生物质改性吸附材料的制备工艺优化及对氨氮的吸附特性

Optimization of preparation technology for biomass-modified adsorption material and its adsorption properties for ammonia nitrogen

为探究农业生物质再利用方法,以香蕉皮为原料,通过化学改性制备改性吸附剂,去除水中的氨氮。通过对比实验选择Na OH作为改性剂对香蕉皮粉末进行改性,单因素实验探讨了改性剂浓度、改性时间、原材料粒径及固液比对制备过程的影响及最佳制备工艺参数,结果表明:香蕉皮粉末粒径为100~120目,以0.2 mol·L^(-1)的Na OH水溶液作为改性剂,以10 g·L^(-1)的固液比,对香蕉皮粉末改性20 min为最佳的制备条件,在此条件下制得的改性吸附剂产率为64.83%。扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)、BET法测定比表面积及孔径分析结果显示,材料经改性后,表面孔道结构和官能团的变化有利于吸附氨氮。利用制得的材料吸附不同浓度的氨氮废水,并对实验结果进行等温拟合分析,Langmuir拟合结果表明改性香蕉皮吸附剂对水中的氨氮具有较高的吸附容量(qm=16.051 mg·g-1),优于沸石和活性炭,Freundlich拟合结果表明材料吸附氨氮属于较易发生的吸附(1/n=0.681)。研究表明,改性香蕉皮对氨氮具有较高的吸附容量,优于沸石和活性炭,对氨氮的吸附较易发生。

This study aimed to explore the agricultural biomass reuse method, a banana peel modified with NaOH as an absorbent to remove ammonia nitrogen. The effect of NaOH dosage, modification time, particle size of banana peel, and the ratio of solid to liquid on the removal of ammonia nitrogen was discussed. Further, the optimal preparation technology for modified banana peel was determined. The results showed that the optimal conditions were as follows：The raw banana peel size of 100-120 mesh, NaOH of 0.2 mol·L-1, solid-liquid ratio of 10 g. L-z, and modification time of 20 min. Under the optimal conditions, the yield of modified banana peel was 64.83%. Scanning electron microscope analysis （ SEM ）, Fourier-transform infrared spectroscopy （FT-IR）, surface area analyzer, and pore analysis （BET） showed that the changes of surface pore structure and surface functional groups were beneficial to adsorb ammonia nitrogen. The results of Langmuir and Freundlich fitting showed that the qm was 16.051 mg·g-1 and 1/n was 0.681. This indicated that the absorption potential for ammonia nitro- gen of the modified banana peel was superior to that of zeolite and activated carbon.