Production of nZVI from LD slagPresented by- Monika Patel

Supervisor- Bharadwaz BhagawatiMaterial Modelling & Product Design

R&D and Scientific ServicesTata Steel

nZVI- what is it?

Iron in the zero valent state

brought down to nanoscale

nZVI= nanoscale Zero Valent Iron

nZVI has a core-shell structure, Fe(0) forming

the core and iron(hydro)oxide covering

as shell

Rationale behind using LD slag

A possible alternative application of this material can prove to be highly beneficial for the steel industry from the economic as well as environmental point of view

Pig iron

Steel

LD slag

Waste

Problems of LD slag• High mineral content• Presence of free lime• Large volumetric expansion

Constituent Composition (%)

Cao 40-52

SiO2 10-19

FeO 10-40

(70-80% FeO, 20-30% Fe2O3)

MnO 5-8

MgO 5-10

Al2O3 1-3

P2O5 0.5-1

S <0.1

Metallic Fe 0.5-10

Composition of LD slag *

*Jyoti Ranjan Mahakul, Dillip Makhija, Prashant Dixit, Report on Beneficiation of LD Slag, Tata Steel

20-40% Iron content

Used for production of nZVI

Applications of nZVI Groundwater remediation Wastewater treatment

Removal efficiency of Cu and Ni ions by nZVI #

• F. Fu et al. / Journal of Hazardous Materials 267 (2014) 194– 205• *R.A. Crane, T.B. Scott Journal of Hazardous Materials 211– 212 (2012) 112– 125• #APPLICATION OF IRON NANOPARTICLES FOR INDUSTRIAL WASTEWATER TREATMENT,16. - 18. 10. 2013, Brno, Czech

Republic, EU

nZVI can successfully remove *

Chlorinated organic compounds Nitroaromatic compounds Arsenic Heavy metals like Cr, Cu, Ni etc. Dyes Phenolic impurities

• Precipitation/co-precipitation of product species

• Reduction by Fe0

• Contaminants adsorbed on surface

Image source: In-Situ Remediation of Soil Contamination http://www.nanotech.dtu.dk/Research-mega/Forskningsgrupper/Surface_Engineering/Research/KAIST-Projekt#partners

Mechanism of impurity removal

Chemical synthesis of nZVI Reduction of aqueous solution of iron(III) chloride by sodium

borohydride

Limitations Toxic, corrosive fumes are evolved from chemical

precursors (borohydride) Evolution of flammable Hydrogen gas Rapid agglomeration on reaction with the oxidisable media

(dissolved O2 or water) Generally require special equipment or high energy

increasing cost of production

C.B. Wang, W.X. Zhang, Synthesizing nanoscale iron particles for rapidand complete dechlorination of TCE and PCBs, Environ. Sci. Technol. 31(1997) 2154–2156

Green synthesis of nZVI Green tea extract is used for reduction of iron as well as acting like a

capping agent on the formed iron nano particles to stabilize them. Green tea contains polyphenols (flavanols), more commonly known as

anti-oxidants, which reduce iron to its zero valent state.

Oakes, Jacqueline S., "Investigation of Iron Reduction by Green Tea Polyphenols for Application in Soil Remediation" (2013). Master's Theses. Paper 528

Advantages Increase reactivity, accelerate reduction, and

improve the physical structure of the Fe0

Synthesize nZVI in a single step without harmful by products

Stabilize the nZVI particles to prevent agglomeration

nZVI from LD slag- synthesis scheme

Sieving of LD slag

Wet Magnetic separation

Preparation of Green Tea

extract

Reaction of slag with GT extract

Recovering nZVI particles

through membrane filtration

Analyses and ResultsSEMXRD

SEM

SEM image of fresh GT-Fe revealed them to be quasi-spherical shaped nanoparticles

Size distribution is due to the different reducing properties of various naturally derived compounds in the green tea

Compared to the chemically synthesized nZVI, there are fewer aggregates in the green synthesized nanoparticles

It is attributed to the polyphenols or antioxidants in the GT-extracts acting as the capping agents

XRD

Fe0

FeOO

H

Fe3O

4

Range 0–118°scanning rate 2.0°/min

Fe(0) peak2θ=44.7º

Conclusion

nZVI has been successfully prepared from LD slag Green tea extract reduced iron nanoparticles and performed capping

action to stabilize them Studies are going on to analyze its efficiency in treating arsenic from

industrial wastewater Problem of slag disposal is thereby mitigated

Thank you !