Effect of Loading and Functionalization of Carbon Nanotube on the Performance of Blended Polysulfone/Polyethersulfone Membrane during Treatment of Wastewater Containing Phenol and Benzene

Enhancing oil-water emulsion separation via synergistic filtration using graphene oxide-silver oxide nanocomposite-embedded polyethersulfone membrane

This study introduces an innovative approach for enhancing oil-water emulsion separation using a polyethersulfone (PES) membrane embedded with a nanocomposite of graphene oxide (GO) and silver oxide (AgO). The composite membrane, incorporating PES and polyvinyl chloride (PVC), demonstrates improved hydrophilicity, structural integrity and resistance to fouling. Physicochemical characterization confirms successful integration of GO and AgO, leading to increased tensile strength, porosity and hydrophilicity. Filtration tests reveal substantial improvements in separating various oils from contaminated wastewater, with the composite membrane exhibiting superior efficiency and reusability compared to pristine PES membranes. This research contributes to the development of environmentally friendly oil-water separation methods with broad industrial applications.

Impact of Nitrate on the Removal of Pollutants from Water in Reducing Gas-Based Membrane Biofilm Reactors: A Review

The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO4-), perchlorate (ClO4-)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO3-), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO3- inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR.

Carbon nanotube-wastewater treatment nexus: Where are we heading to?

Water treatment is crucial in solving the rising people's appetite for water and global water shortages. Carbon nanotubes (CNTs) have considerable promise for water treatment because of their adjustable and distinctive arbitrary, physical, as well as chemical characteristics. This illustrates the benefits and risks of integrating CNT into the traditional water treatment resource. Due to their outstanding adsorbent ability and chemical and mechanical properties, CNTs have gained global consideration in environmental applications. The desalination and extraction capability of CNT were improved due to chemical or physical modifications in pure CNTs by various functional groups. The CNT-based composites have many benefits, such as antifouling performance, high selectivity, and increased water permeability. Nevertheless, their full-scale implementations are still constrained by their high costs. Functionalized CNTs and their promising nanocomposites to eliminate contaminants are advised for marketing and extensive water/wastewater treatment.

Classification of Nanomaterials and the Effect of Graphene Oxide (GO) and Recently Developed Nanoparticles on the Ultrafiltration Membrane and Their Applications: A Review

The emergence of mixed matrix membranes (MMMs) or nanocomposite membranes embedded with inorganic nanoparticles (NPs) has opened up a possibility for developing different polymeric membranes with improved physicochemical properties, mechanical properties and performance for resolving environmental and energy-effective water purification. This paper presents an overview of the effects of different hydrophilic nanomaterials, including mineral nanomaterials (e.g., silicon dioxide (SiO2) and zeolite), metals oxide (e.g., copper oxide (CuO), zirconium dioxide (ZrO2), zinc oxide (ZnO), antimony tin oxide (ATO), iron (III) oxide (Fe2O3) and tungsten oxide (WOX)), two-dimensional transition (e.g., MXene), metal-organic framework (MOFs), covalent organic frameworks (COFs) and carbon-based nanomaterials (such as carbon nanotubes and graphene oxide (GO)). The influence of these nanoparticles on the surface and structural changes in the membrane is thoroughly discussed, in addition to the performance efficiency and antifouling resistance of the developed membranes. Recently, GO has shown a considerable capacity in wastewater treatment. This is due to its nanometer-sized holes, ultrathin layer and light and sturdy nature. Therefore, we discuss the effect of the addition of hydrophilic GO in neat form or hyper with other nanoparticles on the properties of different polymeric membranes. A hybrid composite of various NPs has a distinctive style and high-quality products can be designed to allow membrane technology to grow and develop. Hybrid composite NPs could be used on a large scale in the future due to their superior mechanical qualities. A summary and future prospects are offered based on the current discoveries in the field of mixed matrix membranes. This review presents the current progress of mixed matrix membranes, the challenges that affect membrane performance and recent applications for wastewater treatment systems.

Effect of Silica Sodalite Loading on SOD/PSF Membranes during Treatment of Phenol-Containing Wastewater

In this study, silica sodalite (SSOD) was prepared via topotactic conversion and different silica sodalite loadings were infused into the polysulfone (PSF) for application in phenol-containing water treatment. The composite membranes were fabricated through the phase inversion technique. Physicochemical characteristics of the nanoparticles and membranes were checked using a Scanning Electron Microscope (SEM), Brunauer Emmett-Teller (BET), and Fourier Transform Infrared (FTIR) for surface morphology, textural properties, and surface chemistry, respectively. A nanotensile test, Atomic Force Microscopy (AFM), and contact angle measurement were used to check the mechanical properties, surface roughness, and hydrophilicity of the membranes, respectively. SEM results revealed that the pure polysulfone surface is highly porous with large evident pores. However, the pores decreased with increasing SSOD loading. The performance of the fabricated membranes was evaluated using a dead-end filtration device at varying feed pressure during phenol-containing water treatment. The concentration of phenol in water used in this study was 20 mg/L. The pure PSF displayed the maximum phenol rejection of 95 55% at 4 bar, compared to the composite membranes having 61.35% and 64.75% phenol rejection for 5 wt.% SSOD loading and 10 wt.% SSOD loading, respectively. In this study, a novel Psf-infused SSOD membrane was successfully fabricated for the treatment of synthetic phenol-containing water to alleviate the challenges associated with it.

Resin-Loaded Heterogeneous Polyether Sulfone Ion Exchange Membranes for Saline Groundwater Treatment

Arid areas often contain brackish groundwater that has a salinity exceeding 500 mg/L. This poses several challenges to the users of the water such as a salty taste and damage to household appliances. Desalination can be one of the key solutions to significantly lower the salinity and solute content of the water. However, the technology requires high energy inputs as well as managing waste products. This paper presents the fabrication of ultrafiltration heterogeneous ion exchange membranes for brackish groundwater treatment. Scanning electron microscopy (SEM) images showed a relatively uniform resin particle distribution within the polymer matrix. The mean roughness of the cation exchange membrane (CEM) and anion exchange membrane (AEM) surfaces increased from 42.12 to 317.25 and 68.56 to 295.95 nm, respectively, when resin loading was increased from 1 to 3.5 wt %. Contact angle measures suggested a more hydrophilic surface (86.13 to 76.26° and 88.10 to 74.47° for CEM and AEM, respectively) was achieved with greater resin loading rates. The ion exchange capacity (IEC) of the prepared membranes was assessed using synthetic groundwater in a dead-end filtration system and removal efficiency of K+, Mg2+, and Ca2+ were 56.0, 93.5, and 85.4%, respectively, for CEM with the highest resin loading. Additionally, the anion, NO3- and SO42- removal efficiency was 84.2% and 52.4%, respectively, for the AEM with the highest resin loading. This work demonstrates that the prepared ultrafiltration heterogeneous ion exchange membranes have potential for selective removal for of ions by ion exchange, under filtration conditions at low pressure of 0.05 MPa.

Preparation and Characterization of Polymer Membranes Impregnated with Carbon Nanotubes for Olive Mill Wastewater

In this study, polymer membrane(s) impregnated with carbon nanotubes (CNTs) were developed, characterized and evaluated for removing phenolic compounds from olive mill wastewater; thus, protecting the environment and public health. Polyethersulfone/functionalized, multi-walled carbon nanotube (PES/fCNTs) membranes were synthesized via the phase inversion method using PES and acid-treated CNTs. The prepared membranes were then characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and contact angle. Results obtained from this study indicate a more hydrophilic surface for the prepared PES/fCNTs membranes, with a higher pure water flux compared to the polyethersulfone (PES) membranes. In addition, the amount of fCNTs in the membranes was found to be the most significant factor affecting the morphology and water flux of the membranes. The PES/fCNTs membranes at 1 bar with 0 wt.% and 1 wt.% of CNTs showed water flux of 37.8 and 69.71 kg/h.m², respectively. In addition, PES/fCNTs membranes with 0.5 wt.% fCNTs showed the highest total phenol content removal of 74%.

Effect of carbon nanotubes loading and pressure on the performance of a polyethersulfone (PES)/carbon nanotubes (CNT) membrane

This paper focuses on modifying a PES membrane with acid-functionalised carbon nanotubes (CNT) for industrial wastewater treatment. Embedding acid functionalised carbon nanotubes (CNTs) within the membrane matrix would increase the membrane flux by increasing the membrane pore size and surface area, rejection and thermal stability. Pure PES membranes were prepared by phase inversion method and infused with CNTs at 2.5, 5, 7.5 and 10 wt% loading to fabricate PES/2.5 wt% CNT, PES/5 wt% CNT, PES/7.5 wt% CNT and PES/10 wt% CNT membranes respectively. Characterisation was performed using Transmission Electron Microscopy (TEM) to determine CNT morphology, X-ray Diffraction (XRD) to determine the functional groups attached to CNTs, Thermogravimetric Analysis (TGA) to determine the thermal stability of the membranes, Scanning Electron Microscope (SEM) to determine membrane morphology, Bunauer-Emmett-Teller (BET) method to obtain pore size information and Contact Angle (CA) to determine the membrane hydrophilicity. Membrane performance was then evaluated with a dead-end stirred cell using industrial wastewater containing traces of Cu, Fe, Ni, Zn and Cl. Permeate flux results showed a direct proportion relationship with increasing CNT loading and increasing pressure (100 kPa, 300 kPa, 500 kPa, 700 kPa, 900 kPa and 1100 kPa). PES/5 wt% CNT membrane showed the most enhanced performance compared to the other membranes, achieving reasonably high flux of 43.7 L/m²h and rejection of 89.6% Cu, 100% Fe, 90.5% Ni, 68.8% Zn and 99.99% Cl at 300 kPa. The results obtained showed that the PES membrane embedded with functionalised CNTs could be used for the treatment of industrial wastewater.

Effect of Silica Sodalite Functionalization and PVA Coating on Performance of Sodalite Infused PSF Membrane during Treatment of Acid Mine Drainage

In this study, silica sodalite (SSOD) nanoparticles were synthesized by topotactic conversion and functionalized using HNO3/H2SO4 (1:3). The SSOD and functionalized SSOD (fSSOD) nanoparticles were infused into a Polysulfone (Psf) membrane to produce mixed matrix membranes. The membranes were fabricated via the phase inversion method. The membranes and the nanoparticles were characterized using Scanning Electron Microscopy (SEM) to check the morphology of the nanoparticles and the membranes and Fourier Transform Infrared to check the surface chemistry of the nanoparticles and the membranes. Thermal stability of the nanoparticles and the membranes was evaluated using Themogravimetry analysis (TGA) and the degree of hydrophilicity of the membranes was checked via contact angle measurements. The mechanical strength of the membranes and their surface nature (roughness) were checked using a nanotensile instrument and Atomic Force Microscopy (AFM), respectively. The textural property of the nanoparticles were checked by conducting N2 physisorption experiments on the nanoparticles at 77 K. AMD-treatment performance of the fabricated membranes was evaluated in a dead-end filtration cell using a synthetic acid mine drainage (AMD) solution prepared by dissolving a known amount of MgCl2, MnCl2·4H2O, Na2SO4, Al(NO3)3, Fe(NO3)3·9H2O, and Ca2OH2 in deionized water. Results from the N2 physisorption experiments on the nanoparticles at 77 K showed a reduction in surface area and increase in pore diameter of the nanoparticles after functionalization. Performance of the membranes during AMD treatment shows that, at 4 bar, a 10% fSSOD/Psf membrane displayed improved heavy metal rejection >50% for all heavy metals considered, expect the SSOD-loaded membrane that showed a rejection <13% (except for Al3+ 89%). In addition, coating the membranes with a PVA layer improved the antifouling property of the membranes. The effects of multiple PVA coating and behaviour of the membranes during real AMD are not reported in this study, these should be investigated in a future study. Therefore, the newly developed functionalized SSOD infused Psf membranes could find applications in the treatment of AMD or for the removal of heavy metals from wastewater.

Vertically Aligned Carbon Nanotube Membranes: Water Purification and Beyond

Vertically aligned carbon nanotube (VACNT) membranes have attracted significant attention for water purification owing to their ultra-high water permeability and antibacterial properties. In this paper, we critically review the recent progresses in the synthesis of VACNT arrays and fabrication of VACNT membrane methods, with particular emphasis on improving water permeability and anti-biofouling properties. Furthermore, potential applications of VACNT membranes other than water purification (e.g., conductive membranes, electrodes in proton exchange membrane fuel cells, and solar electricity–water generators) have been introduced. Finally, future outlooks are provided to overcome the limitations of commercialization and desalination currently faced by VACNT membranes. This review will be useful to researchers in the broader scientific community as it discusses current and new trends regarding the development of VACNT membranes as well as their potential applications.