How does BioKollekt work
The junior research group BioKollekt modifies peptides - short protein pieces - to selectively bind particles in a solution. The peptides are anchored to carriers with very specific properties (e.g., water-repellent, magnetic). Thanks to the unique structure of the peptides, the newly formed bio-collectors can then fish any target substance from a complex material mixture. Afterwards, the bio-collector will be recycled and reused.
The most suitable peptides are being selected by using the biotechnological method “Phage Surface Display”, which was first introduced by the 2018 Chemistry Nobel Prize Winner George P. Smith. Phage Surface Display works with bacteriophages, viruses that are specialized to identify bacteria. The biologist modified their surface proteins until their surfaces differ by one additional peptide, only.
A biotechnological selection process determines from a mixture of 109 different bacteriophages ideal peptides that bind substances selectively. This has already been done in the EU IOF project MinePep.
The selected peptides consist of 8-16 protein compounds, the so-called amino acids, and are chemically attached to the surface of spherical carrier materials.
Bound to the carrier material, the peptides now fish for target particles from the water substance mixture.
Bio-collectors which are water-repellent can bind to air bubbles introduced into the solution and float to the surface of the vessel. At the surface, the substance-laden bio-collectors enrich and are being skimmed off as foam. This process is called bioflotation.
Finally, the bound target particles will be removed by interrupting its interaction to the bio-collector. The bio-collector can now be re-used in further separation processes.
Cleaner separation of recyclables
The production of electronic products still very much depends on the metal production from ores, which consumes an extremely high amount of energy and water. For example, to produce 1 kilogram of rare earths almost 200 processing steps are required with 5,500-7,200 mega joules of energy and 1,275-1,800 cubic meters of water. In comparison, 1 kilogram of rare earths can be recycled with 1,000-5,000 mega joules of energy and 250-1,250 cubic meters of water, only [European Commission. Report on Critical Raw Materials and the Circular Economy 2018].
Thus, the current focus of the junior research group is the clean and economic separation of rare earths, more precisely from luminous powder contained in energy-saving bulbs. Until now, the powder is due to its mercury content stored as hazardous waste. By the year 2020, the EU will deposit 25,000 tons of luminous powder including the metals it contains. Bringing all compounds back into the cycle and at the same time reducing the enormous amount of hazardous waste is hence the goal of BioKollekt group. In addition, the junior research group plans to set up a technology platform for processing other recyclables to make a substantial long term contribution to securing raw materials and reducing waste.
Ecological alternative for classical separation methods
The classical separation method, called flotation, binds chemical collectors to the target particles and can afterwards not be recycled. All other collectors as well as any bound residues end up in the tailings. In contrast to that, bio-collectors are recyclable and can be used over and over again. For example, by changing the pH of the solution the target particles can be detached from the bio-collectors.