Impact of physical and chemical parameters on the hydroxyapatite nanopowder synthesized by chemical precipitation method

Abstract

In this paper, the synthesis of hydroxyapatite (HAp) nanopowder was studied by chemical precipitation method at different values of reaction temperature, settling time, Ca/P ratio, calcination temperature, (NH4)2HPO4 addition rate, initial concentration of Ca(NO3)2 and (NH4)2HPO4. Analysis results of properties, morphology, structure of HAp powder from infrared (IR) spectra, x-ray diffraction (XRD), energy dispersive x-ray (EDX) spectra and scanning electron microscopy (SEM) indicated that the synthesized HAp powder had cylinder crystal shape with size less than 100 nm, single-phase structure. The variation of the synthesis conditions did not affect the morphology but affected the size of HAp crystals.

Preparation and characterization of boron-based bioglass by sol−gel process

“…The 2θ XRD patterns of the standard hydroxyapatite are shown in Table 1 [22], as well the experimental data of 45S5 and 45S5B after 60 days of immersion in SBF. The peaks at 2θ = 31.29°and 31.19°d isplayed at 45S5 and 45S5B diffractograms, respectively, correspond to 2θ = 31.74°of the standard hydroxyapatite, and the peaks at 32.24°, corresponding to the (002) crystal plane are typical peaks of hydroxyapatite [31]. The characteristic peaks of hydroxyapatite identified in 45S5 and 45S5B are displayed in Table 1 [31].…”

“…The peaks at 2θ = 31.29°and 31.19°d isplayed at 45S5 and 45S5B diffractograms, respectively, correspond to 2θ = 31.74°of the standard hydroxyapatite, and the peaks at 32.24°, corresponding to the (002) crystal plane are typical peaks of hydroxyapatite [31]. The characteristic peaks of hydroxyapatite identified in 45S5 and 45S5B are displayed in Table 1 [31]. The XRD diffractogram of 45S5 and 45S5B before immersion in SBF revealed the presence of the amorphous peak at 22°corresponding to SiOH and the crystalline peaks attributed to NaCl formed in the precipitation process.…”

Fabrication of Porous Hydroxyapatite Granules as an Effective Adsorbent for the Removal of Aqueous Pb(II) Ions

“…e adsorption process has been studied via isotherms and kinetics. [36]. Accordingly, the aqueous solution of 0.3 M (NH 4 ) 2 HPO 4 is slowly added dropwise into a 0.5 M solution of Ca(NO 3 ) 2 at a rate of 1 mL•min −1 .…”

Estudo, caracterização e propriedades de ortofosfatos multifuncionais

“…A HA possui uma estrutura flexível e aceita facilmente vacâncias e substituições iônicas [35,40]. Quando sintetizada em soluções aquosas, estas modificações comumente acontecem e podem alterar os sinais tanto no infravermelho como no espalhamento Raman [98]. FIGURA 4.5 -Micrografias obtidas por MEV para as amostras preparadas em pH básico.…”

“…Há também os métodos de processamento a alta temperatura, representados pelo método de combustão [59] e a pirólise [94]. Em relação aos métodos por via úmida pode-se destacar os tratamentos hidrotérmicos [7,95,96], a precipitação química [49,97,98], precipitação química assistida por tratamento ultrassônico [28,99], precipitação química com aditivos orgânicos [11,100,101], hidrotérmico assistido por micro-ondas [102], Sol-Gel [103] e a hidrólise dos precursores [104][105][106]. Cada uma das metodologias desenvolvidas apresenta suas próprias vantagens e desvantagens, as quais devem ser levadas em conta durante o desenvolvimento da pesquisa científica.…”