HUALu-lu,HUANGXian-huai,QIANJing,et al.Characteristics of Iron Modified Biochar for Nitrate Nitrogen Adsorption in Water[J].China Water & Wastewater,2022,38(19):61-68.
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Characteristics of Iron Modified Biochar for Nitrate Nitrogen Adsorption in Water

China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU] volume: 第38卷 Number: 第19期 Page: 61-68 Column: Date of publication: 2022-10-01
Author(s):
HUA　Lu-lu1; 2;  HUANG　Xian-huai1; 2;  QIAN　Jing1; 2;  WANG　Kun1; 2
（1. School of Environment and Energy Engineering， Anhui Jianzhu University， Hefei 230601， China； 2. Anhui Key Laboratory of Environmental Pollution Control and Resource Reuse， Anhui Jianzhu University， Hefei 230601， China）
Keywords:
biochar;  Fe3+;  modification;  nitrate nitrogen;  adsorption
Abstract:
Peanut shell-based biochar was prepared at high temperature (600 ℃) and oxygen-limited condition, and then the biochar was loaded with iron (Fe3+) to improve its capacity for nitrate nitrogen (NO3--N) adsorption in water. The adsorption mechanism was investigated by batch experiment. The modified biochar (FeHBC) had the best adsorption performance when the mass ratio of iron to carbon was 0.672, and the adsorption capacity of NO3--N was significantly improved after modification (P<0.05), which was 16 times higher than that of the unmodified biochar (HBC). The pseudo-second-order kinetic model (R2=0.986) could well fit the kinetics of the modified biochar for NO3--N adsorption, and its adsorption behavior was more consistent with Freundlich isothermal adsorption model (R2=0.994). The thermodynamic parameters were as follows: ΔG less than zero, ΔH and ΔS both greater than zero, which showed that the adsorption of NO3--N by FeHBC was a spontaneous endothermic process, and the spontaneity of the reaction increased with the temperature increasing. The acidic environment was more conducive to the adsorption of NO3--N by FeHBC. In addition, the adsorption mechanism was analyzed by characterization methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and zero point of charge (pHPZC). FeHBC had more adsorption sites due to its porous rough particle surface. The adsorption process might be mainly affected by the complex precipitation reaction between Fe3+ and oxygen-containing functional groups. Compared with unmodified biochar, the positive electrical property of FeHBC was enhanced. This change of local microstructure provided theoretical support for improving the adsorption performance of biochar.
Last Update: 2022-10-01