凝胶球负载零价铁活化过硫酸盐降解偶氮染料废水

摘要

Persulfate can be effectively activited by iron. However,iron will leaching in the solution because of the rapid speed of the reaction. The montmorillonite-sodium alginate balls(MABs)with zero-valent iron loading(Fe-MABs)was prepared and characterized by the electron microscope. The results showed the well dispersion of iron on the sodium alginate gelatin ball. In addition,the effects of dosages of sodium peroxydisulfate(PDS)and catalyst to the degradation of Reactive Black 5(RBK5) were examined in batch experiments. The degradation ability to RBK5 follows this order:Fe+C/ PDS>Fe-MABs/PDS>Fe+C>PDS>Fe. The results demonstrated that RBK5 could be degraded by Fe-MABs/PDS system effectively. Under the condition with initial RBK5 concentration 40mg/L,PDS dosage 2.0mmol/L,Fe-MABs dosage 40g/L,pH 7,temperature 298K,the degradation rate of RBK5 in aqueous solution could reach 95.42% and 99.90% within 30min and 60min,respectively. Comparing with Fe+C/PDS,Fe leaching ratio will reduce 90% in Fe-MABs/PDS system within 60min. By using methanol and chloroform as free radical quenchers,the active intermediate SO4–· play a leading role tothe degradation process,which generated from the PDS activation. Finally,the dynamics was also calculated in the Fe-MABs catalyzing system.%铁活化过硫酸盐高级氧化技术中,由于反应速度快引起的铁流失是主要问题之一.本文制备了负载零价铁的海藻酸钠凝胶球催化剂(Fe-montmorillonite-sodium alginate balls,Fe-MABs),电子显微镜图表明海藻酸钠凝胶球和铁结合良好,并考察了过硫酸钠(sodium peroxydisulfate,PDS)用量、催化剂用量等因素对偶氮染料活性黑5(Reactive Black 5,RBK5)染料废水降解的影响,比较了Fe-MABs/PDS、Fe+C/PDS、Fe+C、PDS、Fe五种体系对RBK5的降解能力.结果表明,Fe-MABs/PDS体系能有效地降解RBK5,在RBK5初始浓度40mg/L条件下,PDS投加量为2mmol/L、Fe-MABs投加量40g/L、初始pH为7.0、温度为298K,在反应时间为30min和60min时,对RBK5降解率分别达到95.42%和99.90%;与Fe+C/PDS、Fe+C、Fe体系相比,Fe-MABs/PDS体系Fe的流失率减少可达90%以上.此外,通过采用甲醇和叔丁醇作为自由基淬灭剂发现Fe-MABs/PDS体系中产生的活性中间体硫酸根自由基SO4-·对降解过程起主要作用,并初步探索了Fe-MABs催化过硫酸盐体系对RBK5的降解动力学.