中文摘要：

为提高磷吸附剂Mg/Al-LDO的重复利用性,比较了焙烧一步再生法和解吸-焙烧两步再生法的再生效果;基于XRD、FTIR谱图分析再生过程中吸附剂的晶体结构及层间阴离子的变化,探讨了Mg/Al-LDO的再生机制及再生率下降的原因.结果表明,解吸-焙烧两步再生法更适合作为Mg/Al-LDO的再生方法,最佳再生条件为:解吸液为NaOH-Na2CO3混合液,焙烧条件为温度550℃、时间6h;首次再生率可达到95%,经过5次再生后,再生率降为67%,存在再生率下降问题.根据Mg/Al-LDO吸附磷酸根的吸附机制和XRD、FTIR谱图分析,再生率下降的原因包括两方面:一是由于吸附剂的化学吸附作用导致磷酸根解吸不彻底,高温焙烧后晶体中残存的磷酸根仍占据着吸附剂的吸附位点;二是经多次高温焙烧后部分Mg/Al-LDO转化为尖晶石MgAl2O4,失去吸附能力.

英文摘要：

In order to improve the reuse of phosphorus adsorbent Mg/Al-LDO,the regeneration effects of roastingone-step regeneration and desorption-roasting two-step regeneration were compared.Based on XRD and FTIR spectrumanalysis,the changes of crystal structure and interlayer anionof the adsorbentwere analyzed,and the regenerationmechanism of Mg/Al-LDO and reasons for the declining regenerationratewere then discussed.The results indicatedthatdesorption-roasting two-step regeneration was more suitable for the regeneration of Mg/Al-LDO,with the followingoptimum regeneration condition:desorption solution of NaOH-Na2CO3mixture,roasting temperature of550℃andduration of6h.It was found that the primary regeneration rate reached95%,but the regeneration rate dropped to67%after five regenerations.Thus,a problem of decreased regeneration rate existed.Based on the adsorption mechanism ofMg/Al-LDO and the analysis of XRD and FTIR spectrum,the reasons for the declining regeneration rate include twoaspects:(1)incomplete desorption of phosphate due to the chemical adsorptionof Mg/Al-LDO led toun-removed residualphosphate in the crystal under high temperature calcination that still occupy the adsorbent adsorption site;(2)theconversion of Mg/Al-LDO into spinel(MgAl2O4)after several high-temperature calcinationsled to the loss of adsorptioncapacity.