厌氧颗粒污泥合成纳米钯及强化降解双氯芬酸性能

In-situ formation and immobilization of biogenic nanopalladium into anaerobic granular sludge enhances diclofenac degradation

为了提高厌氧颗粒污泥(AGS)对难降解卤代有机物的还原降解能力,本文研究了厌氧颗粒污泥原位还原制备纳米钯构建载钯型厌氧颗粒污泥(Pd-AGS)的方法与条件,以及Pd-AGS在不同电子供体及烘干方式下对双氯芬酸(DCF)的降解特性.研究表明,当Pd(II)浓度为50~200 mg·L^-1,Pd/生物量比为1/40~1/10时,被颗粒污泥还原的Pd(II)超过90%,且Pd/生物量比越高,与污泥微生物结合的纳米钯(Pd NPs)越多;添加氧化还原介体蒽醌-2,6-二磺酸(AQDS)不能加快Pd(II)的还原速率,但可以使与胞外聚合物(EPS)结合的Pd NPs增多.Pd NPs的负载显著强化了AGS对DCF的降解性能,甲酸钠和氢气都能够作为电子供体激活Pd-AGS降解DCF,氢气更为有效.氢气存在下,初始浓度为20 mg·L^-1 DCF在90 min降解率达到96.47%,而不载钯的AGS最终对DCF的降解率仅为16.19%.烘干处理会降低Pd-AGS对DCF的降解效率,但相比121℃和600℃的烘干方式,冷冻干燥和80℃烘干方法对Pd-AGS的降解性能影响较小.Pd-AGS将微生物降解性能与纳米钯的催化性能相结合,提高了对卤代难降解有机物的降解能力.

Biogenic nanopalladium(Bio-Pd) was formed in-situ and immobilized by Anaerobic Granular Sludge(AGS) aimed to improve its degradation ability to refractory halogenated organic compounds. This study investigated the formation methods and conditions of Bio-Pd by AGS(Pd-AGS), and its degradation of diclofenac(DCF) using different electron donors or after different drying treatments. Results show that more than 90% of Pd(II) was reduced at the initial Pd(II) concentration of 50~200 mg·L^-1 with the Pd/biomass ratio controlled at 1/40~1/10. The higher Pd/biomass ratio, the more palladium nanoparticles(Pd NPs) was found to be associated with the microbes of the AGS. The addition of redox mediator AQDS could not speed up the reduction of Pd(II), but increased the fraction of Pd NPs associated with extracellular polymeric substances(EPS).The loading of Pd NPs significantly enhanced the degradation of DCF. Both formate and H2 could serve as the electron donor to activate the catalytic activity of Pd-AGS to degrade DCF, and H2 was more effective. DCF at initial concentration of 20 mg·L^-1 was degraded by 96.47% in 90 minutes in the presence of H2, while that by the control AGS was only 16.19%. The declorination efficiency of DCF by Pd-AGS droped after different drying treatments under 121 ℃ and 600 ℃, but less inhibited by the ones treated by Freeze-drying at 80 ℃. Overall, the Pd-AGS, which combines microbial degradation ability with catalytic ability of Bio-Pd, demonstrates a strong ability for the degradation of recalcitrant halogenated compounds.