ABSTRACT
Common B7 biodiesels consist of mixtures of mineral oil-based diesel and 7% fatty acid methyl ester (FAME). While biocontent increase can be achieved with these blends at high-quality levels during cold temperature periods, fuel filter blocking events are reported from time to time. Based on a preliminary study on fuel filters, the selection of compounds responsible for filter blocking could be narrowed down to saturated monoglycerides (SMGs). The most abundant SMGs in Europe are 1- and 2-monopalmitin (1-C16:0, 2-C16:0) and 1-monostearin (C18:0), based on the FAME origin. Until now, there has been no simple, precise, and accurate method to quantitatively detect those SMGs in the B7 matrix, which was the aim of the following work. An improved gas chromatography electron ionization tandem mass spectrometry method was developed for the quantitative detection of 1-C16:0, 2-C16:0, C18:0, and C20:0 SMGs. During the method improvement, (a) the sample preparation and (b) the calibration were optimized for low concentrations. (c) The samples were analyzed by multiple reaction monitoring focusing on specific qualifier and quantifier ions with optimized collision energies, (d) time segments and improved scan time were implemented, and (e) limits of detection and limits of quantification were determined. The time-stability of SMG standards in CHCl3 with 4% neat biodiesel and the discrimination effects of the standard components were evaluated to assess method reliability. Overall, a highly sensitive and precise method for the improved detection of SMGs in biodiesel is presented.
ABSTRACT
Lignin has been, for a long time, treated as a low-value waste product. To change this scenario, high-value applications have been recently pursued, e.g., the preparation of hybrid materials with inorganic components. Although hybrid inorganic-based materials can benefit from the reactive lignin phenolic groups at the interface, often responsible for optimizing specific properties, this is still an underexplored field. Here, we present a novel and green material based on the combination of hydroxymethylated lignin nanoparticles (HLNPs) with molybdenum disulfide (MoS2) nanoflowers grown via a hydrothermal route. By bringing together the lubricant performance of MoS2 and the structural stability of biomass-based nanoparticles, a MoS2-HLNPs hybrid is presented as a bio-derived additive for superior tribological performances. While FT-IR analysis confirmed the structural stability of lignin after the hydrothermal growth of MoS2, TEM and SEM micrographs revealed a homogeneous distribution of MoS2 nanoflowers (average size of 400 nm) on the HLNPs (average size of 100 nm). Regarding the tribological tests, considering a pure oil as reference, only HLNPs as bio-derived additives led to a reduction in the wear volume of 18%. However, the hybrid of MoS2-HLNPs led to a considerably higher reduction (71%), pointing out its superior performance. These results open a new window of opportunity for a versatile and yet underexplored field that can pave the way for a new class of biobased lubricants.
ABSTRACT
Invited for this month's cover is the group of Adam Slabon at the University of Wuppertal. The image illustrates the reductive depolymerization of lignin into monomers using copper as electrocatalyst. The Research Article itself is available at 10.1002/cssc.202200718.
Subject(s)
Copper , Lignin , Biomass , SolventsABSTRACT
Breaking down lignin into smaller units is the key to generate high value-added products. Nevertheless, dissolving this complex plant polyphenol in an environment-friendly way is often a challenge. Levulinic acid, which is formed during the hydrothermal processing of lignocellulosic biomass, has been shown to efficiently dissolve lignin. Herein, levulinic acid was evaluated as a medium for the reductive electrochemical depolymerization of the lignin macromolecule. Copper was chosen as the electrocatalyst due to the economic feasibility and low activity towards the hydrogen evolution reaction. After depolymerization, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy revealed lignin-derived monomers and dimers. A predominance of aryl ether and phenolic groups was observed. Depolymerized lignin was further evaluated as an anti-corrosion coating, revealing enhancements on the electrochemical stability of the metal. Via a simple depolymerization process of biomass waste in a biomass-based solvent, a straightforward approach to produce high value-added compounds or tailored biobased materials was demonstrated.
Subject(s)
Hydrogen , Lignin , Biomass , Lignin/chemistry , Polymerization , Solvents/chemistryABSTRACT
In order to reveal the degradation products of oxygen-containing fuel components, in particular fatty acid methyl esters, a novel approach was developed to characterize the oxidation behaviour. Combination of artificial alteration under pressurized oxygen atmosphere, a stable isotopic tracer, and gas chromatography electron impact mass spectrometry (GC-EI-MS) was used to obtain detailed information on the formation of oxidation products of (9Z), (12Z)-octadecadienoic acid methyl ester (C18:2 ME). Thereby, biodiesel simulating model compound C18:2 ME was oxidized in a rotating pressurized vessel standardized for lubricant oxidation tests (RPVOT), i.e., artificially altered, under 16O2 as well as 18O2 atmosphere. Identification of the formed degradation products, mainly carboxylic acids of various chain lengths, alcohols, ketones, and esters, was performed by means of GC-EI-MS. Comparison of mass spectra of compounds under both atmospheres revealed not only the degree of oxidation and the origin of oxygen atoms, but also the sites of oxidative attack and bond cleavage. Hence, the developed and outlined strategy based on a gas-phase stable isotopic tracer and mass spectrometry provides insight into the degradation of oxygen-containing fuels and fuel components by means of the accurate differentiation of oxygen origin in a degradation product.
