Study On Photocatalytic Decolourization Of Reactive Brilliant Red X3B In Steel Slag/Persulfate System

Dye wastewater which is not only complex composition, but also higherconcentration and difficult treatment, is one of the major source of environmentalpollution in printing and dyeing industry. The steel slag has large annual production,which will not only result in a waste of resources, but also a threat to human health andsafety. Because of higher iron content in steel slag, using steel slag activated persulfatewhich can produce stronger oxidizing sulfate radical SO₄^·- to decolourization of reactivebrilliant red X3B azo dye which is used more often in the printing and dyeing industry, hasimportant significance to realize "using waste to treat waste".First of all, this paper studied the photocatalytic decolourization of reactive brilliantred X3B in Fe²⁺/persulfate system, discussed the mechanism of SO₄^·- generating in thissystem and the affect of Fe²⁺concentration, potassium persulfate concentration, pH value,transition metal ions and other factors, and researched the degradation pathway anddegradation mechanism of reactive brilliant red X3B. The results showed that this systemnot only had good photocatalytic performance, but also faster response. The pH value wasan important factor and lower pH was conducive to the reaction proceeds. With theincrease of the FeSO₄concentration, the removal rate of X3B was increased and thendecreased. When the dosage of FeSO₄was0.2mmol/L, the removal rate reached amaximum at89.63%. Also, the removal rate of X3B was enhanced gradually with theincrease of K₂S₂O₈concentration. But when the dosage of K₂S₂O₈reached to2.0mmol/L,the change of removal rate was gradually smoothly. In several transition metal elementswith high content in steel slag, Fe²⁺had strongest ability to activate persulfate.Secondly, this thesis studied the photodegradation effect of X3B in steel slag/persulfate system. The research results indicated that the steel slag/potassium persulfatesystem had good light catalytic, and the removal rate of X3B decreased while the pHvalue increased within a certain range. As the volume of steel slag or K₂S₂O₈dosingincreased, the removal rate of X3B reduced after the first increase, and then the removalrate was efficiency stabilized when the volume of steel slag was10g/L or K₂S₂O₈ exceeded2.0mmol/L, while the removal rate would gradually decreased with theincreasing of X3B’s initial concentration. The X3B’s degradation effect was greaterimpacted by temperature when it exceeded40°C. What’s more, it also showed that thenatural sunlight works much better than simulated sunlight. This series of studies on steelslag/persulfate system of optical degradation of dyeing wastewater provides a certain basisin practical engineering applications.At the same time, the experiment of Fe²⁺/persulfate system and steel slag/persulfatesystem to photocatalytic the reactive brilliant red X3B was also compared, and thedifferent causes of effect and running cost was analysed.Experimental studies had shown that the steel slag/persulfate system could degradedreactive brilliant red X3B photocatalytic with good results, and resource utilization of steelslag had found a new way out.