核桃果皮基活性炭的制备及吸附性能研究

发布时间：2018-12-12 15:34

【摘要】：本文以废弃核桃果皮为原料,氯化锌为活化剂,制备出比表面积高、吸附效果好的活性炭,研究了核桃果皮活性炭及其改性产物对甲基橙和酸性品红、对硝基苯酚、Pb2+和Cd2+的吸附性能,考察了吸附时间,p H,溶液初始浓度等因素对吸附性能的影响,并通过吸附等温线和动力学模型探讨其吸附机理。实验采用正交设计,以活化温度、活化时间、活化剂浓度和粒径大小为四因素,每因素三个水平,马弗炉加热法制备核桃果皮基活性炭,得到了氯化锌活化法制备活性炭的最佳条件,通过极差分析和方差分析排列出最佳的制备工艺组合,即氯化锌浓度50%,粒径大小为60目,活化温度600℃,活化时间1 h,在此条件下制备的活性炭比表面积达到1258.050 m2/g。制备的核桃果皮基活性炭对甲基橙和酸性品红、对硝基苯酚、Pb2+和Cd2+吸附效果较好。氨水改性活性炭和氢氧化钠改性活性炭对对硝基苯酚的最大饱和吸附量分别高达204.080和263.160 mg/g,双氧水改性活性炭对Pb2+和Cd2+最大饱和吸附量为58.498和84.321 mg/g,说明改性后活性炭的吸附效果更好。增加吸附时间,五种污染物的去除率和吸附量都增加,活性炭对甲基橙、酸性品红和对硝基苯酚的吸附平衡时间皆为6 h,而对Pb2+和Cd2+的吸附平衡时间为5 h。增大五种污染物的初始浓度,结果表现为活性炭对其吸附量增大,去除率降低。溶液p H对吸附影响较大。核桃果皮基活性炭对甲基橙、酸性品红和对硝基苯酚的最适宜吸附p H值分别为6、6和3,吸附量和去除率随p H的减小而增大,对Pb2+和Cd2+的最适宜吸附p H值分别为4和4,吸附量和去除率随p H的增大而增大。吸附等温线拟合表明未改性的核桃果皮基活性炭对对硝基苯酚的吸附符合Langmuir模型,氢氧化钠和氨水改性活性炭则符合Freundlich模型。经碱性改性后活性炭对对硝基苯酚的吸附量、去除率都有增大,可得出碱性改性后的活性炭对对硝基苯酚的吸附效果更好。Freundlich模型能更好描述活性炭对Pb2+和Cd2+的吸附等温线;Langmuir模型更能描述氧化活性炭对Pb2+的吸附等温线。而Freundlich模型能更好地描述活性炭及氧化活性炭对Cd2+的吸附等温线;甲基橙的吸附属于单层吸附行为。五种污染物的吸附动力学行为均符合准二级动力学方程。
[Abstract]:In this paper, activated carbon with high specific surface area and good adsorption effect was prepared by using waste walnut peel as raw material and zinc chloride as activator. The modified activated carbon from walnut peel and its modified products, such as methyl orange, acid fuchsin, p-nitrophenol, were studied. The adsorption properties of Pb2 and Cd2 were studied. The influence of the initial concentration of, p H, solution on the adsorption performance was investigated, and the adsorption mechanism was discussed by adsorption isotherm and kinetic model. Orthogonal design was used to prepare walnut pericarp based activated carbon with four factors, activation temperature, activation time, activator concentration and particle size, and three levels of each factor. The optimum conditions for the preparation of activated carbon by zinc chloride activation method were obtained. The optimum preparation conditions were obtained by means of range analysis and variance analysis. The optimum preparation conditions were as follows: zinc chloride concentration 50, particle size 60 mesh, activation temperature 600 鈩，

本文编号：2374828