Environmental Chemistry Commons^™

Vermiculations In Painted Caves: New Inputs From Laboratory Experiments And Field Observations, Perrine Freydier, Eric Weber, Jérôme Martin, Pierre-Yves Jeannin, Béatrice Guerrier, Frédéric Doumenc

International Journal of Speleology

Vermiculations are aggregates of small particles commonly found on cave walls. They are a major concern for the conservation of painted caves, as they can potentially alter valuable prehistoric cave paintings. A previous rheological study of fine sediment deposits on cave walls revealed that this material can undergo a solid-to-liquid transition triggered by variations in the chemical composition of the water film on the wall. Such a transition could occur at the origin of vermiculations by allowing the sediment to flow under low mechanical stress. In this work, we provide quantitative information on the conditions leading to this transition and …

Oxygen Harvesting From Carbon Dioxide: Simultaneous Epoxidation And Co Formation, Han Xu, Muhammad Shaban, Sui Wang, Anas Alkayal, Dingxin Liu, Michael G. Kong, Felix Plasser, Benjamin R. Buckley, Felipe Iza

Bioelectrics Publications

Due to increasing concentrations in the atmosphere, carbon dioxide has, in recent times, been targeted for utilisation (Carbon Capture Utilisation and Storage, CCUS). In particular, the production of CO from CO₂ has been an area of intense interest, particularly since the CO can be utilized in Fischer–Tropsch synthesis. Herein we report that CO₂ can also be used as a source of atomic oxygen that is efficiently harvested and used as a waste-free terminal oxidant for the oxidation of alkenes to epoxides. Simultaneously, the process yields CO. Utilization of the atomic oxygen does not only generate a valuable product, …

Valorization Of Xylan In Agroforestry Waste Streams, Harrison Appiah

Graduate Theses, Dissertations, and Problem Reports

Valorization of Xylan in Agroforestry Waste Streams.

Harrison Appiah

Microwave-assisted deep eutectic solvent and gamma-valerolactone metallic chloride catalyzed conversion of xylan to furfural were investigated using a 2x3 factorial experimental design at two levels of percent microwave power, reaction time, and catalyst concentration. The levels of each factor studied were (20%, 60% microwave power, 2, 4 minutes, and 10, 20mg) respectively. The effect of three metallic chloride catalysts (LiCl, FeCl3.6H20, CuCl2) on the conversion of xylan to furfural was also investigated. The gamma-valerolactone-ferric chloride sent system exhibited the highest mean yield of furfural (56.50%). The next highest furfural yield of …