Optimizing pre-carbonization temperature of sesame residue for hierarchical porous carbon materials in high-performance supercapacitor applications.

In this paper, the sesame residue, a common biomass waste, was used as a precursor to synthesize N,O co-doped porous carbon materials via a simple pre-carbonization and KNO3activation two-step strategy. The apparent morphology and supercapacitor performance of the obtained materials can be regulated by changing the pre-carbonization temperature (0 °C, 300 °C and 600 °C). The consequences demonstrate that a large number of C-C and C-O bonds in sesame residue undergo cleavage and form abundant pore structure at the pre-carbonization temperature of 300 °C. After KNO3activation, the material has a moderate specific surface area (1073.4 m2g-1) and affluent heteroatom content (N: 7.52 at%, O: 17.65 at%). As a result, the SS-300 electrode displays exceptional capacitive performance (specific capacitance up to 312.7 F g-1at 0.5 A g-1) and outstanding cyclic stability (capacitance retention reaching 98.3% at 10 A g-1after 8000 charge-discharge cycles). Moreover, the symmetric supercapacitor assembled by SS-300 exhibits high energy densities in both 6 M KOH (4.58 Wh kg-1) and 1 M Na2SO4(15.60 Wh kg-1), highlighting the potential of this material for energy storage applications.

Elucidating the unexpected importance of intermediate-volatility organic compounds (IVOCs) from refueling procedure.

Evaporative emissions release organic compounds comparable to gasoline exhaust in China. However, the measurement of intermediate volatility organic compounds (IVOCs) is lacking in studies focusing on gasoline evaporation. This study sampled organics from a real-world refueling procedure and analyzed the organic compounds using comprehensive two-dimensional gas chromatography coupled with a mass spectrometer (GC×GC-MS). The non-target analysis detected and quantified 279 organics containing 93 volatile organic compounds (VOCs, 64.9 ± 7.4 % in mass concentration), 182 IVOCs (34.9 ± 7.4 %), and 4 semivolatile organic compounds (SVOCs, 0.2 %). The refueling emission profile was distinct from that of gasoline exhaust. The b-alkanes in the B12 volatility bin are the most abundant IVOC species (1.9 ± 1.4 µg m-3) in refueling. A non-negligible contribution of 17.5 % to the ozone formation potential (OFP) from IVOCs was found. Although IVOCs are less in concentration, secondary organic aerosol potential (SOAP) from IVOCs (58.1 %) even exceeds SOAP from VOCs (41.6 %), mainly from b-alkane in the IVOC range. At the molecular level, the proportion of cyclic compounds in SOAP (12.1 %) indeed goes above its mass concentration (3.1 %), mainly contributed by cyclohexanes and cycloheptanes. As a result, the concentrations and SOAP of cyclic compounds (>50 %) could be overestimated in previous studies. Our study found an unexpected contribution of IVOCs from refueling procedures to both ozone and SOA formation, providing new insights into secondary pollution control policy.

Particulate organic emissions from incense-burning smoke: Chemical compositions and emission characteristics.

Incense burning is a common practice in Asian cultures, releasing hazardous particulate organics. Inhaling incense smoke can result in adverse health effects, yet the molecular compositions of incense-burning organics have not been well investigated due to the lack of measurement of intermediate-volatility and semi-volatile organic compounds (I/SVOCs). To elucidate the detailed emission profile of incense-burning particles, we conducted a non-target measurement of organics emitted from incense combustion. Quartz filters were utilized to trap particles, and organics were analyzed by a comprehensive two-dimensional gas chromatography-mass spectrometer (GC × GC-MS) coupled with a thermal desorption system (TDS). To deal with the complex data obtained by GC × GC-MS, homologs are identified mainly by the combination of selected ion chromatograms (SICs) and retention indexes. SICs of 58, 60, 74, 91, and 97 were utilized to identify 2-ketones, acids, fatty acid methyl esters, fatty acid phenylmethyl esters, and alcohols, respectively. Phenolic compounds contribute the most to emission factors (EFs) among all chemical classes, taking up 24.5 % ± 6.5 % of the total EF (96.1 ± 43.1 µg g-1). These compounds are largely derived from the thermal degradation of lignin. Biomarkers like sugars (mainly levoglucosan), hopanes, and sterols are extensively detected in incense combustion fumes. Incense materials play a more important role in shaping emission profiles than incense forms. Our study provides a detailed emission profile of particulate organics emitted from incense burning across the full-volatility range, which can be used in the health risk assessments. The data processing procedure in this work could also benefit those with less experience in non-target analysis, especially GC × GC-MS data processing.

Addressing new chemicals of emerging concern (CECs) in an indoor office.

Indoor pollutants change over time and place. Exposure to hazardous organics is associated with adverse health effects. This work sampled gaseous organics by Tenax TA tubes in two indoor rooms, i.e., an office set as samples, and the room of chassis dynamometer (RCD) set as backgrounds. Compounds are analyzed by a thermal desorption comprehensive two-dimensional gas chromatography-quadrupole mass spectrometer (TD-GC × GC-qMS). Four new chemicals of emerging concern (CECs) are screened in 469 organics quantified. We proposed a three-step pipeline for CECs screening utilizing GC × GC including 1) non-target scanning of organics with convincing molecular structures and quantification results, 2) statistical analysis between samples and backgrounds to extract useful information, and 3) pixel-based property estimation to evaluate the contamination potential of addressed chemicals. New CECs spotted in this work are all intermediate volatility organic compounds (IVOCs), containing mintketone, isolongifolene, ß-funebrene, and (5α)-androstane. Mintketone and sesquiterpenes may be derived from the use of volatile chemical products (VCPs), while (5α)-androstane is probably human-emitted. The occurrence and contamination potential of the addressed new CECs are reported for the first time. Non-target scanning and the measurement of IVOCs are of vital importance to get a full glimpse of indoor organics.

Ru(II)-SDP-complex-catalyzed asymmetric hydrogenation of ketones. Effect of the alkali metal cation in the reaction.

The Ru(II) complexes of SDP and DPEN combined with t-BuOK in 2-propanol formed a very effective catalyst for the hydrogenation of simple aromatic ketones with high activity and enantioselectivity. The racemic alpha-arylcycloalkanones can also be hydrogenated by this system, providing alpha-arylcycloalkanols in excellent cis/trans stereoselectivity (>99:1) and enantioselectivity (up to 99.9%) for the cis isomer. In the study of the effect of the alkali metal cation in the hydrogenation of acetophenone using RuCl(2)(Tol-SDP)(DPEN) and RuCl(2)(Xyl-SDP)(DPEN) catalysts, we found that t-BuONa provided a faster reaction than t-BuOK, which indicated that the sterically hindered diphosphine ligands preferred the base with the smaller metal cation.