Quantitative analysis of pyrolysis characteristics and chemical components of tobacco materials based on machine learning.

To investigate the quantitative relationship between the pyrolysis characteristics and chemical components of tobacco materials, various machine learning methods were used to establish a quantitative analysis model of tobacco. The model relates the thermal weight loss rate to 19 chemical components, and identifies the characteristic temperature intervals of the pyrolysis process that significantly relate to the chemical components. The results showed that: 1) Among various machine learning methods, partial least squares (PLS), support vector regression (SVR) and Gaussian process regression (GPR) demonstrated superior regression performance on thermogravimetric data and chemical components. 2) The PLS model showed the best performance on fitting and prediction effects, and has good generalization ability to predict the 19 chemical components. For most components, the determination coefficients R 2 are above 0.85. While the performance of SVR and GPR models was comparable, the R 2 for most chemical components were below 0.75. 3) The significant temperature intervals for various chemical components were different, and most of the affected temperature intervals were within 130°C-400°C. The results can provide a reference for the materials selection of cigarette and reveal the possible interactions of various chemical components of tobacco materials in the pyrolysis process.

N-rich chitosan-derived porous carbon materials for efficient CO2 adsorption and gas separation.

Capturing and separating carbon dioxide, particularly using porous carbon adsorption separation technology, has received considerable research attention due to its advantages such as low cost and ease of regeneration. In this study, we successfully developed a one-step carbonization activation method using freeze-thaw pre-mix treatment to prepare high-nitrogen-content microporous nitrogen-doped carbon materials. These materials hold promise for capturing and separating CO2 from complex gas mixtures, such as biogas. The nitrogen content of the prepared carbon adsorbents reaches as high as 13.08 wt%, and they exhibit excellent CO2 adsorption performance under standard conditions (1 bar, 273 K/298 K), achieving 6.97 mmol/g and 3.77 mmol/g, respectively. Furthermore, according to Ideal Adsorption Solution Theory (IAST) analysis, these materials demonstrate material selectivity for CO2/CH4 (10 v:90 v) and CO2/CH4 (50 v:50 v) of 33.3 and 21.8, respectively, at 1 bar and 298 K. This study provides a promising CO2 adsorption and separation adsorbent that can be used in the efficient purification process for carbon dioxide, potentially reducing greenhouse gas emissions in industrial and energy production, thus offering robust support for addressing climate change and achieving more environmentally friendly energy production and carbon capture goals.

Interfacial Hydrothermal Assembly of Three-Dimensional Lamellar Reduced Graphene Oxide Aerogel Membranes for Water Self-Purification.

Energy-saving membrane separation for water purification is increasingly desired, which requires appropriate nanofiltration membranes enabling to reject undesired solutes efficiently and allows high permeation of water. Herein, we report the fabrication of three-dimensional lamellar reduced graphene oxide (rGO) hydrogel membranes with a one-step, environment-friendly and water/vapor interfacial hydrothermal assembly process and the corresponding aerogel membranes by the freeze-drying method. The structures of the aerogel membranes can be tuned from lamellar to porously interconnected morphologies by controlling the volume of GO suspensions during the hydrothermal process. The rGO aerogel membrane was extremely flexible, which can be bent in liquid nitrogen and boiling water without any deformation, and highly stable in various solvents for at least 2 months. When used as nanofiltration membranes, the rGO aerogel membranes showed ∼100% rejection of organic dyes and a moderate water flux (up to 53 L m-2 h-1) only under the gravity of organic dye aqueous solutions of a 30 cm height. This water self-purification property of our flexible and stable aerogel membranes without extra energy consumption provides a possibility to make cheap, portable water purification devices for utilization in emergency and home-used water purification systems in the areas with electricity unavailable or inconvenient.

Facile synthesis of chiral (right-handed) calcium carbonate with exceptional enantioseparation performance of dibenzoyltartaric acid.

The chiral morphology of calcium carbonate (mainly vaterite) was successfully synthesized by using CaCl2 under l-aspartic acid guiding by diffusion of in-site generation of CO2 and NH3 from (NH4)2CO3 and NH3·H2O. Its structure was characterized by XRD, SEM/TEM and FT-IR, it indicated that the helical-shaped chiral calcium carbonate was uniform in a diameter of 10-20 µm and height of 1 µm, and tortuous nanosheets with a thickness of 50 nm were evolved more abundant from center to edge in counterclockwise. The enantioseparation performance for racemic dibenzoyltartaric acid was evaluated, the chiral calcium carbonate showed certain recognition ability for l-dibenzoyltartaric acid due to its better matching with l-dibenzoyltartaric acid molecules in stereochemical structure. Chiral separation ability for dibenzoyltartaric acid could be significantly improved by dibutyl maleate modification of chiral calcium carbonate; the maximal ee values for dibenzoyltartaric acid increased from 20.62% to 62.15%. The synergism of chiral helical-shaped suprastructure, large proportion of vaterite and modification of surface by functional group resulted in the excellent enantiomer separation.