A hybrid thermal-biological recycling route for efficient extraction of metals and metalloids from end-of-life liquid crystal displays (LCDs).

Waste liquid crystal displays (LCDs) are one of the most substantial and rapidly growing e-waste streams that contain a notable amount of critical, precious, and toxic elements. This study presented a novel thermal-biological hybrid method for resource recovery from waste LCDs. Through the design of a multistage thermal treatment process with the addition of optimized 20 wt% B2O3 to waste, the LCD's glass structure was separated into two interconnected phases, resulting in the transfer of metals from the LCD's glass phase to the B2O3 phase that can solubilize in the acid solution. Following the thermal treatment step, the biometabolites of Aspergillus niger were used for bioleaching of In, Sr, Al, and As from the obtained thermally treated product. The optimal bioleaching parameters were a pulp density of 10 g/L, temperature of 70 °C, and leaching time of 2 days, which led to the highest extraction of 82.6% Al, 70.8% As, 64.5% In, and 36.2% Sr from thermally treated LCD waste, representing a multifold increase in Al, As, and Sr extraction levels compared to untreated waste. This study demonstrated that the proposed hybrid method could successfully overcome waste complexities and ensure effective element extraction from discarded LCDs.

Infrared transmission spectroscopy of charge carriers in self-assembled InAs quantum dots under surface electric fields.

We present a study on the intersublevel spacings of electrons and holes in a single layer of InAs self-assembled quantum dots. We use Fourier transform infrared transmission spectroscopy via a density chopping scheme for direct experimental observation of the intersublevel spacings of electrons without any external magnetic field. Epitaxial, complementary-doped and semi-transparent electrostatic gates are grown within the ultra high vacuum conditions of molecular beam epitaxy to voltage-tune the device, while a two dimensional electron gas (2DEG) serves as a back contact. Spacings of the hole sublevels are indirectly calculated from the photoluminescence spectrum by using a simple model given by Warburton et al [1]. Additionally, we observe that the intersubb and resonances of the 2DEG are enhanced due to the quantum dot layer on top of the device.