Synergetic effects of dodecylamine-functionalized graphene oxide nanoparticles on antifouling and antibacterial properties of polysulfone ultrafiltration membranes

The potential use of dodecylamine-functionalized graphene oxide (rGO-DDA) nanoparticles as an antifoulant and antibacterial nanofiller was investigated. GO and rGO-DDA were analyzed using Raman spectroscopy, FTIR, SEM, TEM, and TGA that all confirmed the successful functionalization of GO structure. Polysulfone (PSF) ultrafiltration membranes incorporating varied loadings of GO and rGO-DDA were then fabricated via phase inversion approach. All membranes were characterized in terms of chemical structure, morphology, hydrophilicity, porosity and mean pore size. Cross-section SEM images showed the distribution of GO and rGO-DDA between the pores and on the polymer walls. AFM results demonstrated that GO addition increased the roughness of membrane; while with rGO-DDA addition the surface became smoother. Pristine PSF and rGO-DDA based membranes exhibited similar hydrophilicity, while GO-based membranes exhibited higher hydrophilicity as revealed by contact angle measurements. Permeability, separation and antifouling experiments were performed in a cross-flow membrane setup and showed that flux decreases with the increase in GO and rGO-DDA concentration. rGO-DDA membranes showed higher antifouling and antibacterial performance compared to the pristine PSF and GO membranes. Neat PSF exhibited 65.4 % flux recovery ratio (FRR) against BSA that was increased to 86.9 % and 89.1 % with GO-0.1 and rGO-DDA-0.1, respectively. Against HA, FRR was improved from 87.8 % for neat PSF to 95.6 % and 99.3 % with GO-0.1 and rGO-DDA-0.1, respectively. Additionally, rGO-DDA membrane exhibited higher bacteriostatis rate (83.6 %) against H. aquamarina than GO membrane (62.9 %). Moreover, rGO-DDA nanoparticles exhibited excellent dispersibility in several solvents making them promising nanofillers for various membranes with high antifouling and antibacterial performance.This work was made possible by an Award [GSRA4-1-0504-17043] from Qatar National Research Fund (QNRF, a member of Qatar Foundation). The contents herein are solely the responsibility of the authors. Open access funding is provided by Qatar National Library . Authors would like to thank also the Central Lab Unit (CLU) and Center of Advanced Materials (CAM) in Qatar University (QU) for their support in materials characterization. We also thank Dr. Mohammad Yousaf Ashfaq, Department of Biological & Environmental Sciences of Qatar University, for his support in antibacterial activity measurements.Scopu

Polydopamine functionalized graphene oxide as membrane nanofiller: Spectral and structural studies

High-degree functionalization of graphene oxide (GO) nanoparticles (NPs) using polydopamine (PDA) was conducted to produce polydopamine functionalized graphene oxide nanoparticles (GO-PDA NPs). Aiming to explore their potential use as nanofiller in membrane separation processes, the spectral and structural properties of GO-PDA NPs were comprehensively analyzed. GO NPs were first prepared by the oxidation of graphite via a modified Hummers method. The obtained GO NPs were then functionalized with PDA using a GO:PDA ratio of 1:2 to obtain highly aminated GO NPs. The structural change was evaluated using XRD, FTIR-UATR, Raman spectroscopy, SEM and TEM. Several bands have emerged in the FTIR spectra of GO-PDA attributed to the amine groups of PDA confirming the high functionalization degree of GO NPs. Raman spectra and XRD patterns showed different crystalline structures and defects and higher interlayer spacing of GO-PDA. The change in elemental compositions was confirmed by XPS and CHNSO elemental analysis and showed an emerging N 1s core-level in the GO-PDA survey spectra corresponding to the amine groups of PDA. GO-PDA NPs showed better dispersibility in polar and nonpolar solvents expanding their potential utilization for different purposes. Furthermore, GO and GO-PDA-coated membranes were prepared via pressure-assisted self-assembly technique (PAS) using low concentrations of NPs (1 wt. %). Contact angle measurements showed excellent hydrophilic properties of GO-PDA with an average contact angle of (27.8°).Scopu

On the Development of Part-Scale FEM Modeling for Laser Powder Bed Fusion of AISI 316L Stainless Steel with Experimental Verification

In laser powder bed fusion (LPBF), the effects of operating conditions on thermal gradients and residual stresses are the utmost challenges that require significant attention. The magnitudes of residual stress in the printed layers, as well as the distribution along the printed components, have not been well explained for LPBF parts. In this study, a 3D finite element thermo-mechanical model has been established to investigate the effect of operating conditions on thermal distribution, melt pool evolution, residual stress distribution, and part distortion. The printed AISI 316L stainless steel cubes have been characterized experimentally. The results showed a proportional correlation among the number of layers, thermal distribution, and melt pool dimensions. A combination of compressive and tensile stresses was recorded in the LPBF-ed parts. The Cauchy stresses were maximum in magnitude at the bottom and top surfaces along the xx- and yy-orientations, while these stresses increased in magnitude along with the part-build orientation (zz) within the whole printed cube except the top surface. The Von Mises stresses were minimal than Cauchy stresses. A maximum displacement was identified at the printed components\u27 contours, gradually decreasing from top to side walls and top surface. An inverse correlation was identified among average Von Mises stresses (AVMS), laser power (LP), and hatch distance (HD); however, a proportional relationship is presented between laser scanning speed (LSS) and AVMS. The average displacement (AD) presented an inverse relationship with LSS and HD, while a proportional correlation has been presented between LP and AD. Average thermal distribution (ATD) revealed an inverse effect on AVMS and a proportional effect on AD. In the printed parts, only austenite-gamma phase was identified along (111), (200), and (220) orientations, with a lack-of-fusion defect in the morphology

Bio-Inspired Fabrication of Ultrafiltration Membranes Incorporating Polydopamine Functionalized Graphene Oxide Nanoparticles

Graphene oxide (GO) and its based materials have gained a significant interest in the membrane functionalization sector in the recent years. Inspired by their unique and tunable properties, several GO-based nanomaterials have been investigated and utilized for various membranes in water treatment, purification and desalination sectors. In this dissertation, novel polysulfone (PSF) ultrafiltration membranes incorporating polydopamine-functionalized reduced graphene oxide nanoparticles (rGO-PDA) were fabricated and investigated. Starting from natural graphite, GO nanoparticles with high oxidation degree were synthesized using an improved Hummers' method. A GO functionalization based on the bio-inspired PDA was then conducted to produce rGO-PDA nanoparticles. The high-oxidation degree of graphite and the successful functionalization with PDA were confirmed using several analytical techniques including CHNSO elemental analysis, XPS, FTIR-UATR, Raman spectroscopy and XRD. Several bands have emerged in the FTIR spectra of rGO-PDA attributed to the amine groups of PDA confirming the successful functionalization of GO. Raman spectra and XRD patterns showed different crystalline structures and higher interlayer spacing of rGO-PDA. The change in elemental compositions was confirmed by XPS and CHNSO elemental analysis while the change in the morphological structure was confirmed by SEM and TEM analyses. The second part of the dissertation was on the embedding of the above mentioned nanoparticles in a membrane matrix. Pristine PSF, PSF/GO, and PSF/rGO PDA mixed matrix membranes (MMMs) were prepared by embedding GO and rGO PDA at concentrations from 0 to 0.15 wt% using the phase inversion technique. All membranes were analysed using FTIR-UATR, SEM, AFM, and contact angle. The cross-section SEM images showed better distribution of rGO-PDA nanoparticles in the pores and polymer wall whereas the pristine GO nanoparticles aggregate and partially block the pores. Thus, the flux increased with the embedding of rGO-PDA without affecting the rejection properties, while it decreased with the embedding of pristine GO. The highest pure water permeability (PWP) was obtained with PSF/rGO PDA-0.1 to be approximately twice that of the pristine PSF and PSF/GO-0.1. All membranes exhibited complete rejection of BSA and HA and showed almost similar rejection performance against different dyes. The flux recovery ratio of the pristine PSF after three fouling cycles (FRR3) against BSA and HA were recorded to be 57.8% and 70.7% respectively. FRR3 was enhanced by around 30% with PSF/rGO PDA composites. The MMMs prepared in this work are expected to have great potential on ultrafiltration and provide insights on developing other types of membranes embedding rGO-PDA with different materials and for different purpose

Polydopamine Functionalized Graphene Oxide as Membrane Nanofiller: Spectral and Structural Studies

High-degree functionalization of graphene oxide (GO) nanoparticles (NPs) using polydopamine (PDA) was conducted to produce polydopamine functionalized graphene oxide nanoparticles (GO-PDA NPs). Aiming to explore their potential use as nanofiller in membrane separation processes, the spectral and structural properties of GO-PDA NPs were comprehensively analyzed. GO NPs were first prepared by the oxidation of graphite via a modified Hummers method. The obtained GO NPs were then functionalized with PDA using a GO:PDA ratio of 1:2 to obtain highly aminated GO NPs. The structural change was evaluated using XRD, FTIR-UATR, Raman spectroscopy, SEM and TEM. Several bands have emerged in the FTIR spectra of GO-PDA attributed to the amine groups of PDA confirming the high functionalization degree of GO NPs. Raman spectra and XRD patterns showed different crystalline structures and defects and higher interlayer spacing of GO-PDA. The change in elemental compositions was confirmed by XPS and CHNSO elemental analysis and showed an emerging N 1s core-level in the GO-PDA survey spectra corresponding to the amine groups of PDA. GO-PDA NPs showed better dispersibility in polar and nonpolar solvents expanding their potential utilization for different purposes. Furthermore, GO and GO-PDA-coated membranes were prepared via pressure-assisted self-assembly technique (PAS) using low concentrations of NPs (1 wt. %). Contact angle measurements showed excellent hydrophilic properties of GO-PDA with an average contact angle of (27.8°).</jats:p

Functional GO-based membranes for water treatment and desalination: Fabrication methods, performance and advantages. A review

Graphene oxide (GO) and GO-based materials have gained a significant interest in the membrane synthesis and functionalization sector in the recent years. Inspired by their unique and tuneable properties, several GO-based nanomaterials have been investigated and utilized as effective nanofillers for various membranes in the water treatment, purification and desalination sectors. This paper comprehensively reviews the recent advances of GO utilization in pressure, concentration and thermal-driven membrane processes. A brief overview on GO particles, properties, synthesis and functionalization methods was provided. The conventional and the state-of-art fabrication methods of GO-based membranes were summarized and discussed, and consequently the GO-based membranes were classified into different categories. The applications, types, and the performance in terms of flux and rejection were summarized and reviewed. The advantages of GO-based membranes in terms of antifouling properties, bactericidal effects, mechanical strength and stability have been reviewed, too. The review gives insights on the future perspectives of GO functional materials and their potential use in the various membrane processes discussed herein.Other InformationPublished in: ChemosphereLicense: http://creativecommons.org/licenses/by/4.0/See article on publisher's website: https://dx.doi.org/10.1016/j.chemosphere.2021.129853</p