Antifouling and Antimicrobial Study of Nanostructured Mixed-Matrix Membranes for Arsenic Filtration

Membrane fouling is a major drawback in the membrane filtration industry for water treatment. Mixed-matrix membranes (MMMs) are well known for their enhanced antifouling and antibacterial properties, which could offer potential benefits for membrane filtration processes in the water treatment field. In this work, three electrospun nanofibrous MMMs (P, CP, and MCP, which were, respectively, the pristine polysulfone membrane and mixed-matrix membranes (MMMs) consisting of GO-ZnO and GO-ZnO-iron oxides) were studied for antifouling and antibacterial properties with respect to the arsenic nanofiltration process. The effects of these composites on the antifouling behaviour of the membranes were studied by characterising the bovine serum albumin (BSA) protein adsorption on the membranes and subsequent analysis using microscopic (morphology via scanning electron microscopy) and Brunauer-Emmett-Teller (BET) analyses. The antibacterial properties of these membranes were also studied against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The composite nanoparticle-incorporated membranes showed improved antifouling properties in comparison with the pristine polysulfone (PSF) membrane. The excellent antimicrobial properties of these membranes make them appropriate candidates to contribute to or overcome biofouling issues in water or wastewater treatment applications.

Enhancement of antifouling properties, metal ions and protein separation of poly(ether-ether-sulfone) ultrafiltration membranes by incorporation of poly ethylene glycol and n-ZnO

Composite polymeric membranes with enhanced anti-fouling properties, antimicrobial activities and flux were produced via the phase inversion technique using poly (ether-ether-sulfone) (PEES)/polyethylene glycol (PEG) and n-ZnO. SEM and ATR-FTIR spectroscopy were used to study the morphological and chemical properties of the resulting ultrafiltration membranes. PEG and n-ZnO concentration has an effect on membrane morphologies, ultrafiltration performance, thermal characteristics, metal ion separation studies, surface hydrophilicity and anti-fouling capabilities. The permeate flux increased when the PEG concentration was raised. This results revealed that adding PEG and n-ZnO to membranes increased their surface hydrophilicity and anti-fouling properties. The inclusion of 1.5 wt % n-ZnO and 5 wt % PEG to the pristine PEES membrane resulted in a higher flux of 233.76 L m^-2 h^-1, 70.09 % of water content, 47.46° of contact angle, the porosity of 30.20 %, and hydraulic resistance of 0.22 kPa/Lm^-2h^-1. Anti-fouling properties of the fabricated membrane were assessed using a model foulant BSA, which revealed a high flux recovery ratio value. As a result, the PEG and n-ZnO incorporated membrane is more hydrophilic than the virgin membrane. In addition, the prepared PEES/PEG/n-ZnO membrane showed a significant increase in metal ions and protein rejection. Furthermore, an antibacterial test of the membrane revealed that the PEG and n-ZnO composite membrane outperformed the bare PEES membrane in terms of antibacterial capabilities. Overall, the findings reveal that combining n-ZnO and PEG resulted in a membrane with improved anti-fouling capabilities and hydrophilicity, making it suitable for water purification.

Nanomaterials in membrane bioreactors: Recent progresses, challenges, and potentials

The use of nanomaterials (NMs) in the fabrication and modification of membranes as well as the coupling of nanomaterial-based processes with membrane processes have been attracted many researchers today. The NMs due to a wide range of types, different chemistry, the possibility of various kinds of functionality, different properties like antibacterial activity, hydrophilicity, and large surface area were applied to enhance the membrane properties. In the membrane bioreactors (MBRs) as a highly successful process of membrane technology in wastewater treatment, the NMs have been applied for improving the efficiency of MBR process. This review assessed the application of NMs both as the modifiers of membrane and as the effective part of hybrid techniques with MBR system for wastewater treatment. The efficiency of NMs blended membranes in the MBR process has been reviewed in terms of antifouling and antibacterial improvement and removal performance of the pollutants. Novel kinds of NMs were recognized and discussed based on their properties and advantages. The NMs-based photocatalytic and electrochemical processes integrated with MBR were reviewed with their benefits and drawbacks. In addition, the effect of the presence of mobilized NPs in the sludge on MBR performance was surveyed. As a result of this review, it can be concluded that nanomaterials generally improve MBR performance. The high flux and antifouling properties can be obtained by adding nanomaterials with hydrophilic and antibacterial properties to the membrane, and further studies are required for photocatalytic NMs applications. In addition, this review shows that the low amounts of NMs in the membrane structure could have an effective influence on the MBR process. Besides, since many studies in the literature are carried out at the laboratory scale, it is thought that pilot and real-scale studies should be carried out to obtain more reliable data.

Stimuli-Responsive Hybrid Metal Nanocomposite - A Promising Technology for Effective Anticancer Therapy

Cancer is one of the most challenging, life-threatening illnesses to cure, with over 10 million new cases diagnosed each year globally. Improved diagnostic cum treatment with common side-effects are warranting for successful therapy. Nanomaterials are recognized to improve early diagnosis, imaging, and treatment. Recently, multifunctional nanocomposites attracted considerable interest due to their low-cost production, and ideal thermal and chemical stability, and will be beneficial in future diagnostics and customized treatment capacity. Stimuli-Responsive Hybrid Metal Nanocomposites (SRHMNs) based nanocomposite materials pose the on/off delivery of bioactive compounds such as medications, genes, RNA, and DNA to specific tissue or organs and reduce toxicity. They simultaneously serve as sophisticated imaging and diagnostic tools when certain stimuli (e.g., temperature, pH, redox, ultrasound, or enzymes) activate the nanocomposite, resulting in the imaging-guided transport of the payload at defined sites. This review in detail addresses the recent advancements in the design and mechanism of internal breakdown processes of the functional moiety from stimuli-responsive systems in response to a range of stimuli coupled with metal nanoparticles. Also, it provides a thorough understanding of SRHMNs, enabling non-invasive interventional therapy by resolving several difficulties in cancer theranostics.

Influence of alumina nanoparticles on the performance of polyacrylonitrile membranes in MBR

This study aims to investigate the effect of using Al₂O₃ nanoparticles (NPs) in membrane structure on the operation condition of the membrane bioreactor. To this end, alumina NPs as the high hydrophilic agents with an approximate size of 40 nm and a concentration of 0-3 wt.% were placed within the PAN polymeric membrane matrix structure with high hydrophilicity and high mechanical resistance over the others via the phase inversion method. Characterization of synthesized nanocomposite membranes was carried out by SEM analysis. In the presence of the alumina NPs, the porosity of the membranes improved. The water contact angle measurement confirmed the superior hydrophilicity of mixed PAN membranes compared to the pure polymeric membranes. The best nanocomposite membrane with better antifouling properties was selected to evaluate the MBR's performance in wastewater treatment and assessed in terms of the resistance, flux recovery, and COD removal rates. The result of a comparison with pure membrane showed that by increasing the Al₂O₃ amount up to 2wt.%, irreversible fouling resistance mitigated as much as 50%. Moreover, the flux recovery ratio was increased by 15%, and the COD removal rate was also raised as large as 16%. Our investigation illustrated that the presence of alumina NPs has improved the MBR performance and decreased the irreversible fouling resistance of the membrane.

Intrinsic stimuli-responsive nanocarriers for smart drug delivery of antibacterial agents-An in-depth review of the last two decades

Antibiotic resistance due to suboptimal targeting and inconsistent antibiotic release at bacterial infection sites has driven the formulation of stimuli-responsive nanocarriers for antibacterial therapy. Unlike conventional nanocarriers, stimuli-responsive nanocarriers have the ability to specifically enhance targeting and drug release profiles. There has been a significant escalation in the design and development of novel nanomaterials worldwide; in particular, intrinsic stimuli-responsive antibiotic nanocarriers, due to their enhanced activity, improved targeted delivery, and superior potential for bacterial penetration and eradication. Herein, we provide an extensive and critical review of pH-, enzyme-, redox-, and ionic microenvironment-responsive nanocarriers that have been reported in literature to date, with an emphasis on the mechanisms of drug release, the nanomaterials used, the nanosystems constructed and the antibacterial efficacy of the nanocarriers. The review also highlights further avenues of research for optimizing their potential and commercialization. This review confirms the potential of intrinsic stimuli-responsive nanocarriers for enhanced drug delivery and antibacterial killing. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Employing magnetism of Fe3O4 and hydrophilicity of ZrO2 to mitigate biofouling in magnetic MBR by Fe3O4-coated ZrO2/PAN nanocomposite membrane

The aim of this research is benefiting from the synergistic effect of the simultaneous presence of Fe₃O₄ and ZrO₂ in the form of Fe₃O₄-coated ZrO₂ (Fe₃O₄@ZrO₂) nanoparticles within the structure of PAN membrane to reduce membrane fouling. The role of Fe₃O₄ nanoparticles in increasing the pore size and magnetic saturation as well as the role of ZrO₂ in decreasing surface roughness and hydrophobicity can mitigate membrane fouling in magnetic-assisted membrane bioreactors. For this purpose, Fe₃O₄, ZrO₂, and Fe₃O₄@ZrO₂ nanoparticles were embedded into PAN membrane structure and magnetic (M _nM), hydrophilic (H _nM), and magnetic-hydrophilic (HM _nM) membranes were synthesized. H ₁M (1ZrO₂/PAN) membrane with a contact angle of 31 degrees, M ₁N (1Fe₃O₄/PAN) with a pore size of 90 nm, and H ₃M (3ZrO₂/PAN) membrane with an RMS roughness of 13.5 nm were the most hydrophilic, porous, and smoothest membranes, respectively. High sensitivity to magnetic field along with high porosity, high hydrophilicity and low surface roughness simultaneously exist within the structure of MHMs membranes, such that MH ₁M (1Fe₃O₄@ZrO₂/PAN) indicated 116% greater flux, 121% greater flux recovery, and 85% less total filtration resistance in comparison with the blank membrane in magnetic membrane bioreactor, at a magnetic field intensity of 120 mT and MLSS = 10,000 mg/l. As an overall conclusion, the output of this research was compared with other research in term of normalized flux. Results reveal that at MLSS = 10,000 mg/l, HRT = 8 h and TMP = 0.3 bar, MH ₁M membrane has normalized flux equal to 1.56 g/m² h bar which is an acceptable value compared to normalized flux reported by other researchers.

Application of zinc oxide and sodium alginate for biofouling mitigation in a membrane bioreactor treating urban wastewater

This research aimed to mitigate fouling in membrane bioreactors (MBR) through concurrent usage of zinc oxide as an antibacterial agent (A) and sodium alginate as a hydrophilic agent (H) within a polyacrylonitrile membrane (PM) structure. The antibacterial polymeric membranes (APM) and antibacterial hydrophilic polymeric membranes (AHPM) synthesized showed a higher porosity, mechanical strength and bacterial inhibition zone, and a lower contact angle in comparison with PM membranes. EDS, SEM and AFM analyses were used to characterize the chemical, structural, and morphological properties of PM, APM, and AHPM. The flux of PM, APM, and AHPM in MBR was 37, 48, and 51 l m^-2 h^-1 and COD removal was 81, 93.5, and 96.7%, respectively. After MBR operation for 35 days in an urban wastewater treatment, only 50% of the flux of PM was recovered, while the antibacterial and hydrophilic agents yielded a flux recovery of 72.7 and 100% for APM and AHPM, respectively.

Anti-Fouling and Anti-Bacterial Modification of Poly(vinylidene fluoride) Membrane by Blending with the Capsaicin-Based Copolymer

Membrane fouling induced by the adsorption of organic matter, and adhesion and propagation of bacteria onto the surfaces, is the major obstacle for the wide application of membrane technology. In this work, the capsaicin-based copolymer (PMMA-PACMO-Capsaicin) was synthesized via radical copolymerization using methyl methacrylate (MMA), N-acrylomorpholine (ACMO) and 8-methyl-N-vanillyl-6-nonenamide (capsaicin) as monomers. Subsequently, the capsaicin-based copolymer was readily blended with PVDF to fabricate PVDF/PMMA-PACMO-Capsaicin flat sheet membrane via immersed phase inversion method. The effects of copolymer concentration on the structure and performance of resultant membranes were evaluated systematically. With increase of PMMA-PACMO-Capsaicin copolymer concentration in the casting solution, the sponge-like layer at the membrane cross-section transfers to macroviod, and the pore size and porosity of membranes increase remarkably. The adsorbed bovine serum albumin protein (BSA) amounts to PVDF/PMMA-PACMO-Capsaicin membranes decrease significantly because of the enhanced surface hydrophilicty. During the cycle filtration of pure water and BSA solution, the prepared PVDF/PMMA-PACMO-Capsaicin membranes have a higher flux recovery ratio (FFR) and lower irreversible membrane fouling ratio (R_ir), as compared with pristine PVDF membrane. PVDF/PMMA-PACMO-Capsaicin membrane is found to suppress the growth and propagation of Staphylococcus aureus bacteria, achieving an anti-bacterial efficiency of 88.5%. These results confirm that the anti-fouling and anti-bacterial properties of PVDF membrane are enhanced obviously by blending with the PMMA-PACMO-Capsaicin copolymer.