Zhu Yao, Yi Baojun, Yuan Qiaoxia, Wu Yunlian, Wang Ming, Yan Shuiping
College of Engineering, Huazhong Agricultural University No. 1, Shizishan Street, Hongshan District Wuhan 430070 P. R. China
Key Laboratory of Agricultural Equipment in the Mid-lower Yangtze River, Ministry of Agriculture Wuhan 430070 P. R. China.
RSC Adv. 2018 May 30;8(36):19917-19929. doi: 10.1039/c8ra03018a.
Biochar is a low cost and renewable adsorbent which can be used to remove dye from wastewater. Cattle manure-derived low temperature biochar (CMB) was studied to remove methylene blue (MB) from aqueous solution in this paper. The effect of factors including initial concentration of MB, dosage, contact time, and pH on the adsorption properties of MB onto biochar were studied. Characterization of the CMB and MB adsorbed on CMB was performed using techniques including BET, FTIR and SEM. The adsorption isotherm, kinetics, thermodynamics and mechanism were also studied. The results showed the equilibrium data were well fitted to the Langmuir isotherm model, and the saturation adsorption capacity of CMB was 241.99 mg g. Pseudo-second order kinetics was the most suitable model for describing the adsorption of MB onto biochar. The adsorption thermodynamics of MB on biochar showed that the adsorption was a spontaneous and endothermic process. Through zeta potential measurement, Boehm titration, cation exchange, deashing and esterification experiments, the importance of ash to adsorption was verified, as well as the adsorption mechanism. The adsorption mechanism of MB on CMB involved cation exchange, electrostatic interaction, hydrogen bonding, physical effects and others. This work shows that CMB holds promise to act as an effective adsorbent to remove MB in wastewater.
生物炭是一种低成本的可再生吸附剂，可用于去除废水中的染料。本文研究了牛粪衍生的低温生物炭（CMB）对水溶液中亚甲基蓝（MB）的去除效果。研究了MB初始浓度、用量、接触时间和pH值等因素对MB在生物炭上吸附性能的影响。采用BET、FTIR和SEM等技术对CMB及吸附在CMB上的MB进行了表征。还研究了吸附等温线、动力学、热力学和吸附机理。结果表明，平衡数据很好地符合Langmuir等温线模型，CMB的饱和吸附容量为241.99 mg/g。准二级动力学是描述MB在生物炭上吸附的最合适模型。MB在生物炭上的吸附热力学表明，吸附是一个自发的吸热过程。通过zeta电位测量、Boehm滴定、阳离子交换、脱灰和酯化实验，验证了灰分对吸附的重要性以及吸附机理。MB在CMB上的吸附机理包括阳离子交换、静电相互作用、氢键、物理作用等。这项工作表明，CMB有望成为去除废水中MB的有效吸附剂。
