Environmental Nanoscience

Summary: The point of this lesson is to introduce students to a conventional method for treating contaminated water. Students will become more aware of drinking water sources, common types of contaminants in source water, and treatment using coagulation/sedimentation. They will also consider how particle size relates to surface area, as well as how the charges of metal oxide nanoparticle surfaces and contaminants are essential for explaining how they interact with one another during the treatment process.

Nanoscience Connection: Coagulation and sedimentation is widely used for water treatment because it is relatively cheap and effective at removing a variety of contaminants. The process involves formation of nanosized iron and/or aluminum hydroxides that react with contaminants through surface adsorption and other processes. The properties of nanoparticle surfaces including area, charge, reactivity, and adsorption are key concepts in nanoscience and nanotechnology. By learning about conventional water treatment, students are ready to understand alternative treatment strategies, as well as how contaminants interact with nanoparticles in environmental systems e.g., soils.

Learning Objectives:

• Give examples of common drinking water sources and types of contaminants

• Describe conventional water treatment using coagulation and sedimentation

• Describe the relationship between nanoparticle size and surface area

• Explain how the surfaces of a particle are charged in water

• Define adsorption and explain the role it plays in conventional water treatment

Summary: The point of this lesson is to introduce students to the basic mineralogy of Martian soils, as well as to x-ray diffraction (XRD) which is a method commonly used to evaluate the atomic structures of natural and synthetic materials. Students will become aware that Martian soils contain significant amounts of iron oxide nanoparticles and consider the importance of these particles in physical characteristics of the planet. They will also consider how the presence of nanosized particles (like those formed during the coagulation step in water treatment) can react with contaminants in soils. The lesson is enhanced by a hands-on activity that uses simulated Martian soil containing a minor amount of ferrihydrite to remove dissolved and particulate contaminants from simulated wastewater.

Nanoscience Connection: Ferrihydrite is a nanosized mineral found virtually everywhere in Earth surface environments as well as in Martian soils (including Martian soil simulants). It is a critical component in the environment because it controls the transport and fate of contaminants due to its high surface area and reactivity. By learning about Martian soil (nano)mineralogy, students are ready to understand how the reaction of contaminants with nanoparticles in environmental systems e.g., soils is analogous to what happens in the process of conventional water treatment.

Learning Objectives:

• Describe the general objective(s) of recent Mars rover exploration missions

• Explain what type(s) of information are provided by x-ray diffraction (XRD)

• Describe how Martian soils contain both crystalline minerals and nanosized/amorphous particles

• Explain how ferrihydrite is widespread and important in environmental systems

• Describe a basic column filter experiment

Summary: The point of this lesson is to introduce students to the importance of groundwater as a source of drinking water and the issue of contamination. Students will become more aware of what are the common types of groundwater contaminants, how they enter the subsurface, and how they move and spread due to groundwater flow. They will also become more aware of common remediation techniques and why they are limited due to issues with subsurface complexity. They will be provided with an example of enhanced nanoparticle reactivity, as well as consider how engineered nanomaterials can provide novel nano-enabled approaches to remediation, including applications with challenging emerging contaminants.

Nanoscience Connection: Surface and subsurface contamination threatens freshwater supplies at sites worldwide. Engineered nanomaterials can be developed to overcome challenges to conventional remediation strategies including targeting and selectivity, as well as treating emerging contaminants that resist degradation. By learning about the importance of groundwater and the threats and challenges to remediation, students are ready to build on these concepts and explore nano-enabled solutions.

Learning Objectives:

• Explain what is the water table and what determines the movement of water in the subsurface

• Give an example of a point source of contamination and describe two mass transport processes in groundwater

• Explain why contamination of groundwater supplies is an important problem

• Explain the enhanced reactivity of nanomaterials can cause them to dominate a chemical systems

• Describe how the enhanced reactivity and other selected properties of nanomaterials can be used to develop new remediation agents and treatment strategies

Summary: The point of this lesson is to introduce students to the growing worldwide environmental problems that stem from plastic waste. Students will become more aware of the types of plastic used in commercial products, how it enters the environment, the transformations and degradation behavior, and potential hazards to humans and biota. They will consider the effectiveness of conventional water treatment (coagulation/sedimentation) in removing microplastics from wastewaters. The lesson is enhanced by a hands-on activity that uses magnetic nanoparticles (ferrofluid) to remove microplastic fibers (dryer lint) from simulated wastewater.

Nanoscience Connection: Plastic pollution is a rising concern that requires an interdisciplinary research approach to understand and reduce threats to human and ecosystem health. Nanoscientists use advanced characterization methods and knowledge of nanoscale phenomena to understand the formation, transport, reactivity and chemical behavior, and threats of micro/nanoplastics in the environment. By learning about micro/nanoplastic pollution and processes used to purify and treat water, students are ready to build on these processes and explore nano-enabled solutions.

Learning Objectives:

• Describe ways that they use plastics in their everyday lives and the advantages

• Give examples of primary and secondary sources of micro/nanoplastics in the environment

• Describe transformations and potential hazards of micro/nanoplastics

• Explain the effectiveness of conventional water treatment strategies in removing micro/nanoplastics from wastewater

• Describe a nano-enabled remediation strategy for micro/nanoplastics (hands-on activity)