Evaluation of biochar properties exposing to solar radiation: A promotion on surface activities

Abstract

Biochar is an important bio-material used to mitigate environmental and agronomic problems. The complex outdoor environment, which includes exposure to solar radiation, greatlyinfluencesbiochar structure, which in turn impacts its functions when it is used in outdoors. The objective of this study is to understand the dynamics associated with the physical and chemical changes that occur in bamboo biochar (BB) prepared at different final temperatures during exposure to damaging radiation. The basic physical and chemical properties of fresh and accelerated weathered BBs were investigated by measuring the chemical element, ash content, BET surface area, color changes. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and differential scanning calorimetry were used to determine the changes in functional groups, the variation in the surface element species distribution and the differences in thermochemical property of BBs. The experimental results showed that clear changes in BBs were obtained after 400 h of accelerated weathering. The C and N contents of BBs declined, and its O content increased. The average changes in color and decrease in residue yield of BBs were 1.02 and 1.58%, respectively. The average growth rates of O/C ratio (determined by elemental analysis), C4, and O2 of BBs were 17.04%, 13.88% and 86.63%, respectively. These results illustrate that the BBs underwent a series of photooxidation reactions when exposed to UV radiation. The increase of surface oxygen-containing functional groups may improve the surface activities of BB with respect to soil-amelioration applications,pollutant-degradation efficiency and the adsorbability toward aqueous contaminants.