Yale Center for Green Chemistry and Green Engineering

Nalas: Reduction of Acidic and Toxic Waste Streams in Explosives Manufacturing Using Electrochemical Nitration (2020-2023)

The work proposed aims to develop innovative scalable synthetic approaches leading to production of energetic materials that eliminate or dramatically reduce hazardous waste streams from nitration processes used in manufacturing. Specifically, the objective is to identify and optimize a protocol for performing nitrations electrochemically without the use of large excesses of nitric and sulfuric acids. The use of active nitrating agents electrolytically generated from species such as nitrogen tetroxide (N2O4), nitrite or nitrate salts has the potential to provide improved selectivity while reducing or eliminating acidic and/or toxic waste streams. Ideally, a process or set of complementary processes identified by this effort will be applicable to nitrations of a variety of substrates including aromatic hydrocarbons and polyols, maximizing impact across the portfolio of energetic materials currently in use by the United States DoD.

PI/co-PI: Nalas, Paul Anastas

Funding: DOD

Nanoscale metal oxides for removing inorganic contaminants (2020-2025)

Regulations on inorganic aqueous contaminants are becoming increasingly strict as research brings to light the negative impact of these contaminants on human health and the environment. Inorganic contaminants enter the environment from anthropogenic sources such as mining and industrial waste. The goal of our research is to develop a treatment process that both removes these inorganic contaminants while minimizing negative externalities associated with the process.

We are examining metal oxide nanoparticles, particularly iron oxides, as a possible treatment technology for these contaminants. The metal oxide nanoparticles are able to change the form of the contaminant for easier removal as well as remove the contaminant from solution. Furthermore, we are in the process of isolating and synthesizing iron oxide nanoparticles from mine waste, thereby closing industrial loops and turning mine waste into a value-added product.

PIs: Quan Lu (Julie Zimmerman is co-PI )

Funding: [1] National Science Foundations, Nanosystems Engineering Research Center for Nanotechnology Enabled Water Treatment Systems, 2020-2025; [2] Superfund Research Center, Metals and Metals Mixtures: Cognitive Aging, Remediation, and Exposure Sources (MEMCARE),

Sustainable remediation using nanopowder metal oxide-impregnated chitosan beads, 2020-2025

The depletion of natural resources and the damage being done to the environment as a result of increased demand for these resources has been felt over the past several decades. Our focus is on the development and implementation of a universal and sustainable heavy metal remediation technology to offset the risks posed by wastewater runoff from anthropogenic practices. While many technologies for specific metal remediation already exist, there is no single technology that addresses a large variety of related contaminants. Current efficient removal technologies have the drawback of being highly specific, and this lack of universality results in a difficult and unsustainable use-phase as wastewater is often contaminated with many metals. This project seeks to develop a nanopowder metal oxide-impregnated chitosan bead (MICB) adsorbent to be used for sustainable removal of arsenic and selenium from solution. Chitosan, a waste product from shellfish, also adsorbs metals like mercury, copper, and cadmium which often coexist with arsenic and selenium. The current work attempts to increase the selectivity of MICB adsorbent in highly complex environments, which are commonly seen in wastewater runoffs.

PIs: Quan Lu (Julie Zimmerman is co-PI )

Funding: [1] National Science Foundations, Nanosystems Engineering Research Center for Nanotechnology Enabled Water Treatment Systems; [2] Superfund Research Center, Metals and Metals Mixtures: Cognitive Aging, Remediation, and Exposure Sources (MEMCARE),

Utilizing supercritical fluids (SCFs) as green solvents for biodiesel and nanoparticle synthesis applications (2020-2025)

To advance sustainable nanotechnology, green synthesis methods that can produce a variety of high-quality nanoparticles are vital. Supercritical fluid synthesis is a promising green synthesis method since it not only can finely control nanoparticle features such as composition, size, shape, and surface features for many different nanoparticle compositions, but, in addition, it utilizes a greener synthetic route than alternatives through the employment of green solvents such as water, ethanol, and carbon dioxide. Supercritical fluid synthesis controls nanoparticle features by utilizing the unique properties associated with solvents in their supercritical state, when a solvent is at a temperature and pressure above its critical point. From this state to the subcritical state, properties such as density, dielectric constant, and solubilizing capacity, among others, change drastically and allow for conditions to control size, shape, and/or surface of nanoparticles. The solvent state and these properties are easily adjusted through changes in temperature and pressure allowing the supercritical fluid synthesis in-situ crystallization to be tuned to yield desired nanoparticle features. This work investigates the effect of untested process conditions on nanoparticle features with the goal of composition, size, shape, and surface control.

PI/co-PI: Julie Zimmerman

Silicification and lime wash encapsulation of wood (January 2021 – TBD)

As a collaborator of the Carbon Containment Lab at Yale, Momoko Ishii has been characterizing chemical compositions and mineral phases of lime wash and silica-sources, and also treated native wood with the aforementioned reagents. The goal is to minimize decomposition of wood and capture as much carbon as possible. The techniques used thus far are XRD (mineral phase), XRF (chemical composition), SEM with EDS detector (surface chemistry, elemental mapping), and Raman and IR spectroscopy (chemical composition, functional groups/molecular bonding).

PI: Carbon Containment Lab, Paul Anastas

Funding: Carbon Containment Lab

Advancing Sustainable Nanotechnology: Safter CNTs and CNT Enabled Products (2020-2025)

Carbon nanotubes (CNTs) are a class of nanomaterials that have the potential to significantly impact human health and the environment in both positive and negative ways. The vast number of CNT applications range from antimicrobial coatings, conductive thin films, advanced battery technology, and high strength composites. The unique properties that inspire these promising applications are also the cause of environmental and human health concern. This application-implication paradox serves as the motivation for our research, which focuses on better understanding the underlying physicochemical properties of CNTs that govern specific responses (e.g. antimicrobial and reactivity). Ongoing research projects focus on both the molecular and product level. At the molecular level, various techniques are used to systematically modify the surface chemistry of single- (SWNT) and multi-walled (MWNT) carbon nanotubes and thus, alter their physical and chemical properties. At the product level, our work seeks to evaluate the environmental and human health impacts associated with the production and implementation of nano-enabled products. In doing so, we established a quantitative approach to evaluating upstream impact and downstream benefit tradeoffs that can be applied to emerging technologies.

PIs/co-PI: Julie Zimmerman

Yale Center for the Study of Tobacco Product Use and Addiction: Flavors, Nicotine, and Other Constituents (YCSTP) 2018-2023

The Center provides the laboratory and analytical work to characterize tobacco products for use in the YCSTP (prior: Yale Tobacco Center of Regulatory Science, TCORS). In addition, the Center has pioneered and authored highly cited studies on the reactivity and presence of (1) reaction products within e-liquids and (2) synthetic, but odorless coolants that facilitate inhalation. Routine analyses have supported the YCSTP in determining nicotine, menthol, flavorants, artificial sweeteners, and Vitamin E acetate content in tobacco products such as e-liquids, cigarillos, waterpipe tobacco, nicotine pouches, and cigarettes from the US, Canada, and European countries.

PIs: Krishnan-Sarin, O’Malley (note: Julie Zimmerman is PI of the analytical core)

Funding: NIDA/NIH/FDA

Enabling biorefinery (2021- 2023)

The costs associated with producing renewable biofuels from algae have been prohibitive to their successful realization.  However, pursuing an integrated biorefinery model through the valorization of additional high value and high purity products from algae can favorably shift the economics of the system. Of importance to producing renewable fuels and chemicals sustainably, our work aligns with the Principles of Green Chemistry by replacing toxic organic solvents, typically used for extraction from biomass, with nontoxic, green solvents like carbon dioxide (CO2) through supercritical fluid extraction (SFE). In the supercritical phase, the solvation properties of CO2, such as solvent polarity or hydrogen donating and accepting capacity, can be tuned by adjusting the temperature and pressure to enable a selective extraction of different biomass fractions. In our work, carotenoids (“super-antioxidants” like fucoxanthin) are selectively extracted from the microalgae (e.g. Phaeodactylum tricornutumi) in a supercritical CO2 flow through system to yield a solvent-free, high value enriched extract with commercial applications in pharmaceutical and nutraceutical products. We use Kamlet-Taft solvent parameters to target optimal solvent conditions for the selective separation of carotenoids from other product streams based on polarity and solubility of the target compounds, and we examine the yields of fucoxanthin and other carotenoids achieved experimentally at these conditions. We are also investigating the role of a green and polar co-solvent, ethanol, for the selective extraction of fucoxanthin from P. tricornutum. This work advances a greater initiative towards a large scale algae-based bioeconomy via an environmentally benign, integrated biorefinery approach.

PI: Paul Anastas/Zimmerman

Funding: Betty & Gordon Moore Foundation

Rational design for biodegradation using predictive models

Chemical biodegradation has historically been measured using a variety of standardized tests. Typically, a single test informs the biodegradability of a single substance. However, it is not feasible to test all novel chemicals due to the time and money needed to perform standardized tests. Currently, chemists utilize a number of biodegradation models to better understand the biodegradability of new chemicals. These models commonly rely on calculated or measured descriptors or properties, some of which are not intuitive for chemists in the lab. To enable the rational design of biodegradable substances, predictive models should be based on chemical descriptors that are intuitive for chemists. Due to their ubiquitous use in substance characterization, spectroscopic measurements, in this case infrared (IR) and C-NMR spectroscopy, provide an intuitive and accessible alternative to the variables used in current biodegradation models. This project aims to explore linkages between IR and C-NMR spectra and the biodegradability of several hundred small organic molecules.

PI: Paul Anastas

Funding: Yale

Disulfide-containing polypseudorotaxanes as materials with a triggered degradation

Disulfide containing polymers are potent candidates for the production of recyclable and self-healing materials due to the relatively labile nature of the S-S bond. However, the relatively low BDE of this bond also results in limited thermal stability and light sensitivity of the final products. In this project we aim to address this limitation by designing a disulfide containing polymer with protected disulfide bonds. The protection is realized via the formation of a pseudorotaxane structure where the macrocyclic molecule, cucurbituril 6 (CB6), is placed around the disulfide linkages.The designed system allows to perform a triggered deprotection (sliding of the CB6 from the polymer chain which in turn exposes S-S bonds) via pH change, thus making the material amenable for recycling on demand.

PI: Elena Subbotina

Funding: EU Marie Curie Postdoctoral Fellowship

Biochar Systems for Sustainable Applications in the Food-Energy-Water Nexus (2019-2024).

This project targets bridging knowledge gaps for biochar production and effective applications in enhancing Food-Energy-Water sustainability by integrating LCA, techno-economic analysis (TEA), Geographic Information System (GIS), machine learning, and dynamic modeling.

PI: Yuan Yao

Funding: US National Science Foundation

Wood Honeycombs for Lightweight, Energy-Efficient Structural Applications Bioresource Structural Materials. (2021-2023).

The project will conduct life cycle analysis for the proposed wood technologies to understand the potential implications in reducing carbon footprints and energy consumption of structural materials.

PI: Yuan Yao

Funding: U.S. Department of Energy (through InventWood LLC).

A preconception cohort study of environmental chemicals, fertility, and miscarriage

This project will evaluate the impact of environmental chemicals on reproductive health as part of the Environmental Pregnancy Online (E-PRESTO) Study.

PI: Krystal Pollitt

Funding: Boston University (NIH/NIEHS)