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Leaching with Acids
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2019
The treatment of titanyl sulfate and ferrous sulfate-bearing solution obtained by acid leaching results in generation of large quantities of waste effluent that consist of ferrous sulfate and H2SO4. These effluents should be disposed of without causing pollution. In this respect, the Ishihara Process16 as developed by Ishihara Sangyo Kaisha Ltd., Japan in which the ilmenite is upgraded by waste H2SO4 (from the pigment plant) appears attractive. The process involves pressure leaching of prereduced (with petroleum coke at 900°C), ilmenite with H2SO4. The synthetic rutile thus obtained yields 95% TiO2.
Fabrication and application areas of mixed matrix flat-sheet membranes
Published in Alberto Figoli, Jan Hoinkis, Sacide Alsoy Altinkaya, Jochen Bundschuh, Application of Nanotechnology in Membranes for Water Treatment, 2017
Derya Y. Koseoglu-Imer, Ismail Koyuncu
Aslan and Bozkurt (2014) prepared proton conducting nano-titania composite membranes. They also discussed the production and characterization of proton conducting super acid membranes. During membrane fabrication, sulfated nano-titania was firstly synthesized by hydrolysis and precipitation of titanyl sulfate (TS) and was then blended with sulfonated polysulfone (SPSU). The maximum proton conductivity of the prepared membrane was obtained as 0.002 S cm−1 at 150°C.
Non-Magnetic Metal Oxide Nanostructures and Their Application in Wastewater Treatment
Published in Surender Kumar Sharma, Nanohybrids in Environmental & Biomedical Applications, 2019
Debanjan Guin, Chandra Shekhar Pati Tripathi
The oxide of titanium is chemically inert and has many applications ranging from anticorrosion, photocatalysis, photovoltaics, H2 sensing, lithium batteries, and as an adsorbent for the removal of contaminants in polluted waters (Bavykin et al. 2006). Luo at al. first reported the application of TiO2 for the removal and recovery of arsenic. The wastewater was acquired from a copper smelting industry in China (Luo et al. 2010). The TiO2 was prepared by hydrolysis of titanyl sulfate. The BET surface area was 196 m2/g, and the point of zero charge was 5.8. Batch experiments were employed for the absorption studies. They reported 21 successive treatment cycles using the regenerated TiO2. Arsenic was recovered by pre-concentrating the extracted solutions. Since As(III) forms “inner-sphere bidentate binuclear complexes”, it will bind to the OH surface sites on the TiO2 (Pena et al. 2006). The results were confirmed using extended X-ray absorption fine structure spectroscopy (EXAFS), X-ray photoelectron spectroscopy (XPS), and surface complexation modeling. Engates et al. reported the effect of particle size, sorbent concentration, and exhaustion on the adsorption of Pb, Cd, Cu, Zn, and Ni to TiO2 nanoparticles and TiO2 anatase bulk particles (Engates and Shipley 2011). Adsorption and exhaustion studies were carried out for single- and multi-metal adsorption. Large adsorption capacities for the TiO2 nanoparticles compared to their bulk counterpart were reported. The data correlated to the Langmuir isotherm model indicating monolayer adsorption on the surface of the TiO2 nanoparticles. The exhaustion experiments showed that at pH 6, TiO2 nanoparticles were exhausted after three cycles and at pH 8 after eight cycles. These results supported the possibility of TiO2 nanoparticles as a potential remediation for heavy metal removal from contaminated waters. This group also reported the regeneration of TiO2 nanoparticles for heavy metal removal (Hu and Shipley 2013). In brief, nanosized metal oxides have been found as an efficient adsorbent towards the removal of heavy metal ions. However, their agglomeration due to instability as small particles has hampered their application. An effective solution to this problem is the fabrication of hybrid adsorbents by coating or impregnating metal oxide nanoparticles into supports of larger sizes. The widely used supports include natural hosts such as bentonite, sand, metallic oxide materials such as Al2O3 membranes, porous manganese oxide complexes, and synthetic polymer hosts such as cross-linked ion-exchange resins (Hu et al. 2004, Zhang et al. 2006b, Eren et al. 2010, Lee et al. 2010, Ray and Shipley 2015).
Beneficiation of fluxed titaniferous slag to a marketable titania product using the modified upgraded slag process
Published in Mineral Processing and Extractive Metallurgy, 2021
Xolisa Goso, Jochen Petersen, Merete Tangstad, Jafar Safarian
These slags have not been used to date because they contain low TiO2 and higher impurity grades than the feedstock requirements. In addition, these slags have complex phase compositions that cannot be handled by the available slag-upgrading technologies (Pistorius 2011; Van Vuuren and Tshilombo 2011). Several complex processes have been proposed for processing low-titania resources, including titaniferous slags, to marketable titania materials for direct use as pigment or as feedstock for the production of chloride pigment. Becker and Dutton (2002) patented a modified sulfate process for valorisation of EHSV titaniferous slag, which involved contacting the slag with sulfuric acid to produce titanyl sulfate, followed by hydrolysis to titanyl hydroxide and calcination to produce titania pigment. Xiao-hua et al. (2008) investigated the leaching kinetics of TiO2 from Pangang titaniferous slag using H2SO4 as lixiviant. Hassell et al. (2016) patented a similar sulfate process for beneficiation of titanium-bearing materials.
Preparation technology of Ti-rich material from ilmenite via method of vacuum carbothermal reduction
Published in Canadian Metallurgical Quarterly, 2019
Ke-Han Wu, Guo-Hua Zhang, Kuo-Chih Chou
Ilmenite and rutile are the main minerals for extraction of metallic titanium or titanium dioxide [1]. However, high-grade titanium minerals such as rutile have been substantially exhausted on earth. Therefore, utilisation of low-grade ilmenite should become the trend of the industry [2]. For upgrading the quality of Ti-rich material, several methods have been proposed, primarily focusing on destroying the structure of anosovite [3–5]. The treatments basically include oxidation roasting, reduction roasting, sulfuration, chlorination and salt roasting [6–12]. By these methods, impurities were subsequently removed by water or diluted hydrochloric acid leaching. Among them, two processes have been widely applied: sulfate technology and chloride technology [13–16]. The former one is acidolysis of ilmenite with sulfuric acid to obtain titanyl sulfate and then hydrolysis of titanyl sulfate to produce titanium dioxide [17]. In this process, a large amount of acid mist such as SO3 is produced, causing the problems of equipment corrosion and environmental pollution. The latter one is chlorination of ilmenite with chlorine gas at high temperatures and then condensation of TiCl4 [18]. It has the advantages of high quality of product and environmentally friendly. However, the chloride process has a high requirement for the quality of raw materials, especially low contents of elements Ca and Mg [19]. Ca or Mg could form liquid chlorides in the chlorination process, which could block fluidised bed, resulting in abnormal production or shutdown.
Research progress on electrochemical property and surface modifications of nanodiamond powders
Published in Functional Diamond, 2023
Liang Dong, Guohao Zhu, Jianbing Zang, Yanhui Wang
In addition, TiO2 modified ND can also be obtained by microwave and heat treatment methods. ND50 powder was added to a solution containing 1 mmol/L titanyl sulfate plus 5 mmol/L sulfuric acid, and amorphous TiO2 was obtained after microwave treatment [61]. Then after heat treatment in air at 450 °C, anatase TiO2/ND50 was finally obtained. From the XRD pattern of TiO2/ND50 (Figure 6e), except for the three strong peaks of diamond, the diffraction peaks at 25.26°, 37.80°, 48.02°, 54.56° and 62.58° corresponded to the (110), (004), (200), (211) and (204) crystal planes of anatase TiO2 [62].