Low-energy magnetic excitations in the $S=\frac{1}{2}$ chain compound $\left[\left({\text{C}}_6{\text{H}}_9{\text{N}}_2\right){\text{CuCl}}_3\right]$ ${\text{CuCl}}_3$ [known as (6MAP)${\text{CuCl}}_3$] are probed by means of tunable-frequency electron spin resonance. Two modes with asymmetric (with respect to the $h\nu =g{\mu }_{B}B$ line) frequency-field dependences are resolved, illuminating the striking incompatibility with a simple uniform $S=\frac{1}{2}$ Heisenberg chain model. The unusual ESR spectrum is explained in terms of the recently developed theory for $S=\frac{1}{2}$ chains, suggesting the important role of next-nearest-neighbor interactions in this compound. Our conclusion is supported by model calculations for the magnetic susceptibility of (6MAP)${\text{CuCl}}_3$, revealing a good qualitative agreement with experiment. DOI: http://dx.doi.org/10.1103/PhysRevB.82.014416 © 2010 The American Physical Society

Co-treatment for two kinds of hazardous solid waste is an effective method to reduce cost and increase recycle efficiency of value resource. This work developed an integrated process based on capture of red mud (RM) and a one-step heat-treatment process to efficiently recover PGMs from spent auto-catalysts (SAC) and reuse RM simultaneously. Firstly, the iron oxide in RM was reduced to metallic iron to capture PGMs by the reduction process, without the addition of an extra reducing agent, since SAC contained abundant organic volatiles. Then, the mixed waste of SAC and RM was melted under high temperature with additives of CaO and H₃BO₃. More than 99% of PGMs can be extracted under the optimal conditions of 40–50 wt% of RM addition, 14 wt% of H₃BO₃ addition, 0.7–0.8 of basicity, 1500 °C of temperature, and 40 min of holding time. In addition, PGM content in obtained glassy slag was less than 1 g/t. The mechanism of iron trapping PGMs was also discussed in detailed, which mainly contained two stages: migration of PGMs and separation of PGM-bearing alloy and slag phases. Besides, the obtained glassy slag was further prepared into glass-ceramic by a one-step heat-treatment process. It was found that the prepared glass-ceramic has good thermostability and an excellent stabilizing effect on heavy metals. Overall, the results indicated that the developed integrated smelting–collection process is an efficient and promising method for the reutilization of SAC and RM.

As environmental awareness grows, hydrodesulfurization (HDS) catalysts have become crucial in petroleum refining, yet their use results in oil-laden waste, poses environmental risks, and complicates subsequent treatment. Efficient oil removal is thus critical for processing spent catalysts. This study systematically compares three de-oiling methods, extraction, chemical thermal washing, and pyrolysis, to identify the optimal de-oiling method. In the experiments, extraction achieves a 94.12% oil removal rate at a liquid-to-solid ratio of 10 mL/g, a temperature of 45 °C, and a time of 60 min, maintaining around 90% efficiency after five cycles of solvent recovery. Chemical thermal washing achieves an oil removal rate of 96.26% after 4 h at 90 °C, with 0.15 wt.% SDS, 3.0 wt.% NaOH, and a liquid-to-solid ratio of 10 mL/g. The heavy oil emulsion is then decomposed with 4% CuO and 5% H₂O₂. The pyrolysis method removes 96.19% of oil at 600 °C in 60 min. While the extraction and chemical thermal washing methods are effective, they produce wastewater, raising environmental concerns. In contrast, the pyrolysis method is more environmentally friendly. SEM, EDS, and FT-IR analyses show that after oil removal, the metal structures on the alumina support of the spent HDS catalyst are clearly exposed, facilitating the subsequent recovery of valuable metals.

Spent rare earth molten salt electrolytic slag (REMES) needs to be recovered not only because of its economic value of rare earth elements (REEs), lithium, and fluorine, but also for the environmental benefits. Vacuum distillation has many advantages, such as a short process and less wastewater. Aiming to find an environmentally friendly method to recover REEs, this research studied the challenges in recovering REMES by vacuum distillation and the solutions to handle these obstacles. Distillation experiments for the raw material were initially implemented and XRD, XPS, DSC, and SEM methods were used to investigate the phase changes of REMES, thus discovering that oxide impurities could transform REF₃ into REOF, which significantly affected the REEs recovery. Only 42.04% of the REEs could be evaporated at 1573 K and 0.1 Pa for 4 h with 99.99% of LiF. To tackle this issue, a fluorination pretreatment was proposed. NH₄HF₂ was utilized to transform oxide impurities, RE₂O₃, and REOF to fluorides with almost no waste gas released, significantly improving the recovery efficiency of the REEs, which was 86.23%. Therefore, this paper proposes this fluorination–vacuum distillation method, which has a short process to recover REF₃ from REMES efficiently with almost no wastewater or gas released.