Integrated synthesis and comprehensive characterization of TiO2/AgBi2S3 ternary thin films via SILAR method

AgBi2S3, a copious and innocuous ternary metal chalcogenide affiliated with the I-V-IV group of semiconductors, was synthesized. With an energy gap of 1.2eV, it closely matches the optimal 1.39eV for solar cell absorbers. Importantly, this chalcogenide exhibits a high absorption coefficient of 105 cm-1 at 600 nm. Using the successive ionic layer adsorption and reaction (SILAR) method; we deposited an AgBi2S3 thin film onto a titanium dioxide (TiO2) thin film. Characterization techniques encompassed XRD, SEM, EDXS, UV-Vis, EIS, and PEC performance analyses. The resulting TiO2/AgBi2S3 composite film ranged in thickness from 8 μm to 13 μm, with particle sizes spanning 20 nm-265 nm. Notably, the deposition of AgBi2S3 onto the TiO2 film caused depreciation in the TiO2 energy gap from 3.1eV to 1.7eV. Furthermore, it significantly enhanced the TiO2 film's absorbance across the visible and near-infrared regions. Intriguingly, the TiO2/AgBi2S3 composite film also exhibited discernible photoelectrochemical behavior.

Urban mining of terbium, europium, and yttrium from real fluorescent lamp waste using supercritical fluid extraction: Process development and mechanistic investigation

There is a significant global push towards recycling of waste electrical and electronic equipment (WEEE) to enable the circular economy. In this study an environmentally sustainable process using supercritical carbon dioxide as the solvent, along with a small volume of tributyl-phosphate-nitric acid (TBP-HNO₃) adduct as the chelating agent, is developed to extract rare earth elements (REEs) from fluorescent lamp waste. It is found that mechanical activation using oscillation milling improves extraction efficiency. To elucidate the process mechanism, an in-depth characterization of solids before and after the process using transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS)is performed. Furthermore, UV visible spectroscopy is performed to determine the coordination chemistry of the rare earths of interest, i.e., yttrium, europium, and terbium during the complexation with TBP-HNO₃ adduct. It is found that Al³⁺ and Ca²⁺ cations from the aluminium oxide (Al₂O₃) and hydroxyapatite (Ca₅(PO₄)₃OH) present in the fluorescent lamp waste compete with REEs in reacting with TBP-HNO₃ adduct; hence, REE extractions from real fluorescent lamp waste is less than previously reported extractions from synthetic feeds. Not only can management of fluorescent lamp waste help conserve natural resources and protect ecosystems, but it can also facilitate efficient utilization of materials and promote the circular economy.

Development and Scale-Up of Diversion Strategy for Twin Screw Granulation in Continuous Manufacturing

Successful implementation of Continuous Manufacturing technology requires real time product quality monitoring that can result into rejection strategies for material manufactured outside process control limits. In a twin screw granulation process, parameters like water content, powder feed rate, and granulator screw speed can influence granule quality. Deviations in any of these parameters from the set-point may affect granule quality. Having a sound diversion strategy in place can help divert these implicated granules to waste. Residence time distribution experiments were conducted on a 16-mm Thermo Fisher twin screw granulator (TSG) for a range of process parameters, and the data was modelled to predict the needed diversion time as a function of process parameters. Scale-up from the 16-mm to 24-mm granulator was evaluated and data was found to scale based on mass per unit volume of granulator (channel fill), thus enabling 16-mm data to scale to 24-mm. The diversion strategy proposed is based on utilizing a wash out curve derived from residence time distribution to quantify the maximum concentration of implicated material that could be present in the next downstream unit operation(s) (e.g. a fluid bed dryer) and ensuring it is less than a suitable threshold to prevent product quality impact.