镁铝水滑石的合成及其在废水脱磷中的应用研究

Synthesis of Mg-Al Hydrotalcite Compounds and their Application in Phosphorus Removal from Waste Water

采用共沉淀法合成了镁铝水滑石,考察了镁铝比、沉淀剂用量、反应时间、搅拌速率、焙烧温度等对镁铝水滑石吸附磷性能的影响。实验结果表明:Mg/Al-LDH对水中的磷具有良好的吸附作用。其最佳制备条件为:Mg/Al摩尔比3:1、沉淀剂用量[16OH^-+CO_3^(2-)]/[6Mg^(2+)+2Al^(3+)]摩尔比1:1、反应时间3 h、搅拌速度300 r×min^(-1)。当吸附剂用量为0.3 g,水中磷的吸附率可达到100%。经过500℃焙烧3 h,吸附剂用量0.1 g时,吸附率比未焙烧的水滑石提高了18%。使用X射线衍射(XRD)、红外光谱(FT-IR)、比表面积及孔径分析仪(BET)等手段对镁铝水滑石的结构进行了表征。并对其吸附动力学进行了研究,其吸附动力学表现为假二级动力学。

Mg-Al hydrotalcite compounds（LDHs） were synthesized via co-precipitation and characterized by XRD, FT-IR and BET. Effects of Mg/Al mole ratio, precipitant dosage, reaction time, stirring speed and calcination temperature on phosphorus removal rates from water were investigated. The results show that LDHs are efficient adsorbents for phosphorus removal from waste water. When studied under conditions of Mg/Al mole ratio = 3：1, [16OH^-＋CO_3^（2-）]/[6Mg^（2＋）＋2Al^（3＋）] mole ratio = 1：1, aging time = 3 h, stirring speed = 300 r×min^（-1）,the prepared LDH shows the best adsorption rate. Phosphorus can be 100% removed with 0.3 g adsorbent.Compared with LDH without calcination, calcinated LDH shows 18% increase of adsorption rate when using 0.1 g LDH calcinated at 500 ℃ for 3 h. In addition, the adsorption kinetics is studied which follows the pseudo-second-order kinetic equation.