Preparation and Characterization of MgO-Modified Rice Straw Biochars

Abstract

Rice straw is a common agricultural waste. In order to increase the added value of rice straw and improve the performance of rice straw biochar. MgO-modified biochar (MRBC) was prepared from rice straw at different temperatures, pyrolysis time and MgCl2 concentrations. The microstructure, chemical and crystal structure were studied using X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption desorption isotherms and Elementary Analysis (EA). The results showed that the pyrolysis temperature had significant influence on the structure and physicochemical property of MRBCs. MRBC-2 h has the richest microporous structure while MRBC-2 m has the richest mesoporous structure. The specific surface area (from 9.663 to 250.66 m2/g) and pore volume (from 0.042 to 0.158 cm3/g) of MRBCs increased as temperature rose from 300 to 600 °C. However, it was observed MgCl2 concentrations and pyrolysis time had no significant influence on pore structure of MRBCs. As pyrolysis temperature increased, pH increased and more oxygen-containing functional groups and mineral salts were formed, while MgO-modified yield, volatile matter, total content of hydrogen, oxygen, nitrogen, porosity and average pore diameter decreased. In addition, MRBCs formed at high temperature showed high C content with a low O/C and H/C ratios.

Enhancing MgO efficiency in CO2 capture: engineered MgO/Mg(OH)2 composites with Cl−, SO42−, and PO43− additives

“…41 The H3 hysteresis typically caused by samples that are agglomerated and have the sheet like structures with exible pores. 25,42 The N 2 adsorption observed to be decreased with increasing dopant percentage. The 5% Cl − doped MgO sample determined to have the higher specic surface area of 65.5 m 2 g −1 compared to the other samples.…”

Advances in Micro-/Mesopore Regulation Methods for Plant-Derived Carbon Materials

“…The results ( Figure 14 ) showed that the specific surface area, pore volume and mesoporosity were maximum when the rice straw was mixed with CaCO 3 at a ratio of 1:2, which is carbonized at 400 °C and activated at 800 °C. Qiu et al [ 132 ] employed cork as the carbon precursor and KMnO 4 as the raw material of the MnO template to prepare hierarchically porous carbon and investigated the impact of MnO on the pore structure of the carbon material at different pyrolysis temperatures. It was found that at the pyrolysis temperature of 800 °C, prepared carbon material was dominated by mesopores (60%) and specific surface area up to 1119 m 2 /g.…”

Preparation and characterization of modified corn stalk biochar

“…Adsorption-desorption changes of CBC-300 and MCBC-300 were not obvious, which may be due to lower temperature and incomplete pore development, resulting in a decrease of absorption capacity (Liu et al 2020). When the temperature reached 500 and 600 ℃, the adsorption curve of nitrogen increased linearly at a low relative pressure (P/P0 < 0.05), which may be due to the filling of micropores (Qin et al 2020). In addition, at 500 and 600 ℃, the relative pressure (P/P0 < 0.08) was single-layer adsorption, and the relative pressure (0.08 < P / P0 < 0.4) was multi-layer adsorption.…”