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Fuel From Lignin | Earth Wise

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Lignin is an organic polymer that provides the rigid structure of plants and is what gives wood and bark their characteristic properties.  Lignin typically comprises between 20 and 35% of the mass of wood.  The two major substances extracted from trees, grasses, and other biomass materials are cellulose and lignin.  Cellulose is used to make paper, bioethanol, and other products, but lignin is largely unused because it is difficult to break down into useful substances such as feedstocks for fuels.  As a result, lignin is largely wasted.  Worldwide, some 50 million tons of lignin are produced from paper and bioethanol manufacturing each year and almost all of that is simply burned to generate heat.

Lignin can be broken down using pyrolysis techniques at high temperatures to create bio-oils, but those oils lack sufficient hydrogen and contain too much oxygen to be useful as fuels.  There is a process called hydrodeoxygenation that adds hydrogen and removes oxygen, but it requires high temperatures and very high pressures as well as producing char and tar that reduces the efficiency of the process.

Researchers at Georgia Tech recently published work describing a new process for turning lignin into useful products.  They developed a dual catalyst system of super-acid and platinum particles that adds hydrogen and removes oxygen from lignin bio-oil and makes it useful as a fuel and source of chemical feedstocks. 

The new process could help meet the growing demand for bio-based oils as well as helping the forest product, paper, and bioethanol industries by providing an additional revenue stream from what previously was a waste product.

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New Process Boosts Lignin Bio-oil as a Next-Generation Fuel

Photo, posted August 16, 2017, courtesy of evcabartakova via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Preserving Produce With Eggs | Earth Wise

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Researchers at Brown University have developed an inexpensive coating to protect fruits and vegetables that is made from eggs that would otherwise be wasted.  The micron-thick coating solves problems for the produce and its consumers as well as for the environment.

The coating relies on eggs that never reach the market.  The U.S. produces more than 7 billion eggs a year.  The supply chain rejects about 3% of them, typically because of shell damage, which means that more than 200 million eggs end up in landfills.

The coating is mostly made from egg, the rest consisting of nanoscale cellulose extracted from wood, a tiny amount of curcumin (the main active ingredient in turmeric that has antimicrobial properties), and a bit of glycerol for added elasticity.  The coating is applied to produce by spraying or dipping.  It shows a remarkable ability to resist rotting for an extended period comparable to standard coatings like wax, but without their shortcomings.

Along with being edible, the coating retards dehydration, provides antimicrobial protection, and is largely impermeable to both water vapor to prevent dehydration and to gas to prevent premature ripening.  The coating is entirely natural, and it washes off with water.  So, anyone sensitive to the coating, such as someone with an egg allergy, can easily eliminate it.

Lab tests of the coating studied its effects on strawberries, avocados, bananas and other fruits.  All were seen to maintain their freshness far longer than uncoated produce.

The researchers are continuing to refine the coating.  They are also considering other source materials.  They chose egg proteins because there are so many wasted eggs, but it may be possible to make use of plant proteins instead to address the needs of vegan consumers.

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Egg-based coating preserves fresh produce

Photo, posted July 13, 2012, courtesy of Liz West via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Problem Of Microplastics

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In recent years, there have been multiple reports of microplastic contamination seemingly everywhere:  in the ocean, in lakes and rivers, in beverages and foods, and in the bodies of birds, fish, and even people.  As the world tries to come to grips with this growing problem, there are many things that we simply don’t know.

Microplastics are usually formed by the breakdown of larger pieces of plastic.  Shopping bags and cups degrade into microplastics.  Microfiber clothing generates microplastics in washing machines.  And some manufacturers still intentionally add microplastics to personal care products like toothpaste and facial scrubs.

Technically, a microplastic is any piece of plastic measuring five millimeters in size down to one micron – which is one thousandth of a millimeter.  But there can be even smaller plastic particles classified as sub-microplastics and even nanoplastics.

A real concern is that it is not actually clear how dangerous microplastics are for living organisms.  We know that aquatic and terrestrial species – including humans – can and do absorb microplastic particles, but whether there is actual toxicity and the nature of any detrimental effects is not yet well understood.

Another real problem is that it is actually not easy to distinguish microplastics from other particles in a given sample.   When you are looking at a particle that is smaller than a millimeter in size, it is not easy to tell whether it is a grain of sand, a bit of cellulose from a plant, or a microplastic.  There are reliable and definitive ways to analyze samples for microplastics, but they are not as simple and commonplace as just looking through a microscope.

Microplastics are a rapidly growing problem and we don’t even really know how big and how bad the problem is.

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How dangerous is microplastic?

Photo, posted January 10, 2015, courtesy of Daria Nepriakhina via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Biodegradable Microbeads

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Microbeads are little spheres of plastic less than half a millimeter in diameter that are added to a variety of personal care and cleaning products such as cosmetics, sunscreens and fillers.  They give these products a desirable smooth texture.   However, they are so small that sewage filtration systems can’t remove them and they end up in rivers and oceans where they are ingested by birds, fish and other marine life.

[Read more…] about Biodegradable Microbeads

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