Graphene-Coated PVDF Membranes: Effects of Multi-Scale Rough Structure on Membrane Distillation Performance

Abstract

Graphene-coated membranes for membrane distillation have been fabricated by using a wet-filtration approach. Graphene nanoplatelets have been deposited onto PVDF membrane surfaces. Morphology and physicochemical properties have been explored to evaluate the changes in the surface topography and related effects on the membrane performance in water desalination. The membranes have been tested in membrane distillation plants by using mixtures of sodium chloride and humic acid. The multi-scale rough structure of the surface has been envisaged to amplify the wetting and fouling resistance of the graphene-coated membranes so that a better flux and full salt rejection have been achieved in comparison with pristine PVDF. Total salt rejection and an increase of 77% in flux have been observed for coated membrane with optimized graphene content when worked with NaCl 0.6 M (DCMD, ΔT ≈ 24 °C) over a test period of 6 h. The experimental findings suggest these novel graphene-coated membranes as promising materials to develop functional membranes for high-performing water desalination.

Aliquots of MIL-140 and Graphene in Smart PNIPAM Mixed Hydrogels: A Nanoenvironment for a More Eco-Friendly Treatment of NaCl and Humic Acid Mixtures by Membrane Distillation

“…This is not surprising if we consider that MOFs are ri in carbonyl sites wherein water molecules can be temporarily adsorbed and transport through additional ordered nanoporous pathways. Similarly, defective graphene has be envisaged to have a great ability to assist water diffusion [26,35]. As expected, a slig decrease in flux is detected after 18 running hours, even if mass transfer through LAN continues to be the most consistent.…”

“…Herein, aliquots of hybrid responsive MOF supramolecular structures are demonstrated to already produce positive effects on flux under much softer operating conditions. Concerning graphene, many studies have also focused on the incorporation of few-layer, nanoplatelet, nanosheet, and quantum dot graphene in membranes [26,28,61,92,93]; however, only a few attempts have been made to adhere this material on the membrane surface for DCMD applications [35,92]. Herein, we demonstrate how the deposition of random and discrete aliquots of graphene on PVDF membrane surfaces is In summary, we demonstrated how an ionic hydrogel-based nanoenvironment (0.5 mg/cm 2 ), where aliquots of 2D materials are confined, yields proficient cooperative mechanisms at the membrane surface-solution interface.…”

“…A desired target is to use the minimum quantity of nanofiller to enhance water yield. An option could be to confine small quantities of materials to the membrane surface considering that interfacial interactions between the membrane and surrounding environment can decide the final result [23,[30][31][32][33][34][35]. In every membrane process, including MD operations, engineered membrane surfaces are in fact already expected to establish selective interactions with approaching solutions at the early stage [36][37][38][39][40][41][42][43][44][45][46][47][48][49].…”

“…Specifically, a layer-by-layer (LbL) spray technique [50][51][52][53][54][55][56][57][58][59][60] is used for adsorbing randomly discrete complexes of a Zr-MOF compound and graphene and hydrogels on the surface of a PVDF membrane. While graphene together with other 2D materials has been successfully tested in MD operations [23,26,35,[61][62][63][64][65][66][67][68][69][70][71], there is not yet a solid indication about the potential of metal-organic framework compounds (MOFs) in DCMD applications [72][73][74].…”

Novel Approach to Landfill Wastewater Treatment Fouling Mitigation: Air Gap Membrane Distillation with Tin Sulfide-Coated PTFE Membrane

“…membranes’ water flux and fouling resistance. The graphene-coated PTFE membrane generally displayed improved water flux and fouling resistance due to its surface’s multiscale roughness [ 34 , 35 , 36 ]. Physical coating of the M.D.…”