Étiquette : ASTM D6866

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ASTM D6866 measures renewable carbon but does not measure biodegradability

ASTM D6866 distinguishes carbon resulting from contemporary biomass-based inputs from those derived from fossil-based inputs. Biomass contains a well-characterized amount of carbon 14 that is easily differentiated from other materials such as fossil fuels that do not contain any carbon 14. Since the amount of carbon 14 in biomass is known, a percentage of carbon from renewable sources can be calculated easily from the TOTAL organic carbon in the sample. ASTM D6866 quantifies the biobased content relative to the material’s total organic content and does not consider the inorganic carbon and other non-carbon containing substances present.

To illustrate, here are some hypothetical formulations and their ASTM D6866 results:

Product 1 – liquid with 50% starch-based material and 50% water Biobased Content = 100% (product 1 has 50% organic content and 100% of that fraction is biobased)

Product 2 – liquid with 50% starch-based material, 25% petroleum-based, 25% water Biobased Content = 66.7% (product 2 has 75% organic content but only 50% of that fraction is biobased)

Product 3 – solid that is 50% glass and 50% polyethylene from petroleum Biobased Content = 0% (product 3 has 50% organic carbon but from fossil sources; glass is not carbon-containing)

Product 4 – solid that is 50% glass and 50% polyethylene from biomass Biobased Content = 100% (product 4 has 50% organic carbon and 100% of it is renewable)

Product 5 – liquid with 50% soy-based material, 30% petroleum-based, 10% water, and 10% inorganic substances Biobased Content = 62.5% (product 5 has 80% organic carbon but only 50% of it is renewable)

ASTM D6866 Does Not Measure Biodegradability

It must be noted that ASTM D6866 only quantifies the biobased content of a material but results do not have any implication on the material’s biodegradability. The terms biobased and biodegradability may be related, but they are not synonymous nor are they interchangeable. If a material is biobased, it comes from plants or animals, but it does not necessarily follow that it is biodegradable. A material is biodegradable only if microbes in the environment can break it down and use it as a food source. Some forms of cellulose are, in fact, non-biodegradable while some that are derived from petroleum do biodegrade contrary to popular opinion. Nowadays there are synthetic plastic resins that will biodegrade and compost just like paper. There are also bioplastic materials, such as Braskem’s bio-polyethylene, that do not biodegrade

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ASTM D6866 Measures Organic Carbon vs Total Carbon

ASTM D6866  Measures Organic Carbon vs Total Carbon

• ASTM D6866 looks at Total Organic Carbon and excludes Inorganic Carbon

• Carbonates are excluded from ASTM D6866 computations

ASTM D6866 was written for the US Department of Agriculture to provide a measure of renewable carbon to total organic carbon within carbon-containing solids, liquids, and gases. The term « biobased » is therein defined as « total renewable carbon to total ORGANIC carbon. »

Biobased Products Definition

As defined by the 2002 Farm Bill, biobased products are commercial or industrial products (other than food or feed) that are composed in whole, or in significant part, of biological products, renewable agricultural materials (including plant, animal, and marine materials), or forestry materials. The 2008 Farm Bill extended the definition of biobased products to include biobased intermediate ingredients or feedstocks.

Biobased products like writing papers, paints, insect repellents, plastics, liquid cleaners, diesel fuel additives, and floor tiles contain inorganic carbon in significant quantities. Since ASTM D6866, by definition, only takes into account total organic carbon, inclusion of inorganic carbon in the biobased content calculation will affect the accuracy of the measurement. It is important to know if the product submitted for ASTM D6866 testing has inorganic components so that correction factors will be applied during biobased content calculation. Biobased products with inorganic carbon that has little or no carbon 14 activity will have biobased content values that are too low if corrections will not be applied. Inorganic carbon in biobased products is usually present in the form of carbonates. However, not all carbonate-containing biobased products have sufficient amounts of inorganic carbon to affect the accuracy of the results. Products with high organic carbon content and low inorganic carbon content will generally not be affected by the presence of the latter. Those with very low organic carbon content, on the other hand, will be affected by even small amounts of inorganic carbon because the latter constitutes a significant portion of the product’s total carbon content. For products with inorganic carbon constituting more than 3% of the total carbon, the inorganic carbon must be excluded from the biobased content calculation. Thus, to ensure the accuracy of results, the lab must be informed if a product’s inorganic component concentration is sufficient enough to pose analytical concerns.