【作者】 王秀娟；

【导师】 王海增；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2012， 硕士

【摘要】 本论文在实验室前期工作的基础上，通过改性成型法和直接合成法制备了粒状多孔镁铝复合氧化物(GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6)。研究了其对水体中的无机阴离子(Cr（Ⅵ）、SCN-和SO₄^2-)的吸附性能，克服了粉末镁铝复合氧化物吸附剂高分散、难回收和易堵塞的缺陷。采用比表面积及孔径分析、X射线粉末衍射分析、扫描电镜分析、红外光谱分析和热重-差示扫描量热分析等方法对这两种新型粒状多孔镁铝复合氧化物进行了结构表征。结果发现，改性成型法保留了Mg/Al-LDH的层状结构，当镁含量增加时，层板电荷密度减小，弱化了层板与层间阴离子的作用，层间距增大，GP1-Mg_3.3AlO_4.8中并不存在Al₂O₃物相，Al嵌入到MgO的晶格中。GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6的比表面积分别为269.4m²·g^-1和206.3m²·g^-1，前者的吸附性能稍优于后者，但后者合成步骤少，成本低。静态吸附结果表明， Cr（Ⅵ）、 SCN^-和SO₄^2-在GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6上的等温吸附过程均符合Freundlich等温式。在25⁴5℃范围内，Cr（Ⅵ）初始浓度为1000mg·L^-1时，GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6对Cr（Ⅵ）的吸附量分别为157.84¹64.95mg·g^-1和82.22¹41.72mg·g^-1；SCN^-初始浓度为500mg·L^-1时，GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6对SCN-的吸附量分别为165.82¹89.97mg·g^-1和160.64¹84.44mg·g^-1；SO₄^2-初始浓度为1000mg·L^-1时，GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6的对SO₄^2-的吸附量分别为267.18²98.19mg·g^-1和247.73²84.77mg·g^-1。GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6对Cr（Ⅵ）、SCN^-和SO₄^2-的吸附性能明显优于粉末Mg/Al-LDH的焙烧产物。伪一级动力学方程能很好地描述Cr（Ⅵ）在GP1-Mg_3.3AlO_4.8上、SCN-在GP2-Mg_3.1AlO_4.6上和SO₄^2-在GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6上的吸附动力学过程；伪二级动力学方程能很好地描述Cr（Ⅵ）在GP2-Mg_3.1AlO_4.6上和SCN-在GP1-Mg_3.3AlO_4.8上的吸附动力学过程。两种吸附剂的再生性能较好，吸附-解吸四次后对Cr（Ⅵ）、SCN^-的脱除率均在95%以上，对SO₄^2-在67%以上。动态吸附结果表明，初始浓度、流速、床层高度和溶液pH对穿透曲线均有影响，在最佳吸附条件下，GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6对Cr（Ⅵ）的饱和吸附量分别可达51.78mg·g^-1和51.30mg·g^-1；对SCN^-的饱和吸附量分别可达56.32mg·g^-1和51.27mg·g^-1；对SO₄^2-的饱和吸附量分别可达193.28mg·g^-1和182.86mg·g^-1。Yoon-Nelson模型能很好地预测Cr（Ⅵ）、SCN^-和SO₄^2-在GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6上的整个穿透曲线，而Bohart-Adams模型更适合于描述初始阶段的穿透曲线（ct/c0<0.5）。上述结果表明，通过改性成型法和直接合成法制备的粒状多孔镁铝复合氧化物GP1-Mg_3.3AlO_4.8和GP2-Mg_3.1AlO_4.6对水体中无机阴离子Cr（Ⅵ）、SCN^-和SO₄^2-具有较好的吸附性能，因此两种吸附剂具有较大的工业应用价值。更多还原

【Abstract】 Granular porous Mg/Al mixed oxides (GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6)are preparaed by modified molding method and direct sythesis method, on the basis oflaboratory’s preliminary work. Its adsorption behaviors for inorganic anions (Cr（Ⅵ）,SCN^-and SO₄^2-) from aqueous solution are investigated. Granular porous Mg/Almixed oxides can solve the defects of high dispersibility, poor recycling performanceand easy blocking performance.The structure of GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are characterized byanalytical methods of specific surface area and porosimetry system, X-ray powderdiffraction analysis, scanning electron microscopy analysis, fourier transform infraredspectroscopy analysis and thermogravimetry and differential scanning calorimetryanalysis. The results show that the layered structure of Mg/Al-LDH is retained in thepreparation process of modified molding method. The layer charge density decreaseswith an increasing magnesium content, which make the interaction of layers andanions intercalated weakened and layer spacing enlarged. There is not Al₂O₃phase inGP1-Mg_3.3AlO_4.8,however, Al is embedded in MgO lattice. The specific surface areaof GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are269.4m²·g^-1and206.3m²·g^-1,respectively. Adsorption behaviors of the former is better than the latter, but the latterneeds less synthetic steps and lower costs.Static adsorption results show that the static adsorption processes of Cr（Ⅵ）,SCN^-and SO₄^2-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6follow Freundlichisotherm equation. The adsorption capacity of Cr（Ⅵ） on GP1-Mg_3.3AlO_4.8andGP2-Mg_3.1AlO_4.6are157.84¹64.95mg·g^-1and82.22¹41.72mg·g^-1from25℃to45℃when the initial concentration of Cr（Ⅵ） is1000mg·L^-1. The adsorptioncapacity of SCN^-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are165.82¹89.97mg·g^-1and160.64¹84.44mg·g^-1from25℃to45℃when the initial concentrationof SCN^-is500mg·L^-1. The adsorption capacity of SO₄^2-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are267.18²98.19mg·g^-1and247.73²84.77mg·g^-1from25℃to45℃when the initial concentration of SO₄^2-is1000mg·L^-1. The adsorptionbehaviors of Cr（Ⅵ）, SCN^-and SO₄^2-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6aresignificantly improved than the calcined product of Mg/Al-LDH powder. Theadsorption dynamic processes of Cr（Ⅵ） on GP1-Mg_3.3AlO_4.8, SCN^-onGP2-Mg_3.1AlO_4.6and SO₄^2-on the two adsorbents follow pseudo-first order kineticequation, while the adsorption dynamic processes of Cr（Ⅵ） on GP2-Mg_3.1AlO_4.6andSCN^-on GP1-Mg_3.3AlO_4.8follow pseudo-second order kinetic equation. Theregeneration performance of two adsorbents are so perfect that the removal rate areabove95%for SCN^-and Cr（Ⅵ）,67%for SO₄^2-after adsorption-desorption for fourtimes.Dynamic adsorption results show that some factors such as initial concentration,flow rate, bed height and pH of solution have effects on breakthrough curves. Thestaturated adsorption capcity of Cr（Ⅵ） on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are51.78mg·g^-1and51.30mg·g^-1under the best conditions, respectly. The staturatedadsorption capcity of SCN^-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are56.32mg·g^-1and51.27mg·g^-1under the best conditions, respectly. The staturated adsorptioncapcity of SO₄^2-on GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6are193.28mg·g^-1and182.86mg·g^-1under the best conditions, respectly. Yoon-Nelson model can predict thebreakthrough curves of Cr（Ⅵ）, SCN^-and SO₄^2-on GP1-Mg_3.3AlO_4.8andGP2-Mg_3.1AlO_4.6well, while Bohart-Adams model is more suitable for describing theinitial stage of the breakthrough curves （ct/c0<0.5）.The above results show that GP1-Mg_3.3AlO_4.8and GP2-Mg_3.1AlO_4.6which aresynthesized by modified molding method and direct sythesis method, have perfectadsorption behaviors for inorganic anions of Cr（Ⅵ）, SCN^-and SO₄^2-. So they havesignificant industrial value.更多还原