RESUMEN
A series of activated biochar (KBBC-700, KBBC-800 and KBBC-900) which were modified by KOH and pyrolysis at various temperatures from ball-milling bamboo powder were obtained. The physicochemical properties and pore structures of activated biochar were investigated by scanning electron microscopy (SEM), fourier transform infrared spectoscopy (FT-IR), X-ray diffraction (XRD) and N2 adsorption/desorption. The adsorption performance for the removal of methylene blue (MB) was deeply studied. The results showed that KBBC-900 obtained at activation temperature of 900 °C exhibited a great surface area which reached 562 m2/g with 0.460 cm3/g of total pore volume. The enhancement of adsorption capacity could be ascribed to the increase of surface oxygen-containing functional groups, aromatization and mesoporous channels. The adsorption capacity was up to 67.46 mg/g under the optimum adsorption parameters with 2 g/L of adsorbent dose, 11 of initial solution pH and 298 K of the reactive temperature. The adsorption capacity was 70.63% of the first time after the material was recycled for three cycles. The kinetics indicated that the adsorption equilibrium time for MB on KBBC-900 was of about 20 min with the data fitted better to the pseudo-second-order kinetics model. The adsorption process was mainly dominated by chemical adsorption. Meanwhile, the adsorption isotherm showed that the Langmuir model fitted the best, and thermodynamic parameters revealed that the adsorption reaction was the endothermic nature and the spontaneous process. Adsorption of MB mainly attributed to electrostatic interactions, cation-π electron interaction and redox reaction. This study suggested that the activated biochar obtained by KOH activation from bamboo biochar has great potentials in the practical application to remove MB from wastewater.
RESUMEN
Bamboo contains abundant hemicellulose, cellulose, and lignin, which are a high-quality insoluble dietary fiber (IDF) raw material. To investigate IDF- induced changes in the production of short-chain fatty acids (SCFAs) and the composition of human gut microbiota, IDF was extracted by alkaline hydrogen peroxide (named BIDF), complex enzymatic hydrolysis method (named OIDF) from bamboo, and commercial bamboo fiber BF90. The in vitro fecal fermentation characteristics of BIDF, OIDF, BF90 and its impacts on human gut microbiota were studied for the first time. Results showed that BIDF, OIDF, and BF90 could promote the production of total SCFAs after 24 h fermentation. Additionally, BIDF could alter the composition and microbial diversity of gut microbiota, especially increase the relative abundance of Bacteroides and decrease the ratio of Firmicutes to Bacteroidetes (F/B) value. These results revealed that the IDF from bamboo could be partially utilized by specific bacteria in human intestines and provide a reference for the study of the effects of IDF fermentation on SCFAs production and microbial composition.