Study On Catalytic Ozonation Of Typical Pollutants In Acrylic Fibers Wastewater By Metal Chelates

Acrylic fibers wastewater emissions in our country increase year by year,and the wastewater quality,released into the adjacent waters,barely meets the national emission standard.The high concentrated toxic pollutants,leaving in waters,seriously damage the environment of discharge area through the way of constant migration and accumulation.Although there were a lot of research about acrylic fibers wastewater treatment both at home and abroad,these research were only limited to the wastewater treatment and didn't go deep into the research on the degradation of typical pollutants in the wastewater,which didn't reach the purpose of targeted treatment.This paper focuses on the studies of the wastewater typical pollutants and choose a comparatively typical pollutant such as succinonitrile as the research object.And the method of catalytic ozonation by metal chelates is applied to oxidize succinonitrile,aiming to find a efficiently advanced oxidation process to degrade succinonitrile.It can provide technical support for treating the wastewater by the method of metal chelates catalytic ozonation and has positive significance for promoting the development of ozone treatment technology.The paper uses the technology of catalytic ozonation by metal chelates to oxidize succinonitrile,and utilizes strong oxidizing hydroxyl free radical,generated by ferrous ion reacting with ozone,to degrade it without selectivity to achieve good degradation effect.Firstly the paper briefly describes catalytic ozonation theory of metallic ions and complexation theory to establish the theory foundation for subsequent experimental study.Next the process of catalytic ozonation by metal chelates is choosed through comparing the oxidation effectiveness of succinonitrile by three processes.And the metal chelates are choosed.Then Some single factor experiments and the orthogonal experimental design of oxidation effectiveness of succinonitrile are discussed.Finally,the biochemical performance research and dynamics research are studied.The result shows that the oxidation effectiveness of succinonitrile by the process of metal chelates catalytic ozonation is the best.The oxidation effectiveness of succinonitrile under the five single factors of the process is the following: it is increased slowly after a rapid increase respectively along with the increase of Fe(II)ion concentration,gas phase ozone concentration and hydraulic retention time;the synergistic effect of metal ion on theoxidation effectiveness is small;it continues to increase respectively along with the increase of initial pH value.The effect of concentration variation on the oxidation effectiveness is small.The orthogonal experimental design shows that the primary and secondary order of the selected four influence factors are the hydraulic retention time,the Fe(II)ion concentration,the initial pH value and the gas phase ozone concentration,and the first two influence factors have significant effect on the experimental results.And the optimum condition is that the initial pH value is 7,the Fe(II)ion concentration is 0.2mmol/L,the gas phase ozone concentration is 25~30mg/L and the hydraulic retention time is 120 min.Under the optimum condition,three parallel oxidation experiments are conducted to oxidize succinonitrile and when the the hydraulic retention time is 120 min,the average oxidation effectiveness is 72.4%.The biochemical performance is improved and the B/C ratio increases from 0.18 to 0.46.In addition,the oxidation of succinonitrile by the process of metal chelates catalytic ozonation accords with pseudo first order kinetics,and when the initial pH value is in the range of 1~7,the synthetical reaction rate constant is between0.00486 and 0.00869(min)-1.