污泥基活性炭吸附空气中甲醛的研究

以城市污水处理厂脱水污泥为原料,氯化锌为活化剂制备污泥基活性炭,采用BET比表面积测试、扫描电镜(SEM)、傅里叶红外光谱(FTIR)等方法研究其理化性能,利用动态吸附实验系统和蒸馏装置,将污泥基活性炭与选定的商业活性炭进行了甲醛吸附性能对比,并利用热重分析法研究了甲醛在各活性炭上的脱附情况.结果表明,污泥基活性炭对空气中浓度分别为498,0.41mg/m3的甲醛均有很好的吸附效果,吸附量分别可达74.27,7.62mg/g,最大去除率分别为83.72%和89.56%,其吸附性能与选定的商业活性炭相当,特别是在处理浓度为0.41mg/m3甲醛时超过选定的商业活性炭.该污泥基活性炭BET比表面积为509.88m2/g,氮吸附等温线属于BDDT分类中的I-B型,表明其具有大量的超微孔和极微孔,更适用于低浓度甲醛的吸附.FTIR分析表明其表面含有各种含氮基团,特别是-NH2的存在,可能形成化学吸附中心,但从吸附甲醛后各活性炭的微商热重分析(DTG)曲线可以看出,各甲醛在活性炭上的吸附主要为物理吸附.

Application of sewage sludge based activated carbon in formaldehyde adsorption

sewage sludge based activated carbon (SSAC) was prepared by taking dewatered sewage sludge as raw material with ZnCl2 as activating agent. BET test, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were utilized to analysis all of the Acs. Using dynamic adsorption system and distiller, adsorption performance of SSAC was compared with some commercial activated carbons (CACs), and the performances for desorption of formaldehyde in different activated carbons were investigated by using thermogravimetry. The adsorption capacity of SSAC, in formaldehyde concentration of 498, 0.41mg/m3, could achieve 74.27, 7.62mg/g and the removal efficiency was 83.72% and 89.56 %, respectively, and such was comparable with CACs’. Especially, in 0.41mg/m3, the result of SSAC exceeded that of CACs. The BET specific surface area of SSAC was 509.88m2/g and its nitrogen adsorption isothermal curve belonged to I-B in the BDDT classification. SSAC had high proportion of micropores, which made it more suitable to adsorb low concentration formaldehyde. The FTIR spectra indicated that on the surface of SSAC, there were lots of nitrogen-containing groups, especially amino-groups. These groups might form chemical reaction centers. However, the Derivative thermogravimetry (DTG) curves of the activated carbons which had adsorbed formaldehyde indicated that the major adsorption of formaldehyde on activated carbons was physical adsorption.