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