Worn out paper money could be used for decontamination

UN/DICYT Worn out bills will now have a second useful life. They may be turned into material which would help decontaminate wastewater and remove pollutants from the environment. When a bill deteriorates it is destroyed in high speed machines which chop it into small confetti-size pieces. This waste is handled differently in each country; although common practice is to dispose it in sanitary landfills or incineration.

In Colombia high-denomination bills have a useful life which ranges from one to two years and four months. Therefore the amount of deteriorated bills reaches 169 million destroyed pieces, which is equal to close to 172.4 tons of waste.

In face of this scenario UNal masters in Chemical Engineering María Paula Franco carried out a research project in which she turned this material into activated charcoal which would help decontaminate discharges produced by the money manufacturing and printing process.

This ecological transformation emerged when analyzing different forms of using this material, for instance as recycled material for manufacturing activated charcoal, a crystalline adsorbent material with very developed high internal porosity and great superficial area.

According to Franco, amongst the main applications of activated charcoal is removing pollutants from water and air and effluent cleaning (discharges resulting from numerous industrial processes).

Colombian bills are manufactured in cotton fiber, a compost recycling suitable material. Composting is also carried out with the purpose of returning the material back to the environment.

Taking this into account the purpose of the project was to determine if the material could turn into a product which could effectively remove organic matter from the discharge produced by the bill manufacturing process.

Therefore Franco carried out a groundbreaking process mixing bill waste with urea, a residual component from several living organisms, which may be found in human urine, for instance.

In this manner they obtained a favorable input from removing organic matter from industrial discharges and also a reduction in the chemical oxygen demand (COD), a test is commonly used to indirectly measure the amount of organic compounds in water in degradation processes.

Therefore the COD is measured in polluted water before putting it in contact with activated charcoal produced from paper money waste, which given its high internal porosity and great superficial area, traps the liquid polluting contaminant.

Experimentally they achieved a 69% removal of organic matter. This percentage was estimated in terms of change of the COD before and after treating water with activated charcoal. Professor Hugo Ricardo Zea of the UNal Department of Chemical and Environmental Engineering says that the most important aspect of this result was the innovative rationale used.

Furthermore he also revealed that the research project, result of Franco’s master’s thesis opened a range of ideas from where other research projects are emerging as obtained charcoal may be used as catalyzer support for other chemical reactions, not just as adsorbent for contaminating molecules.