Oleate Adsorption at an Apatite Surface Studied by Ex-Situ FTIR Internal Reflection Spectroscopy

Lu, Yongqiang; Drelich, Jaroslaw; Miller, Jan D.

doi:10.1006/jcis.1998.5466

Cited by 100 publications

(60 citation statements)

References 37 publications

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“…These changes suggested that both Ca and Mg were active sites for chemical reaction with NaOL [5,25]. Moreover, the shift of Ca2p binding energy of dolomite was larger than that of apatite, revealing that the interaction between Ca of dolomite and NaOL was more intensive, which was in accordance with the flotation results of Figure 3 and the contact angle measurements of Figure 6.…”

Section: Xps Analysissupporting

confidence: 80%

“…These changes suggested that both Ca and Mg were active sites for chemical reaction with NaOL [5,25]. Moreover, the shift of Ca2p binding energy of dolomite was larger than that of apatite, revealing that the interaction between Ca of dolomite and NaOL was In addition, to obtain more detailed information about the selective depression of NaPP on apatite flotation, broad scan XPS analyses of apatite and dolomite under different reagent conditions were also employed, and the results are shown in Figure 8 and Table 2.…”

Section: Xps Analysismentioning

confidence: 99%

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Effect of Sodium Pyrophosphate on the Reverse Flotation of Dolomite from Apatite

Chen,

Feng,

Zhang

et al. 2018

Minerals

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In this study, the effect of sodium pyrophosphate (NaPP) on the separation of apatite from dolomite by flotation was systematically investigated. Flotation results revealed that NaPP could selectively depress the flotation of apatite, thus realizing the separation of apatite from dolomite. Further, the selective depression mechanism of NaPP was studied through zeta potential measurements, contact angle measurements, and X-ray photoelectron spectroscopy (XPS) analysis. The results demonstrated that the adsorption of sodium oleate (NaOL) onto apatite surface was depressed by the preferential interaction of NaPP with active Ca sites. For dolomite, while the presence of NaPP hindered the interaction of NaOL with active Ca sites, it appeared to enhance the reactivity with active Mg sites. Thus, the adsorption of NaOL onto dolomite surface was hardly influenced. In this way, the separation of apatite from dolomite was achieved.

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Section: Xps Analysissupporting

confidence: 80%

“…These changes suggested that both Ca and Mg were active sites for chemical reaction with NaOL [5,25]. Moreover, the shift of Ca2p binding energy of dolomite was larger than that of apatite, revealing that the interaction between Ca of dolomite and NaOL was In addition, to obtain more detailed information about the selective depression of NaPP on apatite flotation, broad scan XPS analyses of apatite and dolomite under different reagent conditions were also employed, and the results are shown in Figure 8 and Table 2.…”

Section: Xps Analysismentioning

confidence: 99%

Effect of Sodium Pyrophosphate on the Reverse Flotation of Dolomite from Apatite

Chen,

Feng,

Zhang

et al. 2018

Minerals

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“…In the presence of Na-oleate, it can be observed that the zeta potential of the precipitate assumes more negative values in the concentration range studied, as shown in Figure 4B, which suggests the surfactant adsorption on the precipitate. According to the oleate adsorption isotherm on apatite reported by Lu et al (1998), in the less concentrated range of Naoleate (2-20 mg L -1 ), the adsorption occurs by means of a chemisorption mechanism: the interaction between the dissociated ions (Ol-(CH3(CH2)7CH=CH(CH2)7COO-) and Ol22-) of the oleate with the precipitate surface cations (Ca2+ e CaOH+), forming hemimicelles and rendering the surface hydrophobic. This kind of chemical interaction is a specific adsorption, and therefore of difficult desorption, which justifies the increase of phosphate recovery in this concentration range, achieving the maximum recovery of 90% in the presence of 20 mg L -1 of Na-oleate.…”

Section: Effect Of Sodium Oleate On the Phosphate Recoverymentioning

confidence: 99%

Electroflotation of precipitated phosphate from synthetic solution

Cruz

Monte

Dutra

2017

Braz. J. Chem. Eng.

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-The phosphate recovery from a 20 mg L -1 Na2HPO4 solution through precipitation with Ca(OH)2 followed by electroflotation was evaluated. X-ray diffraction and particle size measurements indicated that the precipitates were a mixture of hydroxyapatite and calcium-deficient hydroxyapatite, with size ranging from 3 to 10 mm. Electroflotation with Na-oleate as surfactant was used to recover the precipitates. The surfactant adsorption was evaluated through zeta potential measurements. The influence of Na-oleate concentration, pH and bubble size on phosphate recovery was investigated. In the absence of Na-oleate, a phosphate recovery of 50% was achieved, while in the presence of 20 mg L -1 of Na-oleate it was increased to 90%, at pH 11. The phosphate recovery also increased with Ca(OH)2 concentration increase and bubble size decrease, reaching 100% at 300 mg L -1 Ca(OH)2 and bubble size around 39 µm.

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“…The absorptivity 15000 L/mol cm 2 was not determined by experiment but taken as a mean value (2500-3000 L/mol cm 2 for each CH 2 group) obtained by comparing values from, e.g., ref. 17. In this context it should be mentioned that absorptivity values determined by transmission experiments may differ considerably from the values determined for an adsorbed layer (18).…”

Section: Amount Of Adsorbed Collectormentioning

confidence: 94%

“…The adsorption density was calculated by using the formula given in ref. 17 (formula 1) and the absorptivity 15000 L/mol cm 2 , the mean value of the effective path lengths (12), and the integrated absorbance of the asymmetric stretching of CH 2 . The absorptivity 15000 L/mol cm 2 was not determined by experiment but taken as a mean value (2500-3000 L/mol cm 2 for each CH 2 group) obtained by comparing values from, e.g., ref.…”

Section: Amount Of Adsorbed Collectormentioning

confidence: 99%