Study On The Removal And Mechanism Of Oil Pollution In Water By ZnSO₄-K₂FeO₄ Coupling System

Petroleum pollution in the water environment has become one of the global public hazards.The toxic compounds released by petroleum pollution,such as polycyclic aromatic hydrocarbons,resins and asphaltenes,may take decades to remove.In addition,these toxic substances can also enter the human body through the food chain,leading to diseases such as cancer.The reasonable and effective treatment of oily wastewater has become an environmental issue that cannot be ignored.Currently,physical,biological,and chemical methods are mainly used to treat oily wastewater,but these methods have drawbacks such as incomplete treatment,long time cycles,and secondary pollution.Therefore,it is particularly important to seek a fast and green method for treating oily wastewater at this stage.Ferrate is a strong oxidizing inorganic agent,known as a green water treatment agent.It has advantages such as fast oxidation effect,no residual toxicity,and convenient use,and has outstanding advantages in water environment remediation.This article selects diesel and engine oil commonly used in the market as the target materials,investigates the treatment effect of potassium ferrate and potassium ferrate coupling system on oil pollution in water,and studies the mechanism of system degradation of oil pollution,The main research content and conclusions are as follows:（1）The experimental study investigated the influencing factors and reaction kinetics of potassium ferrate in removing oil stains from water,and optimized the experimental conditions using response surface optimization experiments.When the dosage of K₂Fe O₄is 10mg,the reaction temperature is 45℃,and p H=3,K₂Fe O₄ has the best removal effect on diesel and engine oil in water,with 86.30%and 60.51%,respectively.In the analysis of reaction kinetics,it was found that the reaction follows first-order reaction kinetics,and the K value reaches its maximum when the dosage of K₂Fe O₄ is 10mg,with values of 0.0384 and 0.0329,respectively.According to the Box Behnken design experiment,The greatest impact of p H on oil pollution removal rate.The fitting effect of diesel/oil removal rate in the model is good.Under the optimal reaction conditions,the theoretical maximum removal rates of diesel and oil are 86.67%and 63.38%,which are similar to the experimental values.（2）In the study of the potassium ferrate coupling system for removing oil pollution from water,corresponding discussions were mainly conducted through catalyst screening experiments,system influencing factor experiments,and experiments on the influence of background components in water.The experiment found that a single catalyst has a certain removal effect on oil pollution.In the enhanced system,the zinc sulfate/potassium ferrate system has the best removal effect on oil pollution,with removal rates of 69.9%and 64.4%for diesel and engine oil;Using first-order reaction kinetics for corresponding fitting,the R² obtained is greater than 0.95,and the reaction rate constants are 0.4616 and0.4614,respectively.Compared to the other three systems,this system has the highest reaction rate constant.The experimental results showed that the optimal reaction conditions for removing diesel and engine oil were Zn SO₄/K₂Fe O₄ dosage ratios of 0.5:1and 1:1,reaction temperature of 35℃,solution p H=3,and removal rates of 92.3%and87.8%,respectively.Among the effects of anions and cations(Ca²⁺,Mg²⁺,SO₄^2-,and CO₃^2-)on the removal of oil pollution,each ion has an inhibitory effect on the system’s removal of oil pollution,with CO₃^2-having the most obvious inhibitory effect,with a removal inhibition of 20%and 16.21%for the two types of oil pollution,respectively.The addition of humic acid reduces the removal rates of diesel and engine oil by 31.02%and 29.82%,respectively,and its inhibitory effect is greater than that of anions and cations.（3）The experiment studied the relevant mechanism of potassium ferrate in removing oil pollution from water,and discussed the contribution of free radicals,trivalent iron,and tetravalent and pentavalent iron to oil pollution removal under the optimal reaction conditions.At a concentration of 7200mg/L tert butanol,the removal rates of diesel and engine oil decreased by 15.91%and 20.76%,respectively,indicating that·OH has a certain contribution to the removal of oil pollution,but is not the main active substance in the degradation process;And it was found that the reduction in removal rates of diesel and engine oil by the K₂Fe O₄ system was lower than that by the Zn SO₄/K₂Fe O₄ system.During the oxidation of oil pollution,there is a 1-e^-/2-e^-transfer mechanism in K₂Fe O₄,with Fe³⁺mainly generated,but the additional Fe³⁺hardly affects the degradation of diesel and engine oil.In the study of the contribution of tetravalent and pentavalent iron to the removal of oil pollution,the removal rates of diesel and engine oil in the K₂Fe O₄/Zn SO₄/PMSO system decreased by 60.50%and 40.87%,respectively,indicating that Fe（V）/Fe（IV）is the main active substance for the degradation of oil pollution in the K₂Fe O₄/Zn SO₄ system;A comparison was made between the removal of oil stains by K₂Fe O₄ and K₂Fe O₄/Zn SO₄ systems under the action of PMSO.The results showed that the reduction in diesel and engine oil removal rates in the K₂Fe O₄/Zn SO₄ system was greater than the reduction in removal rates under the action of K₂Fe O₄ alone.By studying the removal effect and mechanism of diesel and engine oil in water,a certain process parameter reference is provided for the removal of oil pollution by potassium ferrate,and a basis is provided for the treatment of water pollution related to oils.