粉煤灰基免烧高强滤料的制备及其对Ni2+的去除

Preparation of Fly Ash-Based No-Sintered High-Strength Filter and Its Removal of Ni^(2+)

随着粉煤灰堆存量逐年增加,其资源化利用迫在眉睫.以粉煤灰(FA)为主要原料,硅灰(SF)为增强剂和外加硅源采用高温蒸养法制备免烧粉煤灰基沸石化陶粒(FACZ),从而实现粉煤灰的高值化利用.采用比表面及孔径分析仪(BET)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、红外光谱仪(FTIR)等手段,表征了各阶段样品的孔结构、晶体结构、微观形貌及官能团特征,并探究了碱浓度、SF质量分数、温度、蒸养时间对FACZ的影响,以及pH值、Ni^(2+)浓度、时间、FACZ投加量、温度对FACZ去除Ni^(2+)的影响.XRD、SEM、FTIR均表明FACZ中合成了结晶度良好的方沸石,优化后的工艺为8 mol/L NaOH、15%SF、190℃蒸养48 h;优化后的FACZ的比表面积可达14.4 m2/g,强度可达27.25 MPa.在最佳条件下,FACZ对Ni2+去除效率可达99.9%,最大去除量为31.934 mg/g;去除机理为硅羟基和沸石离子交换联合作用,且离子交换为主要原因.

It is important to utilize fly ash(FA)as a resource due to its increasing amount.In this paper,a no-sintered fly ash-based zeolitised ceramsite(FACZ)was prepared by a high-temperature steaming method with FA as a main raw material,silica fume(SF)as a reinforcing agent and additional silicon source to achieve the high-value utilization of fly ash.The pore structure,crystal structure,microscopic morphology and functional group characteristics of the samples at each stage were characterized by specific surface area and pore size analyzer(BET),X-ray diffractometer(XRD),scanning electron microscope(SEM)and Fourier transform infrared spectrometer(FTIR).The effects of alkali concentration,SF mass fraction,temperature and steaming time on FACZ were investigated.The results show that analcime with a good crystallinity can be synthesized in FACZ under the optimized conditions(i.e.,8 mol/L NaOH,15%SF and steaming at 190 C for 48 h).The specific surface area of FACZ can reach 14.4 m^(2)/g and the strength is 27.25 MPa after steaming.The removal efficiency of FACZ can reach 99.9%,and the maximum removal amount is 31.934 mg/g under the optimal removal conditions.The removal mechanism is a combined action of silanol and zeolite ion exchange,in which the ion exchange is the main cause.