One-step Formation of Urea from Carbon Dioxide and Nitrogen Using Water Microdroplets.

Water (H2O) microdroplets are sprayed onto a graphite mesh covered with a CuBi2O4 coating using a 1:1 mixture of N2 and CO2 as the nebulizing gas. The resulting microdroplets contain urea [CO(NH2)2] as detected by both mass spectrometry and 13C nuclear magnetic resonance. This gas-liquid-solid heterogeneous catalytic system synthesizes urea in one step on the 0.1 ms time scale. The conversion rate reaches 2.7 mmol g-1 h-1 at 25 °C and 12.3 mmol g-1 h-1 at 65 °C, with no external voltage applied. Water microdroplets serve as the hydrogen source and the electron transfer medium for N2 and CO2 in contact with CuBi2O4. Water-gas and water-solid contact electrification are speculated to drive the reaction process. This strategy couples N2 fixation and CO2 utilization in an ecofriendly process to produce urea, converting a greenhouse gas into a value-added product.

Microextraction and its application for petroleum and crude oil samples.

Petroleum is an extremely heterogeneous material. It consists of a wide range of aliphatic, aromatic, and compounds containing heteroatoms such as metals, sulfur, and nitrogen. The American Society for Testing and Materials (ASTM) methods are used globally as accepted analytical methods for petroleum, petrochemicals, and fuels. A major drawback of ASTM methods is that they require multistep sample preparation that consumes substantial volumes of samples. Thus, the challenge in the petrochemical analysis is to develop rapid and simpler sample preparation procedures that can be automated. An assessment based on the current literature, specifically on the sample preparation of petroleum samples, leads to the authors' conclusion that microextraction provides an excellent complement to current methods. In this review, solvent and sorbent-based microextraction techniques in the context of the consideration of petroleum and crude oil, and samples related to the petrochemical industry, are discussed.