Removal of NO at low concentration from air in urban built environments by activated miscanthus biochar

This work presents an innovative and sustainable approach to remove NO emissions from urban ambient air in confined areas (underground parking areas or tunnels) using low-cost activated carbons obtained from Miscanthus biochar (MSP700) by physical activation (with CO2 or steam) at temperatures ranging from 800 to 900 °C. The NO removal capacity of the activated biochars was evaluated under different conditions (temperature, humidity and oxygen concentration) and compared against a commercial activated carbon. This last material showed a clear dependence on oxygen concentration and temperature, exhibiting a maximum capacity of 72.6% in air at 20 °C, whilst, its capacity notably decreased at higher temperatures, revealing that physical NO adsorption is the limiting step for the commercial sample that presents limited oxygen surface functionalities. In contrast, MSP700-activated biochars reached nearly complete NO removal (99.9%) at all tested temperatures in air ambient. Those MSP700-derived carbons only required low oxygen concentration (4 vol%) in the gas stream to achieve the full NO removal at 20 °C. Moreover, they also showed an excellent performance in the presence of H2O, reaching NO removal higher than 96%. This remarkable activity results from the abundance of basic oxygenated surface groups, which act as active sites for NO/O2 adsorption, along with the presence of a homogeneous microporosity of 6 Å, which enables intimate contact between NO and O2. These features promote the oxidation of NO to NO2, which is further retained over the carbon surface. Therefore, the activated biochars studied here could be considered promising materials for the efficient removal of NO at low concentrations from air at moderate temperatures, thus closely approaching real-life conditions in confined spaces.J. Fermoso gratefully acknowledges the financial support from the Comunidad de Madrid through the Talent Attraction Programme (2018-T1/AMB-10023)

Effect of co-gasification of biomass and petroleum coke with coal on the production of gases

The co-pyrolysis and co-gasification of binary blends of a bituminous coal (PT), a petcoke (PC) and two types of biomass (olive stones, OS; chestnut, CH) were studied at atmospheric pressure in a fixed bed reactor. The pyrolysis and gasification were performed under nitrogen, and steam/oxygen atmospheres, respectively. In a fixed bed reactor, the particles of the different fuels are in close contact, providing an optimum means for evaluating possible synergetic effects. Pyrolysis tests showed a lack of chemical interaction between the components of the blend. Therefore, the composition of the gas produced during the pyrolysis tests can be predicted from those of the individual components and their mass fractions. During the co-gasification tests, different interactions were observed depending on the heating rate. Low heating rates produced higher amount of CO and CO₂, whereas tar yield decreased. At high heating rates, the biomass and coal blends produced more tar but less H₂ and CO. The effect of co-gasification on apparent thermal efficiency was also evaluated

Promising Chalcogenide Hybrid Copolymers for Sustainable Applications as Bio-lubricants and Metal Adsorbents

9 Páginas.-- 4 Tablas.--5 FigurasInverse vulcanization has emerged as a reaction to achieve hybrid inorganic-organic polymeric materials, which allows us to use the high amount of sulfur produced during refining crude oil as a raw material. In this study, a gamut of copolymers has been formulated using a quantitative atom economy, that is, elemental sulfur and castor oil (CO), as can be seen from the appearance of gels to crystalline copolymers. The physical and chemical characterization has been carried out using techniques such as Fourier transform infrared spectroscopy, NMR, differential scanning calorimetry, and thermogravimetric analysis. Furthermore, two types of copolymers have been selected to test their capabilities in different applications. Copolymers with S ratios higher than 30% have been tested for water remediation, with high removal rates for metals such as lead and cadmium. Although copolymers with a percentage of up to 10% sulfur have been tested as bio-based lubricants, showing improvements in terms of viscosities compared to the initial vegetable oil.The authors thank financial support from Junta de Andalucía, Consejería de Economía y Conocimiento, and University of Huelva (P.O. Feder UHU-1257728).Peer reviewe