Tag Archives: biofeedstocks

What do you think? Is SynBio the next big scary thing?

The Sins of Syn Bio

How synthetic biology will bring us cheaper plastics by ruining the poorest nations on Earth.

By Jim ThomasPosted Wednesday, Feb. 2, 2011, at 10:00 AM ET

This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. A Future Tense conference on whether governments can keep pace will scientific advances will be held at Google D.C.’s headquarters on Feb. 3-4. (For more information and to sign up for the event, please visit the NAF Web site.)

An aerial view of rainforest. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities.

Syn bio is feted as the next big thing, but we should be clear-eyed about what makes syn bio such a big deal and about whom it will harm. Its advocates predict that synthetic bio will lead to the “New Bioeconomy,” in which we harness biology to perform tasks now accomplished by manufacturing. Read more.

Novel, sugar-based surfactants more stable and sustainable.

Synopsis by Evan Beach and Wendy Hessler. Jan 12, 201

Foley, PM, A Phimphachanh, ES Beach, JB Zimmerman, and PT Anastas.  2011.  Linear and cyclic C-glycosides as surfactants. Green Chemistry http://dx.doi.org/10.1039/C0GC00407C.


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xrrr/flickr

Context

Surfactants – the active ingredients in many household products, including cleaners and personal care products – are produced on the scale of millions of tons per year. In nearly every application, after a few minutes of use, they are rinsed with water either down the drain or directly into the environment.

Unsurprisingly, there have been harmful effects from such large-scale releases. When surfactants are slow to break down in the environment, problems range from unsightly foaming to toxic effects on aquatic organisms. Some of these chemicals – for example, the widely used nonylphenol ethoxylates – have been implicated in endocrine disruption. The term is used to describe substances that can alter hormone activity in the body.

There has been a push in recent years toward sugar-based surfactants because of improved biodegradability and lower toxicity. They are also derived from natural and renewable sources, adding another “green chemistry” benefit.

Sugar-based surfactants have been commercially available for more than a decade. Formulations of the alkyl polyglycosides (APGs) are used in a variety of consumer products for laundry, hair and skin care. On an ingredient label they are usually identified as a variety of “glucosides,” for example decyl glucoside or lauryl glucoside. The use of APGs is growing at a faster rate than petroleum-based surfactants.

However, chemists are trying to improve APGs. Many of the sugar-derived chemicals can fall apart when exposed to acids in water because the link between the water-loving and oil-loving ends of the APG molecules is vulnerable. Also, depending on the variety of the APG produced, the manufacturing process relies on high temperature and pressure and energy-consuming purification steps.

What did they do?

Researchers investigated a new process to make a stronger chemical bond in one particularly weak spot of sugar-based surfactant molecules. The researchers transformed a precursor chemical by treating it with a chemical mix that included alkyl aldehydes.

Several sugar derivatives with straight or cyclic tails were produced, depending on the conditions that were used to convert the intermediary chemical. The new chemicals were tested for surface tension and foaming and the results were compared to current APG surfactant performance.

The researchers showed that the new surfactants could be prepared in a two-step reaction under mild conditions, using only a minimum of solvent. It was not necessary to purify the products by column chromatography, a procedure that would consume large volumes of potentially hazardous solvents. This improves the prospects for producing the chemicals on a large scale.

The scientists show that the technical performance of the new surfactants is as good as existing APG technology. This was determined by measuring surface activity – how efficient the chemicals are at reducing the surface tension of water. It is important for surface tension to drop quickly with just a small amount of added chemical, for surfactant applications. The best chemical tested in the study worked at just 40 milligrams (the weight of a few grains of rice) per liter.

The researchers also explored the foaming properties of the new chemicals. Foaming is desirable for some personal care products like shampoos, but would be a disadvantage in laundry applications and some industrial cleaners. The Yale chemicals were low foamers compared to a conventional surfactant, sodium dodecyl sulfate (SDS). But when mixed with SDS, the resulting foam lasted longer. Thus they could be useful in either low- or high-foam formulations.

The biodegradability of the new chemicals was not measured, but U.S. Environmental Protection Agency software suggests that the changes made to improve acid stability will not affect how microbes disassemble the chemicals. The glucose end of the molecule contains many carbon-oxygen bonds that are common places for microbial attack. If the surfactants are made from long, straight-chain aldehydes, that should also provide bacteria with a familiar food source.

What does it mean?

The new sugar-based surfactants may offer more stable and sustainable varieties to use in consumer products. The novel chemicals are more stable under harsh conditions and work just as well in laboratory tests as the sugar-based surfactants currently used. In addition, their chemical production is a significant improvement over current methods in that it uses less resources and produces a wider array of chemicals with surfactant properties.

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Evan Beach

This new family of sugar-based surfactants complements APGs that are already on the market. A wider variety of molecular structures means that manufacturers of green consumer products are more likely to come up with formulations that meet all the goals of function, performance, economy and low environmental footprint.

Replacing the weak spot in APGs with a sturdier alternative allows the sugar-based chemicals to be used in more applications. The two parts of the new molecule are linked with a bond between two carbon atoms instead of a bond between an oxygen and a carbon atom. The stronger carbon-carbon bond is unaffected by strong acid. That robustness could help in industrial applications and heavy-duty household formulations, for example acidic tile cleaners.

The new surfactants are made from glucose, which is widely found in nature. It is one of the components of table sugar and is the repeating chain unit in cellulose, which gives plants their supporting structure. Glucose acts as the water-loving part of the surfactant. The oil-loving part of the surfactant is made from aldehydes. Aldehydes are a diverse set of chemicals; some occur in nature and others are produced from petrochemicals. In this study, the aldehydes could be obtained by treating plant oils.

The researchers say their next step will be to explore algae as a possible source for all of the surfactants’ starting materials. The carbohydrate portion of algal biomass could provide the sugar, and algal oils could give the right kinds of aldehydes. Algae oils are particularly rich in carbon-carbon double bonds that can react with ozone to produce aldehydes. If that approach is successful, surfactant production could supplement algae-to-fuel technology.

Bacteria clean up metal waste, then serve as catalysts.

Synopsis by Evan Beach, Dec 09, 2010

Gauthier, D, LS Sobjerg, KM Jensen, AT Lindhart, M Bunge, K Finster, RL Meyer and T Skrydstrup. 2010. Environmentally benign recovery and reactivation of palladium from industrial waste by using gram-negative bacteria. ChemSusChem 3:1036-1039.

A group of Danish scientists has developed a method to recycle valuable metals that would ordinarily have to be mined and refined before ending up in chemists’ hands. Their discovery means that the metals could be sourced instead from electronic waste or polluted water and soil.

The researchers used two species of bacteria and added hydrogen gas to recover the waste metals – palladium, platinum and rhodium – in a cheaper and more efficient way than conventional processes. Interest in using microbes to remove metals from waste is growing among scientists who are searching for the best methods.

This is the first time that researchers report that they can remove these platinum group metals from industrially contaminated water without altering the bacteria or diluting the liquid. Remarkably, the bacteria could remove up to 100 percent of the palladium from the polluted water.

Mining, industrial activities and manufacturing release these specific metals into the environment, where they can contaminate soil and water. All three of the metals examined are widely used in automotive, chemical, glass, electrical, medical and jewelry applications.

The microbes used in the study are naturally tolerant of metals. One species can be found in typical soils, and the other is more commonly found in industrial areas, near mines and metal factories.

The bacteria bind and absorb metal ions dissolved in water. Hydrogen gas can also remove metal from the water. Metal uptake and recovery are enhanced when the two are combined.

The contaminated water used in the study contained a mixture of eight different metals and was deep orange colored. Hydrogen gas and bacteria with and without added palladium were added to test tube samples.

The liquid cleared after 24 hours, indicating the metals had been removed. The bacteria were most selective for palladium – the recovery rates were 96-100 percent, compared to 70-74 percent for platinum and 55-57 percent for rhodium.

After recovering the bacteria, researchers asked what could be done with the metal-rich material. They went a step further and found a productive use. They showed that the microbes could drive a common chemical reaction that uses palladium to connect two hydrocarbon building blocks, a method often used in synthesizing pharmaceuticals. The conversion rates were 50-100 percent. The effectiveness was higher when the bacteria were pretreated with a small amount of pure palladium before exposure to the wastewater.

Further experiments will be aimed at understanding how the metals compete for the absorption sites on the bacterial surface, and thus, produce treatment methods that select for specific metals. In turn, the selective, one-metal binding could result in more active catalysts to be used in conventional processes.

Distinctions between biopolymers and bio-based polymers important (Media review).

Posted by Evan Beach at Nov 08, 2010 04:00 AM | Permalink

The origins of bio-based plastics need to be clarified in a Vancouver Business Journal article that highlights the use of the materials in industrial applications.

A recent story in the Vancouver Business Journal provides an overview of the challenges manufacturers face when trying to work with plastics that incorporate natural molecules – so-called bio-based plastics. Companies are exploring new ways to handle the raw materials and optimize the molding process.

The article draws attention to an important trend in the world of plastics and green chemistry, but could have been more precise in the language used when referring to the polymers involved. Polymers are large molecules made of smaller, repeating molecules that are chained together.

The reporter does a good job of explaining the difference between two major types of bio-based polymers: “biodegradable” and “compostable” polymers. The distinction can be important  when manufacturers or consumers choose an environmentally friendly disposal method for a particular material. International standards define a biodegradable polymer as one that breaks down into smaller fragments due to the action of bacteria and other microorganisms. To be “compostable,” a polymer must degrade completely into carbon dioxide, water, minerals and biomass; and it has to do this quickly without hurting the overall compost process.

He could have also clarified that biopolymers and bio-based polymers are different.  “Biopolymer” refers to polymers that occur in nature or are produced by biological action. Cellulose, starch, proteins and polyesters made by bacteria (known as PHAs) are examples of biopolymers.

Then there are the synthetic polymers – like polylactic acid (PLA). These materials usually biodegrade and are made from biological raw materials, but are prepared by chemical methods.  PLA is made up of small molecules found in nature, but the polymerization process is a human invention. Similarly, nitrocellulose, which was historically used in photographic film, is a chemically modified version of a natural material, but does not occur naturally. PLA and nitrocellulose would be more accurately referred to as “bio-based” or “bio-derived” polymers.

These distinctions may seem minute, but they help clarify for manufacturers, regulators and consumers to what extent a material is truly natural.

Soy plastics targeted for electronic circuit boards.

Zhan, M and RP Wool. 2010. Biobased composite resins design for electronic materials. Journal of Applied Polymer Chemistry 118:3274-3283.

Synopsis by Evan Beach
New materials made from soybean oil have excellent electronic properties and offer a low-carbon-footprint alternative to conventional plastics that are used in printed circuit boards.

Soybean oil can be mixed with conventional chemicals and converted into a strong, rigid plastic that could be used for high-speed, energy-efficient, electrical components, report researchers at the University of Delaware.

The greasy liquid could provide a cheap, abundant and renewable alternative to some of the plastics, resins and other petroleum-based materials now used to make the parts. The use of renewable ingredients in the new plastics may reduce greenhouse gas emissions and slow depletion of petroleum resources. In principle, other plant oils besides soy would work in the same way.

One target area for the new plastic is circuit boards – the internal units that relay signals in computers, radios and other electronics. They are often made from materials called epoxy resins, a family of plastics that frequently rely on bisphenol A (BPA) for stiffness. BPA is known to interact with the hormone system, most famously as an estrogen. The use of BPA has raised health concerns over harmful effects seen in animals at low doses. Human exposure is widespread and studies suggest the chemical may contribute to obesity, behavior problems and altered fertility and reproduction in people.

The researchers wanted to modify soybean oil so the individual oil molecules would create a chain and the other added ingredients would lend rigidity. They mathematically predicted that structures similar to benzene – six carbon atoms linked together in a planar ring – would give the desired properties. Bisphenol A, for example, contains two benzene rings in its structure.

The researchers manufactured the soybean-based material to validate the theory. A key ingredient needed was phthalic anhydride, which is best known as a raw material for phthalate plasticizers that are used in a variety of products and have been linked to health effects in animal studies. At levels of 10 – 20 percent, it improved both the mechanical and electrical properties of the soy-based plastics.

All of the soy-based materials had lower dielectric constants than epoxy resins – about 3.6 to 3.8 compared to 4.2 to 4.7. A low dielectric constant is important for high signal speed and low “crosstalk” of signals between lines in a circuit. The materials also have very low dissipation factors – a measure indicating that circuits could operate using less power.

Further research is needed to improve the environmental impacts of the soy plastics. It would be ideal to progress away from adding chemicals such as phthalic anhydride that have known health effects and moving toward a 100 percent biobased material. More benign sources of benzene ring structures also should be considered.

Plastic from algae: How green?

Plastic from algae: How green?

Posted by Evan Beach at May 18, 2010 08:30 AM | Permalink

A story in Discovery News on new algae-based plastic highlights green benefits but misses the challenges.

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An article in Discovery News offers a rare look at how algae can be used to make something other than fuel or animal feed: plastic.

The story would have been more informative if the reporter had discussed the challenges that remain before algae fuels or plastics can become widespread. It is still not clear how algae can be produced sustainably on a large scale.

Reporter Alyssa Danigelis describes a new plastic that can be made with up to 50 percent algae. The company developing it hopes it will be 100 percent algae in a few years. Danigelis draws attention to the major green benefits of this new technology: it uses what would probably be a waste material from biodiesel production, it should not have any impact on the food supply, and further research and development could lead to a compostable material.

The 50 percent algae product also contains polypropylene (PP), a plastic often encountered in everyday life, for example, in microwaveable food containers. Such blends of natural and synthetic materials are not completely biodegradable but they often help to reduce consumption of limited resources.

By using algae left over from fuel extraction, this new plastic supports the idea of a “biorefinery.” The oil, coal and gas industries don’t just produce fuels – they produce the chemical building blocks for everything from industrial solvents to pharmaceuticals, leaving almost nothing to waste. Similarly, biofuel production will be more competitive if all of the raw materials are used productively. Plastic from algae is a step in that direction.

However, water, nutrient and energy demands can be extremely high and these issues are just as serious as whether the technology will compete with food production. Until the science is worked out, the “greenness” of algae – beyond its actual color – is not yet certain.  The story could have made this more clear.