废弃粉状活性炭制备多孔炭陶瓷及其吸附性能研究

Preparation of porous carbon ceramics from waste powdered activated carbon and its adsorption properties

为了实现废弃粉状活性炭的再生与资源化利用,笔者以废弃粉状活性炭为原料,以凹凸棒土为黏结剂,通过混合捏合、挤压成型、干燥烧结制备了多孔炭陶瓷。采用氮气吸附、扫描电子显微镜、X射线衍射表征了多孔炭陶瓷的孔隙结构和形态,测试了多孔炭陶瓷对碘、亚甲基蓝、苯酚和腐殖酸的吸附能力。考察了黏结剂用量、烧结温度和时间对炭陶瓷孔隙结构、吸附性能和强度的影响,分析了多孔炭陶瓷吸附水体中腐殖酸的性能。结果表明,黏结剂用量、煅烧温度和时间均对炭陶瓷的孔隙结构、强度和吸附能力具有较为明显的影响:当黏结剂与原料炭的质量比为1∶4,烧结温度和时间分别为800℃和0.5 h时,可以制备出强度达98%、比表面积和比孔容积分别为607 m2/g和0.720 cm3/g的中孔发达的多孔炭陶瓷。该成型炭陶瓷具有发达的中孔结构,对腐殖酸的平衡吸附量可达193.3 mg/g,显著高于商用的成型活性炭。溶液的p H和吸附温度影响炭陶瓷对腐殖酸的吸附量,在溶液p H为3、吸附温度为45℃时,炭陶瓷表现出较好的腐殖酸吸附能力。

In order to provide a newmethod to reuse the waste powdered activated carbon,porous carbon ceramics were prepared by kneading,extruding and sintering of mixture of waste powdered activated carbon as carbon sources and attapulgite clay as binders. The pore structure and morphology of the prepared porous carbon ceramics were analyzed by using nitrogen adsorption,scanning electron microscopy and X-ray diffraction. The adsorption ability and mechanical strength of the porous carbon ceramics were evaluated by testing their adsorption capacity of iodine,methylene blue,phenol and humic acid,and hardness. The effects of binder dosage,sintering temperature and time on the hardness,pore structure of carbon ceramics and their adsorption capacity of humic acid in aqueous solution were investigated; and the effect of p H value,the adsorption temperature on the adsorption capacity of humic acid were studied. The results showthat the binder dosage,sintering temperature and time have an influence on the pore structure,hardness and adsorption capacities of the carbon ceramics. This method can be used to prepare porous carbon ceramics that have specific surface area as high as 607 m2/g,total pore volume of 0.720 cm3/g and strength of 98% when the mass ratio of the binder to rawmaterial is 1 ∶4,sintering temperature is 800℃ and sintering time is 0.5 h. These carbon ceramics are characterized by developed mesopores,and the equilibrium adsorption capacity of humic acid can reach 193.3 mg/g,which is much higher than that of commercially available extruded activated carbon products. The p H value of humic acid solution and adsorption temperature have significant influence on the adsorption ability of carbon ceramic to humic acid. The adsorption capacity of humic acid reaches the maximum when p H value increases to 3.The increase of the adsorption temperature from 30℃ to 45℃ enhances the humic acid adsorption performance of the porous carbon ceramics.