Extraction and Purification of Nicotine from Tobacco Rhizomes by Supercritical CO2.

Currently, in the ongoing development of the tobacco industry, a large amount of tobacco rhizomes is discarded as waste. These wastes are usually disposed of through incineration or burial. However, these tobacco wastes still have some economic value. High-purity nicotine has a promising market outlook as the primary raw material for electronic cigarette liquid. Nicotine is not only found in tobacco leaves but also in the rhizomes of tobacco plants. This study presents a method for treating tobacco waste and extracting high-purity nicotine from it. After mixing the raw material powder and entrainer in specific ratios, as much of the nicotine in tobacco roots can be extracted as possible using supercritical carbon dioxide extraction. The effects of temperature, the ratio of the entrainer, and the volume fraction of ethanol in the entrainer on the nicotine yield in supercritical fluid extraction (SFE) at 25 MPa for 120 min were discussed. By using 90% ethanol (a raw material mass-to-volume ratio of 1:5) as the entrainer, we obtained the highest nicotine yield of 0.49% at 65 °C. Meanwhile, the purity of the crude extract was 61.71%, and after purification, it increased to 97.57%. In this way, we can not only obtain nicotine with market value but also further reduce the harm to the environment caused by tobacco waste disposal.

Making multi-twisted luminophores produce persistent room-temperature phosphorescence.

Multi-twisted molecules, especially those with more than four branched rotation axes, have served as superior prototypes in diverse fields like molecular machines, optical materials, sensors, and so forth. However, due to excessive non-radiative relaxation of these molecules, it remains challenging to address their persistent room-temperature phosphorescence (pRTP), which limits their further development. Herein, we develop a host-guest energy-transfer relay strategy to improve the phosphorescence lifetime of multi-twisted luminophores by over thousand-fold to realize pRTP, which can be witnessed by the naked eye after removing the excitation light source. Moreover, we employ photoexcitation-induced molecular rearrangement to further prolong the phosphorescence lifetime, which, to the best of our knowledge, is the first example of photoactivation in ordered host-guest systems. Our systems show superior humidity and oxygen resistance, enabling long-term (at least over 9-12 months) stability of the pRTP properties. By achieving pRTP of multi-twisted luminophores, this work can advance the understanding of molecular photophysical mechanisms and guide the study of more molecular systems that are difficult to achieve pRTP.