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BACKGROUND Spent fluorescent lamps, classified as hazardous waste in the EU, are segregated at source. Processes for the recovery of critical rare-earth (RE) elements from the phosphor powder waste, however, often involve use of aggressive acid or alkali digestion, multi-stage separation procedures, and production of large aqueous waste streams which require further treatment. RESULTS To overcome these difficulties phosphor powder pre-treated with dilute HCl was leached with a 1:1 wt. [Hmim][HSO4]:H2O solution at a solid:liquid ratio of 5%, at 80 °C for 4 h with stirring at 300 rpm to recover 91.6 wt% of the Y and 97.7 wt% of the Eu present. The yttrium-europium oxide (YOX), (Y0.95Eu0.05)2O3, recovered by precipitating the dissolved RE elements from the leach solution with oxalic acid and converting the oxalate to an oxide phase by heating, was characterised by FTIR, XRD and luminescence analysis. The analyses suggest the recovered oxide has the potential to be directly reused as YOX phosphor. Regeneration and reuse of the ionic liquid is achieved with only minor leaching efficiency losses found over four leaching/recovery cycles. CONCLUSION The recovery of yttrium europium oxide from waste fluorescent tube phosphor by a simple efficient low cost ionic liquid process has been developed.

BACKGROUND: The increasing value of pure vegetable oils has made the use of waste cooking oils an attractive alternative feedstock for biodiesel production but the presence of free fatty acids in the waste significantly reduces efficiency of the conversion. RESULTS: A low-temperature mixed ionic liquid system with dual extraction and catalytic functions for the conversion of waste oils containing high levels of free fatty acids to biodiesel was successfully trialled. The solvent, a totally miscible system of HPyrBr and the Brønsted acid, SPyrHSO4, allows the key properties of each ionic liquid, as extractant or catalyst, to work uninhibited by the presence of the other. Extraction of free fatty acids from vegetable oils and their conversion to methyl esters in high yield is demonstrated for vegetable oils, containing single and mixed fatty acids, and for a model waste cooking oil. The oil separated from free fatty acids in the waste has a low acid value and can be converted efficiently to biodiesel; with the ionic liquid solvent recovered unchanged for reuse. CONCLUSIONS: A mixed ionic liquid extraction-esterification solvent process has been developed to effect efficient conversion of free fatty acids in waste vegetable oils to biodiesel and their conversion to esters.