Russian researchers from Mendeleev University of Chemical Technology know how to make activated carbon filters for purifying air from petrol vapours and light-end oil products from fruit pits and nut shells.

When volatile organic compounds, such as petrol, acetone, and white spirit, for instance, are poured into a cistern, part of them readily evaporates into the atmosphere. Losses for business in this case are enormous – and Russian has an oil-based economy, remember? Just imagine – average annual consumption of petrol in our country is about 50 million tons, and 3.5 million tons of petrol disappear in the atmosphere. Moreover, these substances are a serious threat to our environment.

Run-away hydrocarbons can be partly removed from the air by means of absorption, but sorbing agents can cost a lot. Chemists from Moscow suggest a technology for making relatively cheap microporous activated carbons from agricultural plant wastes – fruit pits and shells of various nuts. Apart from being cheap, these materials are ecologically friendly compared to synthetic polymers and natural carbons.

Sorbing agents were synthesized by means of pyrolysis technique, in other words, by means of thermal decomposition in the absence of air of plum pits and shells of walnuts, peanuts and coconuts. Pits and shells were crushed to particles, not exceeding 1-3 millimetres in size. After that fruit and nuts were dried in a vacuum oven at the temperature of 105 degrees Celsius, and then were pyrolyzed. Scientists have determined optimal conditions for the reaction, which were the following: heating in the nitrogen atmosphere up to 800 degrees Celsius for one hour. Resulting carbon was pierced with small pores – 0.31-o.35 nanometres.

 

 

Following step was carbon activation by means of water vapour. Water molecules very easy get deep inside carbon and promote formation of microscopic pores. Exposure to water vapour is a fast and ecologically friendly technique of carbon activation, which is also cheaper, than chemical methods. Researchers also optimized water vapour treatment in order to get best microscopic pores possible.

Scientists used new sorbing agents for two technique of retrieving hydrocarbons back from vapour-air mixtures. First technique is heating activated carbons, which release substance they have absorbed. In this case sorbing agents should be flushed with nitrogen in order to prevent explosion of hydrocarbon mixture. Another technique utilizes vacuum method of carbon regeneration. Both technologies have benefits and implications, but both of them are effective.

Air from cisterns, in which various fuels are stored and transported, needs to be purified. When an activated carbon is regenerated, it releases a mixture of liquid gasoline and aromatic hydrocarbons, which is similar to antiknock additives to motor fuel. Researchers suggest returning mentioned mixture into main production processes and add to gasoline in order to improve its quality.