Study On Removal Of Antimony Pollution From Dyeing Wastewater By Enhanced Coagulation Based On Ferrous Sulfate

In recent years,the problem of antimony?Sb?pollution in the printing and dyeing industry has been widely concerned.As a common catalyst for the production of textile raw materials,Sb-containing compound will be released into the water environment during the printing and dyeing process,and threaten the environment and human health.Therefore,it is of great significance to develop cost-effective antimony pollution treatment technologies for printing and dyeing wastewater.Based on the high-concentration antimony pollution of printing and dyeing wastewater,this study carried out research on enhanced coagulation for antimony removal process based on ferrous sulfate coagulant.On the one hand,the effect and mechanism of calcium hydroxide enhanced ferrous sulfate coagulation for antimony removal were investigated.On the other hand,the effects and mechanisms of enhanced coagulation for antimony removal process in wastewater by intu Fe-Mn from potassium permanganate oxidizing ferrous sulfate were studied.The main results were as follows:1.By optimizing the process parameters of calcium-enhanced coagulation for antimony removal,the optimized parameters are determined as follows:the final pH is 6,and the dosage is 75 mg·L^-1?in terms of Fe?.At this time,the removal rate of antimony in wastewater was 96.24%which the initial concentrations was 2000?g·L^-1;the effect of coexisting substances on calcium-enhanced coagulation showed that PAM?Cl-?reactive dyes and disperse dyes at pH 6 and 8 have no significant effect for antimony removal,but PAM would accelerated precipitation;sulfate would decreased the removal rates of antimony to a certain extent;the presence of phosphate would significantly inhibited the removal of antimony,.2.The comparison experiment of ferrous sulfate coagulation and pre-formed hydrolysate adsorption in the removal of antimony,SEM,FTIR,XPS and other characterization methods showed that ferrous sulfate coagulation is mainly based on adsorption.The antimony mainly combined with the surface hydroxyl group of the hydrolysate and formed the inner layer complexation.The enhancing removal for antimony by calcium can be attributed to calcium ions increased the positive charge on the surface of the hydrolyzate under alkaline conditions,making negatively charged ions adsorbed to the surface of iron oxide or iron hydroxide more easily;calcium ions and hydrolyzed products may formed FeO-Ca-OSb ternary complex,which makes more efficient and stable in the process under alkaline conditions.3.For the insitu Fe-Mn-enhanced coagulation process,the optimal parameters were determined as follows:final pH was 6,Mn and Fe dosages were 4.91 mg·L^-1?in terms of Mn?and 20 mg·L^-1?in terms of Fe?respectively,the flocculation time was 10 min,and the antimony removal rate is 95.40%.It was found that high concentration of PAM and dyes slightly reduced the removal rate of antimony;while sulfate and phosphate inhibited it;Ca?OH?₂ would promoted it in the process of insitu Fe-Mn-enhanced coagulation process under alkaline conditions.4.Experimental comparison found that the insitu Fe-Mn?KMnO₄-FeSO₄?was more effective in the removal of antimony compared with MnO₂,Fe²⁺,Fe³⁺,aged iron-manganese?KMnO₄-Fe₂?SO₄?₃?and insitu iron?H₂O₂-FeSO₄?existed,which proved that the insitu iron and the insitu manganese formed by the reaction of ferrous sulfate and potassium permanganate had better synergistic ability to remove antimony,and the insitu iron was the main role.At pH 5 and 6,the proportion of the adsorption by insitu Fe-Mn was 96.19%and 98.56%,respectively,so the antimony was almost completely removed by adsorption.In the neutral and alkaline range,there are a few antimony which was removed by coprecipitation.The surface group and component analysis of the insitu Fe-Mn hydrolysate showed that animony was removed through the combination of hydroxyl groups on the surface of iron-manganese oxide.