改性多孔生物炭的制备及其对水中四环素的吸附性能研究

以常见的农业废弃物玉米秸秆为原料,以NaHCO_3和三聚氰胺为活化剂,一步碳化活化制备得到了一种改性多孔生物炭,研究了其对模拟四环素(TC)废水的吸附行为,同时采用SEM、XRD、Raman、FTIR、BET和元素分析对材料进行表征分析.探究了热解温度、三聚氰胺添加量、吸附剂投加量、反应时间、初始浓度、环境温度和pH对改性多孔生物炭去除水溶液中TC的影响.相比于原始生物炭(C800),改性后的秸秆生物炭(MPC800-10)对TC拥有更优异的吸附能力,能在短时间内快速高效地去除TC.由表征结果可知,同时添加NaHCO_3和三聚氰胺得到的改性多孔生物炭(MPC800-10)相对于原始生物炭(C800)比表面积更大,孔结构更丰富,芳香性增强,且亲水性和极性也有所增大,表面官能团更丰富,含氧官能团增加.MPC800-10对TC的吸附更符合Pseudo-second-order动力学模型和Freundlich等温吸附模型,且最大吸附量达到347 mg·g~(-1).热力学分析表明MPC800-10对TC的吸附是一个自发、吸热的过程.在酸性和中性条件下MPC800-10对TC都有较好的吸附能力,且具有一定的抗离子干扰能力和良好的再生性能.本研究将为农田废弃物的资源化利用及废水中抗生素的污染治理奠定坚实的基础.

Preparation of modified porous biochar and its adsorption properties for tetracycline in water

In this study, a porous biochar was prepared by using one-step carbonization activation, with common agricultural waste corn straw as raw material, and with NaHCO₃ and melamine as activator. The adsorption of simulated tetracycline (TC) by biochar in wastewater was studied. The Characteristics of the modified porous biochar were performed by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), Brunner-Emmet-Teller (BET) and elemental analysis. The effects of pyrolysis temperature, melamine addition, adsorbent dosage, reaction time, initial concentration, ambient temperature and pH on the removal of TC from aqueous solution by modified porous biochar were investigated. It was found that the modified porous biochar (MPC800-10) has better adsorption capacity for TC, compared with the original biochar (C800), and can quickly and efficiently remove TC. The characterization results show that the modified porous biochar (MPC800-10) obtained by adding NaHCO₃ and melamine has larger specific surface area, more porous structure and enhanced aromaticity than the pristine biochar (C800). The hydrophilicity is also increased, with more abundant surface functional groups and the oxygen-containing functional groups. The adsorption of TC by MPC800-10 was fitted well with the Pseudo-second-order kinetic model and the Freundlich isotherm adsorption model, and the maximum adsorption capacity reaches 347 mg·g^-1. Thermodynamic analysis results show that the adsorption of TC by MPC800-10 was a spontaneous and endothermic process. MPC800-10 had a good adsorption capacity for TC under both acidic and neutral conditions, and had a good selectivity against ions and regeneration performance. This study will lay a solid foundation for the resource utilization of farmland waste and the pollution control of antibiotics in wastewater.