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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
Industrial
Development
CHEM & BIO-PROCESSING
MINING & MINERALS
ADV MAT & MANUFACTURING
Social
Development
WATER HEALTH
ENERGY
The DST National Nanotechnology Strategy of 2005
• Human Capital Development
• Develop research platforms
• Develop collaborative plan
• Innovation
Objectives
DST/ MINTEK Nanotechnology Innovation Center
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.
Mintek
Univ. Johannesburg
Research Group
Univ. Western
Cape Research
Group
Rhodes Univ.
Research Group
Wat
er N
anot
echn
olog
y U
nit
Governance Operations
S- Comm.
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
Commercial membranes
• Increase hydrophilicity
• Impart catalytic activity
Adsorbent beads • Scale-up of process
• Adsorbent bead assessment
In-house membrane formulation
• New polymer design
• With increased hydrophilicity
• Low pressure catalytic systems
• High flux membranes
• Anti-bacterial activity
Leading to lower operating costs and cheaper systems
WNU intervention – Current Projects
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
• Biofouling mitigation • Disinfection of water
• Selective removal of substances
• Stimuli responsive materials
• Organic pollutant degradation
• Fouling mitigation • Flux manipulation
Hydrophilic functionalities
Catalytic nanomaterials
Antibacterial nanomaterial
Functional groups
Core Science - Applications Functional polymers
as
Filtration membranes
Biofouling mitigation
Catalytic degradation
Coatings
Biofilm retardation
Disinfection
Adsorbents
Heavy metal
recovery
Homogeneous Ag@GO, PES
and PVP solution
Ag and Ag@GO composites
Graphene oxide sheets (0.5%)
AgNO3 (0.25, 0.5 and 1%)
PES and PVP solution
Filtration Membranes Preparation and Assessment
Ag nanoparticles
Cast Ag@GO/PES membranes
Filtration Membranes Preparation and Assessment
Membrane ID PES (wt.%)
PVP (wt.%)
GO (wt.%) AgNO3 (wt.%)
NMP (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
Table: composition of the casting solution for Ag@GO/PES membranes
Automatic casting equipment Cast membranes Dead-end cell
Filtration Membranes Preparation and Assessment Contact angle measurement
B
D
G
A
B
D
G
A
BD G
A
SEM AFM
A
B
Filtration Membranes – Assessment
v Overall membrane flux increase on nanomaterial addition
v Variation on contact angle and flux due composition of nanomaterials
Dead-end cells
Average flux @ 10 KPa
>3X
Pre-compacted at 20 KPa for 30 min. BSA rejection above 98% for all membranes
Contact angle
B D G A C E A B D GE C
ca b
Catalytic Membranes – Dechlorination of PCB77
PCB77 = 3,3’,4,4’-tetrachlorobiphenyl; 200ppm, 2l reactor at 0.5l/min., analysis by GC
Comm. PVDF
Washed PVDF (a)
Modified PVDF (b)
Antibacterial Action - Membranes and Coatings
MgO composites GO and Ag@GO composites
Control (PES) MgO Control (PES) GO Ag@GO
96%
81%
65% 71%
20% 77%
Filtration Membranes – scale-up production Ø Grafting optimisation, scale-up and membrane casting
Ø Initial membrane scale-up and potting
Scale-up 20 L
Grafting optimisation PES 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
Plenaries by Three (3) Nobel Laureates
MAM-14 Conference
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