Hydrotalcites and their role in coordination of anions in Bayer liquors: Anion binding in layered double hydroxides

Palmer, Sara J.; Frost, Ray L.; Nguyen, Tai

doi:10.1016/j.ccr.2008.01.012

Cited by 201 publications

(143 citation statements)

References 133 publications

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“…A broad band placed around 1446 cm -1 is due to carbonate species which should be different from those existing in hydrocalumite 9 . These carbonate species could be associated to formation of surface CaCO 3 due to exposure to an air atmosphere (atmospheric CO 2 and humidity) and basicity of solid 11 .…”

Section: Evaluation Of Calcined Hydrocalumite-type Materials As Suppomentioning

confidence: 74%

“…Bands at 3639 and 3485 cm -1 can be associated to surface OH -groups of Ca(OH) 2 present in the hydrocalumite-type material 9 . The wide band in 3500-3600 cm -1 can be also associated OH-groups and/or to the ν(OH) mode ascribed to interlayer water molecules located in the hydrocalumite interlaminar region 10 .…”

Section: Characterization Of Hydrocalumitementioning

confidence: 98%

“…Bands at: 3639, 3485 and 1022 cm -1 corresponding to OH -groups from Ca(OH) 2 and observed in HC, disappeared during the calcination procedure (HC 420). This is product of dehydration of hydrocalumite 9 . Figure 1.…”

Section: Characterization Of Hydrocalumitementioning

confidence: 99%

“…A main band at 834 cm -1 , absent in the spectrum of hydrocalumite, and a broad band around 550 cm -1 , are due to the major changes originated by the phase transformations during the calcination process. They are due to metal-oxygen bonds 9 . By examining the results of Vieille et al 6 , López-Salinas et al 7 and Campos-Molina et al 12 , it can be concluded that the transformation of hydrocalumite during the calcination occurs in three steps: in the first one (25-200°C), the physisorbed water is lost from the hydrocalumite structure.…”

Section: Evaluation Of Calcined Hydrocalumite-type Materials As Suppomentioning

confidence: 99%

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Evaluation of calcined hydrocalumite-type materials as supports of CoMo and NiMo for thiophene hydrodesulfuration reaction

et al. 2014

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A hydrocalumite-type material (HC) was synthesized by the co-precipitation method, mixing Ca and Al nitrate solutions in a NaOH solution (pH ≅ 11). This solid was characterized by using different physico-chemical techniques such as: Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), temperature programmed reduction (TPR) and BET surface area measurements. Then, a portion of as-synthesized solid was calcined at 420 ºC (HC 420). Both calcined and pristine solids were impregnated with Mo (15% w/w as MoO 3 ). Ni or Co was also impregnated on Mo/HC or Mo/HC 420 in 1(Co or Ni):3 (Mo) atomic ratios to get catalytic precursors. These solids were also characterized by the above mentioned techniques. Catalytic precursors were tested in the thiophene hydrodesulfuration reaction at 280 ºC and atmospheric pressure. Cobalt promoted catalysts were more active than those promoted with Ni. However, thiophene conversions were lower than that of a conventional CoMo/γ-Al 2 O 3 catalyst.

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Section: Evaluation Of Calcined Hydrocalumite-type Materials As Suppomentioning

confidence: 74%

Section: Characterization Of Hydrocalumitementioning

confidence: 98%

Section: Characterization Of Hydrocalumitementioning

confidence: 99%

Section: Evaluation Of Calcined Hydrocalumite-type Materials As Suppomentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of calcined hydrocalumite-type materials as supports of CoMo and NiMo for thiophene hydrodesulfuration reaction

et al. 2014

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“…In addition to dissolve alumina content, caustic soda will also react with reactive silica contained in the bauxite tailing as described in chemical reaction bellows (Palmer et al, 2009) Sodalite will combine with red mud to be wasted that should be managed properly. Based on a thermodynamic point of view, bauxite digestion primarily is controlled by alumina mineral phase, caustic concentration, and digestion temperature (Hond, et all., 2007).…”

Section: Introductionmentioning

confidence: 99%

Implementation of mathematical equation for calculating alumina extraction from bauxite tailing digestion

Husaini

2017

IMJ

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Research on bauxite tailing digestion using pressurized batch reactor at a feed capacity of 86.66 kg had been conducted. Bauxite with -150 mesh of particle size is reacted with 42.15 kg of caustic soda (433.49 g/l) at 140 o C for 1.0 to 2.5 hours using steam as heating media. Lime added are varied from 3 to 9 kg. After processing for a certain period of time, slurry product is transfered into a mixer. To evaluate percent extraction of Al2O3 from this process, the height of slurry level in the mixer, densities of the slurry, filtrat, and solid residue are measured and determined. The head sample of bauxite, filtrate and residue are analysed by using wet method to obtain Al2O3 content of each sample taken from the mixer. There are four equations that are used for obtaining the alumina extraction, namely : Vsl=4.176x+15.83 Wsl=(4.176x+15.83)ρsl S=(ρsl -ρl)/ (ρs -ρl) (ρs/ ρsl)*100% E= [10 (4.176x+15.83) The calculation results show that by increasing lime added into the slurry, percent yield of alumina extraction tend to decrease from 46.63% for 3 kg of lime to 15.84% by using 9 kg of lime. Whereas by varying reaction time between 1.0-2.5 hours, percent yield of alumina extraction are fluctuation in the range of 42.07-60.54%, and the highest result was obtanined for 1,5 hours of reaction time. By implementing those four equations above for evaluating the data, we do not need to weigh the slurry in the reactor.Keywords: bauxite tailing, digestion, alumina extraction, mathematical model, Bayer process. ABSTRAK

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Surface Complexation Modeling

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Hydrotalcites and their role in coordination of anions in Bayer liquors: Anion binding in layered double hydroxides

Cited by 201 publications

References 133 publications

Evaluation of calcined hydrocalumite-type materials as supports of CoMo and NiMo for thiophene hydrodesulfuration reaction

Evaluation of calcined hydrocalumite-type materials as supports of CoMo and NiMo for thiophene hydrodesulfuration reaction

Implementation of mathematical equation for calculating alumina extraction from bauxite tailing digestion

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