Investigation Of Removal Of Organic Pollutants In Water By Fenton And Fenton-like Oxidation Technology

Organic pollution of water environment is a global problem, and its severity, nature andharm is developing and changing along with the development of the industry. Chemosyntheticorganic compounds because of its degradation-resistant nature, ease to stranded andcumulative in biological body, and leading to deformity, cancer, and mutation has become aserious threat to human health. FENTON technology is a kind of sewage treatmenttechnology which is processing range and high treatment efficiency, especially for thedegradation-resistant organic matter.In this paper, the target pollutant is p-nitrophenol. This dissertation investigates thetreatment efficiency, influencing factors of Fenton technology,iron Fenton-like technonglyand iron chip Fenton-like technology for removing chemosynthetic and degradation-resistantorganic matter. In addition, the iron chip Fenton-like reactor is designed for the experiment ofcontinuous operation and dynamic simulation. The main research and results of thisdissertation are shown below:FENTON technology can effectively degrade p-Nitrophenol. PNP initial concentration,pH and H₂O₂and FeSO₄dosing quantity, have different degrees of influence of reactioneffect. In the pH=3, the speed of degradation is fastest, pH <3, hydroxy free radicalsproduce efficiency is decreased, the initial reaction rate is slow, pH>5, the generation ofhydroxyl radicals and the proceeding of the reaction are inhibited. Under different of PNPinitial concentration, corresponding to different H₂O₂and FeSO₄optimal dosing quantity isdifferent: H₂O₂is the generation of hydroxyl radicals agent and scavenger, H₂O₂amount ofadditive is to promote the generation of REDOX reaction, and excessive additive inhibitoryreaction, and it is medicament waste; While FeSO₄is catalyst of Fenton reaction, but itsdosing quantity also affects the reaction effect. The mainly reason is that the FENTONreaction process is accompanied by a series of chain reaction,in which Fe2+is involved andaffects reaction process. The best conditions for experimental study: pH=3, PNP initialconcentration of100mg/L,30%H₂O₂dosing volume is3.0ml/L,0.01mol/L FeSO₄dosingquantity is20ml/L, in which after the response time of20min, the PNP removal rateachieves more than97.5%.Zero-valent iron FENTON-like technology can effectively degrade p-Nitrophenol. Fromcondition parameters of process, zero-valent iron FENTON-like technology and FENTONtechnology is similar,and it is more demanding pH conditions that pH <4. Zero-valent ironFENTON-like reaction needs zero-valent iron reduction reaction occuring as the prerequisite,and in which the organic matter needs lower acid condition, for pH of the reaction system willrise, so for initial pH of zero-valent iron FENTON-like reaction should be lower. The best conditions for experimental study: pH=2³, PNP initial concentration of100mg/L,30%H₂O₂dosing volume is3.0ml/L, zero-valent iron dosing quantity is4.000g/L, in which afterthe response time of20min, the PNP removal rate achieves more than95%.Iron chip FENTON-like technology principle of PNP degradation is relatively complex,including the reduction reaction of zero-valent iron, iron carbon micro-electrolysis andFENTON reaction. For the degradation of organic matter, including oxidation and reductionprocess, the process data of experiment is fluctuate. That may be competing parts, but thecompetition for degradation of p-nitrophenol may be in the same direction, which isincreasingly vulnerable to degradation. The main reason is that reduction reaction makes-NO₂of less oxidation become–NH2of more oxidation. The result of competition is that thereaction rate is increased. The best conditions for experimental study: pH=3, PNP initialconcentration of100mg/L,30%H₂O₂dosing volume is3.0ml/L, iron chip dosing quantity is5.0g/L, in which after the response time of20min, the PNP removal rate achieves more than95%.By iron chip FENTON-like reactor of continuous running, the effect of PNP degration isbetter than the beaker experiment. The main reason is that the combination of reactor is morehomogeneous and the probability of collisions between iron is increased. This reactor in filterbed was not added too much iron, but a moderate amount of scrap iron and fixed in thereactor as uniformly as possible. In continuous reactor HRT=30min, including the ironfilings degradation alone10min, and20min FENTON-like system, running effect is better.Initial PNP concentration of100mg/L, along with stable runtime, PNP concentration is less4mg/L. The reactor is running continuously for10days, and the longest cycle to continuerunning PNP concentration is more than5mg/L. Continuous operation appearing flocculationand the passivation of iron filings, needs iron chips activated. COD and TOC test of reactoreffluent show that the good effect on organic matter degradation. Nuclear magneticcharacterization of degradation products shows that p-nitrophenol has been degrated andbecome long straight chain structure.