负载磁性废茶生物炭活化过一硫酸盐高效降解水中腐殖酸和富里酸

Efficient degradation of humic acid and fulvic acid in water by magnetic waste tea biochar activated persulfate

城市污水厂二级处理出水中含有大量的溶解性有机物(Dissolved organic matters,DOM)会对生物和受纳水体构成潜在的危害,因此有必要对二级处理出水进行深度处理.本研究以农业废弃物茶叶渣为原料,通过对废弃茶叶改性和负磁制备一种磁性废茶生物炭(Fe-tea biochar,Fe-TB),用于活化过一硫酸盐(Peroxymonosulfate,PMS)氧化降解水中的腐殖酸(Humic acid,HA)和富里酸(Fulvic acid,FA).考察Fe-TB铁负载量、PMS浓度、Fe-TB投加量、初始pH、HA和FA的初始浓度对Fe-TB/PMS体系氧化降解HA和FA的影响.结果表明,在铁碳比为2/1(W/W)、PMS=0.2 g·L^(-1),2Fe-TB投加量分别为0.6 g·L^(-1)(HA体系)和0.4 g·L^(-1)(FA体系)、初始pH=7条件下,50 min时对初始浓度为20 mg·L^(-1)的HA和FA的去除率分别达到95.3%和77.4%;经过4次重复循环使用,HA和FA的去除率均在59.0%以上,表明其良好的稳定性和重复使用性.淬灭实验及电子顺磁共振(EPR)分析结果证明2Fe-TB/PMS体系以单线态氧(1O2)为主要氧化活性物种降解HA和FA.实际二级处理出水中的DOM降解结果表明,2Fe-TB/PMS体系可以有效降解实际水体中的DOM,具有良好的应用前景.

Abundant dissolved organic matters(DOM)in the secondary effluent from the wastewater treatment plants would cause potential harm to organisms and the receiving water.Therefore,it is deemed necessary to find out an advanced method for the secondary effluent treatment.In this study,a modified Fe-tea biochar(Fe-TB)was successfully prepared using the agricultural tea wastes.The Fe-TB was used to activate peroxymonosulfate(PMS)and their combination could oxidize the humic acid(HA)and fulvic acid(FA)in the wastewater.The effects of the iron loading of the Fe-TB,PMS concentrations,Fe-TB dosages,and initial pH as well as the concentrations of HA and FA on their degradation in Fe-TB/PMS process were investigated.Results showed that the removal efficiency of HA with the initial concentration of 20 mg·L^(-1)was 95.3%,while FA with the same concentration was 77.4%at 50 min under the conditions of 2/1(W/W),0.2 g·L^(-1)of PMS,Fe-TB dosage of 0.6 g·L^(-1)(HA)and 0.4 g·L^(-1)(FA),respectively,and initial pH 7.After recycling 4 times,the removal efficiency of HA and FA were both over 59.0%,indicating that 2 Fe-TB/PMS system has an excellent stability.The results of the quenching free radical experiments and electron paramagnetic resonance(EPR)showed that in the 2 Fe-TB/PMS system,1O2 as the main reactive oxygen species could efficiently degrade HA and FA.Furthermore,the 2 Fe-TB/PMS system could effectively degrade DOM in the actual secondary effluent,which confirmed the efficiency of this system.Thus,the 2 Fe-TB/PMS system has a promising application prospect.