Biochars function as electron transfer mediators and thus catalyze redox transformations of environmental pollutants. A previous study has shown that bone char (BC) has high catalytic activity for reduction of chlorinated ethylenes using layered Fe­(II)–Fe­(III) hydroxide (green rust) as reductant. In the present study, we studied the rate of trichloroethylene (TCE) reduction by green rust in the presence of BCs obtained at pyrolysis temperatures (PTs) from 450 to 1050 °C. The reactivity increased with PT, yielding a maximum pseudo-first-order rate constant (k) of 2.0 h–1 in the presence of BC pyrolyzed at 950 °C, while no reaction was seen for BC pyrolyzed at 450 °C. TCE sorption, specific surface area, extent of graphitization, carbon content, and aromaticity of the BCs also increased with PT. The electron-accepting capacity (EAC) of BC peaked at PT of 850 °C, and EAC was linearly correlated with the sum of concentrations of quinoid, quaternary N, and pyridine-N-oxide groups measured by XPS. Moreover, no TCE reduction was seen with graphene nanoparticles and graphitized carbon black, which have high degrees of graphitization but low EAC values. Further analyses showed that TCE reduction rates are well correlated with the EAC and the C/H ratio (proxy of electrical conductivity) of the BCs, strongly indicating that both electron-accepting functional groups and electron-conducting domains are crucial for the BC catalytic reactivity. The present study delineates conditions for designing redox-reactive biochars to be used for remediation of sites contaminated with chlorinated solvents.

No abstract

Spray-dried lactose consists of an amorphous component (10-20%) as well as the crystalline monohydrate form [1]. It is commonly used as a diluent in direct compression, mainly because of its better flow characteristics compared to pure crystalline lactose. The amorphous form is metastable and can relative easily crystallize, which will affect the functionality of the pharmaceutical product. It is therefore of interest to establish methods for non-invasive and rapid assessment of the level of crystallinity in a pharmaceutical formulation. In this study, two spectroscopic methods, near infrared (NIR) spectroscopy and terahertz time domain spectroscopy (THz-TDS), are compared for their ability to determine low levels of crystalline lactose in a mixture. The aim was to 3 THz-TDS: terahertz time domain spectroscopy XRPD: x-ray powder diffraction

No abstract

No abstract