污泥焚烧灰预处理-水热法合成NaSOD型沸石的试验

摘要

NaSOD type zeolite was synthesized from sewage sludge incineration ash (SSIA) through a hydrothermal reaction,which was pretreated by acid immersion and alkaline calcination.The prepared samples were characterized by X-Ray diffraction,scanning electron microscope and Fourier transform infrared spectra analysis.The results show that the optimal pH of acid treatment is 1,under this condition the total content of SiO2 and Al2O3 can be raised from 55.48 ％ to 77.65 ％; Further analysis indicates that the best NaOH/Ash ratio is 3:2 and the optimal temperature is 700 ℃ during the process of calcination.XRD,SEM and FT-IR characterization show that the prepared NaSOD zeolite from pretreated SSIA has a complete and single crystal form,exhibitting a ball-cage-like morphology.FT-IR spectrum shows free water content is high.However,samples synthesized from un-pretreated SSIA has a very low crystallinity,existing a large quantity of quartz.Thus,pretreatment is essential for NaSOD type zeolite synthesis from SSIA.Results from property measurements show that NaSOD zeolite synthesized from pretreatment SSIA can make cation exchange capacity (CEC),specific surface area and total pore volume increase by 40,78 and 24 times.However,the increases are only 14,30 and 12 times using un-pretreated SSIA.These indicate significant increase of properties in ion exchange,adsorption and catalysis of synthetic product from pretreated SSIA.%以污泥焚烧灰为原料,通过酸处理和加碱煅烧预处理后,采用水热法合成了NaSOD型沸石,并对其进行了表征和性能测定.结果表明:酸处理可显著提高焚烧灰中硅铝成分的含量,加碱煅烧能够有效激活存在于石英等晶体中的硅铝元素;酸预处理的最佳pH为1,此时SiO2和Al2O3含量的百分比之和可达77.65％,比焚烧灰原料高出22.17％;最佳煅烧碱灰比为3:2,最佳煅烧温度为700℃.对合成样品的X射线衍射(XRD)、扫描电镜(SEM)以及傅里叶红外光谱(FT-IR)表征结果显示,污泥焚烧灰经过预处理后合成的样品,其结构呈NaSOD型沸石,且结晶完整、晶型单一,晶体形貌为球形笼状结构,合成沸石中自由水的含量高.而未经预处理直接水热合成的样品,结晶度低,且存在大量未被活化的石英晶体.因此,预处理对污泥焚烧灰合成NaSOD型沸石起着至关重要的作用.性能测定的结果显示,经预处理合成的NaSOD型沸石,其阳离子交换容量(CEC)、比表面积和总孔容,相对于焚烧灰原料分别提高了40、78和24倍,而未经预处理直接水热合成的产物则分别只提高了14、30和12倍.这意味着经预处理的合成产物在离子交换、吸附和催化等方面的性能有了很大的提升.