ZnCl2活化废弃咖啡渣制备活性炭的工艺研究

Preparation of Activated Carbon from Waste Coffee Grounds with Zinc Chloride

文章采用化学活化法,以废弃咖啡渣为原料,ZnCl2为活化剂制备活性炭。分析WCG的元素组成和热解温度后,通过单因素实验,考察了浸渍比、活化剂浓度、活化温度、活化时间等工艺参数对活性炭比表面积和吸附性能的影响规律。通过X射线光电子能谱仪、傅立叶变换红外光谱仪、场发射扫描电子显微镜、比表面及微孔介孔孔径分析仪等对最优活性炭进行表征。结果表明:WCG中碳元素质量分数为52.81%,是制备活性炭良好的废弃生物质材料,适宜活化温度范围为350~600℃。ZnCl2活化废弃咖啡渣制备活性炭的最佳工艺条件为:浸渍比为3 mL/g,活化剂浓度为3 mol/L,活化温度450℃,活化时间2 h。WCGAC/ZC-3-3-450-2表面呈疏松蜂窝状,含有丰富的微孔及介孔,对水中亚甲基蓝的去除率为99.9%,比表面积达893.47 m2/g,平均孔径为3.37 nm。XPS和FTIR分析表明,ZnCl2具有较强的活化造孔作用,WCGAC/ZC-3-3-450-2中形成了类石墨微晶炭结构,其表面含有丰富的-COOH、OC-O、C=O等含氧官能团。

Activated carbons were prepared from waste coffee grounds(WCG)by chemical activation with zinc chloride in a series of single-factor experiments.The elemental composition and pyrolysis temperature of the WCG were initially analyzed.The influences of the impregnation ratio,zinc chloride concentration,activation temperature,and activation time on the surface area and adsorption properties were then investigated to explore experimental approaches and technological conditions.The activated carbon prepared under the optimum conditions was characterized by XPS,FTIR,SEM-EDS,N2 adsorption–desorption,and pore-size distribution analyses.The results showed that the WCG were good biomass for preparing activated carbon.The carbon mass content reached 52.81%,and the appropriate activation temperature range was 350~600℃.The optimized conditions were an impregnation ratio of 3 mL/g,zinc chloride concentration of 3 mol/L,activation temperature of 450℃,and activation time of 2 h.The activated carbon had a honeycomb shape,was rich in micropores and mesopores,and exhibited an average pore size of 3.37 nm,and a specific surface area of 893.47 m^2/g.A high adsorption capacity for methylene blue(99.9%)was demonstrated.Additionally,the XPS and FTIR results showed that the zinc chloride played an important pore-making function.WCGAC/ZC-3-3-450-2 had a graphite-like crystallite structure,and its surface chemical composition contained oxygen-containing functional groups such as–COOH,O–C–O,and C=O.