Ageing of rice husk biochar along a freeze-thaw cycles

Abstract

Abstract. In order to elucidate the aging possess of biochar, the experiment with treatment biochar with soil were performed. For accelerating aging process, freeing-thawing cycle were conducted to simulate the changing process of the physical and chemical properties of biochar and explore the roles of biochar in the changes of the soil nutrition. Aging treatment has a significant impact on the physical and chemical properties of biochar. The pH values, element composition, oxidation of the surface, absorption capacity of biochar changed in the ageing process. In the simulation test of freeze-thaw cycles, pH of biochar displayed upward trend after the first decline in 25 cycles, and then return to the initial level, indicating that the pH of biochar is not easy to change. Biochar surface oxidation occurs rapidly and significantly in the early, and then stabilized in the latter stage. Surface oxidation degree is higher than the whole. The results showed that surface oxide of biochar protect the internal particles from further oxidation. In the first 25 freeze-thaw cycles, adsorption capacity of biochar to hydroquinone changes from the 5.928 mg.g-1 to 11.73 mg.g -1 , indicating that freeze-thaw cycle treatment increase adsorption capacity of biochar.

Surface Characterization of Aged Biochar Incubated in Different Types of Soil

“…The results were consistent with previous studies (Yao et al 2010;Hale et al 2011). While a significant decrease in carbon was found after one year of moist aging of oak biochars at temperatures ranging from -22 °C to 70 °C ), carbon content of aged biochar was reduced in freeze-thaw cycles (Miao et al 2016). Thus, in the present study, the effect was mainly due to moderate incubation environment leading to a low aging degree.…”

Effects of Biochar Application before and after Freeze-Thaw on Soil Hydrothermal and Cotton Growth under Drip Irrigation

“…Still, the excessive application of biochar had adverse effects [18]. In addition, the structure of biochar was broken during the seasonal freeze-thaw process [43]. Compared to the biochar application treatments After freezing, the nitrate-nitrogen content in the soil treated with biochar application before freezing decreased [44], and the porous structure of biochar changed [45], indirectly affecting the physical and chemical properties of biochar.…”