Queen’s University researchers discover a novel way to recycle household aluminium foil

A groundbreaking development in combating the problems of household aluminium foil waste has been realised.

A groundbreaking development  in combating the problems of household aluminium foil waste has been realised. Researchers at the Queen’s University, Belfast, school of chemistry and chemical engineering have engineered a new eco-friendly, cost effective method to convert common aluminium foil into very pure aluminium salts. These salts can, in turn, be used to manufacture a vital catalyst in producing the renewable fuel dimethyl ether.

The Problem

Aluminium is one of the more valuable resources in global industry, yet recycling aluminium foil has remained difficult. Although it can be broken down to produce several valuable chemical products, many of the methods used to break down aluminium foil are either expensive, high energy use or release dangerous chemicals in the process. These problems arise from the difficulty with recycling machinery, which is unable to process the cooking oils that are present in most aluminium foil being disposed.

This has lead to the majority of aluminium waste ending up in landfills or incinerators,  exacerbating the  rising global waste and emission problem. The demand for aluminium has been rising 4% every year of the last ten. With growing demand propelling production, there are  high environmental costs in an already wasteful industry.  

Aluminium is synthesised from mined bauxite. Processing this bauxite releases a significant amount of waste such as tailings, red mud and CO2 emissions. This does not include the huge environmental footprint made by transporting and shipping the raw materials from the West Indies, West Africa and Australia. These countries, in turn, see their ecosystems damaged  from the difficult and expensive mining process. This means that the successful recycling of aluminium is crucial for both the economy and environment.

The Solution

Ahmed Osman, a postgraduate researcher,  and his team of engineers at Queen’s have seemingly solved the problem of recycling Aluminium foil. An innovative new crystallisation technique converts the aluminium foil to an important dimethyl ether biofuel catalyst. The technique is easy and eco-friendly. The method itself involved dissolving the aluminium foil in HCl and recrystallising it to form an intermediary compound. This compound is then soaked in ammonia and reheated to form the aluminium salt. The beauty of this technique lies in its apparent simplicity. Osman and his team have shown that the method is environmentally sound, with none of the components producing waste. The key is in how the crystal structure of the aluminium is altered into the desired compound. The resulting product is also found to be very pure which makes it an ideal catalyst for the biofuel. According to Osman he was “astonished by the ultrapure single crystals – I didn’t expect them to be 100% pure”.

The solution is set to revolutionise the aluminium industry. The catalyst is more effective than the current catalysts used commercially in the industry not only due to its purity but also for its larger surface area, higher acidity and larger pore volumes which each  improve the catalysts efficiency.

The catalyst’s properties also has potential applications in several other fields including electronic tool fabrication, cutting tool material and surgical implant material.  Economically, this new technique shows promise. Ahmed and his team have shown that production of this catalyst costs half the price of its commercial counterpart which can only be produced from the bauxite ore that is used to synthesise the aluminium in the first place. According to Osman and his team the new catalyst will cost about £120/kg compared with the current £305/kg that the commercial counterpart costs.

This solution has a threefold benefit. Whilst recycling otherwise wasted aluminium the researchers have found a solution that both produces more effective and cheaper compounds for use in the production of dimethyl ether. In the meantime less bauxite is being mined and less aluminium foil is ending up in incinerators or landfill sites. The ripples from this research could have a significant impact on how a whole industry manages its waste and its production.

Dimethyl Ether

A cheaper alternative to producing dimethyl ether is also a welcome consequence of this innovation. Dimethyl ether is widely considered one of the front runners in the search to find renewable biofuel. It is non-toxic, cheap and can be stored without high pressure containers. It has already seen widespread use in China, Japan, Korea, Egypt and Brazil as it can be produced from a wide range of organic feedstock such as urban or agricultural organic waste. These properties make it an inexpensive, viable replacement for diesel. With the discovery of the easy-to-produce aluminium catalyst, dimethyl ether might become the fuel of the future and excitement for this prospect rises with this new discovery.

The discovery has been praised as an example of engineers and scientists working “hand in hand” to reach a common goal. Osman’s research has explained his inspired, saying “One day I took a walk through our laboratories at Queen’s and found lots of aluminium foil waste so I did a little digging and after speaking to my colleagues, I ran my experiment”.

Osman’s work doesn’t stop here. He hopes to continue his research to keep improving the uses of his new found catalyst.The aim is to eventually transition from diesel to dimethyl ether. He also hopes to apply his knowledge of catalysis in other fields such as developing new catalytic converters for use in engines. The full research is published in the journal Nature.