A Fluorometric Investigation of a Peptide-assisted Interaction between Composite Magnetic Beads and Phosphors for the Recycling of Rare Earth Elements

The recovery of rare earth elements through recycling of end-of-life electronics has become a goal of increasing importance as this helps create a more sustainable economy. Nevertheless, the recycling rates are still low. Rare earth elements could potentially be recovered from phosphors in end-of-life compact fluorescent lamps. In this thesis, LAP-specific peptides were immobilized on composite magnetic beads and these were brought in contact with LAP to see how much LAP interacts with the magnetic beads. LAP is an inorganic phosphor particle that emits green light when exposed to ultraviolet radiation. To be able to interpret the binding experiments, the fluorescent spectra of five different phosphors were measured and a simple quantification method was developed. In addition to this, the ratio of elements present in five different phosphors was investigated. This thesis has provided several insights into the fluorometric properties of suspended phosphors, single or in mixture, and into the effect of media on binding experiments. These insights can help in future work e.g. to be able to adapt the binding experiments for a mixture of phosphors. Furthermore, the proof-of-concept for binding experiments developed in this thesis could easily be applied for the investigation of other peptides phosphors as well.