Nanohybrid Membrane Synthesis with Phosphorene Nanoparticles: A Study of the Addition, Stability and Toxicity

Phosphorene is a promising candidate as a membrane material additive because of its inherent photocatalytic properties and electrical conductance which can help reduce fouling and improve membrane properties. The main objective of this study was to characterize structural and morphologic changes arising from the addition of phosphorene to polymeric membranes. Here, phosphorene was physically incorporated into a blend of polysulfone (PSf) and sulfonated poly ether ether ketone (SPEEK) doping solution. Protein and dye rejection studies were carried out to determine the permeability and selectivity of the membranes. Since loss of material additives during filtration processes is a challenge, the stability of phosphorene nanoparticles in different environments was also examined. Furthermore, given that phosphorene is a new material, toxicity studies with a model nematode, Caenorhabditis elegans, were carried out to provide insight into the biocompatibility and safety of phosphorene. Results showed that membranes modified with phosphorene displayed a higher protein rejection, but lower flux values. Phosphorene also led to a 70% reduction in dye fouling after filtration. Additionally, data showed that phosphorene loss was negligible within the membrane matrix irrespective of the pH environment. Phosphorene caused toxicity to nematodes in a free form, while no toxicity was observed for membrane permeates.

Highly fouling-resistant brominated poly(phenylene oxide) membranes using surface grafted diethylenetriamine

Composite BPPO/DETA ultrafiltration membranes show decreased membrane fouling and enhanced protein rejection with very high flux recovery ratios.

Effects of polymer blend composition on membrane properties and separation performance of PEES/PEI blend membrane

In this work, an attempt has been made for protein rejection from aqueous solution using ultrafiltration blend membrane based on poly(phenylene ether ether sulfone) (PEES) and polyetherimide (PEI) was prepared in various blend compositions. Prepared membranes were characterized in terms of pure water flux, water content, membrane hydraulic resistance, porosity, contact angle, scanning electron microscopy, thermogravimetric analysis, and attenuated total reflectance-Fourier transform infrared spectroscopy. Studies were carried out to find out the rejection of proteins such as trypsin, pepsin, egg albumin, and bovine serum albumin. The extent of protein separation is directly proportional to molecular weight of protein. Pristine PEES membrane exhibited high-percentage protein rejection of BSA (92.7%), EA (88.2%), pepsin (85.8%), and trypsin (82.2%) compared to PEES/PEI blend membranes. PEES/PEI blend membranes have better hydrophilic property compared to pristine PEES membrane. Pristine PEES has a contact angle of 97.8°, embedded with PEI and reduced to 67.9°. The thermal stability of the membrane was slightly decreased when the percentage of PEI composition into the PEES/PEI blend increased and observed that the pure PEES membrane has superior thermal stability than PEES/PEI blend membranes

Synergy Effect of PEG and LiCl as Additives on PVDF UF Membrane Performance

PVDF flat UF membranes were optimized to get relative high protein rejection with high permeation fluxes. The effects of PVDF content and the additive species on the membrane performance were investigated. The synergy effect between LiCl and PEG8kcan increase the flux remarkably than the single additive. With the increase of PEG8kcontent, the synergy effect of LiCl decreased. In addition, when the PEG8kcontent was higher than LiCl, the pure water flux was relatively high, while with the increasing of LiCl content, the membrane tensile strength was increased. The addition of PEG8kand LiCl should constitute an appropriate method to prepare a series of membranes with controlled flux.

Treatment of dairy wastewater by two-stage membrane operation with ultrafiltration and nanofiltration

Treatment of dairy wastewater by a two-stage membrane process with ultrafiltration (UF) and nanofiltration (NF) was investigated. The results showed that the flux of UF was higher at pH = 4.6 than that at pH = 8 because the resistance of the fouling membrane was lower at the isoelectric point of protein (pH = 4.6) in UF operation. Protein rejection exceeded 99% by UF + NF operation. Lactose rejections were 98.5 and 54% for UF + NF90 and UF + NF270 respectively. Experiments on membrane cleaning showed that the fouling layer of UF and NF was mainly protein and casein which could be removed by aqueous NaOH with pH = 10. The result of long-term experiments showed that the chemical oxygen demand (COD) of NF90 permeates was below 70 mg/L consistently and the wastewater could be concentrated to 24% by a two-stage membrane process.