关键词: 凹凸棒石;硅酸盐;吸附;水热;重金属

Abstract: 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.

Key words: attapulgite;silicate;adsorption;hydrothermal;heavy metal