三聚磷酸钠在层状氢氧化镁铝及其焙烧产物上的吸附特性

ADSORPTION OF SODIUM TRIPOLYPHOSPHATE ON Mg-Al LAYERED DOUBLE HYDROXIDE AND ITS CALCINED PRODUCT

通过静态吸附实验,研究了水溶液中三聚磷酸钠(STPP)在层状氢氧化镁铝(Mg-AlLDH)及其焙烧产物(Mg-AlCLDH)上的吸附性能,并用多晶X射线衍射对Mg-AlLDH,Mg-AlCLDH及Mg-AlCLDH吸附STPP后Mg-AlRLDH的结构进行了表征.结果表明,STPP在层状氢氧化镁铝及其焙烧产物上的吸附量和脱除率在pH为4.7—10.0时受溶液初始pH值的影响较小;饱和吸附量随温度的升高而增大,在25—50℃下,STPP在层状氢氧化镁铝上的饱和吸附量为34.52—40.20mgP3O105-·g-1,在25—60℃下,STPP在焙烧层状氢氧化镁铝上的饱和吸附量为118.67—179.57mgP3O105-·g-1.静态吸附热力学结果证明STPP在层状氢氧化镁铝及其焙烧产物上的吸附为自发的物理吸热过程,焓变与熵增是吸附的主要驱动力.

The adsorption behavior and mechanism of sodium tripolyphosphate （STPP） from aqueous solution on Mg- Al layered double hydroxide（ Mg-Al LDH） and its calcined product（ Mg-Al CLDH 500℃ ）were investigated through static adsorption experiments. Mg-Al LDH, Mg-Al CLDH and STPP adsorbed by Mg-Al CLDH （Mg-Al RLDH） have been characterized by XRD. The adsorption capacity and removal of STPP on Mg-Al LDH and Mg-Al CLDH changed inconsiderably for an initial pH of 4. 7-10. 0. The maximum adsorption capacity was 34. 52 to 40. 20 mg P3O10^5-·g^-1 from 25℃ to 50℃ on Mg-Al LDH, 118.67 to 179. 57mg·P3O10^5-·g^-1 from 25℃ to 60℃ on Mg-Al CLDH. The thermodynamic data showed that the adsorption of STPP on Mg-Al LDH and Mg-Al CLDH was a physical endothermic sorption process and spontaneous.