Synthesis and Microwave Absorption Properties of Sulfur-Free Expanded Graphite/FeO Composites.

In this study, sulfur-free expanded graphite (EG) was obtained by using flake graphite as the raw material, and EG/FeO composites with excellent microwave absorption properties were prepared by a facile one-pot co-precipitation method. The structure and properties of as-prepared EG/FeO were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Raman, X-ray photoelectron spectrometry (XPS), thermogravimetric (TG), and vibrating sample magnetometry (VSM) characterizations. The FeO intercalated between the layers of expanded graphite forms a sandwich-like structure which is superparamagnetic and porous.

Identifying the reducing capacity of biomass derived hydrochar with different post-treatment methods.

In this study, hydrochar was prepared from wheat straw (WS) and Spartina alterniflora (SA) biomass by hydrothermal carbonization, and further treated with HCl and NaOH washing, HNO oxidization and low temperature thermal heating. The reducing capacity (RC) of sample was quantified by I titration to explore how these modification methods affected the redox properties of hydrochar. The results indicated HNO and thermal oxidization increased the RC of hydrochar by 2-5 folds while NaOH washing had the negative effect on samples' RC.

Improving abiotic reducing ability of hydrothermal biochar by low temperature oxidation under air.

Oxidized hydrothermal biochar was prepared by hydrothermal carbonization of Spartina alterniflora biomass (240°C for 4h) and subsequent oxidization (240°C for 10min) under air. Oxidized hydrochar achieved a Fe(III) reducing capacity of 2.15mmol/g at pH 2.