低品位凹凸棒石黏土水热合成介孔硅酸盐吸附剂

以低品位凹凸棒石(APT)黏土为原料,在硅酸钠和氯化钙存在的条件下,通过一步水热法制备了新型介孔硅酸盐吸附剂.采用红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)和BET孔结构分析等手段表征了吸附剂的结构、形貌和理化性质.结果表明,反应初始Si/Ca比对产物结构和形貌有显著影响,在Si/Ca比为3:1和2:1条件下,APT形成了介孔硅钙石型吸附剂,而在Si/Ca比为1:1和1:2条件下,则形成了1.1 nm铝取代托贝莫来石.在Si/Ca比2:1条件下制备的最优硅酸盐吸附剂比的表面积和表面负电位分别达到了APT黏土的3.42和1.83倍.吸附研究表明,在Si/Ca比为2:1条件下制备的硅钙石型吸附剂对Cd(II)的吸附量达到了136.87 mg/g,是APT黏土吸附量的6.4倍,吸附速率也有明显提高.

Hydrothermal Synthesis of Mesoporous Silicate Adsorbents from Natural Low-grade Attapulgite Clay

Mesoporous silicate adsorbents were prepared by a one-pot hydrothermal process using low-grade attapulgite(APT)clay as raw materials in the presence of sodium silicate and calcium chloride.The structure,morphology and physicochemical features of the adsorbents were characterized by fourier transform infrared spectra(FTIR),X-ray diffraction(XRD),scanning electronic microscope(SEM)and BET analysis.The results show that the initial Si/Ca ratio affects the structure and morphology of the adsorbent.At the Si/Ca ratio of 3:1 and 2:1,the APT and the associated minerals simultaneously transforme as amorphous mesoporous wollastonite-type adsorbent.At the Si/Ca ratio of 1:1 and 1:2,1.1 nm tobermorite is mainly formed.The specific surface area and surface negative potential of the as-prepared adsorbent are 3.42 and 1.83 folds of the raw APT,respectively.The adsorption test indicates that the wollastonite-type adsorbents with Si/Ca ratio of 2:1 show the adsorption capacity of 136.87 mg/g toward Cd(II),which is 6.4 folds of the adosorption capacity of APT,and the adsorption rate is higher than that of raw APT clay.