Topotactic exchange and intercalation of calcium phosphate

Lima, Cícero Bosco Alves de; Airoldi, Cláudio

doi:10.1016/j.solidstatesciences.2004.06.009

Cited by 17 publications

(7 citation statements)

References 23 publications

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“…In considering the conversion mechanisms that can lead to the formation of phosphocalcic phases, two mechanisms are possible: dissolution-reprecipitation reactions or solid-state topotactic ion-exchange reaction mechanisms [12,39,40]. When the transformation involves ion-exchange mechanisms, the reaction produces pseudomorphs with crystals quite similar to the original crystals.…”

Section: Discussionmentioning

confidence: 99%

Conversion of snail shells (Achatina achatina) acclimatized in Benin to calcium phosphate for medical and engineering use

et al. 2019

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This is an author's version published in: http://oatao.univ-toulouse.fr/25561 Abstract Most methods for producing calcium phosphates involve synthetic calcium and phosphates sources. However, it has recently been proposed that calcium phosphate can be produced with bio-based calcium sources such as nacre, coral, and cuttlefish bones. One specific source of bio-based calcium is found in the Achatina snail shell, which becomes a waste product after flesh consumption. The present work aimed to assess the effectiveness of Achatina snail shells and to study the conversion kinetics in both acid and alkaline environment rich in phosphate ions. It was observed that in acidic conditions, the calcium released by the dissolution of the aragonite precipitates with the phosphate ions ofreaction medium induces brushite formation which is rapidly converted into monetite. In alkaline conditions, calcium released from aragonite reacts with surrounding phosphates and car bonate ions and induces carbonated apatite precipitation. Regardless of the source of calcium used in the presence of phosphate, the conversion is carried out according to complex phenomena that involve topotactic transformation or dissolution-precipitation mechanisms.

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Section: Discussionmentioning

confidence: 99%

Conversion of snail shells (Achatina achatina) acclimatized in Benin to calcium phosphate for medical and engineering use

et al. 2019

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“…Onde d é o espaço basal e θ variando é o ângulo de difração para n, um valor inteiro (Lima et al, 2004, Hyuk-Nyun et al, 1997.…”

Section: Dsen=nunclassified

“…A seguir, o material foi filtrado e centrifugado a 6000 rpm, durante 60 min. As soluções sobrenadantes foram armazenadas em refrigerador e utilizadas como fonte enzimática na construção de membranas para biossensor (Lima et al, 2004, Hyuk-Nyun et al, 1997, Skladal, 1991, Anderson et al, 1968, Carneiro et al, 2003.…”

Section: Obtenção Do Extrato Bruto De Polifenoloxidaseunclassified

“…O fosfato de cálcio (CaP) foi sintetizado adicionando-se lentamente uma solução diluída de cloreto de cálcio diidratado a uma solução de fosfato de fosfato de amônio dibásico e aquecida a 363 K (keller et al, 1994, Lima et al, 2004). O composto obtido foi esfoliado com soluções de hidróxido de tetrabutilamônio (TBA+OH-).…”

Section: Síntese Do Fosfato De Cálciounclassified

“…Analisando o espectro da Figura 5, após a enzima ser introduzida na matriz inorgânica lamelar se identificam as bandas: a) em 1550 cm -1 e em 1600 cm -1 atribuídas às ligações N-H, b) em 1400-1500 cm -1 características de estiramentos C=C (aromático), c) em 1730 cm -1 relativa a C=O ou efeito de conjugação similar a C=N e d) em 1040 cm -1 e outra em 1200 cm -1 dos estiramentos relacionados ao fosfato. Nota-se que há, portanto, reações de grupos funcionais específicos da enzima com substrato e não existe qualquer banda que possa ser atribuída ao modo de estiramento vibracional de grupos OH e de molécula de água (Lima et al, 2004, Yamauchi et al, 2004, Zang et al, 1996, Göni et al, 1996.…”

Section: Tabela 2 Tensão Superficial (Ts) E Densidade (D) Das Amostras Envolvendo a Enzima No Fosfato De Cálcio (Enzcapesf)unclassified

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Incorporation of the Polyphenoloxidade Enzyme in Lamellar Calcium Phosphate

Cesário¹,

Bezerra²,

Lima³

2013

PTQ

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The present investigation deals the production, purification and incorporation of the enzyme polyphenoloxidase (PPO), from yam crude extracted (Alocasia macrorhiza), on exfoliated calcium phosphate with tetrabutylammonium, it was followed by a subsequent treatment with cellulose acetate. The X-ray diffractogram shows an amorphous exfoliated calcium phosphate compound after adding the enzyme solution. In the thermogravimetric curve this final compound presented also mass losses due to the output of the enzyme polyphenoloxidase and through infrared spectrum were identified the bands assigned to NH bonds at 1550 cm-1 and at 1600 cm-1. Also bands at 1040 and 1200 cm-1 related to phosphate stretching groups. The intercalation process occurs because of change in crystallinity of the phosphate with the addition of PPO.

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