Investigating the effect of graphene oxide on scaling in thin-film composite polyamide reverse osmosis membranes Ali Ansari, Bo Cao, Xinyi Yi, Yandi Hu, and Debora Rodrigues Civil and Environmental Engineering, University of Houston, Houston, TX, USA Sixth Sustainable Nanotechnology rganization Conference November 5-7, 2017 1
Introduction bjectives Methodology Results Conclusions Water crisis Rapid population growth Water pollution from agricultural residues, sewage, and industrial waste Climate change Economy Water management 2
Introduction bjectives Methodology Results Conclusions Solutions Water reuse Seawater desalination 3
Introduction bjectives Methodology Results Conclusions Membrane technologies Micro filtration (MF) Ultra filtration (UF) Nano filtration (NF) Reverse osmosis (R) Forward osmosis (F) Membrane distillation (MD) Electrodialysis (ED) 4
Introduction bjectives Methodology Results Conclusions Reverse osmosis membrane Seawater desalination Drinking water production Brackish water treatment Wastewater treatment High water permeability High salt rejection 5
Introduction bjectives Methodology Results Conclusions Fouling in R membrane Accumulation of undesired deposits on the membrane surface or inside the membrane pores Increase salt passage through the membrane Creates hydraulic resistance of water flow through the membrane Induce potential for accelerated scale formation 6
Introduction bjectives Methodology Results Conclusions Fouling in R membrane In terms of place: Surface fouling Internal fouling Biofouling rganic fouling In terms of type: Biofouling Adhesion and proliferation of microorganisms rganic fouling Inorganic scaling Colloidal fouling Deposition of organic matters Inorganic scaling Crystal growth or deposition Colloidal fouling Deposition of small particles S. Jiang et al. / Science of the Total Environment 595 (2017) 567 583 7
Introduction bjectives Methodology Results Conclusions Scaling Ions exceeding the solubility equilibrium will trigger crystal growth R membrane S. Lee et al. / Journal of Membrane Science 163 (1999) 63 74 8
Introduction bjectives Methodology Results Conclusions Factors affect scaling Concentration Polarization Ionic Strength Co- Precipitation ph Pressure Velocity Temperature Surface Morphology Surface Chemistry 9
Introduction bjectives Methodology Results Conclusions Graphene xide (G) Well known antimicrobial property Anti scaling property? 10
Introduction bjectives Methodology Results Conclusions Graphene oxide effect on scaling Research Questions: How G affect the scaling and membrane recovery? What are the mechanism of the scaling? What type of scalant will form on the membrane coated with G? 11
Introduction bjectives Methodology Results Conclusions Coating R membrane (ESPA2) with G N CH N HC CH EDC N HH NHS H H CH H H N HC N CH Graphene N xide H C H C H H C H EDC H NHS N ED H 2 N N H H C H H N N H C H Polyamide active layer 12
Introduction bjectives Methodology Results Conclusions Coated membrane (ESPA2-G) characterization Surface zeta potential Water contact angle SEM Salt rejection Permeability 13
Introduction bjectives Methodology Results Conclusions ESPA2-G characterization: SEM ESPA2 ESPA2-G G coating makes surface smoother 14
Introduction bjectives Methodology Results Conclusions ESPA2-G characterization 99.6 98.9 ESPA2 ESPA2-G 82.2 43.1 Coating effects: No changes in permeability and salt rejection 4.86 4.87 Surface more negatively charged Permeability (L.m -2.h.bar -1 ) Salt rejection (%) -20.8-38 Surface zeta Potential (mv) Water contact angle Surface more hydrophilic 15
Introduction bjectives Methodology Results Conclusions Scaling tests Test 1 Test 2 SEM XRD High pressure Pump R cell Rejected or concentrated water Permeate or product water 16
Normalized Flux Normalized Flux Introduction bjectives Methodology Results Conclusions Scaling test: Flux decay Test 1 Test 2 Time (min) Time (min) G repels negatively charged gypsum crystals thus decreases formation of a cake on the membrane surface 17
Normalized Flux Normalized Flux Introduction bjectives Methodology Results Conclusions Scaling test: Recovery Test 1 Test 2 Time (min) Time (min) G makes more stable crystals, due to heterogeneous nucleation (higher number of CH) 18
Introduction bjectives Methodology Results Conclusions Characterization of the scales: SEM Test 1 Test 2 ESPA2 ESPA2 ESPA2-G ESPA2-G More nucleation sites on the ESPA2-G cause smaller size crystals 19 VL. 44, N. 6, 2010 / ENVIRNMENTAL SCIENCE & TECHNLGY
Introduction bjectives Methodology Results Conclusions Characterization of the scales: XRD Background All the scales are in gypsum form 20
Introduction bjectives Methodology Results Conclusions Conclusions G coating doesn t have negative effect on permeability and salt rejection G coating decreased scaling by repelling negatively charged gypsum, but decreased the flux recovery by making more stable crystals The size of the crystal decreased in ESPA2-G due to increase in nucleation sites The scales only form in gypsum structure on both ESPA2 and ESPA2-G 21
Introduction bjectives Methodology Results Conclusions Acknowledgments This presentation was made possible by NPRP grant # 9-318-1-064 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Thank you 22