Study On Treatment Of PAHs Dye Wastewater By Fenton Advanced Oxidation Process

This research subject, sponsored by CSTC (07BB7145), is part of a major creative research subject (50621403) of NFSC.Polycyclic Aromatic Hydrocarbons (PAHs) dye wastewater is one of the key sources of persistent organic pollutants which are hard to be degraded. The trend to photodegradation resistance, heat resistance and anti-biological oxidation of dyestuff especially hardens the difficulty of wastewater processing, so the traditional wastewater treatment technique cannot meet the needs of discharge standard. Therefore, it has far-reaching significance to find an economical and applicable technique of wastewater treatment with high efficiency to protect the water environment and promote the development of printing and dyeing industry.This dissertation, with the purpose of PAHs dye wastewater and Rhodamine B dyestuff as simulative research object, has an experimental research of simulative Rhodamine B and PAHS dyestuff wastewater with the adoption of Photo-Fenton reaction, microwave promoting fenton reaction and microwave promoting fenton-like reaction. Four aspects has been studied in this dissertation: (1)the degradation characteristics of Bhodamine B dyestuff wastewater of pHoto-fenton reaction are studied with the introducing of sunshine, high-voltage mercuric lamps and indoor light as lamp-house and scrap iron reaction; (2) To improve the efficiency of oxidation process, microwave-Fenton process was investigated; in the meanwhile, to avoid or lessen the secondary pollution of Fe3+ into wastewater in Fenton reaction, to broaden the usage scale of pH in Fenton reaction and to reduce the cost of the wastewater treatment bringing by the new technique and novel technology, the degradation characteristics of Rhodamine B are studied under the effect of microwave promoting and Fenton reaction in which transition metal ion Cr(VI) is used instead of Fe2+ in the wastewater;(3)the Dynamic Behavior of Rhodamine B in oxidation degradation is studied under the reactions of Photo-Fenton, microwave promoting fenton and microwave promoting fenton-like, the degradation mechanism and methods of Rhodamine B are also discussed under the reaction of Photo-Fenton;(4)the feasibility of advanced fenton oxidation technology processing dye wastewater in practical industries were discussed systemically.The following results are achieved in this dissertation from the above experimental research and theoretical analysis:①Photo-Fenton reaction can effectively decolor and degrade PAHs dye Rhodamine B, and it is more obvious under the light source of sunshine or high-voltage mercuric lamps and lower of indoor light; the oxidation degradation of optimizing conditions of Photo-Fenton reaction aimed at 500ml 100mg·L-1 Rhodamine B liquor are: pH=3.5,18mmol?L-1Fe2+ liquor 5.0ml,30%H2O2 5.00ml, and one hour later, the removal rate of Rhodamine B reaches 99.9% and CODcr is 93.8%.②The co-use and Synergistic effect of microwave and Fenton reagent can speed the degradation of Rhodamine B. The optimizing oxidation degradation conditions of 500ml 100mg·L-1 Rhodamine B reagent in Microwave-Fenton are: pH=3.0, 0.70ml 30% H2O2 liquor, 4.00ml 0.020mol·L-1 Fe2+ liquor, microwave 8min and the removal rate of Rhodamine B reaches 99.9%, while CODcr is 90.2%.③The catalytic degradation or Rhodamine B with micro radiation(Cr(Ⅵ) -H2O2)Fenton-like reagent has achieved favorable results; the optimizing oxidation degradation conditions of 500ml 100mg·L-1 Rhodamine B reagent in microwave-Fenton are: pH=3.4, 1.00ml 30% H2O2 liquor, 4.00ml 0.040 mol·L-1 Cr(Ⅵ) liquor, microwave 8min and the removal rate of Rhodamine B reaches 99.9%, while CODcr is 80.24%.④Under the condition of pH=3.5, the degradation reaction order of dye Rhodamine B of pHoto-Fenton is 2.57, and apparent kinetics equation is V = 5×1 0?9×P1 .2845×F 0.3660×E0.9204; pH=3.0, the reaction oder of microwave promoting Fenton is 2.13 and the equation is V = 0.064085×P 0.4089×F 1.4655×E0.2562;pH = 3.4, the reaction order of microwave(Cr(Ⅵ)-H2O2)promoting Fenton-like reagent is 2.85 and the equation is V = 8.29182×1 0?5×P 0.8763×G 1.3719×E0.5975。⑤Under the reaction of Photo-Fenton, Hydroxyl·OH will attack unsaturated conjugation bond of conjugated Chromophoric Group in Rhodamine B, make it broken and lead to the analytic oxidation of dyestuff. During the analytic process, Rhodomind B mainly remove the intermediate product of 1-4 Ethyl and other intermediate products produced after the break of Chromophoric Ring structure, such as Benzoic Acid, phthalic Acid, 4-Hydroxybenzoic Acid and oxalic acid; amido in Rhodamine B is changed into NO3? totally and there is no other form of nitrogen existed like NO2 ? and N O?in the wastewater.Moreover, on the analysis basis degradation Pathways for Rhodomind B was proposed.⑥In addition,preliminary feasibility analysis the application of Fenton advanced oixdation process in industries were carried out, and it was considered that there is still a huge gap between Fenton advanced oxidation technology and its use into practice. However, Fenton advanced oxidation technology is one potential dye wastewater treatment technology because of its advantages, the convenience of operation and management and the declining space of technology treatment.The major creative parts and learning values are as the followings:①Instead from the aspect of primitive reaction of Rhodamine B dye waste water degraded from Fenton Advanced Oxidation Technology, the research of this dissertation is focused on the study and equation establishment of reactive apparent dynamic behavior, grasping the reactive rule of pollutants oxidative degradation of this kind of dye waste water treatment techniques and thus settling the theoretical foundation of accelerating the oxidative degradation and optimizing the reactive conditions.②O n the basis of the intermediate and final products of Rhodamine B dye waste water after photo-Fenton reaction oxidative degradation, this dissertation has revealed the oxidative degradation mechanism of Rhodamine B, proposing the possible degradative approaches of Rhodamine B dye waste water, achieving the basic rule of pollutants oxidative degradation of this kind of dye waste water treatment techniques and proposing the critical theoretical foundation and techniques of exploring the oxidative degradation rule of PAHs dye waste water.③On the basis of PAHs dye waste water experiments and theoretical studies ofFenton advanced oxidation technology, this dissertation, for the first time, has systematically discussed the following key questions, such as the degradative characteristics of the dye waste water in the practice of industry, the technological adaptability after the spread of treatment dimensions, the cost of treatment and the sanitation, toxicity and logos during the degradative process, thus establishing the practice foundation of boosting the industrialization of this kind of dye waste water treatment techniques and providing the theoretical guidance for it.