Fan Yi, Wang Zhe, Zhao Lian-Qin, Wu De-Yi
School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Huan Jing Ke Xue. 2017 Apr 8;38(4):1490-1496. doi: 10.13227/j.hjkx.201609132.
Zirconium modified diatomite was obtained by modifying raw diatomite with zirconium and the mass fraction of zirconia was 12.39% in the obtained material, which was proved to be amorphous via XRD. SEM images showed that porous floccules covered the surface of diatomite after modification and the specific surface area of the zirconium modified diatomite was 75.22 m·g, larger than that of raw diatomite (14.00 m·g). XPS spectra indicated that zirconia and diatomite were bonded together through chemical linkage, rather than physical deposition. The adsorption isotherm of phosphate by zirconium modified diatomite was fitted better to the Langmuir model with a calculated maximum adsorption capacity reaching 10.56 mg·g. The adsorption amount of zirconium oxide component in the material was estimated to be 81.67 mg·g ZrO, which was higher than that of pure zirconium oxides reported in previous studies. The adsorption amount of phosphate by zirconium modified diatomite decreased with the increase of pH. The adsorption was proved to be a ligand exchange process, supported by the XPS spectra of Zr3 region before and after adsorption. Chloride ion, sulfate ion and nitrate ion did not inhibit the adsorption of phosphate on the material, whereas coexistence of bicarbonate ions competed with phosphate ions to a certain extent. When treating eutrophic lake water with a phosphate concentration of 2 mg·L, the phosphate concentration level could meet the Ⅲ rank of Surface Water Environment Quality Standard of China by adopting the dosage of zirconium modified diatomite ≥1.25 g·L.
通过用锆对天然硅藻土进行改性得到了锆改性硅藻土，所得材料中氧化锆的质量分数为12.39%，经X射线衍射（XRD）证明其为非晶态。扫描电子显微镜（SEM）图像显示，改性后硅藻土表面覆盖有多孔絮凝物，锆改性硅藻土的比表面积为75.22 m²/g，大于天然硅藻土的比表面积（14.00 m²/g）。X射线光电子能谱（XPS）表明，氧化锆和硅藻土是通过化学键结合在一起的，而不是物理沉积。锆改性硅藻土对磷酸盐的吸附等温线更符合朗缪尔模型，计算得出的最大吸附容量达到10.56 mg/g。材料中氧化锆组分的吸附量估计为81.67 mg/g ZrO，高于先前研究报道的纯氧化锆的吸附量。锆改性硅藻土对磷酸盐的吸附量随pH值的升高而降低。吸附被证明是一个配体交换过程，吸附前后Zr 3d区域的XPS光谱支持了这一点。氯离子、硫酸根离子和硝酸根离子不会抑制材料对磷酸盐的吸附，而碳酸氢根离子的共存会在一定程度上与磷酸根离子竞争。当处理磷酸盐浓度为2 mg/L的富营养化湖水时，采用≥1.25 g/L的锆改性硅藻土用量，磷酸盐浓度水平可达到中国地表水水质标准Ⅲ类。
