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By Christiana Briddell, Sr. Communications Manager, ACS Green Chemistry Institute, and featuring Yalinu Poya, Ph.D. student at the University of Glasgow.

 

When you start to scratch the surface of the U.N. Sustainable Development Goals (SDGs), the first thing that becomes apparent is that they are often interconnected and have synergistic relationships. A world without hunger is the ideal of Goal #2. This goal alone reaches beyond agriculture practices and touches social and financial systems, land development trends, equality and access issues; grapples with the threats from climate change (to which agriculture also contributes); and impacts the health of land, air, and water.

 

The key, however, to ending hunger has to be in developing a comprehensive, fundamentally sustainable food production system that is resilient to the effects of climate change, maintains and promotes biodiversity, water and land management practices, and can be applied by the small-scale farmers that make up the 40-85% of food production in many parts of Asia, Latin America and Africa.

 

Currently, the U.N. estimates that 1 in 9 people in the world are undernourished, a number that has risen over the last three years rather than declined. In Africa, 20% of the population is considered undernourished, but even in wealthy countries like the United States, food insecurity affects 11% of the population.

 

There are many areas related to Goal #2 that are relevant to chemists. Increasing agricultural production and fighting pests has been the focus of agricultural scientists for decades. New technology-assisted farming promises a smarter approach to fertilizer application, crop protection management, and water management.

 

Innovations such as Dow AgroSciences LLC’s Instinct Technology, (which won a Green Chemistry Challenge Award in 2016), helps reduce nitrogen pollution from fertilizer runoff by making the nitrogen in fertilizer applications more available to crops and slower to degrade into unusable forms.

 

Phosphorus, like nitrogen, is essential for plant growth and one of the main ingredients in fertilizer, but phosphorus will become increasingly difficult to mine in the future, with peak production estimated to hit between 10-60 years from now. Currently, most phosphorus that is not absorbed by plants, runs off into water bodies where it contributes to eutrophication. Research is needed to find ways to recover and recycle phosphorus from sewage treatment plants using low-energy, highly-efficient separations.

 

Alternative pesticides, fungicides and herbicides that are more environmentally friendly are another area of ongoing research and development. Biopesticides, derived from microorganisms that naturally attack crop pests and diseases, have been explored for a variety of applications. For example, Agraquest, Inc. (now Bayer CropScience) was an early Green Chemistry Challenge Winner for their biofungicide Serenade, which makes use of a naturally occurring bacteria. Companies like Marrone Bio Innovations have developed a number of bio-based solutions derived from microorganisms and plant extracts.

 

Genetic resilience is important to this goal, with a focus on preserving the genetic diversity of crop species for the future. Finding varieties and modifying genes in order to develop qualities such as drought resistance may be an important tool as some regions dry out. In other regions, there will be a need for salt-resistant crops, or protection from molds and fungus, and in all cases, increased yields.

 

Improving the Sustainability of Nitrogen Production through Catalysis

 

One of the biggest challenges to making the modern agricultural system more sustainable is the energy demands of a reaction at its heart—the Haber-Bosch Process for the production of ammonia. I asked Yalinu Poya, originally from Papua New Guinea, and currently a Ph.D. student in Prof. Justin Hargreaves research group at the University of Glasgow, U.K., to share her approach to this issue:

 

Picture 1: Sourced from https://www.greentalents.de/yalinu-poya.php

Catalysis is continuously making great contributions towards improving, or in some cases, resolving some of the world’s most common and demanding challenges that we continue to face. My specialty is in heterogeneous catalysis with my Ph.D. research focusing on synthesizing catalysts for ammonia production in the Haber–Bosch Process. The Haber–Bosch Process is a mature technology developed in the early 20th Century, however there are many currently pressing challenges to make it more sustainable. By addressing its catalyst component through my research, I believe many of the problems associated with the process can be solved, or my research could contribute to a greater solution.

 

The Haber–Bosch Process, which was developed in the early 1900’s, was a landmark achievement of the 20th Century. Currently, the process produces over 174 million tonnes of ammonia annually, establishing an accessible route for the production of over 450 million tonnes of synthetic fertilizer. In itself, this sustains food production for 40% of the global population.

 

The Haber–Bosch Process involves combining pure H2 and N2 feedstreams directly over a promoted iron catalyst at temperatures of around 400°C and reaction pressures of over 100 atmospheres. The reaction is exothermic and is equilibrium limited, thus it is thermodynamically favoured at lower reaction temperatures. Despite this, the temperature of operation is dictated by the requirement to achieve acceptable process kinetics.

 

Due to the reaction conditions involved in the process at a global scale, including the generation of feedstock, the operation of the Haber–Bosch Process currently consumes 1-2% of the world’s energy demand and produces 1.6% of man-made CO2 emissions. To reduce these harmful effects and yield massive rewards both in terms of economic and environmental benefits, there is great interest in the development of small-scale local ammonia production plants based on renewable hydrogen generated from water via electrolysis and powered by sustainable electricity sources such as wind energy. In such a context, which would facilitate the production of ammonia on a localized scale close to its point of use such as on a farm, it is necessary to develop novel ammonia synthesis catalysts which are active under less severe operational conditions appropriate to smaller scale reactors.

 

It is notable that a number of active ammonia synthesis catalysts are comprised of cobalt in addition to other active metals – a combination of cobalt and rhenium as a bimetallic catalyst shows high ammonia synthesis activity. Despite its low surface area, cobalt rhenium is an active catalyst in ammonia synthesis, however a more highly dispersed catalytic phase can be obtained by application of a suitable catalyst support. It can be anticipated that this would lead to enhanced catalytic performance.

 

The United Nations has designed and implemented 17 Sustainable Development Goals specifically to make the world a better place by facilitating a sustainable future for everyone. It is estimated that the world population will reach 9.1 billion by the year 2050, consequently food production will need to rise by 70% to keep up with global demands. Farmers will require more fertilizers to maintain fertile soil in order to produce healthy crops, which will result in an increased demand in the production of fertilizers. Since ammonia is the main component in fertilizers, it too will need to increase in production in order to fulfill Goal 2–Zero Hunger.

 

Picture: Sourced from https://www.greentalents.de/yalinu-poya.php

By David Constable, Science Director, ACS Green Chemistry Institute

 

In 2013, members of the American Chemical Society Green Chemistry Institute (ACS GCI) Chemical Manufacturers Roundtable (ChMRT), conceived a project to identify how to fundamentally change the way separations technologies are applied in the chemical processing industries. The Roundtable formed a collaborative partnership with the American Institute of Chemical Engineers (AIChE) and received funding from a NIST AmTech grant, to make this project, the Road Map to Accelerate Industrial Adoption of Less-Energy Intensive Alternative Separations (AltSep), a reality.  The initiative was led by ACS GCI ChMRT members, Robert Giraud of Chemours and Amit Sehgal of Solvay, with assistance from David Sullivan of Kraton Industries and Samy Ponusammy of MilliporeSigma. Today, the ACS GCI released the project’s final report, which is considered a key step forward in advancing the rational design and predictable, widespread, industrial application of less energy-intensive separations processes as alternatives to distillation.

 

The implementation of alternative separations technologies, as identified in the AltSep report, has the potential to transform the competitiveness and sustainability of the global chemistry enterprise.  Conventional fluid separations account for over 33% of the energy use and over 50% of the capital investment of chemical plants. Despite the cost of these conventional systems, the technology infrastructure changes needed to facilitate industrial availability of less energy-intensive alternative separations processes are so fundamental and significant that they are far beyond the resources of one, or even a small group of companies. The AltSep team recognized early on that a cross-cutting, integrated approach to identifying and prioritizing research, development and demonstration projects would be needed to solve technical challenges, and these challenges were best met by starting at the molecular level.    

 

To enable cost-effective, energy-efficient, fluid separations, the Road Map suggests that beginning with a molecular property-based framework for the selection, simulation and design of industrial separations processes could lead to:

 

  • Reduction of substantial energy use and the associated greenhouse gas emissions compared to separations via traditional approaches, primarily, distillation.
  • The recovery of valuable components in dilute process or waste streams, thereby supporting increasing the U.S. chemical industry's competitiveness and substantially improving its environmental performance.
  • The creation of good, high-technology manufacturing jobs by promoting and advancing new technologies and engineering tools.
  • Educating next generation business, science and engineering leaders in a range of more sustainable separations technologies.

 

The Road Map was developed based on the output from a series of six workshops with a total of 185 participants held over three years and resulted in the articulation of nine research and technology areas shown in the figure below. Workshop participants included experts in separations technologies, molecular modeling, physical/chemical property estimation, self-organizational or interfacial processes, process simulation and design, and other innovators from chemical sciences, physics, and engineering from the chemical process industries, universities, separations equipment and separating agent providers, national labs, and federal agencies. A publicly available version of the AltSep Road Map in PDF format may be downloaded here: AltSep Report 2019

annotation graphic

 

Figure 1:  AltSep key research, development and demonstration needs.

By Jenny MacKellar, Program Manager, ACS Green Chemistry Institute

 

Here at ACS GCI, ensuring that the next generation of chemists is educated with a green chemistry perspective is one of our strategic priorities. Over the years, ACS GCI has developed and led many programs to support this objective, such as our awards programs, student workshops, summer school, and webinars and other resources for ACS undergraduate chemistry chapters. However, we realized the development of a green chemistry education roadmap was needed—a strategic initiative that articulates the goals, implementation strategies and resources needed, while aligning the community around its vision.

 

The vision of the roadmap is to advance chemistry education that equips and inspires chemists to solve the grand challenges of sustainability. Our multi-pronged approach to addressing this vision includes:

 

  1. Describing what green chemistry looks like in the practice of chemistry
  2. Identifying what students need to know to advance sustainability
  3. Offering professional development opportunities to enable faculty to effectively teach green and sustainable chemistry concepts
  4. Creating pull, or demand, from employers seeking to hire chemists with this type of knowledge

 

Through a series of workshops with green chemistry and chemistry education practitioners, a set of green chemistry core competencies for chemistry graduates was developed. The core competencies are highly aspirational, inspirational goals for the next generation of chemists. In order to achieve these goals, a systems thinking approach to chemistry is necessary. However, since the vision and competencies are very high level, extensive work needs to be done to bridge from the aspirational ideas to concrete examples.

 

We are using a multi-pronged approach to advance the vision of the green chemistry education roadmap and adoption of green chemistry into the undergraduate curriculum. One of these approaches has been a partnership with the ACS Examinations Institute to develop a green chemistry theme for the organic and general chemistry Anchoring Concepts Content Maps (ACCM). This process was described in a publication released last week in the Journal of Chemical Education.

 

The product of this collaboration draws connections between green chemistry concepts and the typical content found in general chemistry and organic chemistry courses. Using the ACCMs, we are able to demonstrate that we are not removing fundamental chemistry concepts in favor of green chemistry, rather we are suggesting modifications to existing concepts that would better prepare students to practice chemistry in a more sustainable way.

 

Another reality that we are facing is a crowded curriculum. Demonstrating where green chemistry concepts fit into the foundational chemistry content will also help educators select the most appropriate and meaningful examples for their setting. We understand that flexibility is paramount and that no two institutions are the same.

 

Over the next three years, we will use the green chemistry-themed ACCMs to develop education materials and host capacity-building, or train-the-trainer, workshops to support educators in adopting green chemistry content into their courses. As we move forward with this project, one of the most important things we can have is strong support and engagement from this community and the chemistry education community. We need your candid and productive participation in this process to create the best possible materials and to help create the network to support educators. We will be partnering with other key stakeholders in the community to move this forward as well. So how would you like to be involved? Contact us at gci@acs.org.

By Evan Riley, Communication Associate, ACS Green Chemistry Institute

 

In order to reimagine chemistry for a more sustainable future, the next generation of chemists needs to have a working knowledge of green and sustainable chemistry principles and practices. Attending and presenting at a scientific conference is an important milestone and professional development opportunity for young researchers. To enable this experience for more early-career scientists, the ACS Green Chemistry Institute (ACS GCI) administers several annual awards for students and postdoctoral scholars pursuing research that incorporates green chemistry and engineering design principles. To date, over 100 scholars have benefited from these awards. Many of these scholars have gone on to become scientists and engineers leading the way, as we strive to develop chemistry solutions for the world’s grand sustainability challenges.

 

This year, eight awardees were selected from an impressive pool of applicants. We were excited to see innovative green chemistry work being done by young researchers both domestically and internationally.

 

Thank you to our dedicated judging panels for volunteering their time to review the ever-growing number of applications. This was not an easy task! And, last but certainly not least, congratulations to these outstanding researchers! We’re excited to see what’s in store for you.

 

Kenneth G. Hancock Memorial Award

The Kenneth G. Hancock Memorial Award provides national recognition and honor for outstanding student contributions to furthering the goals of green chemistry through research and/or studies. The ACS Division of Environmental Chemistry and the National Institute of Standards and Technology support the award. Recipients receive $1,000, and an additional $1,000 is available to support travel.

 

The 2020 award will be presented during the 24th Annual Green Chemistry & Engineering (GC&E) Conference, June 16-18, 2020 in Seattle, Washington.

Fernandez 

Ariel Fernandez is an undergraduate chemistry student from the University of Costa Rica. Fernandez’s research is aimed at developing an alternative use for a ubiquitous waste product: cigarette butts. The study finds a way to reuse all parts of the waste product. The extraction of any remaining nicotine to be used locally as a more environmentally friendly pesticide; tar can be converted into biochar and used to filter heavy metals from water; filter material can be decontaminated and used for water filtration; and the paper portion can be recycled into paper business cards.

 

Metin 

Metin Karayilan, a Ph.D. candidate in organic and polymer chemistry at the University of Arizona, is being honored for his work on biomimetic metallopolymers with enhanced catalytic activity for sustainable hydrogen production in water. His research aims to improve the electrochemistry of H2 production as an energy storage solution for renewable energy sources using earth-abundant catalysts.

 

 

Joseph Breen Memorial Fellowship

The Joseph Breen Memorial Fellowship supports the participation of young green chemistry scholars from around the world to attend an international green chemistry technical meeting, conference or training program. The award was established in 2000 through the ACS International Endowment Fund in commemoration of the late Dr. Joe Breen, first director of the Green Chemistry Institute. Each winner receives up to $2,000 for travel and conference expenses.

 

From the nominations received, the 2020 winners are:

chapman 

Emily Chapman is an undergraduate chemistry student from Augsburg University in Minnesota. Chapman has helped to develop a greener alternative to the classic Biginelli reaction using microwave irradiation and a urea catalyst.

 

 

 

 ischia

Giulia Ischia is a Ph.D. student from The University of Trento in Italy. Her work investigates thermochemical processes for the valorization of waste biomass into bio-based products, sustained completely by solar energy.

 

Both women will be presenting their research at the 24th Annual Green Chemistry & Engineering Conference in Seattle, Washington next June.

 

Ciba Travel Awards in Green Chemistry

Established in 2009 through the Ciba Green Chemistry Student Endowment, the Ciba Travel Awards in Green Chemistry aim to expand students’ understanding of green chemistry by facilitating their participation in a scientific conference. The award amount covers conference travel expenses up to $2,000.

 

The winners of the 2020 Ciba Travel Award in Green Chemistry are:

 enright

Mollie Enright, a second-year graduate student in chemistry at the University of Toledo, is studying iron-catalyzed cross-coupling of heterocycles. Her study involves utilizing inexpensive, abundant and less-toxic metals to perform chemical transformations. Enright has been a passionate advocate of green chemistry throughout her academic and professional career. She will present her work at the GC&E meeting in Seattle.

 

 

Tyler Roberts, a M.Sc. candidate in chemistry from the University of Arizona, is developing an alternative glycolipid surfactant using biocatalysis. He will attend and present his research at the GC&E meeting next June.

 

Alia Rubaie is an undergraduate student of biochemistry and chemistry at Santa Clara University in California. Rubaie looks to improve the efficiency of copper use in atom transfer radical polymerization during polymer synthesis by using activators generated by electron transfer (AGET) and radical trap assistance. She will attend and present her work at the ACS National Meeting in Philadelphia in March 2020 at the poster session in the Division of Polymer Chemistry.

 

 

Lorianne Shultz, a first year Ph.D. student in materials chemistry from the University of Central Florida, is developing noble metal-free catalyst systems for remediation of emerging contaminants (e.g. pseudo-estrogens, polyaromatic hydrocarbons and pharmaceuticals), utilizing both photochemical and traditional redox processes. Shultz will present her findings at the GC&E conference next summer.

 

 

By Ian Mallov, Ph.D., Research Chemist at inkbox Tattoos

 

You might have seen news of the young sperm whale who died on a beach in Scotland two weeks ago. A necropsy of the animal found more than 100 kilograms of plastic in its stomach. Fishing nets, plastic cups, bags and rope were among the debris. It’s as yet undetermined whether the plastic contributed to the animal’s death.

 

Perhaps we’ve become immune to this type of news lately – a dull reminder of the accumulating impact humans have on the planet’s other inhabitants. But, disturbingly, this is not the end of these plastics’ life cycle: the recovered plastic will likely go to a landfill and await a degradation process in the tens or hundreds of years. Assuming sufficient light and oxygen, gradual oxidation of the polymers will occur until brittle enough that physical breakage into smaller and smaller pieces allows microbes to metabolize them. Perhaps, before this happens, they will be swept out to sea again.

 

Essentially, the end-of-life issues are a problem of chemical kinetics. I work on the other end of the life cycle. Each day the company I work for, like so many others, rolls out products packaged in plastic to ship throughout the United States, Canada and overseas. To paraphrase the first principle of green chemistry, it’s better to prevent waste than to clean it up later. But how do manufacturers prevent waste when plastics are often the cheapest and most efficient protective packaging?

 

We are all familiar with the excellent barrier properties and light weight of plastics. But since the first synthetic plastic, Bakelite, was patented in 1909, a century of manufacturing optimization has resulted in formidably cheap, widely customizable materials composed of one or more of several common polymers: low- and high-density polyethylene (LDPE and HDPE), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and silicones, among others. The efficiency of manufacture of most traditional plastics, including material and energy inputs, makes it difficult for other materials to compete, and indeed this optimization contributes positively to minimizing the environmental impact of their early life cycle.

 

But it is the end-of-life problem that is increasingly urgent. Most plastics in North America still end up in the landfill. Alternatives to landfills such as recycling, pyrolysis to hydrocarbon fuels, and incineration are available, but fillers, stabilizers, plasticizers and colorants complicate these processes, as does food, adhesives, and other contamination from mixed solid waste streams, particularly when trying to recycle plastics. As of 2017, only 8% of U.S.-generated plastics were recycled, 16% incinerated, and the rest went to landfill. This is especially challenging in other parts of the world, especially in Southeast Asia, where a lack of waste management practices result in far less recycling, incineration or landfilling.

 

So what functions do we need from plastics? Their ubiquity makes this seem almost a rhetorical question, and depending on the application, there will be different functions. After all, the functions we need from plastics that go into building, automobile, marine, packaging or other applications vary tremendously and represents a formidable challenge in designing new plastics. For example, as a manufacturer of any good with a limited shelf life, you need a few key benefits from packaging: protection from physical damage, protection from dirt, and reduced exposure to water vapor and oxygen, to name just a few.

 

Measuring the effectiveness of packaging can be quantified by measuring hardness, density, tensile strength, heat resistance and glass transition temperatures. Just as importantly, moisture vapor transmission rate (MVTR) and oxygen transmission rate (OTR), often measured in grams per square inch per twenty-four hour period, give an indication of how packaging will slow spoilage of food, goods and chemicals from oxidative processes.

 

Having a rudimentary idea of what to measure, and which metrics are key for your product, allows you to begin the process of evaluating options beyond traditional polymer materials. In the case of plastic packaging, one of the desirable functions that has been suggested is the ability for the plastic to be biodegradable and compostable. A few resources have been developed to help chemists answer the question of whether or not the plastic will be biodegradable and compostable. One such resource is the New York-based Biodegradable Products Institute (BPI), founded in 1999. The BPI has developed a scientifically-based certification system for products to be considered industrially compostable, that is, degrading under typical conditions of industrial compost facilities on a timescale of weeks. The BPI requests physical samples of materials to test for certification.

 

Another venerable resource is ISO 17088: Specifications for Compostable Plastics, published in 2008. While not free, the availability of an ISO standard for over a decade is testament to the slow progress industries have made on this problem.

 

More recently, a myriad of small companies offer bio-based and renewable alternatives to traditional plastics in the form of industrially compostable polymers such as the class of polyhydroxyalkanoates (PHA) including the most recognizable, polylactide (PLA), or paper or cellulose-based materials that mimic the properties of traditional plastics. Companies such as Australia-based Grounded Packaging offer a range of products that are certified compostable under even the milder conditions of home compost piles, mitigating the problem of access to municipal composting facilities.

 

Recent articles in this newsletter have highlighted other approaches to plastics production such as using the pyrolysis of sugar or other biomass to produce monomers through a Fischer-Tropsch process for use in more than just hydrocarbon fuels. The most notable example of this approach is the “Plant Bottle”, developed by Coca-Cola, and now used by a number of drinks manufacturers.

 

Legislation is beginning to catch up with growing consumer demand for more sustainable alternatives to traditional plastics. The parliament of the European Union passed a single-use plastics ban in March of 2019, while Canada followed suit in June. Both are to come into effect in 2021. Countries such as Bangladesh, South Korea, Rwanda and Colombia have announced more limited bans on plastic items. Many cities and municipalities have single-use plastic bans or taxes.

 

With legislation gaining momentum, it is up to chemists to help ensure that laws are informed and effective, and to continue to push the boundaries of their creativity, to think beyond the consumer to a systemic solution for plastics use in modern society. This responsibility includes influencing decisions made in the production and manufacturing of chemicals and consumer goods. After all, the functions plastics impart are essential. It is imperative that we learn how to design and manage them in a way that does not adversely affect human health or the environment. After all, it’s a problem of kinetics.

Amazingly, another year is drawing to a close – it is hard to believe that 20 years ago we were worried about Y2K!  The end of every year brings a time for reflection on the current year and anticipation for the coming year.  2019 has been a good year for the ACS Green Chemistry Institute (ACS GCI), with more than 600 individuals registering for the Green Chemistry & Engineering Conference, which was held jointly with the International Conference on Green & Sustainable Chemistry in June.  The 2020 conference, with a theme of “Systems-Inspired Design,” will be held from June 16-18, 2020 in Seattle, Washington.  Abstract submission opens on January 6, and next year’s conference will feature about 40 technical sessions, the product showcase, a poster session, and ample opportunities for networking with colleagues.  I encourage you to submit an abstract by the February 17 deadline at www.gcande.org.

 

Education has been at the forefront of ACS GCI’s work in 2019.  Connections between green chemistry and systems thinking continue to grow, and a special issue of the Journal of Chemical Education, featuring articles on these two topics, has just been published.  We continue working with the ACS Exams Institute to integrate green chemistry into the Anchoring Concepts Content Maps.  And as reported in my last column, we will be embarking on a new project in 2020 to develop a suite of education resources designed to integrate green and sustainable chemistry into general and organic chemistry.

  

On December 2, the ACS GCI began accepting applications for a new fellowship, the Heh-Won Chang, PhD Fellowship in Green Chemistry.  This fellowship provides graduate students conducting green chemistry research with $5,000 to be used for any purpose, including conference travel, professional development, and living expenses.  Recipients of the fellowship must present their research at the Annual Green Chemistry & Engineering Conference.  Applications are due by 5:00 PM EST on January 5, 2020.  The fellowship was established through the generosity of Mrs. Cecilia Chang in memory of her husband Dr. Heh-Won Chang.

 

Pacifichem will be held one year from now in Honolulu, Hawaii, from December 15-20, 2020.  Along with colleagues in Canada and New Zealand, ACS GCI is organizing a symposium on “Green Chemistry and Engineering’s Role in Achieving the UN Sustainable Development Goals.”  Numerous other symposia will focus on green chemistry, including “Green Techniques for Organic & Medicinal Chemistry,” “Green Chemistry and Engineering for a Sustainable Circular Economy,” “Innovations for Green Chemistry:  Striving Towards Zero Waste API Manufacturing,” and “Chemistry for Global Challenges:  A Role for Systems Thinking in Chemistry Education.”  The call for abstracts will open on January 2, 2020 at https://pacifichem2020.abstractcentral.com/.   

 

Significant progress has been made in advancing green chemistry and engineering research and education across the chemistry enterprise, yet much work remains in order to achieve a sustainable planet.  I am grateful for your dedicated efforts to transform the practice of chemistry, and wish you joyous holidays and a happy new year! 

 

 

Mary Kirchoff

 

“The Nexus Blog” is a sister publication of “The Nexus” newsletter. To sign up for the newsletter, please email gci@acs.org, or if you have an ACS ID, login to your email preferences and select “The Nexus” to subscribe.

 

To read other posts, go to Green Chemistry: The Nexus Blog home.

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