Study On The Pretreatment Of The Pyrazole Heterocycle Wastewater

In recent years,Pyracfonil was a new and highly effective herbicide in the market.In the production process,wastewater with high salt,high nitrogen,high toxicity and strong biological inhibition will be produced.Because of sTab.structure,pyridine22 heterocyclic degradation is difficult.Traditional biological treatment alone can not achieve the discharge standards.In order to exert the Biological treatment advantages of low toxicity,low investment and low operating cost,effective wastewater pretreatment is necessary.The degradation of heterocyclic compounds in wastewater to biodegradable materials can reduce the biological toxicity of heterocyclic compounds and solve the difficulty of biological treatment.In this paper,intermediate BIS pyrazole in the process of nitrile bipyrazole from the XiangHe Company’s production was used to make simulated wastewater.Actual is also from this company.High performance liquid chromatography（HPLC）,SEM scanning electron microscopy（SEM）and specific surface determination were used to examine the effects of pH,reaction time,the ratio of Fenton reagent and the amount of activated carbon.The oxidation mechanism of Fenton and the adsorption and regeneration of activated carbon were studied.Therm and of carbon were discussed.Theresearch works andachievements are as follows:1 Treatment of simulated wastewater containing Pyrazole heterocycle by Fenton oxidationThe configuration of 300mg/L based pyrazole heterocycle simulated wastewater.Fenton oxidation experiment results show that the optimum processing conditions were:initial pH=3,n(Fe²⁺):n（H₂O₂）=1:54,H₂O₂ dosage is 50m L/L,the reaction time is 30min,adjust the pH=10 after completion of the reaction,the bipyrazole removal rate was97.5%.Increasing the dosage of H₂O₂ or Fe²⁺is beneficial to the removal of pyrazole,but more than a certain amount of H₂O₂ or Fe²⁺can reduce the treatment efficiency,and it is beneficial to the degradation of organic compounds in Fenton under acidic conditions.Within a certain range of prolonged stirring time is conducive to the removal of pollutants;The effects of the removal of bipyrazole of Fenton ethanol significantly,indicating poor selectivity of hydroxyl radical oxidation of organic compounds in wastewater,organic matter and other pollutants simultaneously with target Fenton reagent reaction,increased Fenton the dosage of reagent.HPLC analysis showed that Fenton reagent can react quickly and bipyrazole,but bipyrazole structure has not been completely degraded,the structure part bipyrazole is decomposed into several more hydrophilic material structure exists in water,which corresponds to the residence time in the 1.2min material was degraded most slowly.We can speculate on hydroxyl radicals（·OH）under the action of the first open loop is C-N key bipyrazole in a ring,but another ring still exists,with the hydroxyl radical（·OH）was further increased,slowly open loop,the production of organic acid;this is the Fenton degradation mechanism of double triazole heterocyclic structure provides a certain theoretical basis.2 Treatment of Actual wastewater by Fenton oxidationThe concentration of COD in the wastewater was 10031mg/L,and the concentration of the heterocyclic compound was 2254mg/L.The experimental results show that the optimal treatment conditions are as follows:the initial pH is 4,the dosage of Fe²⁺is2.5g/L,the dosage of H₂O₂ is 50mL/L,the reaction time is 40min,and the removal rate of COD is about 70%.It was found that the increase of Fenton reagent was beneficial to the removal of pollutants and COD in the optimization of treatment conditions.The possible reason is the excessive hydrogen peroxide will produce pseudo COD value so that the COD value cannot be increased by COD;pollutant removal rate reached the maximum value no longer increases,COD continue to increase the removal rate of Fenton degradation of wastewater,reaction part of Fenton reagent and double triazole heterocyclic substances,and also a large part of other organic reactions.3 Adsorption Treatment of wastewater by activated carbonRespectivelyweigh 0.1g three kinds of activated carbon which called number1,number2,number3,which were added into 100mL wastewater respectively,equilibrium adsorption rate were 10.2%,98.5%and 19.8%,we can see that the 2 activated carbon adsorption capacity is 1,9 times,5 times the number 3 the.Through SEM scanning electron microscopy,surface area and pore size distribution test,1550 times 2,the specific surface area of active carbon is 1,is 2.3 the number 3;the total pore number 2 activated carbon content is 5 times the number 3,Kong Rong in the hole is 2.4 the number 3.Large pore volume is 7 times the number 3.The main factors affecting the adsorption of activated carbon double triazole heterocyclic compounds is the pore size distribution of activated carbon,two triazole heterocyclic compounds mainly by macroporous adsorption of activated carbon pore size,aperture is too small is not conducive to its adsorption,so the choice of 2 activated carbon as adsorbent in this experiment.0.1g activated carbon to100mL wastewater,at room temperature,the stirring rate is 160r/min,the adsorption of60min reached adsorption equilibrium,the adsorption capacity of the activated carbon was 294mg/g,the removal rate of pollutants is 98.82%,the adsorption process accorded with the two level dynamic model;Freundlich equation for describing the isotherms of activated carbon adsorption of bipyrazole activated carbon adsorption;wastewater 7adsorption reached saturation,the adsorption capacity of activated carbon is 914mg/g;in a certain temperature range,high temperature to adsorption,after more than 60 degrees with the temperature increasing adsorption efficiency decreased;acidic condition is conducive to the removal of pollutants,the removal rate of pH increased with a small decline no effect;the efficiency of other organic compounds such as butanol and ethanol on activated carbon adsorption of bipyrazole,shows that activated carbon for pyridine22heterocyclic compounds Selective adsorption.Activated carbon adsorption experiments showed that the addition of 1g activated carbon to 100mL wastewater,at room temperature,the stirring rate is 160r/min,3h reached adsorption equilibrium,the removal rate of COD was 88.2%,two triazole heterocyclic compounds adsorption rate was 84.8%.The adsorption effect of activated carbon on simulated wastewater and real wastewater is very satisfactory.4 Activated carbon regeneration testExperiment studied four methods like Fenton oxidation,acid washing,ultrasonic wave and microwave digestion that were used on the activated carbon adsorption saturation regeneration.The experimental results show that Fenton oxidation regeneration,the adsorption of 0.1g wastewater activated carbon saturated,in Fenton reagent n(Fe²⁺):n（H₂O₂）=1:54,H₂O₂ dosage was 6mL,the regeneration at room temperature under the condition of 30min,a regeneration efficiency of 68.25%.1g adsorption of the actual wastewater saturated activated carbon,the dosage of Fe²⁺was 0.075g,the dosage of H₂O₂was 25mL,and the regeneration rate was only 40%under the condition of normal temperature 30min.The adsorption of actual wastewater activated carbon saturated the other regeneration experiment results show that the acid has a certain effect on the regeneration of 15mL36%HCl and 85mLdeionized water,static 24h,the regeneration rate was 32.4%;short time ultrasonic regeneration has certain effect,add 100mL deionized water,15min regeneration,regeneration rate of 33%growth the time no on regeneration activated;microwave digestion regeneration method is ideal,add 25mL deionized water,microwave power 850W,12min regeneratio conditions,activated of rate carbo reached 61%.