This document discusses the use of colloidal nanostructures for environmental contaminant capture. It provides two case studies: (1) Zr-based metal organic frameworks (MOFs) that have high surface areas and pore sizes allowing them to effectively adsorb various organic and inorganic contaminants; and (2) CuZr bimetallic nanoparticles that show favorable binding of carbon dioxide through computational modeling and experiments. The document also briefly mentions other applications of multifunctional nanoparticles for water treatment and challenges in scaling up these colloidal structures.

1. Colloidal Applications for
Environment - Contaminant
Capture
Jaskaran Singh Malhotra

2. Contents
● Colloidal chemistry and Nanostructures
● Case study - Zr-based Metal Organic Frameworks (MOFs)
● Case study - CuZr bimetallic NPs for Carbon Capture
● More design strategies
● Challenges
● Future scope

3. Colloidal synthesis of nanostructures
Colloidal chemistry
Colloidal chemistry
Nanoparticles
Nanorods/Nanowires
Metal Organic
Frameworks (MOFs)
Nanomembranes
Colloidal cluster
synthesis, Sol-gel,
hydrothermal
growth,
microemulsion,
co-precipitation

4. Why nanostructures?
Colloidal chemistry
Nanostructures
Large Surface Area High reactivity
Easy synthesis Tunability

5. Zr-based Metal Organic Frameworks (MOFs)
● Porous materials
● Tunable pore size
● Can bind to Organic and Inorganic
contaminants
● Capturing/Catalysis/Filtration
● Why Zr? - High chemical and
thermal stability
Drout (2019) Trends in Chemistry

6. Zr-based Metal Organic Frameworks (MOFs)
Drout (2019) Trends in Chemistry
Contaminant MOF BET Surface Area
(m2/g)
Pore size (Å) Adsorption capacity (mg/g)
Atrazine
(Organic)
UiO-67 2350 12,16 26
Methylene Blue
(Inorganic)
UiO-66 1280 17 70
Methyl Orange
(Inorganic)
UiO-66 1280 17 84
Tetracyline
(Pharmaceutical)
UiO-66 590 10.3 23
Adsorption of some common contaminants with specific Zr-based MOFs

7. Zr-based Metal Organic Framworks (MOFs)
Some synthesis routes for Zr-based MOFs
● Room temperature - Refluxing Zr-precursor with benzoic acid in 1-propanol overnight. Followed by
dissolution in acetic acid and adding linker solution dropwise (Noh, 2018, Chem. Mater.); low energy
input, low cost
● Water based - Use of effective proportions of modulators (acetic acid/formic acid/trifluoroacetic acid)
and tuning temperature with Zr-precursors in water (Hu, 2016, Cryst. Growth Des.); easy tunability,
milder conditions
● Supercritical Fluid approach - Precursors dissolved 1:1 Dimethyl Sulfoxide(DMSO)/methanol and
crystallization induced with CO2 at 40oC and 40-100 bar pressure (Doan, 2017, ACS Sustain. Chem.
Eng.); high purity
● Mechanochemical - Milling of precursors and linkers (Fidelli, 2018, Chem. Commun.); fast, potential for
industrial scalability
Drout (2019) Trends in Chemistry

8. Carbon capture
● Computational approach (DFT)
● Icosahedral Cu55 Nanoparticle
● Cu54M (M=Au, Mn, Mo, Ni, Pd, Rh, Ru, Sc, V,
Zn, and Zr) were analysed
● CO2 adsorption binding energy was
studied
● Zr - Strong segregation on Cu NP surface;
strongest Carbon binding capability
Dean (2018) ChemSusChem

9. Carbon capture
● Cu54Zr, Cu54ZrO2, Cu54ZrO4 oxidised
species were also analysed
● CO2 adsorption binding energy was slightly
decreased but still favorable
● Chemisorption; localized site has higher dc
orbital energy than CO2 LUMO
Dean (2018) ChemSusChem

10. Carbon capture
● CuZr bimetallic NPs were synthesized
using wet impregnation method -
Stoichiometric precursors were mixed in
ethanol, dried and then calcined. SiC was
used for support
● TEM, EDS, XRD shows formation of some
bimetallic phase CuZRO3 particles as well
as pure Cu and ZrO2 particles
Dean (2018) ChemSusChem

11. Carbon capture
● CO2 capture ability was studied by
Temperature Programmed Desorption
(TPD) on CuZr, pure ZrO2 and pure Cu (all
on SiC substrate) for reference
● For pure Cu, almost no CO2 signal is
observed
● For Bimetallic CuZr, strong CO2 signal is
observed
Dean (2018) ChemSusChem

12. MOFilters for PM capture
● Different MOF powders (ZIF-8, UiO-66-NH2, MOF-199,
Mg-MOF-74) were prepared on different polymers
(polyacrylonitrile, polystyrene, & polyvinylpyrrolidone) by
electrospinning
● ZIF-8 highest Zeta potential, hence high adsorption
capability
● High loading (~60 wt%) without segregation
● 33 μm MOFilters can capture PM2.5 and PM10 with a
high efficiency (~90%)
● Highly selective towards SO2 adsorption
Zhang (2016) JACS

13. Multifunctional Nanoparticles
● Photocatalytic degradation
● Superparamagnetic core + active
degradation shell particles
● Selectivity via size/crystal structure tuning
● Useful in water treatment
Alvarez (2018) Nature Nanotechnology

14. Challenges
● Scaling
● Rigidity - loss of structure
● Environmental concern - when the structures themselves disintegrate
● Functional device feasibility
● High Selectivity

15. More Applications and future scope
● “Capturing Nanostructures” can also be synthesised to capture rare elements
from seawater
● Can also be used as catalysts reactions highly efficient
● Medical - Artificial Red Blood Cells

16. Thank You