层状氢氧化镁铝的改性与成型及其对PO_4^(3-)的吸附脱除性能

Magnesium and aluminium layered double hydroxide: modification, granulation and the adsorptive removal of PO_4^(3-)

利用大型工业设备制备出性能稳定的粉末层状氢氧化镁铝(500kg/批,记为Mg-Al LDH),利用沉积法将Mg-Al LDH进行改性与成型,并对其进行材料表征,探索了Mg-Al LDH的改性机理,研究了改性与成型层状氢氧化镁铝(记为MG Mg-Al CLDH)对PO43-的动态吸附脱除及再生性能。结果表明,Mg-AlLDH经改性与成型后,比表面积为233.34m2/g,比未改性时提高了40%,Mg-Al LDH的改性主要是通过氢键键合和离子交换实现的。MG Mg-Al CLDH对PO43-的穿透吸附量是13.49mg/g,是未改性时的6倍以上,再生率为126.24%,MG Mg-Al CLDH吸附脱除PO43-后能够满足污水综合排放一级标准0.5mg/L。解决了Mg-Al LDH在实际应用中存在粉末易堵塞床体、无法实现固液分离和再生的问题,同时为水体中磷的脱除提供了一条新型可行之路。

Powder layered double hydroxide of Mg-Al LDH has been prepared by hydrothermal technology with 500 kg/batch,modified and granulated（MG Mg-Al CLDH） by deposition method.After modification and granulation,the fixed bed could not be accumulated and cloged by the adsorbents.MG Mg-Al CLDH has been characterized with SEM-EDX,specific surface area and pore volume,XRD,FT-IR.The surface area of MG Mg-Al CLDH was 233.34m2/g,40% higher than G Mg-Al CLDH（granulated but without modification）.The mechanism of modification was hydroxyl group and ion exchange.PO43- was removed from aqueous solution by MG Mg-Al CLDH with column experiments,the breakthrough adsorption capacity was 13.49mg/g,more than 6 times of G Mg-Al CLDH.The exhausted MG Mg-Al CLDH could be desorbed with 0.1mol/L NaOH and 3mol/L NaCl and regenerated with 25% MgCl2.The regeneration rate was 126.24%.After removal,the water quality could satisfy with 0.5mg/L,the first degree of integrated wastewater discharge.So this work is very useful for the practical application of Mg-Al LDH and the removal of phosphorus.