Fabrication Of Ferrite-based Composites As Photocatalyst And Sorbent For Removal Of Organic Pollution From Wastewater

The development of the industrial revolution makes human life increasingly sweet and comfortable,but makes a certain damage to the surrounding environment,and many persistent organic pollutants?POPs?with high toxicity,refractory,long residence time were produced with wastewater.If these POPs containing wastewater were discharged directly,it will seriously do great harm to ecological environment and human health.Compared with these traditional process,removal of POPs by photocatalytic degradation and adsorption using nanomaterials have many advantages including low cost,high efficiency,and low secondary pollution,which has become a research hotspot.Herein,spinel ferrite-based composites were fabricated,and the photocatalytic activities and adsorption properties of as-prepared ferrite-based commposites were investigated using 4-NP,carbamazepine?CBZ?,Congo red?CR?,etc,as the target pollutant.Furthermore,to explore practical application for treatment of wastewater,the stability and anti-interference ability of the composites was also studied.1.ZnFe₂O₄-ZnIn₂S₄ photocatalyst with the different mass ratio were prepared by two-step solvothermal method,and series of techniques were used to analysis the phase,morphology,and photoelectric properties of the samples.The 4-NP was choosed as the target pollutants to test the photocatalytic activities of the photocatalyst.The obtained results showed that the ZnFe₂O₄-ZnIn₂S₄ composites with 2.5 wt%ZnFe₂O₄ loading possessed the highest photocatalytic performace with degradation of90% 4-NP after 180 min irradiation.In addtion,the analysis of intermediate products and photocatalytic mechanism showed that the 4-NP could be mineralizated into harmless small molecule inorganic directly,and ·O2-and h+ were the main active species in the process of the photocatalytic degradation.Moreover,after 3 times recycle,the 2.5 wt% ZnFe₂O₄-ZnIn₂S₄ was stable,only the photocatalytic efficiency was reduced about 10%.When the catalyst was used in the mixed solution with CR+MO or CR+4-NP or MO+4-NP or CR+MO+4-NP,it still shows high photocatalytic performance,indicated that 2.5 wt% ZnFe₂O₄-ZnIn₂S₄ composites had high stability and anti-interference ability.2.Magnetic CoFe₂O₄/GO nano adsorbent with different amount of GO wereprepared by solvothermal method and calcined method.The phase,and morphology of these samples were characterized by series of characterization techniques,the CBZ was choosed as the target pollutants to investigate the adsorption performance of these materials.The obtained results showed that the adsorption model of the CBZ adsorption on these materials were all followed the Langmuir adsorption model and pseudo-second-order kinetics model.The adsorption capacities of CBZ on CoFe₂O₄/GO were consistent with the specific surface area of CoFe₂O₄/GO,and the best addition amount of GO was 2 mL.The maximum adsorption capacity of CBZ on CoFe₂O₄/2GO was 50.5 mg/g,and the adsorption capacity decreased with the increase of temperature,indicating a typical exothermic reaction.After 5 times magnetic recycles,the adsorption capacity of the CBZ on CoFe₂O₄/2GO remained about 90% of initial capacity,showing that it has good magnetic properties and stability.Furthermore,comparsion of adsorption of CBZ,BPA,atrazine on CoFe₂O₄/2GO was also studied in the single solution or the competition system with three mixed solution,and the adsorption capacity of CBZ,BPA,atrazine on CoFe₂O₄/2GO always followed the order of BPA>CBZ> atrazine.3.ZnFe₂O₄/ZnO nanomaterials with the different Zn/Fe ratio was prepared by high temperature calcination method used urea zinc and urea iron as the precursor.Organic dyes were choosed as the treatment object to study the photocatalytic performance and the adsorption properties of the ZnFe₂O₄/ZnO nanomaterials.The obtained results showed that the phase and morphology of the products prepared by this method were changed with the increase of Zn/Fe ratio.When the ratio of Zn or Fe was 0,the products were hematite Fe2O3 or hexagonal ZnO,respectively.With the increase of the Zn/Fe ratio,the diffraction peak intensity of ZnO increased,and the agglomeration of nanoparticles was inhibited.The removal of CR was dominated by the synergistic effect of adsorption and photocatalytic degradation,and the best Zn/Fe ratio was 1.5:1,and the ·OH plays the key role in this photocatalytic process.In addtion,the CR adsorption on ZnFe₂O₄/ZnO were followed Langmuir model and pseudo-second-order kinetics model,and this composite plays a high removal effectiveness of the weak alkaline or acidic organic dyes in water.