How does BioKollekt work
The junior research group BioKollekt modifies peptides - short protein pieces - to selectively bind particles in a suspension. 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 biocollectors can then fish any target substance from a complex material mixture. Afterwards, the biocollector 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 infect bacteria. The biologist modified their surface proteins until their surfaces differ by one additional type of 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. These peptides are produced chemically in higher amounts without phage and are attached to the surface of spherical magnetic carrier materials.
As so-called biocollectors, composed of peptides bound to the carrier material, the peptides now fish for target particles from the water surrounding material mixture.
Biocollectors, which are magnetic, can bind to a bigger magnet that is immersed into the suspension. By rising the magnet out of the suspension, all the magnetic biocollectors with their attached target material are removed as well. This process is called magnetic separation.
Finally, the bound target particles will be removed by interrupting its interaction to the biocollector. The biocollector can now be re-used in further separation processes.
Cleaner separation of recyclables
The world’s raw material resources are limited. However, 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 fluorescent powder contained in energy-saving lamps. Until now, the powder is due to its mercury content stored as hazardous waste. By the year 2020, the EU deposits 25,000 tons of fluorescent powder including the metals it contains. Bringing all components 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 particle 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, biocollectors are recyclable and can be used repeatedly. For example, by changing the pH of the suspension the target particles can be detached from the biocollectors. The magnetic carriers as well as the peptides are completely biologically degradable and generate no additional environmental problem.