载磷Mg/Al/Fe-LDO的微波辅助溶剂解吸方法特性

针对载磷Mg/Al/Fe-LDO再生利用与解吸液富集回收磷的问题,通过对比直接溶剂解吸法与微波辅助溶剂解吸法在解吸条件、吸附性能与材料层状结构恢复方面的差异,考察了微波辅助溶剂解吸方法的技术特性,并分析了其解吸机制.结果显示,与直接溶剂解吸法相比,微波辅助溶剂解吸法解吸时间由4 h缩短为10～30 min,解吸效果提高15%以上;在同等解吸效果前提下,组合解吸剂(Na_2CO_3+NaOH)浓度降低2倍;解吸剂用量减少10倍.载磷Mg/Al/Fe-LDO经微波辅助溶剂解吸-焙烧再生后,吸附性能得到较好地恢复,3次吸附-解吸-焙烧后再生率接近90%,比直接溶剂解吸-焙烧再生提高40%.由于微波能够强化溶剂离子热运动、促进离子传质与扩散过程,加快离子交换速率,有利于材料层状结构的有效恢复,因此,微波辅助溶剂解吸法能够在较低解吸剂浓度与用量条件下,实现对载磷Mg/Al/Fe-LDO的高效、快速解吸,有利于污水中磷的富集回收.

Characteristics of microwave assisted solvent desorption for phosphorus-adsorbed Mg/Al/Fe-LDO

The microwave assisted solvent desorption (MASD) method was examined, compared with direct desorption, on the regeneration of Mg/Al/Fe-LDO and the recovery of phosphorus. These two methods were investigated in terms of their desorption conditions, adsorption capability, and the structure recovery of the Mg/Al/Fe-LDO material, to reveal the desorption mechanism of microwave assisted solvent desorption. The results show that by using MASD, the desorption time was reduced from 4 h to 10~30 min and the desorption efficiency improved by more than 15%. Moreover, under the similar desorption efficiency, the concentration and the usage of combined desorption agent (Na₂CO₃+NaOH) can be decreased by 2 an 10 fold, respectively. After regeneration by MASD-roasting, the adsorption capability of Mg/Al/Fe-LDO material was well recovered. The regeneration rate of such adsorbent was nearly 90% after three cycles, and is 40% higher than that of direct solvent desorption, owing that microwave can enhance the ionic thermal movement of solvents, promote the process of ion mass transfer and diffusion, and accelerate the rate of ion exchange. These advantages are conducive to the effective restoration of the layered structure of adsorbent material. Therefore, the MASD can achieve high-efficiency and rapid desorption of phosphorus from the Mg/Al/Fe-LDO with low dosage of agent, which is helpful for the enrichment and recovery of phosphorus in sewage.