouling level.

Functionalized MWCNTs in improving the performance and biocompatibility of potential hemodialysis membranes

Functionalized multi-walled carbon nanotube incorporated polyetherimide mixed matrix membranes for blood purification application.

Performance and antifouling enhancement of polyethersulfone hollow fiber membranes incorporated with highly hydrophilic hydroxyapatite nanoparticles

Membrane fouling is one of the main drawbacks in water purification applications. The present work indicated that the fabricated HAp/PES hollow fiber membranes presented better hydrophilicity, permeation and anti-fouling performance compared to PES membranes.

Improved antifouling and antimicrobial efficiency of ultrafiltration membranes with functional carbon nanotubes

In this study, functional polymer brush grafted carbon nanotubes (p-CNTs) were developed as multifunctional modifiers for PES membrane modification.

Enhanced hydrophilicity of a thermo-responsive PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane via surface segregation induced by temperature

The hydrophilicity of a thermo-responsive PVDF/palygorskite-g-PNIPAAM hybrid ultrafiltration membrane was enhanced via surface segregation induced by coagulation bath temperature (CBT).

Protein mediated textile dye filtration using graphene oxide–polysulfone composite membranes

Protein mediated textile dye filtration using graphene oxide (2%)–polysulfone composite membranes is studied for which the maximum rejection was recorded at pH = 2.

Greatly enhanced porosity of stretched polypropylene/graphene oxide composite membrane achieved by adding pore-forming agent

With the combined effects of a pore-forming agent and graphene oxide, greatly enhanced porosity is achieved for a stretched PP composite membrane.

Preparation and characterization of PEG-g-MWCNTs/PSf nano-hybrid membranes with hydrophilicity and antifouling properties

MWCNTs were successfully functionalized with PEG. PEG-g-MWCNTs/PSf membranes showed higher hydrophilicity and good antifouling capability. The nano-hybrid membranes exhibited excellent mechanical properties.

Few- and multi-layer graphene on carbon fibers: synthesis and application

In the current study, we investigated the influences of chemical vapor deposition parameters on the formation of uniform structures of few- and multi-layer graphene (FLG and MLG) as a coating phase on carbon fiber (CF).

Investigation of antifouling universality of polyvinyl formal (PVF) membranes utilizing atomic force microscope (AFM) force curves

Adhesion force between proteins and PVF/F127 membranes with different ratios are measured by AFM force curves with well calibrated cantilevers.

The effects of hydroxyapatite nano whiskers and its synergism with polyvinylpyrrolidone on poly(vinylidene fluoride) hollow fiber ultrafiltration membranes

By introducing hydroxyapatite (HAP) nano whiskers as well as polyvinylpyrrolidone (PVP), poly(vinylidene fluoride) (PVDF)/PVP/HAP hollow fiber membranes were fabricated with the wet spinning method.

From hydrophobic to hydrophilic polyvinylidenefluoride (PVDF) membranes by gaining new insight into material's properties

From hydrophobic to hydrophilic PVDF membranes by a combination of functionalization by blending chemical additives and selection of manufacturing procedure.

Facile and low-cost approach towards a PVDF ultrafiltration membrane with enhanced hydrophilicity and antifouling performance via graphene oxide/water-bath coagulation

Introduction of GO into a coagulation bath indicates a candidate for a GO-mixed method in tailoring the performance of PVDF ultrafiltration membranes.