February 17 - useful enzymes

We all know that carbon dioxide is the major player in the greenhouse debate. Scientists have been proposing ways to capture it and prevent it from adding to the load of gases causing problems for our ozone layer. No cost-effective systems have been found to date.

Today it was announced that a team of scientists from four universities in India say they have discovered a low-cost method of converting carbon dioxide emissions into a useful building material.

What they've managed to do is to use 7 enzymes that convert carbon dioxide into calcium carbonate, which is the mineral found in limestone, shells and chalk, etc. The calcium carbonate can then be used in many different ways. Currently, it's used for the following -

The main use of calcium carbonate is in the construction industry, either as a building material in its own right (e.g. marble) or limestone aggregate for roadbuilding or as an ingredient of cement or as the starting material for the preparation of builder's lime by burning in a kiln.

It is also used in the purification of iron from iron ore in a blast furnace.

Precipitated Calcium carbonate, pre-dispersed in slurry form, is also now widely used as filler material for latex gloves.

Calcium carbonate is widely used as an extender in paints and as a filler in plastics.

It is also used in a wide range of trade and DIY adhesives, sealants, and decorating fillers. Ceramic tile adhesives typically contain 70 to 80% limestone. Decorating crack fillers contain similar levels of marble or dolomite. It is also mixed with putty in setting stained glass windows, and as a resist to prevent glass from sticking to kiln shelves when firing glazes and paints at high temperature.

Calcium carbonate is known as whiting in ceramics/glazing applications, where it is used as a common ingredient for many glazes in its white powdered form.

In North America, calcium carbonate has begun to replace kaolin in the production of glossy paper. Europe has been practicing this as alkaline papermaking or acid-free papermaking for some decades.

It is used in swimming pools as a pH corrector for maintaining alkalinity "buffer" to offset the acidic properties of the disinfectant agent.

It is commonly called chalk as it has been a major component of blackboard chalk.

Ground calcium carbonate is further used as an abrasive (both as scouring powder and as an ingredient of household scouring creams).

So you can see that if it's possible to convert Carbon Dioxide, which we have too much of, into Calcium Carbonate, which we have many uses for, and do it economically, then it's an all-round win-win situation.

A few hours after I heard this news I excitedly told a scientist friend of mine about it and he was not surprised because the knowledge that it's possible to convert CO2 into CaCO3 is old news. He said that it hasn't been done because it was an expensive process. I guess the reason why this is such good news now is because the Indian scientists have worked out a cost-effective way to do it. I'm very happy that there are people around who pursue lines of enquiry persistently until they find solutions.

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