Influence of a Catalyst in Obtaining a Post-Consumer Pet-Based Alkyd Resin That Meets Circular Economy Principles

The paper studied the influence of a catalyst, comparing it with its traditional counterparts, in the process of obtaining a polyethylene terephthalate (PET)-based alkyd resin from post-consumer beverage bottles and how it consumes raw materials and generates waste. The resin was obtained in two phases: 1) glycerol and soybean oil alcoholysis reaction, a renewable material, for polyalcohol production, and 2) polyalcohol and polyacid esterification reaction to obtain the alkyd resin (reaction via solvent). A lithium octoate catalyst (OctLi) was used, not traditional in the alcoholysis reaction, and a fraction of the polyacid replaced by post-consumer PET at a proportion of up to 24% by weight in the esterification reaction. The OctLi catalyst caused a reaction in 30 min, compared to zinc acetate (120 min) and lithium hydroxide (LiOH, 60 min). Using post-consumer PET in obtaining the alkyd resin also decreased the esterification reaction time by 22% (8% PET), 67% (16% PET) and 72% (24% PET), compared to esterification without PET. The reaction time, considering alcoholysis with OctLi and partial esterification with PET (with 24% PET), was 180 min. Adding alcoholysis time with the LiOH catalyst and esterification without PET raises the reaction time to 600 min. Process water formed during the esterification stage declined by 15% (8% PET), 50% (16% PET) and 77% (24% PET), compared to the reaction without PET. The shorter reaction time resulted in less equipment use and consequent lower energy consumption. Another result was that the alkyd resin obtained with 8% PET was adequate for paint formulations.

A comprehensive investigation of Li-ion conductivity in lithium hydroxy halide antiperovskite solid electrolytes

Lithium hydroxide halide antiperovskite Li-ion conductors are ideal model systems for the systematic investigation of the effect of grain, grain boundary and interfacial resistance on the total Li-ion conductivity in solid-state batteries. Their low melting point (<300°C) empowers the use of melting and solidification to prepare pellets with high relative density without additional sintering steps and with control over grain size. The tunability of the halogen anion site enables control over grain conductivity and interfacial chemistry, with minimal structural perturbation. In this study, we conduct a comprehensive investigation of Li-ion conduction in Li2OHCl(1-x)Brx antiperovskites. We identify Li2OHCl0.9Br0.1 as the composition with the highest Li-ion conductivity of 2.52 E-3 mS/cm at room temperature. We highlight how the thermal expansion coefficient can serve as an indicator for the presence of structural defects hard to probe directly with X-ray techniques and essential in improving bulk Li-ion conduction. The detrimental effect of grain boundaries on ionic conductivity is demonstrated by atomistic calculations and validated experimentally by electrochemical impedance spectroscopy on pellets with controlled grain size. In-situ X-ray photoelectron spectroscopy experiments of Li2OHCl0.9Br0.1 demonstrate its chemical stability in contact with metallic lithium at room temperature. These insights provide design principles to improve Li-ion conductivity of lithium hydroxide halide antiperovskites.

Recycling Lithium from Waste Lithium Bromide to Produce Lithium Hydroxide

Lithium resources face risks of shortages owing to the rapid development of the lithium industry. This makes the efficient production and recycling of lithium an issue that should be addressed immediately. Lithium bromide is widely used as a water-absorbent material, a humidity regulator, and an absorption refrigerant in the industry. However, there are few studies on the recovery of lithium from lithium bromide after disposal. In this paper, a bipolar membrane electrodialysis (BMED) process is proposed to convert waste lithium bromide into lithium hydroxide, with the generation of valuable hydrobromic acid as a by-product. The effects of the current density, the feed salt concentration, and the initial salt chamber volume on the performance of the BMED process were studied. When the reaction conditions were optimized, it was concluded that an initial salt chamber volume of 200 mL and a salt concentration of 0.3 mol/L provided the maximum benefit. A high current density leads to high energy consumption but with high current efficiency; therefore, the optimum current density was identified as 30 mA/cm2. Under the optimized conditions, the total economic cost of the BMED process was calculated as 2.243 USD·kg−1LiOH. As well as solving the problem of recycling waste lithium bromide, the process also represents a novel production methodology for lithium hydroxide. Given the prices of lithium hydroxide and hydrobromic acid, the process is both environmentally friendly and economical.