微波活化过硫酸盐耦合混凝处理二硝基重氮酚工业废水

Removal of refractory organic compounds in DDNP industrial wastewater by MW activated PS coupling coagulation process

利用微波(MW)活化过硫酸盐(PS)体系耦合混凝法处理二硝基重氮酚(DDNP)工业废水,考察了PS投量、n(Fe2+/PS)、初始pH值、MW功率对废水中有机物的去除效果,通过控制实验比较了单一方法处理DDNP工业废水效果及协同机制,采用紫外可见光谱和红外光谱研究了有机物的结构经氧化后的变化特征,并对该体系的主要活性氧化物种(ROS)进行了识别.结果表明,在PS投量为8g/L,初始pH值为3,MW功率为600W,n(Fe^(2+)/PS)为0.04,反应时间8min时的条件下,COD和色度(CN)去除率分别达70.79%和94.53%.与此同时,混凝后出水COD去除率有一定上升,但是CN的去除有小幅下降的趋势.另外,MW、PS和Fe^(2+)三者存在协同效应,在反应时间为14min时出水可生化性大幅改善(B/C从0.05提高至0.56).最后,体系主要产生以硫酸根自由基和羟基自由基为主的活性物种,能够破坏DDNP工业废水中有机物所含的苯环结构、硝基(-NO_2)和偶氮基(-N=N-),形成含N-H、C-O-H的中间产物.

MW activated PS coupling coagulation process was applied to treat the dinitrodiazophenol(DDNP)industrial wastewater in this study.The effects of PS dosage,n(Fe^2+/PS),initial pH and MW power on organic compounds removal efficiency of DDNP wastewater were investigated.The effect and synergistic mechanism of DDNP wastewater degradation were compared by using control experiments,and the structural transformation of organics by oxidation of MW-Fe^2+/PS system was characterized by UV-Vis and FTIR spectra.The reactive oxidative species(ROS)were identified by adding radical scavengers.The results indicated that under optimum condition of PS dosage of8g/L,initial pH of3,MW power of600W,n(Fe^2+/PS)ratio of0.04,and reaction time of8min,the COD and CN removal efficiency were70.79%and94.53%,respectively.Meanwhile,the COD removal rate of the effluent after coagulation increased,but the removal rate of CN decreased slightly.In addition,MW,PS and Fe^2+had the synergetic effect.The increase of B/C from0.05to0.56indicated that the biodegradability of the wastewater was significantly improved.Moreover,·SO4-and·OH are the most critical ROS in the system,which can destroy benzene ring,nitro(-NO2)and azo group(-N=N-)and form by-products containing N-H and C-O-H.