Catalytic Degradation Of Estrogen By Persulfate Activated With Iron-doped Graphitic Biochar: Process Variables Effects And Matrix Effects

Since the inception of global industrialization,environmental estrogens have become an emerging and serious concern,and its concentration in water around the world has increased rapidly.Among them,17β-estradiol（E2）is a common and potent estrogen compound.Given the serious threat posed by E2 to human and wildlife health,it is necessary to remove it from water with efficient techniques.Advanced oxidation processes（AOPs）based on highly reactive radicals are widely regarded as an effective and green technology for degradation of recalcitrant organic contaminants into harmless or low toxic compounds,or even CO₂ and H₂O.Among them,sulfate radical(SO₄^?-)based AOPs generated from persulfate（PS）have attracted much attention in recent years.Recently,some researches have attempted to immobilize metals or metal oxides on carbonaceous materials to activate PS.In this work,a novel iron-doped graphitic biochar（Fe@GBC）,which was synthesized by one-step method using biomass-derived biochar as precursor and potassium ferrate（K₂Fe O₄）as activator,was applied to activate persulfate（PS）for the degradation of 17β-estradiol（E2）.The characterizations indicated that Fe@GBC was successfully doped with iron particles and possessed a porous graphitic carbon structure.In order to evaluate the applicability of Fe@GBC,the effects of various reaction parameters,such as initial p H,catalyst dosage,PS concentration,as well as the reusability and stability of Fe@GBC were systematically investigated.With the synergistic effect of doped iron particles and porous graphitic carbon structure,Fe@GBC exhibited a high activity for PS activation and great degradation capacity to E2（almost 100%degradation effciency within 90 min）.Through radical quenching experiments and electron spin resonance（ESR）analysis,it found that both SO₄^?-and OH^?were responsible for the degradation of E2,while SO₄^?-played a dominant role.Moreover,Fe@GBC/PS also exhibited good degradation performance in complex water matrices.Overall,the facile one-step synthetic strategy and superior performance make Fe@GBC an alternative catalyst for persulfate activation and aqueous pollutants degradation.