Sustainable Synthesis Of Iron And Zinc Oxide Heterogeneous Photocatalytic Materials From Fabric Filter Dust

For solving the increasingly serious environment problems generated from the iron and steel metallurgy industry, building energy conservation and emission reduction system and green cyclical economy has become imperative. In this paper, a kind of high zinc and iron-bearing metallurgical solid waste called zinc-bearing fabric filter dust was studied as a raw material to explore a new way of its resource utilization. The research mainly includes: respective extraction of zinc and iron from the dust to prepare the multiple doped M-Zn O and Fe2O3. Besides, we tried to one-step recycling zinc and iron from zinc-bearing dust to prepare photocatalytic composite Zn Fe2O4/Fe2O3. Pretreatment and acid leaching of zinc-bearing dust as well as the preparation of photocatalyst derived from zinc-bearing dust had been implemented in our study. Photodegradation experiment had been used to characterize the catalytic performance of the dust-derived photocatalysts.XRD, XRF, and C-S analysis was used to determine the mineral phase, chemical composition of the zinc-bearing dust. For the difficulty of acidic leaching zinc and iron from zinc ferrite phase, we took the method of reduction roasting to decompose the zinc ferrite into zinc and iron oxide. This method effectively promoted the subsequent acid leaching process of the zinc-bearing dust, avoiding waste of resources caused by the low leaching rate of zinc and iron. On this basis, the optimal experiment of reduction roasting for extracting zinc and iron from zinc-bearing dust was investigated. The experimental results demonstrate that the optimal leaching rate appeared to the dust samples calcined at 800 ℃ for 2 h without adding external carbon. In addition, further investigates on extracting zinc and iron under the condition of acid leaching were also implemented. The highest leaching rate of zinc and iron reaches 92.8 % and 95.4 % under the condition of leaching temperature at 80 ℃, and leaching acidity of 3 mol/L.After the acid leaching experiment, the zinc and iron element are mainly in the form of sulfate precipitation. Adjusting p H of lixivium to precipitate out large amount of iron and then collecting the filtrate and filtrate cake for preparing irons doped Zn O and Fe2O3 photocatalyst respectively. Subsequently, one-step coprecipitation was utilized to prepare composite photocatalyst Zn Fe2O4/Fe2O3. A serious of characterizations TG-DSC, XRD, SEM, EDX, FT- IR, BET, laser particle size analysis and PL spectrum had been carried out to study the structure, organization, and optical performance of the obtained materials. Ultimately, the degradation of MB was used to characterize the relationship between above-mentioned performance and photocatalytic performance.XRD analysis showed that the ions doped Zn O had been successfully prepared, and scheeler formula calculation results showed that the ions doping refine the grain size of Zn O evidently. FTIR test not only showed the stretching vibration peak of Zn-O bond but also gave the metal oxygen bond stretching vibration peak. SEM analysis demonstrated that the ions doping alleviated the particles aggregation. BET tests showed that ions doping increased the specific surface area. And most of all PL spectra ensured that doping effectively restrained the recombination of electron-hole pair. Photocatalytic experiment results revealed that the doping significantly improved visible light catalytic properties, which was caused by the separation of electron-hole pair and the enlargement of specific surface area. On the other hand, the photocatalyst Fe2O3 derived from filtrate cake was also successfully obtained. The photocatalytic degradation of methylene blue test proved its excellent photocatalytic performance. It worth noting that the sample calcined at 500℃exerted the best absorption performance and the sample calcined at 700℃revealed the best photocatalytic performance.One-step recovery of zinc and iron from zinc-bearing fabric filter dust for the purpose of obtaining zinc and iron hydroxide by means of coprecipitation method. Subsequently, we calcined the hydroxide at different temperatures for preparing composite photocatalyst Zn Fe2O4/Fe2O3. It worth noting that the band gap of Zn Fe2O4/Fe2O3 was gradually increased with the increased of calcination temperature. 300 W xenon lamp was used for simulating the sunlight degradation of methylene blue. The experimental results showed that the composite photocatalyst Zn Fe2O4/Fe2O3 calcined at 500 ℃ had the best photocatalytic activity.