Environmental Nanoscience

Marc Michel

Associate Professor

Geosciences & Nanoscience

Virginia Tech

Leader, Division of Nanoscience

Deputy Director, NanoEarth

2022 Nanoscience Professional Development Workshop

Credit: Hochella et al.

Outline & Overview

• What is Earth & Environmental Nanoscience?
• What are some positive and negative impacts of nano?
• How can we get students excited to learn about E&E nano?
• Demo 1: Martian Water Challenge
• Demo 2: Micro- and Nanoplastics Remediation

Earth & Environmental Nanoscience

Credit: Georgia Tech

Clean Room

Credit: M. Schreiber (VT)

Nature (messy)

Nanoparticle Size vs. Surface Area

• Surface area increases with decreasing particle size
• 5 nm particle has approximately 50% of atoms at the surface
• Surfaces atoms important for chemical reactions

Big particle

Medium particles same overall size 20x more surface area

Tiny particles same overall size 60x more surface area

Nanoparticle Size vs. Surface Area

Credit: Good Food Grower

Credit: Virginia Tech

A spoonful (approximately 1 gram) of ferric oxide nanoparticles can have the same surface area as a basketball court (~500 m²)!

Size-Dependent Properties

Surface area-normalized

oxidation rate of Mn²⁺

Madden & Hochella (2005) GCA 69, 389-398

• Reactivity of nanoparticles can be dramatically higher than larger counterparts
• Due to fundamental change in (electronic) properties with size
• Small proportions of nanomaterials can dominate chemical systems

Earth & Environmental Nanoscience

1. Incidental - Byproducts of human activity
2. Engineered – Designed & manufactured
3. Natural – Since the beginning of time…

Formation, distribution, and critical roles played by nanomaterials in vital Earth system components, including direct human impact

Hochella et al. (2019) Science 363, 1414

Credit: Virginia Tech

Incidental Nanomaterials

Azcentral.com

Edward Burtynsky

Tennessean.com

Fires

Mining

Fossil Fuels

Engineered Nanomaterials

Sustainable-nano.com

Openpr.com

Oxides

The Conversation

Metallics

The Conversation

Metallics

Plastics

Natural Nanomaterials

Google images

Soils

Smart Water Magazine

NASA

Volcanoes

Sediments

Inventory of �Environmental Nanomaterials

Hochella et al. (2019) Science 363, 1414

• Natural NMs are critical components of biogeochemical systems
• Vastly more abundant than incidental and engineered
• Anthropogenic NMs can pose threats to ecosystem & human health

Opportunities for Innovation

Pesticides

Fertilizers

Remediation

Treatment

• Use Fun & Real-World Challenges
• Active Learning: Hands On, Minds On
• Scalable & Adaptable Activities
• The Future of Science is Interdisciplinary

How can we get students excited to learn?

Conventional Water Treatment

Credit: Genesis Water Technologies

Credit: ReNew the New – Regional New River Cleanup

Cleanwisconsin.org

• Process forms nanosized iron or aluminum hydroxides
• Removes a wide variety of dissolved and particulate inorganic and organic contaminants
• Surface chemical reactions (i.e., adsorption) are key

Martian (Nano)Mineralogy

Curiosity

NASA

• Martian soils contain abundant amounts of natural nanomaterials
• Ferrihydrite - a highly reactive natural nanoparticle that controls element cycling due to its high surface area and reactivity

Demo 1:

Martian Water Challenge

How could an astronaut stranded on Mars maintain a source of clean water?

Premise: The water treatment system in your Mars space station breaks and there are no spare parts to fix it. How could you use your knowledge of nanoscience and the materials available naturally on Mars to create a new solution?

Demo 1:

Martian Water Challenge

Martian Soil

Play Sand

Microplastics and Nanoplastics in the Environment

• Increasing concern due to impacts to human and ecosystem health
• Clothes fibers are a primary source
• Conventional water treatment only partly effective

Emerging Contaminants & �Nano-Enabled Solutions

• Groundwater contamination threatens drinking water supplies worldwide
• New remediation agents and strategies needed to treat traditional and emerging contaminants
• Engineered nanomaterials can be designed to overcome many challenges

Demo 2:

Micro- and Nanoplastics Remediation

• Challenge: How can a primary type of microplastic (dryer lint) be removed from a simulated wastewater?
• Illustrates concepts: Surface charge, magnetism, hydrophobicity, polar/nonpolar

Credit: Virginia Tech

Sustainable Earth:

Geo-inspired materials for cleaner energy, water/soil/air, and waste storage

Environmental implications of anthropogenic NPs (engineered/manufactured & incidental)

Natural Nanoparticles

Formation, abundance, and importance in Earth/planetary & environmental processes

Detection:

Advanced scattering, spectroscopy, imaging, and computation

Samples from complex media (soils, sediments, water treatment technologies, etc.)