Efficient Membrane Research Articles

Exploring ammonia adsorption and filtration efficiency of ceramic membranes derived from weathered basalt: Fabrication analysis and application in wastewater treatment

This study aims to develop an innovative ceramic membrane derived from naturally-occurring weathered basalt (NWB) for the effective adsorption and filtration of ammonium ions (NH+4) from wastewater. The NWB was subjected to calcination to produce CWB-750 and further combined with activated carbon to form CWB-AC-950. Comprehensive characterization using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) analysis revealed that CWB-AC-950 possessed a significantly high surface area of 121.7 m²/g and a minimal pore volume of 6.2 nm, indicating its enhanced adsorption capabilities. In practical filtration tests, CWB-AC-950 demonstrated a remarkable reduction in NH+4 concentration, decreasing it from an initial 30 mg/L to 15.25 mg/L. This substantial decrease underscores the membrane's efficiency in adsorbing and removing ammonium ions from contaminated water. Furthermore, the integration of activated carbon with calcined basalt not only improved the adsorption performance but also maintained the structural integrity and reusability of the membrane. These findings illustrate the potential of CWB-AC-950 as a promising and cost-effective medium for adsorption and filtration in wastewater treatment applications.The development of CWB-AC-950 contributes significantly to environmental remediation efforts by offering an efficient and low-cost alternative to conventional filtration materials. Its ability to maintain performance across multiple cycles underscores its potential for practical applications in large-scale wastewater treatment facilities, thus providing a sustainable solution to address the growing global water pollution crisis.

Candle soot-modified rPET electrospun nanofibrous membrane for separating on-demand oil-water mixture and emulsions

The CS-rPET electrospun nanofibrous membrane is fabricated from recycled polyethylene terephthalate (rPET) through electrospinning and enhanced with candle soot (CS) to separate oil-water mixtures and emulsions when pre-wetted by oil or water. Using rPET polymers and CS waste reduces the environmental impact of plastic bottle waste and improves its value. The CS-rPET electrospun nanofibrous membrane showed excellent separation performance in oil-water mixtures, achieving over 81.18 % and 71.38 % of separation efficiency through 40 separation cycles after pre-wetting by oil and after washing with ethanol and pre-wetting by water, respectively. The membrane maintained high separation performance after being pre-wetted by oil for water-in-oil emulsions with efficiencies above 99 % and flux exceeding 12,200 L m−2 h−1. Similarly, the efficiencies remained above 98 % for oil-in-water emulsions after being pre-wetted by water, with a flux over 8000 L m−2 h−1. Additionally, the CS-rPET electrospun nanofibrous membrane exhibited high separation efficiencies above 97 % and flux over 14,000 L m−2 h−1 after pre-wetting by oil and 7700 L m−2 h−1 after pre-wetting by water in harsh environmental conditions. Its adaptability of switchable wettability on-demand after pre-wetting by oil or water highlights its potential for a wide range of challenging oil-water separation applications. However, multiple separation cycles, separation efficiency and flux were reduced, indicating the necessity to improve the membrane's efficiency and reduce the chance of water accumulation in multicycle separation.

A novel electroactive biopolymer-graphene oxide nanocomposite membrane for high-performance electrochemical sensing of ethylene

This study focuses on formulating an electroactive composite membrane using polyvinyl alcohol (PVA), chitosan (CHT), and graphene oxide (GO), specifically emphasizing its application in electrochemical ethylene detection. Through the surface functionalization of the PVA-CHT-GO membrane via GO activation, the nanocrystallite GO-based composite, when incorporated into a microelectrode chip, exhibited a transformative enhancement in electrochemical ethylene sensing. Comprehensive characterizations of both the synthesized GO and the PVA-CHT-GO composite membranes were conducted by employing X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy, Energy Dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FE-SEM), and Thermal gravimetric analysis (TGA). The XRD pattern provides insights into the stacking height, interplanar spacing, and the number of layers along the (002) direction. The synthesized GO's average nano-crystallite size was determined to be 10.38 nm. The Raman spectrum revealed prominent D and G bands at 1353 and 1591 cm-1, respectively. FE-SEM images depicted the overlapping of GO nanolayers, each layer having a thickness in the range of 20–30 nm. Following surface activation, thin layers developed on the membrane surface, with numerous folds accumulating, exhibiting thickness in the range of 20–50 nm. The intricate characterization underscored the structural and morphological features of the membrane, enhancing our understanding of its surface properties. The effectiveness of ethylene detection using the GO-activated PVA-CHT-GO membrane was evaluated via cyclic voltammetry (CV) measurements. These measurements confirmed the membrane's efficiency, demonstrating ultra-sensitive ethylene detection, even upon initial exposure to ethylene.

The improvement of nanofiltration membrane performance with lignin Cu complex as interlayer

Nanofiltration (NF) membranes are instrumental in separating small molecular organics and salts, finding widespread application in industrials such as food, pharmaceuticals, and dye printing for product purification and wastewater treatment. However, the performance of these membranes is often restricted by the inherent “trade-off” effect between selectivity and permeability. In this study, a copper- demethylated lignin (Cu-DL) interlayer between the substrate and the selective layer was fabricated, aimed at augmenting the NF membrane's efficiency. This enhancement primarily results from Cu2+ coordination adsorption with piperazine (PIP), serving to regulate the diffusion and optimize the structure of the selective layer. Concurrently, the interlayer prevents the infiltration of the selective layer to reduce the mass transfer resistance. Compared to conventional NF membranes, the NF membrane based on the Cu-DL interlayer, exhibited a marked increase in permeability from 6.2 L m-2h-1bar-1 to 12.9 L m-2h-1bar-1, while essentially maintaining its retention capabilities for Na2SO4 solutions. Additionally, this membrane exhibits the excellent separation of salts and dyes under various concentrations. This work can provide a solution for the fabrication of high-performance NF membranes and new ideas for the utilization of biomass.

High-performance f-GO/MWCNTs-COOH nanohybrid-based polylactic acid mixed matrix membrane for wastewater treatment

To enhance the green polylactic acid (PLA) membrane's efficiency for removing organic materials, self-assembled functionalized graphene oxide carboxylic multi-walled carbon nanotubes (f-GO/MWCNTs-COOH) was incorporated into the membrane matrix followed by immersion precipitation. The successful formation of the negatively charged f-GO/MWCNTs-COOH nanohybrid was verified by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and zeta potential analyzer. The effect of different nanohybrid contents (1.5, 3 and 6 wt%) on the PLA membrane performance was investigated. The prepared mixed matrix membranes were analyzed by FT-IR, XRD, SEM, contact angle, porosity, and pore size analysis. Synthetic organic foulant bovine serum albumin (BSA), humic acid (HA) solutions were utilised to test the antifouling behaviour of membranes. In addition, raw wastewater from a wastewater treatment plant (WWTP) was used to further assess the performance of the membranes. The results indicated that with only 3 wt% f-GO/MWCNTs-COOH nanohybrid in the PLA membrane matrix, the fouling tendency was attenuated (superior rejection rates for BSA and HA of 96 % and 98 %, respectively.) and the pure water flux was increased to almost 80 L/m2hbar, compared to the neat PLA membrane (27 L/m2hbar), without compromising the high organic removal efficiency. According to the results of this study, the f-GO/MWCNTs-COOH nanohybrid has great potential to enhance the performance of mixed matrix membranes in raw wastewater treatment applications.

Molecular sieving through 'layer-by-layer' self-assembly of polyelectrolytes and highly crosslinked graphene oxide

Lack of access to potable water and abating levels of ground water level demands the reuse of unconventional water sources after remediating it in a sustainable way. In this context, purifying brackish, land and sea water seems a feasible solution to the ever-growing population.In this work, a novel composite membrane was fabricated by 'layer-by-layer' self-assembly of poly-dopamine (PDA) and polystyrene sulfonate (PSS) supported on a highly crosslinked graphene oxide (GO) membrane to sieve ions to purify contaminated water as well as enhance the resistance towards chlorine. This GO membrane was sandwiched between layers of various nanoporous polyvinylidene difluoride (PVDF) membranes obtained by selectively etching out the PMMA component from the demixed blends. The blend membranes were designed following the melt-extrusion process and subsequent quenching to facilitate confined crystallization of PVDF and selective etching of PMMA. The membranes with different pore sizes were tuned on varying the composition in blends and a gradient in microstructure was achieved by stitching the membranes. Pure water flux, salt rejection, dye removal, and antibacterial activity were performed to study the membrane's efficiency. The GO membrane was chemically crosslinked with methylenediamine to impart dimensional stability and to enhance rejection efficiency through the nanoslits that GO offers. Besides effective rejection, the sandwiched membrane was modified with ‘layer-by-layer’ self-assembly of polyelectrolytes on the surface to improve the chlorine tolerance performance. This strategy resulted in an excellent salt (about 95% and 97% for monovalent and divalent ion, respectively) and dye rejection (100% for both cationic and anionic dye), besides facilitating excellent chlorine tolerance performance. Moreover, this modified membrane showed superior antifouling properties (flux recovery ratio is more than 90%) and excellent antibacterial performance (near about 3 log reduction).Thus the concept of using layer-by-layer self-assembly of polycations (PDA) and polyanions (PSS) onto a hierarchical chemically modified GO sandwiched PVDF membrane proved to be a productive strategy to purify contaminated water. Thus the membrane can be a potential candidate for domestic as well as industrial application.

Ultrafiltration of cheese whey: Achieving high protein rejection and sustaining membrane efficiency

The objective of this study is to characterize the ultrafiltration (UF) of cheese whey (CW) by measuring permeate flux variations and observing changes in the water permeability of the membrane throughout the process. We also aimed to analyze the differences between the compositions of CW and the materials generated after UF (ultrafiltration concentrate (UC) and permeate (UP)). UF lasted 66 min, after which a volume concentration factor of 2.54 was reached. Flux decline during UF was caused by concentration polarization, and not by fouling, because cleaning recuperated 94.55% of membrane efficiency. Though lactose was more retained than usual, gel electrophoresis demonstrated the 1.77-fold increase in protein content, depicting stronger bands of β-lactoglobulin and α-lactalbumin in UC. Therefore, UF satisfactorily separated proteins from CW; however, to effectively remove lactose we suggest a previous filtration step with higher molecular weight cutoff to retain larger molecules before using 10 kDa. Novelty impact statement Over 99% of protein rejection was achieved in the UF of cheese whey (CW). Membrane's efficiency was regained to 100% of its capacity after cleaning procedures. Lactose was not efficiently separated from CW when compared to other studies.

A full-scale study of nanofiltration: Separation and recovery of NaCl and Na2SO4 from coal chemical industry wastewater

This study focuses on the application of nanofiltration membrane in separating NaCl from Na2SO4 of a “zero discharge” process designed for a particular coal chemical wastewater (60 m3/h) in full scale. The front-end inlet water's residual chlorine content seriously affects the subsequent nanofiltration membrane's long-term efficiency. The nanofiltration membrane was oxidized when the front-end inlet residual chlorine exceeds 0.1 mg/L. In 1-year operation, the rejection rate of the nanofiltration membrane for chemical oxygen demand (COD) dropped from ~70% to ~50%, and the rejection rate for silica dropped from ~30% to ~20%; in the same period, the rejection rate for sodium sulfate dropped from 99.5% to ~88%. It was found that coconut shell activated carbon, a pre-treatment unit integrated in front of the nanofiltration membrane unit, could remove up to 98% of residual chlorine in the system. The chlorine concentration entering the nanofiltration unit was kept below 0.05 mg/L, thus maintaining the nanofiltration membrane's efficiency and extending its lifespan. This work provides a foundation for the nanofiltration in separation and resource of NaCl and Na2SO4 from a large-scale perspective and implication for the development of Nanofiltration membrane for coal chemical wastewaters.

Carbon adhered iron oxide hollow nanotube on membrane fouling

Ultrafiltration membrane's efficiency and antifouling properties can be enhanced by blending with benign tailor made inorganic nano-materials. Carbon adhered Fe3O4 hollow nanotube, nanosheet synthesized from iron alkoxide using iron (III) acetate source refluxed with methanol. The prepared Fe3O4 (nanotubes & nanosheets) were characterised by PXRD, FE-SEM, TEM, FT-IR and elemental analysis. Polymer nanocomposite membranes were prepared by blending PVDF (14 wt%)/Fe3O4 (2 wt%)/DMF and characterised in detail. PVDF/Fe3O4 (hollow nanotube) composite membrane showed enhanced flux property and antifouling efficiency confirmed by BSA rejection and molecular weight cut-off (MWCO). The biofilm formation studies of PVDF/Fe3O4 hollow nanotube composite membrane were evaluated using E. coli, fresh water Bacillus subtilis and marine Bacillus bacteria showed excellent control of biofilm growth by PVDF/Fe3O4 (hollow nanotube) membrane. The antifouling studies of PVDF blank and PVDF/Fe3O4 (holow nanotube) with B. subtilis and P. aeruginosa showed 0.943 ± 0.02, 0.932 ± 0.01 A.U for PVDF blank and 0.88 ± 0.02 and 0.802 ± 0.02 A.U, and this indicates the significant antifouling control arise from the Fe nanomaterial.

Fouling control in a lab-scale MBR system: Comparison of several commercially applied coagulants

The Membrane bioreactors (MBRs) integrate the biological degradation of pollutants with membrane filtration-separation during wastewater treatment. Membrane fouling, which is considered as the main process drawback, stems from the interaction between the membrane material and the (organic or inorganic) foulants, leading to membrane's efficiency deterioration. It is widely recognized that the mixed liquor colloidal and Soluble Microbial Products (SMP) are in principal responsible for this undesirable situation. As a result, the appropriate pretreatment of wastewater feed is often considered as necessary procedure and the coagulation/flocculation (C/F) process is regarded as a relevant viable option for wastewater treatment by MBRs in order to improve the effective removal of suspended solids (SS), of colloidal particles, of natural organic matter (NOM), as well as of other soluble materials. The objective of this study is the application of coagulation/flocculation for fouling control of MBR systems by using several commercially available chemical coagulant/flocculant agents. For this purpose, an appropriate lab-scale continuous-flow, fully automatic MBR system has been assembled and various (inorganic) coagulants (i.e. FeCl3∙6H2O, Fe2(SO4)3·5H2O, FeClSO4, PFS0.3, PAC A9-M, PAC-A16, Al2(SO4)3·18H2O, FO4350SSH, NaAlO2) have been examined. Filterability tests and SMP concentration measurements were also conducted in order to investigate the reversible, as well as the irreversible fouling, respectively. Based upon the obtained results and after selecting the most efficient coagulants (FeCl3·6H2O, Fe2(SO4)3·5H2O, FeClSO4, PAC-A9, PAC-A16), an attempt was subsequently performed to correlate the major fouling indices (i.e. TMP, TTF, SMP concentration) in order to improve the overall process operability by this fouling control method.

Selection of OBM salinity through effective osmotic pressure evaluation in carbonera shale for colombian foothills

Wellbore instability in shales is attributed to many factors. Two of them are mechanical effects and physico-chemical effects. Drilling and drilling fluid cause physico-chemical interaction and the flux of water and ions that may alter the shale stress state through pore pressure and shale strength. This paper presents the analysis of the chemical osmosis phenomenon between drilling fluids and shale formations to evaluate the chemical parameters necessary for modeling the aqueous flux. These parameters are the drilling fluid activity (Adf), shale activity (Ash) and membrane efficiency (ME). This work also characterizes the shales for drilling purposes and describes an integrated methodology to obtain the magnitude of the chemical parameters. Furthermore, it is stated how the generation of effective osmotic pressure between the formation and drilling fluid define the water flux direction. Finally, the application of the results of the chemical analysis to Carbonera shale is presented. The design of laboratory tests for two mud formulations, Mud A and Mud B, and the field application is also showed. The Mud A is a balanced activity mud and the Mud B is a high salt concentration mud which may produce water flux out of the shale formation (dehydration) during drilling, in some sections of the wellbore, increasing the formation strength. The results presented in this paper will help to reduce the risks associated with wellbore instability during the drilling of shale formations and thereby lowering the overall non-productive time and reducing drilling costs.

ASSEMBLY OF A METHODOLOGY FOR DETERMINATION OF MEMBRANE EFFICIENCY IN PRESERVED SHALES

Determination of Membrane Efficiency (ME) is a very useful tool in the study of the chemical component of wellbore stability since it is a variable input in chemical-elastic models (Lomba, Chenevert & Sharma, 2000). This article presents a novel methodology for the determination of ME using the Electrochemical Potential Test (EPT) in shale rocks. This method is based on the development of correlations with Ionic Selectivity (IS) values in presence of NaCl, KCl and CaCl2 at diverse solution concentrations. The correlation, not reported previously in the literature, depends on the type of salt used. The EPT is a generic test easily applied to any rock type from any well or basin. It is simpler and quicker than other tests used for the ME determination, like the Pressure Transmission Test (PTT). Correlations between ME and IS are applicable to any type of argillaceous rock. Samples of unperturbed plugs with diverse properties belonging to different Colombian formations were used. The results obtained with the application of the proposed methodology indicate that it is possible to obtain IS and ME values through EPT in any type of argillaceous rock by applying the developed correlations.

Lipid peroxidation both inhibits Ca(2+)-ATPase and increases Ca2+ permeability of endoplasmic reticulum membrane.

Incubation of reticular membranes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA at 37 degrees C for 30 min led to the loss of membrane's efficiency to sequester Ca2+ to 21.8% and 3.6% of control values, respectively. The incubation of microsomes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA also caused decrease of Ca(2+)-ATPase activity; to 44.9% and 44.4% (measured under the same conditions as Ca(2+)-uptake) or to 79.6% and 62.1% (uncoupled from Ca2+ transport by detergent). In addition, incubation of membranes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA at 37 degrees C for 30 min led to the increase of Ca2+ permeability to 125.1% and 124.2%, respectively. Preincubation of membranes with membrane-soluble antioxidants (U-74500A, U-83836E, t-butyl hydroxytoluene and stobadine) protected the reticular membranes against depression of Ca2+ uptake values and Ca(2+)-ATPase inhibition in a dose and an antioxidant nature dependent manner. Our results indicate that both processes, Ca(2+)-ATPase inhibition and increase of endoplasmic reticulum membrane Ca2+ permeability, participate in the lipid peroxidation induced loss of membrane's efficiency to sequester Ca2+.