Chemical Recycling of WEEE Plastics—Production of High Purity Monocyclic Aromatic Chemicals

More than 200 kg real waste electrical and electronic equipment (WEEE) shredder residues from a German dismantling plant were treated at 650 °C in a demonstration scale thermochemical conversion plant. The focus within this work was the generation, purification, and analysis of pyrolysis oil. Subsequent filtration and fractional distillation were combined to yield basic chemicals in high purity. By means of fractional distillation, pure monocyclic aromatic fractions containing benzene, toluene, ethylbenzene, and xylene (BTEX aromatics) as well as styrene and α-methyl styrene were isolated for chemical recycling. Mass balances were determined, and gas chromatography–mass spectrometry (GC-MS) as well as energy dispersive X-ray fluorescence (EDXRF) measurements provided data on the purity and halogen content of each fraction. This work shows that thermochemical conversion and the subsequent refining by fractional distillation is capable of recycling WEEE shredder residues, producing pure BTEX and other monocyclic aromatic fractions. A significant decrease of halogen content (up to 99%) was achieved with the applied methods.

Enhancement of Lignin Extraction of Poplar by Treatment of Deep Eutectic Solvent with Low Halogen Content

A novel choline-based deep eutectic solvent (DES) with low halogen content—namely choline lactate-lactic acid (CLL)—was synthesized by replacing the chloride anion with lactate anion in choline chloride-lactic acid (CCL). CLL and CCL treatments were conducted at 140 °C for 12 h with hydrogen bond acceptor/hydrogen bond donor =1/10, thereafter composition analysis and characterizations of the lignin extracted by DES treatment (DES lignin) and the solid residue were carried out. The proposed low halogen content DES presented an improved lignin extraction efficiency. The CLL treatment extracted 90.13% of initial lignin from poplar, while CCL extracted 86.02%. In addition, the CLL treatment also provided DES lignin with an improved purity (91.17%), lower molecular weight (Mw/Mn=1805/971 g/mol) and more concentrated distribution (polydispersity index=1.86). The efficient lignin extraction was mainly ascribed to the cleavage of β-O-4 bonds in lignin macromolecule, especially in the guaiacyl units, thereby breaking them into smaller molecules, facilitating the lignin extraction. The replacement of chloride anion allowed CLL acting as a more efficient DES to interact with lignin macromolecules, thus providing lignin with higher uniformity and suitable molecular weight. The low halogen content DES system proposed in present work could benefit the fractionation of biomass, improve the valorization of lignin compounds and facilitate industrial process in the downstream.

Halogens in amphibole and mica from mantle xenoliths: Implications for the halogen distribution and halogen budget of the metasomatized continental lithosphere

This study reports halogen contents (F and Cl) of amphibole and phlogopite derived from mantle xenoliths and one peridotite massif, for amphibole and phlogopite megacrysts and ultramafic magmatic cumulates (hornblendites) found in alkaline volcanic rocks from 12 localities in Europe and Africa. Amphibole and phlogopite contain more F than Cl with F/Cl ratios reaching about 160 in phlogopites and 50 in amphiboles. Phlogopites are higher in F (median of 3400 μg/g) than amphibole (median of 1000 μg/g), while median Cl contents are higher in amphibole (290 μg/g) compared to phlogopite (180 μg/g). The Cl contents and the F/Cl ratios in amphibole and phlogopite from mantle xenoliths exhibit large differences between samples of the same region, recording very large variations of halogen contents in the continental lithosphere. We suggest that the halogen content in such samples largely depends on the initial composition of percolating melts and fluids in the continental lithosphere. During reaction of these agents with peridotitic wall-rocks, Cl is preferentially retained in the fluid as it is much more incompatible compared to water and F. This desiccation effect continuously increases salinity (Cl content) and decreases the F/Cl ratio in the agent with time, causing variable Cl contents and F/Cl ratios in amphibole and phlogopite at a specific locality. Subsequent partial melting processes may then sequester and re-distribute, especially Cl among amphibole, phlogopite and melts/fluids as a result of its strong incompatibility, whereas F is much less affected as it behaves slightly compatible. The impact of even small amounts of amphibole and mica on the total halogen budget in the continental lithosphere is significant and both minerals can effectively contribute to the high halogen contents typical of alkaline melts.

Update on Monoterpenes from Red Macroalgae: Isolation, Analysis, and Bioactivity

Macroalgae produce a wide range of monoterpenes as secondary metabolites of mevalonate (MVA) and/or methylerythritol phosphate (MEP) pathway (often including haloperoxidase action). Great biodiversity of macroalgal monoterpenes was reported including acyclic, monocyclic, and bicyclic structures. Halogenated monoterpenes exhibited significant biological activity (e.g., anticancer, antiplasmodial, and insecticidal) that is influenced by the number of present halogens (higher halogen content is preferable, especially bromine) and their position within the monoterpene skeleton. In distinction from the existing reviews, the present review provides novelty with respect to: (a) exclusively monoterpenes from red macroalgae are targeted; (b) biosynthesis, isolation, and analysis, as well as bioactivity of monoterpenes are represented; (c) the methods of their isolation, analysis, and structure elucidation are summarized; (d) the bioactivity of macroalgal monoterpenes is systematically presented with emphasis on anticancer activity; (e) the literature references were updated.