Incorporation of nanotechnology into water treatment systems Current progress within the NIC 23-24 April 2014 Richard M. Moutloali Nano4Water
Outline Introduction Mandate and Aims of the DST/Mintek NIC Materials/Polymers Design and Application Areas Membrane Preparation and Assessment Catalytic membranes Biocidal membranes and coatings Summary Acknowledgements
Nanotechnology in South Africa The DST National Nanotechnology Strategy of 2005 Social Development Industrial Development WATER HEALTH CHEM & BIO- PROCESSING MINING & MINERALS ENERGY ADV MAT & MANUFACTURING Objectives Human Capital Development Develop research platforms Develop collaborative plan Innovation
DST/ MINTEK Nanotechnology Innovation Center Governance S- Comm. Operations Water Nanotechnology Unit Univ. Johannesburg Research Group Mintek Rhodes Univ. Research Group Univ. Western Cape Research Group A national facility that is geographically spread across the country and undertakes research, development and innovation activities towards addressing socio-economic challenges facing the country through nanotechnology.
National Nanotechnology Strategy - Water Social Cluster Research Questions and Challenges for Water Ø Supply of clean water Develop water purification modules Develop biodegradable, stimuli responsive nanoparticles for water treatment agent delivery Develop techniques to remove pathogens and chemical pollutants from water Preservation of water cleanliness Develop sensors for pathogens and chemical pollutants Ø Water scarcity and access to water Alternative and cost effective systems for sea water desalination New techniques for water harvesting Develop systems for water recycling at point of usage Effect an improvement in the portability of water Create appropriate conditions for rain (e.g. cloud seeding) Prevent or minimise water evaporation from water bodies Ø Water pollution Sensors for detection of water pollution Develop systems for removal of pollutants (recovery and/or inactivation) Beneficiate effluent Minimise contaminants through the use of nanotechnology Recover water from diluted mine effluent
WNU intervention Current Projects Commercial membranes In-house membrane formulation Increase hydrophilicity New polymer design Impart catalytic activity With increased hydrophilicity Adsorbent beads Low pressure catalytic systems Scale-up of process High flux membranes Adsorbent bead assessment Anti-bacterial activity Leading to lower operating costs and cheaper systems
Aims To develop membrane and nanotechnology systems to remove pollutants and pathogens from water at lower costs and higher efficiencies
Core Science - Functionalities Ø Polymer Design through: Ø Chemical grafting and click chemistry improve hydrophilicity Ø Nanomaterial blending multifunctional materials Fouling mitigation Flux manipulation Organic pollutant degradation Hydrophilic functionalities Catalytic nanomaterials Functional groups Antibacterial nanomaterial Selective removal of substances Stimuli responsive materials Biofouling mitigation Disinfection of water
Core Science - Applications Functional polymers as Filtration membranes Coatings Biofouling mitigation Biofilm retardation Catalytic degradation Disinfection Adsorbents Heavy metal recovery
Filtration Membranes Preparation and Assessment Cast Ag@GO/ PES membranes Homogeneous Ag@GO, PES and PVP solution Ag and Ag@GO composites PES and PVP solution Graphene oxide sheets (0.5%) AgNO 3 (0.25, 0.5 and 1%) Ag nanoparticles
Filtration Membranes Preparation and Assessment Table: composition of the casting solution for Ag@GO/PES membranes Membrane ID PES (wt. %) PVP (wt. %) GO (wt.%) AgNO 3 (wt. %) A 18 2 - - 80 B 18 2 0.2-79.8 C 18 2 0.2 0.5 79.3 D 18 2 0.5-79.5 E 18 2 0.5 0.5 79 F 18 2 1.0-79 G 18 2 1.0 0.5 78.5 NMP (wt. %) Automatic casting equipment Cast membranes Dead-end cell
Filtration Membranes Preparation and Assessment Contact angle measurement SEM G A D B AFM G D B B A A A B D G
Filtration Membranes Assessment v Overall membrane flux increase on nanomaterial addition v Variation on contact angle and flux due composition of nanomaterials >3X A Dead-end cells B C D E G Contact angle A B C D E G Average flux @ 10 KPa Pre-compacted at 20 KPa for 30 min. BSA rejection above 98% for all membranes
PCB77 = 3,3,4,4 -tetrachlorobiphenyl; 200ppm, 2l reactor at 0.5l/min., analysis by GC Catalytic Membranes Dechlorination of PCB77 a b c Comm. PVDF Washed PVDF (a) Modified PVDF (b)
Antibacterial Action - Membranes and Coatings MgO composites Control (PES) MgO GO and Ag@GO composites 65% 71% 81% 20% Control (PES) GO 96% 77% Ag@GO
Filtration Membranes scale-up production Ø Grafting optimisation, scale-up and membrane casting Scale-up 20 L Grafting optimisation PES Ø Initial membrane scale-up and potting PES-g-SS Bars = 20 µm
Filtration Membranes Piloting and Demonstration Ø Piloting and Technology demonstration - Long term assessment and validation
R&D Summary New Polymer Formulation and Assessment Scale-up and Demonstrations
Conclusion Through the DST Nanotechnology Strategy, the country has made strides in the application of Nanotechnology in water R&D
Acknowledgements
Thank You
MAM-14 Conference Plenaries by Three (3) Nobel Laureates