Very simple chemistry can result in the rapid and high-yield production of key prebiotic inorganic molecules. The two reactions investigated here involve such simple systems, (a) carbon disulfide (CS2) and acetate (CH3COO¯) and (b) sulfur dioxide (SO2) and formate (HCOO¯). They have been carried out under non-aqueous conditions, either in an organic solvent or with a powdered salt exposed to the requisite gas. Under such dry conditions the first reaction generated the thioacetate anion [CH3COS]¯ while the second produced the radical [SO2·]¯anion. Anhydrous conditions are not rare and may have arisen on the early earth at sites where an interface between different phases (liquid/gas or solid/gas) could be generated. This is one way to rationalize the formation of molecules and ions (such as we have produced) necessary in the prebiotic world. Interpretation of our results provides insight into scenarios consistent with the more prominent theories of abiogenesis. 相似文献
Poly(limonene carbonate) (PLC) has been highlighted as an attractive substitute to petroleum derived plastics, due to its utilisation of CO2 and bio-based limonene as feedstocks, offering an effective carbon capture and utilisation pathway. Our study investigates the techno-economic viability and environmental sustainability of a novel process to produce PLC from citrus waste derived limonene, coupled with an anaerobic digestion process to enable energy cogeneration and waste recovery maximisation. Computational process design was integrated with a life cycle assessment to identify the sustainability improvement opportunities. PLC production was found to be economically viable, assuming sufficient citrus waste is supplied to the process, and environmentally preferable to polystyrene (PS) in various impact categories including climate change. However, it exhibited greater environmental burdens than PS across other impact categories, although the environmental performance could be improved with a waste recovery system, at the cost of a process design shift towards energy generation. Finally, our study quantified the potential contribution of PLC to mitigating the escape of atmospheric CO2 concentration from the planetary boundary. We emphasise the importance of a holistic approach to process design and highlight the potential impacts of biopolymers, which is instrumental in solving environmental problems facing the plastic industry and building a sustainable circular economy. 相似文献
From urea to nucleobases : Freeze–thaw cycles in urea ( 1 ) solutions under methane/nitrogen atmospheres lead, with application of an energy source, to the synthesis of pyrimidines (mainly cytosine ( 2 ) and uracil ( 3 )), triazines (such as cyanuric acid ( 4 )), and adenine. This synthesis appears to be dependent on the atmosphere and the freezing conditions. At room temperature, hydantoin ( 5 ) is obtained. However, a freezing urea/water system subjected to an energy source under an inert atmosphere generates s‐triazines.
Recently, the existence of a relation between the rupture of 1,4-β-glycosidic bonds in the cellulose during thermal-ageing of paper/oil systems and the detection of methanol in the oil has been reported for the first time in this journal (Jalbert et al. 2007). The present study addresses the rate constants of the reaction for standard wood kraft papers, two immersed in inhibited naphthenic oil under air (paper/oil weight–volume ratio of 1:18) and one in non-inhibited paraffinic oil under nitrogen (paper/oil weight–volume ratio of 1:30). The isotherms in the range of 60–130 °C show that the initial rate of methanol production markedly increases with temperature and to a lesser extent with the moisture of the specimens (initially between 0.5 and 2.25% (w/w)), similarly to what is noted for the depolymerization through the Ekenstam’s pseudo-zero order model. The Arrhenius expression of the rate constants reveals linear relationships that confirm the dominance of a given mechanism in both cases. A very good agreement is also noted for the activation energy over the entirely paper/oil systems studied (106.9 ± 4.3 and 103.5 ± 3.7 kJ mol?1 for methanol and scissions, respectively). Furthermore, a comparison of the rate constants $ \left( {k_{{{\text{CH}}_{ 3} {\text{OH}}}} /k_{\text{scissions}} } \right) Recently, the existence of a relation between the rupture of 1,4-β-glycosidic bonds in the cellulose during thermal-ageing of paper/oil systems and the detection of methanol in the oil has
been reported for the first time in this journal (Jalbert et al. 2007). The present study addresses the rate constants of the reaction for standard wood kraft papers, two immersed in inhibited
naphthenic oil under air (paper/oil weight–volume ratio of 1:18) and one in non-inhibited paraffinic oil under nitrogen (paper/oil
weight–volume ratio of 1:30). The isotherms in the range of 60–130 °C show that the initial rate of methanol production markedly
increases with temperature and to a lesser extent with the moisture of the specimens (initially between 0.5 and 2.25% (w/w)),
similarly to what is noted for the depolymerization through the Ekenstam’s pseudo-zero order model. The Arrhenius expression
of the rate constants reveals linear relationships that confirm the dominance of a given mechanism in both cases. A very good
agreement is also noted for the activation energy over the entirely paper/oil systems studied (106.9 ± 4.3 and 103.5 ± 3.7 kJ mol−1 for methanol and scissions, respectively). Furthermore, a comparison of the rate constants shows approximately constant values indicating an apparent yield for the methanol of about one-third molecule per every scission
for the tests under air (0.27 ± 0.04 for Clupak HD75 and 0.37 ± 0.14 for Munksj? TH70) and even lower for the ones under N2 (0.12 ± 0.03 for Munksj? E.G.). As expected from a pseudo-zero order model, these values were shown to be consistent with
a similar comparison of the amount of CH3OH and chain-end groups produced under specific time–temperature ageing conditions (168 h at 120 °C). Finally, an additional
test carried out with unaged cellulose in contact with a fresh solution of methanol in oil (cellulose/oil weight–volume ratio
of 1:18) shows that at equilibrium, over 58% of the species is lost from the solution due to penetration into the fibres.
Such results reveal the importance of the species partitioning in establishing the true correspondence between the molecules
of CH3OH produced and the scissions. 相似文献