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A potentially more eco-friendly chemical pathway for production of high purity TiO2 from titanium slag
摘要： TiO2 is an important inorganic material which is commercially produced by either the chloride or the sulfate process. In general, the latter has lower cost and lower entry barrier than the former. However, the environmental impact associated with the sulfate process is more visible than the chloride process because the sulfuric acid with a low concentration (~20 wt%) cannot be cost-effectively recycled; therefore, it has to be neutralized, generating a large amount of wet and useless red gypsum (RG). In this research, a potentially more eco-friendly chemical pathway for TiO2 production from concentrated titanium ore, aka titania slag, is presented. The new method consists of three critical steps including transformation of the titania slag to a lower valence titanium sub-oxide by aluminothermic reduction, digestion by using mild acid, and controlled hydrolysis accompanied by acid recycling. As a result of the phase transformation, the digestion of titanium from the titanium feedstock becomes easier such that it is feasible to use relatively mild acid to replace concentrated acid, reducing the environmental impact from the red gypsum because the need for neutralizing the waste acid can be eliminated. High purity hydrous TiO2 can be prepared after hydrolysis, and the spent liquor can be effectively recycled back to the digestion unit.
关键词： Aluminothermic reduction,Titania slag,Controlled hydrolysis,Titanium dioxide,Mild acid digestion
更新于2025-09-19 17:15:36
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Synthesis of Si NPs from River Sand Using the Mechanochemical Process and its Applications in Metal Oxide Heterojunction Solar Cells
摘要： In this article, simple two-steps process for the synthesis of silicon nanoparticles (Si NPs) from river sand of Bangladesh and application of the synthesized Si NPs for the improvement of the performance of the metal oxide heterojunction solar cells (HJSCs) have been investigated. A modified aluminothermic reaction was performed to extract highly pure silicon from sand. Later, ultrasonication on the extracted silicon in hydrofluoric acid (HF) was done to synthesis Si NPs from extracted Si. Afterward, the prepared Si NPs were used to dope CuO absorber for the fabrication of CuO/ZnO heterojunction solar cell. Properties of extracted Si and its effect after doping in copper oxide (CuO) were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), X-ray Fluorescence (XRF), Fourier Transform Infrared Rays (FTIR), UV-Vis Spectroscopy, Raman and Photovoltaic study. Experimental results indicate that the extracted Si is polycrystalline in nature. The optical absorbance of CuO was enhanced significantly as a result of Si NPs doping and consequently, photoconversion efficiency was found to enhance more than 30% when Si NPs doped CuO was used in the Al/Si NP-CuO/ZnO/FTO heterostructure as a solar cell. This all spin-coated heterojunction solar cell showed a photoconversion efficiency of 1.16%. The photovoltaic responses reveal that the prepared Si NPs can be utilized for the improvement of the performance of HJSCs. This study on modified aluminothermically extracted Si NPs provide valuable insight and easy route for the preparation of Si NPs from sand and its applications in photovoltaic technology.
关键词： Mechanochemical process,Aluminothermic reduction,Si NPs,Sand,ZnO/CuO heterojunction,Si-Al eutectic mixer
更新于2025-09-19 17:13:59