好氧颗粒污泥对钇离子的吸附-解吸性能

Adsorption-desorption performances of aerobic granular sludge for yttrium ion

探究了好氧颗粒污泥(AGS)对钇离子(Y^(3+))的吸附-解吸效果。相比于搅拌及振荡,曝气混合下AGS具有更好的Y^(3+)吸附效果,80%以上的吸附在前10 min完成。当初始Y^(3+)质量浓度≤50 mg/L时,AGS能完全吸附废水中Y^(3+)。H^(+)、Na^(+)和Pb^(2+)会与Y^(3+)竞争AGS上的吸附位点,导致吸附率减小。0.6~1.0 mm的AGS吸附量最大,经过人工破碎后,2.4~3.0 mm的AGS吸附量增大约15%。AGS对Y^(3+)吸附动力学符合伪二级动力学模型(R^(2)=0.99),表明化学吸附起主导作用,颗粒内扩散是影响吸附速率的主要因素。AGS对Y^(3+)吸附热力学符合Langmuir模型(R^(2)=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24.39 mg/g MLSS(MLSS为污泥)。XPS表征发现,参与吸附官能团有酯基、羧基、氨基,同时Y^(3+)与K^(+)进行离子交换。HNO_(3)的单次解吸率(99.8%)明显高于NH_(4)Cl(63.2%),但5次吸附-解吸附循环后,HNO_(3)解吸率降至10%,NH_(4)Cl解吸率仍维持在50%。

The adsorption-desorption performances of aerobic granular sludge(AGS)for yttrium ion(Y^(3+)) under different reaction conditions were investigated,of which adsorption effect under aeration,with more than 80%of Y^(3+) adsorbed in the first 10 min,was higher than that under agitation and oscillation conditions.It was also found that AGS could adsorb all Y^(3+) from wastewater when the initial mass concentration of Y^(3+) was less than or equal 50 mg/L.However,adsorption efficiency would decrease due to competition for the adsorption sites on AGS by H^(+),Na^(+) and Pb^(2+).Moreover,AGS with particle size of 0.6~1.0 mm exhibited maximum adsorption capacity while that in 2.4~3.0 mm,when crushed manually,showed an increase of about 15%in adsorption capacity.The adsorption kinetics of AGS to Y^(3+) was fitted to the pseudosecond-order model(R^(2)=0.99),indicating that chemisorption played a dominant role with intra-particle diffusion the main factor affecting the adsorption rate.The thermodynamics of adsorption of AGS to Y^(3+) was consistent with Langmuir model(R^(2)=0.9849),showing that the adsorption process was a monolayer adsorption process with the fitted maximum adsorption capacity 24.39 mg/g MLSS(MLSS represents sludge).Meanwhile,XPS characterization displayed that the functional groups contributing to the adsorption were mainly ester group,carboxyl group and amino group as well as ion exchange between Y^(3+)and K^(+).For desorption,the single desorption efficiency of HNO_(3)(99.8%)was significantly higher than that of NH_(4)Cl(63.2%).However,after five cycles of adsorption-desorption,the desorption efficiency of HNO_(3) decreased to 10%,while that of NH_(4)Cl remained at 50%.