Fabrication and separation performance of polyethersulfone/sulfonated TiO₂ (PES–STiO₂) ultrafiltration membranes for fouling mitigation

Ayyaru, Sivasankaran,Ahn, Young-Ho THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.67 No.-

<P><B>Abstract</B></P> <P>Polyethersulfone (PES)/sulfonated TiO<SUB>2</SUB> (STiO<SUB>2</SUB>) nanoparticles (NPs) UF blended membranes were fabricated with different loadings of STiO<SUB>2</SUB>. The modified membranes exhibited significant improvement in surface roughness, porosity, and pore size when compared to the PES membrane. The P-STiO<SUB>2</SUB> 1 and P-TiO<SUB>2</SUB> 1 blended membranes exhibited higher water flux, approximately 102.4% and 62.6%, respectively, compared to PES. SPP-STiO<SUB>2</SUB> and P-STiO<SUB>2</SUB> showed lower Rir fouling resistance than the P-TiO<SUB>2</SUB> blended membrane. Overall, the STiO<SUB>2</SUB>-blended membranes provide high hydrophilicity permeability, anti-fouling performance, and improved BSA rejection attributed to the hydrogen bonding force and more electrostatic repulsion properties of STiO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new hydrophilic surface-modified additive, sulfonated TiO<SUB>2</SUB>, was prepared. </LI> <LI> The PES/STiO<SUB>2</SUB> modified UF membranes were prepared via phase inversion method. </LI> <LI> For the P-STiO<SUB>2</SUB>, 102.4% showed higher water flux compared to PES membrane. </LI> <LI> The STiO<SUB>2</SUB> membranes showed lower Rir fouling resistance of 3.4% than TiO<SUB>2</SUB> (23.2%). </LI> <LI> –SO<SUB>3</SUB>H group in the STiO<SUB>2</SUB> has a stronger hydrophilic group, than to the TiO<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Biofouling reduction in a MBR by the application of a lytic phage on a modified nanocomposite membrane

Ayyaru, Sivasankaran,Choi, Jeongdong,Ahn, Young-Ho The Royal Society of Chemistry 2018 Environmental science Vol.4 No.10

<P>Biological contamination of membranes is an unavoidable problem in membrane bioreactor (MBR) systems. In addition, biofouling caused by antibiotic resistant bacteria (ARB) has become a critical issue not only for environmental health but also for the operation of membrane processes. This paper highlights the potential applications of lytic phage therapy on a modified nanocomposite membrane (polyvinylidene fluoride (PVDF)-sulfonated graphene oxide (SGO)) to control bacterial fouling on membranes and ARB in MBRs. An antibiotic resistant bacterium (E2) and a respective phage (P2) were isolated from municipal wastewater and used in a MBR system as a membrane foulant and antifoulant, respectively. The isolated bacteria were screened further for antibiotic susceptibility and the minimum inhibitory concentrations (MICs) were determined. E2 was found to be resistant to various concentrations of ampicillin, cefotaxime, vancomycin, tetracycline, and gentamicin. The phage treatment efficiency was examined by membrane flux. In the nanocomposite membrane, the E2 + P2 suspension showed a much higher flux (125 L m<SUP>−2</SUP> h<SUP>−1</SUP>) than the E2 suspension (60 L m<SUP>−2</SUP> h<SUP>−1</SUP>). Up to 57% higher flux was observed in the phage treatment, suggesting that the lytic phage prevented bacterial multiplication and biofilm formation. The multiplicity of infection (MOI) was examined to determine the optimal number of phages required to kill the bacteria. Scanning electron microscopy (SEM) was used to observe the bacterial infection and biofouling reduction due to the phage treatment. The modified nanocomposite membrane was aimed at protein fouling reduction (pore blocking resistance) and lytic phage addition was aimed at bacterial fouling reduction (cake layer resistance). The different types of fouling resistance of the membrane were estimated to distinguish between phage treatment and modified membrane efficiency. Based on the results of fouling resistance and SEM, the phage could reduce the membrane cake layer resistance and the modification of the membrane reduced the pore blocking resistance. The synergistic combination of phage treatment and the modified membrane reduced both types of biofouling. A separate cleaning system was installed and examined to avoid disturbing the normal MBR process (killing of bacteria in the feed solution by the phages).</P>

Fabrication and separation performance of polyethersulfone/ sulfonated TiO2 (PES–STiO2) ultrafiltration membranes for fouling mitigation

Sivasankaran Ayyaru,안영호 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.67 No.-

Polyethersulfone (PES)/sulfonated TiO2 (STiO2) nanoparticles (NPs) UF blended membranes were fabricated with different loadings of STiO2. The modified membranes exhibited significant improvement in surface roughness, porosity, and pore size when compared to the PES membrane. The P-STiO2 1 and P-TiO2 1 blended membranes exhibited higher water flux, approximately 102.4% and 62.6%, respectively, compared to PES. SPP-STiO2 and P-STiO2 showed lower Rir fouling resistance than the P-TiO2 blended membrane. Overall, the STiO2-blended membranes provide high hydrophilicity permeability, anti-fouling performance, and improved BSA rejection attributed to the hydrogen bonding force and more electrostatic repulsion properties of STiO2.

Non-toxic properties of TiO₂ and STiO₂ nanocomposite PES ultrafiltration membranes for application in membrane-based environmental biotechnology

Pandiyan, Rajesh,Ayyaru, Sivasankaran,Ahn, Young-Ho Elsevier 2018 Ecotoxicology and environmental safety Vol.158 No.-

<P><B>Abstract</B></P> <P>In membrane bioreactor (MBR) technology, nanocomposite membrane has a great potential to improve the filtration performance and antifouling. However, antibacterial activity of nanoparticles (NPs) is a significant disadvantage which can be impacted to bacterial growth and microbial community in MBRs. The modified polyethersulfone (PES) ultrafiltration (UF) membranes in the study were prepared by using TiO<SUB>2</SUB> NPs and TiO<SUB>2</SUB> NPs functionalized with sulfonation (STiO<SUB>2</SUB>). The antibacterial effect of NPs and non-toxic properties of nanocomposite membranes were examined by using three different Gram-negative bacterial species isolated from a local full scale membrane bioreactor treating municipal wastewater (<I>Escherichia coli, Pantoea agglomerans</I>, and <I>Pseudomonas graminis</I>). Results are revealed that the TiO<SUB>2</SUB> and STiO<SUB>2</SUB> NPs have 60% of antibacterial activity based on disc diffusion, viability tests, and TEM analysis. However, the PES-TiO<SUB>2</SUB> and PES-STiO<SUB>2</SUB> nanocomposite UF membranes showed significantly lower antibacterial activity (<95%, significance at <I>p</I> < 0.0001), indicating innocuous to bacterial growth. This study highlights that the PES-TiO<SUB>2</SUB> and PES-STiO<SUB>2</SUB> nanocomposite membrane is more sustainable than PES membrane and promising materials for MBRs, by taking advantage of non-toxic properties to bacterial growth.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TiO<SUB>2</SUB> and STiO<SUB>2</SUB> NPs showed 60% of antibacterial activity in all three bacterial species. </LI> <LI> PES-TiO<SUB>2</SUB> and -STiO<SUB>2</SUB> membranes revealed 95% non-toxic in bacterial cell viability test. </LI> <LI> PES-TiO<SUB>2</SUB> and -STiO<SUB>2</SUB> UF membranes are sustainable materials for MBR system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced cathode performance of a rGO-V₂O₅ nanocomposite catalyst for microbial fuel cell applications

Mahalingam, Shanmugam,Ayyaru, Sivasankaran,Ahn, Young-Ho The Royal Society of Chemistry 2018 Dalton transactions Vol.47 No.46

<P>A reduced graphene oxide-V2O5 nanocomposite was synthesized by a low temperature surfactant free hydrothermal method and its MFC performance was assessed. The structural properties of the synthesized nanocomposite were studied by X-ray diffraction. Field emission scanning electron microscopy of the nanocomposite revealed a wrinkled paper-like structure of rGO and a nanobelt-like structure of V2O5. This study estimated the viability of the graphene-based nanocomposite rGO-V2O5 as a novel cathode catalyst in single chamber air-cathode MFCs. A series of MFCs with different catalyst loadings were produced. The electrochemical behavior of the MFCs was calculated by cyclic voltammetry. The MFCs with the rGO-V2O5 nanocomposite cathode exhibited superior maximum power densities (83%) to those with the pure V2O5 cathodes. The rGO-V2O5 with a double-loaded nanocomposite catalyst achieved an enhanced power density of 1668 ± 11 mW m<SUP>−2</SUP> and an OCP of 698 ± 4 mV, which was 83% of that estimated for the Pt/C 2004 ± 15 mW m<SUP>−2</SUP> nanocomposite cathode. The significant increase in power density suggests that the reduced graphene oxide-V2O5 nanocomposite is a promising material for MFC applications. The CV result showed good agreement with the MFC result. The prepared rGO-V2O5 nanocomposite cathode, particularly with a double loading catalyst, is promising as a sustainable low-cost green material for stable power generation and long-term operation of MFCs.</P>