Heterogeneous Fenton Reagent Preparation And Applied Research In The Treatment Of Coking Wastewater

Coking wastewater is a kind of typical organic wastewater that difficult to degrade due to its complex composition, high concentration, deep color, toxicity and stability of pollutants.Fenton reagent is one of homogeneous oxidation methods that apply H2O2 as oxidation and Fe2+ as catalyst. In reaction,·OH is one of free radicals with excellent oxidation properties. Therefore, it can oxidize most organic compounds in order to reduce chroma and COD value in the wastewater. However, homogeneous Fenton reagent is hard to be separated from reaction medium, and it is easy to loss. If a new heterogeneous catalyst which is convenient to be separated from reaction medium recycled, and it can't cause secondary pollution. it will have a good perspective in application.According to principle of Fenton, author has prepared a new, high efficient and recycled heterogeneous Fenton-like catalyst, focuses on the perspectives in technical and condition of catalyst preparation. The new heterogeneous catalyst combine chemical coagulation with chemical precipitation has gotten good results in treating coking wastewater. In addition, the content of COD and NH3-N is reduced effectively. The main conclusions of the study are as follows:(1) By steeping, activated carbon as carrier is modified by acid and alkali. Fe3+ is the active component of catalyst. According to experimental results, under the reaction condition (Fe3+ of 2.5%, curing temperature of 270℃), catalyst has more activity. When the catalyst is reused for 5 times, the wastewater have been met national second emission standard, which proved man-made Fe3+ supported on activated carbon have good recycling.(2) In the experiment of chemical coagulation, chroma is reduced effectively, but removal efficiency of COD is bad. Only together with other control measures can meet emission standards.(3) NH3-N concentration of coking wastewater is reduced by chemical precipitation. different initial pH value, chemical volume(MgCl2·6H20 and Na2HPO4·12H20 as chemicals) and reaction temperature will have effect on treatment results.(4) The major influences include catalyst volume, H2O2 concentration and adding way, initial pH value and reaction time in the treatment of degrading coking wastewater by heterogeneous Fenton-like reagents. Use the orthogonal method and range analysis to study the order of priorities about influences, and result is catalyst volume> initial pH> reaction time> H2O2 volume. Treatment result is excellent by heterogeneous Fenton-likereagents.(5) The COD value by heterogeneous Fenton-like reagent has been met national first emission standard. However, the COD value by homogeneous Fenton reagent has been met national second emission standard at the same test conditions.(6) Heterogeneous Fenton-like reagents, together with chemical coagulation and precipitation degrades coking wastewater. The major data of water quality are as follow: chroma is 10 times, COD value is 38.5 mg/L, and NH3-N value is 8.4mg/L. In addition, the removal efficiency of COD and NH3-N reach to 99%, have been met national first emission standard.