好氧颗粒污泥对钇离子的吸附/解吸性能

为实现稀土尾水中钇离子（Y3+）的回收，探究了好氧颗粒污泥（AGS）对Y3+的吸附-解吸附效果。考察了混合方式、初始Y3+浓度、pH、盐度、铅离子及粒径对AGS吸附效果的影响。相比于搅拌及振荡，曝气混合下AGS具有更好的吸附效果，80%以上的吸附在前10 min完成。当初始Y3+浓度<50 mg/L时，AGS能完全吸附废水中Y3+离子，此后吸附率随着Y3+浓度的增大而减小。H+、Na+和Pb2+会与Y3+竞争AGS上的吸附位点，导致吸附率减小。0.6～1.0 mm的AGS吸附容量最大，2.4～3.0 mm的AGS经人工破碎后吸附容量增大15%。对吸附过程进行动力学和热力学拟合。动力学符合伪二级模型（R2=0.9999），表明化学吸附起主导作用；Webber-Morris方程分析表明颗粒内扩散是影响吸附速率的主要因素。热力学符合Langmuir模型（R2=0.9849），表明吸附过程是一个单分子层吸附过程，拟合得到最大吸附量为Qmax=24.39 mg/gSS。利用XPS对吸附前后AGS进行表征，发现参与吸附官能团有酯基、羧基、氨基，同时与K+进行离子交换，钇在AGS表面的主要化学态是Y2(CO3)3。探究了硝酸及氯化铵对吸附饱和AGS的解吸效果。HNO3的单次解吸附率（99%）明显高于NH4Cl（64%），但五次吸附-解吸附循环后，HNO3组解吸附率降至10%，NH4Cl组解吸附率仍维持在50%。

Performance of aerobic granular sludge for yttrium ion Adsorption and desorption

To recover yttrium ion Y(III) from rare earth mine wastewater, performance of aerobic granular sludge (AGS) for Y(III) adsorption and desorption was investigated. The effects of mixing mode, initial concentration of Y(III), pH, salinity, lead ion concentration and particle size on adsorption performance of AGS were explored. Compared with agitation and oscillation, aeration has better adsorption performance, and more than 80% of Y(III) were adsorbed in the first 10 min. When the initial Y(III) concentration was less than 50 mg/L, AGS could adsorb all the Y(III) from wastewater, and then the adsorption efficiency decreased with the increase of Y(III) concentration. H+, Na+ and Pb2+ competed with Y(III) for the adsorption sites on AGS, resulting in the decrease of the adsorption efficiency. The AGS with particle size of 0.6-1 mm had the maximum Y(III) adsorption capacity, and the adsorption capacity of AGS with particle size of 2.4-3.0 mm after artificial crushing increased by 15%. The adsorption process was fitted with kinetics and thermodynamics. The kinetics was in accordance with the pseudo-second-order model (R2 was 0.9999), indicating that chemisorption played a dominant role. Webber-Morris equation showed that intra-particle diffusion was the main factor affecting the adsorption rate. The thermodynamics was consistent with Langmuir model (R2 was 0.9849), indicating that the adsorption process was a monolayer adsorption process, and the fitted maximum adsorption capacity was 24.39 mg/gSS. AGS before and after Y(III) adsorption was characterized by XPS. Functional groups involved in adsorption included ester group, carboxyl group and amino group, and ion exchange between Y(III) and K+ was detected. The desorption effect of nitric acid and ammonium chloride on saturated AGS was investigated. The single desorption efficiency of nitric acid (99%) was significantly higher than that of ammonium chloride (64%). However, after five cycles of adsorption and desorption, the desorption efficiency of nitric acid group decreased to 10%, whereas that of ammonium chloride group remained at 50%.