Jianguo Yu

This paper reports the chiral separation of menthol enantiomers using the VARICOL process to improve productivity. Amylose 3,5-dimethylphenylcarbamate coated on silica gel was employed as the chiral stationary phase, and n-hexane/2-propanol (95/5, v/v) was used as the eluent. To design and optimize the VARICOL process, a linear driving-force model was developed to predict the separation performance. Separation regions of the conventional simulated moving bed (SMB) and VARICOL processes were evaluated and compared. It was found that, under an outlet purity requirement of 95.0%, the five-column VARICOL process has a separation region comparable to that of the six-column conventional SMB process. As an illustrative example, a five-column VARICOL unit and a six-column conventional SMB unit, both operating under the same conditions, were employed to resolve the menthol racemate. Purities for both the extract and raffinate were above 95.0%, and a productivity of 0.400 g_racemate/(L_CSP∙min) and a solvent consumption of 0.355 L/g_racemate were achieved in the VARICOL process. Productivity increased by 20% while solvent consumption maintained relative to the conventional SMB process, though product purities decreased slightly.

L-menthol is one of the most popular flavors in the world. The separation of menthol enantiomers is crucial because of the unpleasant taste of d-menthol. This work presents the chiral separation of racemic menthol by simulated moving bed chromatography for the first time. Six preparative columns packed with amylose 3,5-dimethylphenylcarbamate coated on silica gel were used for separation, and a mixture of n-hexane/isopropanol was selected as the mobile phase. The hydrodynamic properties of the SMB columns were studied to minimize the packing asymmetry in the SMB experiment. The binary adsorption isotherm of menthol enantiomers was measured by the adsorption–desorption method. Fixed-bed batch chromatography was carried out to evaluate the adsorption kinetic behavior. Mathematical models, considering the mass transfer resistance and axial dispersion, were applied to describe the dynamics of the chromatographic separation process. The SMB process for chiral separation of racemic menthol was designed by evaluating the separation region using simulations. Reasonable agreements were achieved between the predicted results and the experimental results. Purities for both the extract and raffinate were above 99.0%, and a productivity of 0.267 g_racemate/(L_CSP∙min) and a solvent consumption of 0.431 L/g_racemate were achieved.

In the pursuit of optimizing the reaction–extraction–crystallization-coupled mineralization process for carbon capture, utilization, and storage (CCUS) technology, this study presents a pioneering investigation into the solvent effects on the thermal decomposition of tri-n-octylamine hydrochloride (TOAHCl). Density functional theory (DFT) calculations have determined the structure parameters, solvation free energy, infrared spectrum, and charge distribution of TOAHCl in 41 solvents and obtained a universal law for the effects of solvents on the thermal decomposition process of TOAHCl, enabling the rapid screening of optimal solvents for experimental application. With the experiment results, the standout finding is the identification of n-undecane as the most favorable solvent, distinguished by its rapid thermal decomposition rate, high final conversion rate of 93.8%, minimal environmental impact, and cost-effectiveness. These attributes mark a significant advancement over solvents reported in existing literature. Furthermore, molecular dynamics (MD) simulations corroborate that n-undecane can enhance the decomposition process, underscoring their role in diluting reactants and products to facilitate mass transfer. This work not only sheds light on the solvent-mediated thermal decomposition pathways of TOAHCl but also provides a new idea for thermal decomposition solvent screening.

With the rapid development of the electric vehicle industry, an enormous amount of spent lithium-ion batteries (LIBs) has been generated. However, the traditional electrochemical recycling method suffers from high cell potentials (E_cell) and environmental burdens. In addition, anode material recycling has not always attracted much attention. Herein, the strategy of oxidizing an anode current collector and the concept of a “sandwich-type” electrode structure is proposed, which enables the recycling of both spent cathode and anode materials simultaneously in a low energy consumption manner. Electrochemical leaching experiments demonstrate that the proposed method outperforms traditional ways with lower E_cell values (98% Li⁺ and Co²⁺), and a shorter pretreatment process. Meanwhile, the Al foil and graphite are separated from the electrode residues from spent LIB cathodes and anodes, respectively. The recovered graphite can be reutilized for the re-manufacture of anode materials. The life cycle assessment uncovers that the proposed electrochemical process shows a significant reduction of the environmental and human health impacts compared with traditional processes.

Mustard tuber wastewater (MTW) is an ultra-hypersaline high-strength acid organic wastewater. Aerobic granular sludge (AGS) has been demonstrated to have high tolerance to high organic loading rate (OLR), high salinity, and broad pH ranges. However, most studies were conducted under single stress, and the performance of AGS under multiple stresses (high salinity, high OLR, and low pH) was still unclear. Herein, mature AGS was used to try to treat the real MTW at 9% salinity, pH of 4.1–6.7, and OLR of 1.8–7.2 kg COD/m³·d. The OLR was increased, and the results showed that the upper OLR boundary of AGS was 5.4 kg COD/m³·d (pH of 4.2) with relatively compact structure and high removal of TOC (~93.1%), NH₄⁺-N (~88.2%), and TP (~50.6%). Under 7.2 kg COD/m³·d (pH of 4.1), most of the AGS was fragmented, primarily due to the multiple stresses. 16S rRNA sequencing indicated that Halomonas dominated the reactor during the whole process with the presence of unclassified-f-Flavobacteriaceae, Aequorivita, Paracoccus, Bradymonas, and Cryomorpha, which played key roles in the removal of TOC, nitrogen, and phosphorus. This study investigated the performance of AGS under multiple stresses, and also brought a new route for highly-efficient simultaneous nitrification–denitrifying phosphorus removal of real MTW.