Study On Hydroxylamine Promoting The Degradation Of Dye Wastewater By Pyrite Advanced Oxidation Technology

Dye wastewater has the characteristics of deep color,poor biodegradability,high total organic carbon concentration,carcinogenicity,teratogenicity,and mutagenicity,which cause serious harm to ecology and human health.Therefore,this type of wastewater must be effectively treated.Due to its high efficiency and non-selectivity,advanced oxidation technology has attracted wide attention in the dye wastewater treatment.Among them,the pyrite advanced oxidation technology has been studied by many scholars due to its strong reactivity,low cost,and turning pyrite waste into treasure.However,the pyrite advanced oxidation technology still has the disadvantages of slow Fe(II)/Fe(III)cycle and a significant decrease in the continuous reactivity of pyrite.In order to solve the above problems,hydroxylamine(HA)was added to promote the reaction performance of pyrite advanced oxidation technology to degrade dye wastewater in this paper,and the influencing factors and reaction mechanism of each system were investigated.The main research content and conclusions are as follows:1.Use pyrite/H₂O₂/HA system to degrade rhodamine B(Rh B)dye wastewater.Under the optimal conditions of HA 0.8 m M,H₂O₂ 1.6 m M,pyrite 0.4 g L^-1 and initial p H 4.0,Rh B could be almost completely decolorized.The degradation process was mainly dominated by hydroxyl radicals(·OH)that produced by the reaction of H₂O₂ with leached Fe²⁺.HA primarily had two roles:in the solution,HA could accelerate the Fe(II)/Fe(III)cycle through its strong reducibility to enhance Rh B decolorization;on the pyrite surface,HA could improve the continuous reactivity of pyrite by inhibiting the oxidation of pyrite.In addition,complete decolorization and more than 52%mineralization of different dye pollutants could be achieved in the pyrite/H₂O₂/HA system.2.Use pyrite/peroxymonosulfate(PMS)/HA system to degrade Rh B dye wastewater.Under the optimal conditions of pyrite 0.4 g L^-1,HA 0.8 m M,PMS 1.6 m M and initial p H4.0,the decolorization efficiency of Rh B could reach 99.3%,and the system could achieve high-efficiency degradation of Rh B in a wide p H range of 3.0-10.0.Quenching experiments showed that both radical and non-radical oxidation processes led to the decolorization of Rh B,but the radical oxidation process dominated by sulfate radicals(SO₄^·-)was the main way to decolorize Rh B.HA could act as a metal-free activator for PMS activation,and a reductant to boost Fe(III)/Fe(II)cycle in solution and on pyrite surface,which not only increased the production of radicals but enhanced the stability of pyrite via inhibiting the S₂^2-consumption.Moreover,the pyrite/PMS/HA system could completely decolorize and partially mineralize other dye contaminants.3.Use pyrite/persulfate(PS)/HA system to degrade Rh B dye wastewater.Under the optimum conditions of pyrite 0.6 g L^-1,HA 0.4 m M,PS 1.6 m M and initial p H 4.0,the decolorization of Rh B could reach 98.84%,and the system could achieve high degradation performance of Rh B in a wide p H range of 3.0-10.0.Quenching experiments showed that SO₄^·-,·OH and superoxide radicals(O₂^·-)were the main reactive substances,and SO₄^·-was the main radical that causes the pyrite/PS/HA system to degrade Rh B under different oxygen contents.In addition,although the increase in O₂ content could enhance the production rate of Fe²⁺and O₂^·-,thereby generating more radicals,too much O₂ content would produce excessive Fe²⁺to quench the radicals,which was not conducive to the degradation of Rh B.In addition,HA could not only promote the Fe(II)/Fe(III)redox cycle,but also improve the continuous reactivity of pyrite by inhibiting the oxidation of pyrite under different oxygen content.Finally,the pyrite/PS/HA system could completely decolorize and partially mineralize other dye pollutants.4.Compared with H₂O₂ and PMS,PS has some outstanding advantages such as low price,higher stability,reactivity,and water solubility.In addition,the pyrite/PS/HA system is superior to other catalyst/PS/HA systems reported in the literature in terms of pollutant degradation efficiency and effective p H range.Therefore,the pyrite/PS/HA system is more conducive to the large-scale practical application of dye wastewater.All in all,the above experimental results prove that the pyrite/oxidant/HA system provides an effective technology for the pyrite advanced oxidation technology to better degrade dye pollutants.In addition,compared with the other two systems,the pyrite/PS/HA system has a better application research prospect in the treatment of organic dye pollutants.