Dioxin-like polychlorinated biphenyls (dl-PCB) in hydrochars and biochars: Review of recent evidence, pollution levels, critical gaps, formation mechanisms and regulations.

Contamination of chars with dioxin-like polychlorinated biphenyls (dl-PCB) significantly limits their use and hinders their deployment in the circular bioeconomy, specifically in applications that may lead to dietary exposure. Here, for the first time, we review the levels of contamination of chars produced from pyrolysis and hydrothermal carbonisation (HTC) with dl-PCB congeners. We conduct a detailed and critical examination of the role played by the processing parameters, such as temperature and residence time, and the reaction mechanisms, to detoxify the biomass under an oxygen-free atmosphere during its valorisation.

Alteration of biomass toxicity in torrefaction - A XDS-CALUX bioassay study.

Torrefaction constitutes one of the promising technologies for the management of waste biomass and the production of high-carbon products for combustion, gasification, adsorption of pollutants or soil treatment. Unfortunately, waste biomass may be contaminated with toxic persistent organic pollutants, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) and dioxin-like biphenyls (dl-PCB). Literature does not provide consistent measurements on how the low-temperature thermochemical processing, such as torrefaction, affects the toxicity of biomass.

Thermal decomposition of perfluorinated carboxylic acids: Kinetic model and theoretical requirements for PFAS incineration.

Thermal decomposition of high-fluorine content PFAS streams for the disposal of old generations of concentrates of firefighting foams, exhausted ion-exchanged resins and granular activated carbon, constitutes the preferred method for destruction of these materials. This contribution studies the thermal transformation of perfluoropentanoic acid (CFC(O)OH, PFPA), as a model PFAS species, in gas-phase reactions over broad ranges of temperature and residence time, which characterise incinerators and cement kilns. Our focus is only on gas-phase reactions, to formulate a gas-phase submodel that, in future, could be used in comprehensive simulation of thermal destruction of PFAS; such comprehensive models will need to comprise fluorine mineralisation on flyash and in clinker material.

Low-temperature oxidation of monobromobenzene: Bromine transformation and yields of phenolic species.

Brominated benzenes and phenols constitute direct precursors in the formation of bromine-bearing pollutants; most notably PBDD/Fs and other dioxin-type compounds. Elucidating accurate mechanisms and constructing robust kinetic models for the oxidative transformation of bromobenzenes and bromophenols into notorious Br-toxicants entail a comprehensive understanding of their initial oxidation steps. However, pertinent mechanistic studies, based on quantum chemical calculations, have only focused on secondary condensation reactions into PBDD/Fs and PBDEs.

Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate.

The conventional process of lithium extraction from α-spodumene (LiAlSiO) is energy-intensive and associated with high byproduct management cost. Here, we investigate an alternative process route that uses potassium sulfate (KSO) to extract lithium while producing leucite (KAlSiO), a slow release fertilizer. Presenting the first-ever in situ record of the reaction of α-spodumene with potassium sulfate, we use synchrotron X-ray diffraction (XRD) and differential scanning calorimetry (DSC) to document the reaction sequence during prograde heating.