Abstract:The specific adsorption of oxalic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method ( 14 C) as a function of oxalic acid ions concentration, NaCl concentration and pH. Application of hydroxyapatite has become extensive in the biomaterial field due to its biocompatibility with human hard tissue. Hydroxyapatite was synthesized using wet methods. Physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy. Physicochemical prope… Show more
“…The first weight loss of 8.3 wt.% is observed from 30 to 225 • C due to the removal of trapped water in the sample. The second weight loss of approximately 31.6 wt.% occurs from 226 to 700 • C and was attributed to the decomposition of the other components (CO 3 2− according to the weight loss observed in TGA curves between 550-950 • C [31,38]. The results obtained for the non-treated and treated specimens with carbonated hydroxyapatite solutions 0.25 g/L concentration, revealed that by brushing, acicular crystals of approximately 500 nm in length and 10 nm in width were obtained ( Figure 8); and the second one, when the solution was sprayed on the stone surface, agglomerates of spheroidal crystals of approximately 10 ± 20 nm in diameter were obtained (marked by arrows).…”
Carbonated hydroxyapatite derivatives (CHAp) and its metallic derivatives (Ag, Sr, Ba, K, Zn) have been prepared and characterized in this paper and their coating capacity on some model stone samples have been evaluated and discussed. These compounds were characterized by using several analytical tools, including X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), to determine the purity of the CHAp sample. The XRD and FTIR results confirmed the presence of AB-carbonated type CHAp. The thermal analysis (TGA) established two stages of weight loss that occured during the heating process: The first weight loss between 30–225 °C corresponding to the partial carbonate release from OH-channel and the second one between 226–700 °C, corresponding to some thermal reactions, possibly to the generation of calcium phosphate. The efficiency and suitability of these products on model stone samples were evaluated by monitoring the resistance to artificial weather (freeze–thaw), and pore structure changes (surface area, pore volume, pore diameter). Meanwhile, optical microscopy (OM) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM–EDS) techniques showed the particles size and surface morphology of the samples, as well as information on its chemical composition. Also, the compressive strength of these new compounds as coatings revealed a homogeneity and strengthen of these model stone samples.
“…The first weight loss of 8.3 wt.% is observed from 30 to 225 • C due to the removal of trapped water in the sample. The second weight loss of approximately 31.6 wt.% occurs from 226 to 700 • C and was attributed to the decomposition of the other components (CO 3 2− according to the weight loss observed in TGA curves between 550-950 • C [31,38]. The results obtained for the non-treated and treated specimens with carbonated hydroxyapatite solutions 0.25 g/L concentration, revealed that by brushing, acicular crystals of approximately 500 nm in length and 10 nm in width were obtained ( Figure 8); and the second one, when the solution was sprayed on the stone surface, agglomerates of spheroidal crystals of approximately 10 ± 20 nm in diameter were obtained (marked by arrows).…”
Carbonated hydroxyapatite derivatives (CHAp) and its metallic derivatives (Ag, Sr, Ba, K, Zn) have been prepared and characterized in this paper and their coating capacity on some model stone samples have been evaluated and discussed. These compounds were characterized by using several analytical tools, including X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), to determine the purity of the CHAp sample. The XRD and FTIR results confirmed the presence of AB-carbonated type CHAp. The thermal analysis (TGA) established two stages of weight loss that occured during the heating process: The first weight loss between 30–225 °C corresponding to the partial carbonate release from OH-channel and the second one between 226–700 °C, corresponding to some thermal reactions, possibly to the generation of calcium phosphate. The efficiency and suitability of these products on model stone samples were evaluated by monitoring the resistance to artificial weather (freeze–thaw), and pore structure changes (surface area, pore volume, pore diameter). Meanwhile, optical microscopy (OM) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM–EDS) techniques showed the particles size and surface morphology of the samples, as well as information on its chemical composition. Also, the compressive strength of these new compounds as coatings revealed a homogeneity and strengthen of these model stone samples.
“…What is more, the isoelectric point of the solid without the polymer is located at pH 3.4. Such big difference between pH pzc and pH iep values of activated carbon may be a result of overlapping of the electrical double layers formed on the mesopore walls [38, 39]. Fig.…”
The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.
“…As can be seen in Figure 3 the isoelectric points (iep) of metal oxides without the polymer are located at pH values 6, 6.4 and 8.4 for Cr 2 O 3 , ZrO 2 and Al 2 O 3 adsorbents, respectively. Some differences between the pH pzc and pH iep values of applied oxides are a result of overlapping of the electrical double layers formed on the mesopores surface existing in the solids structure (Skwarek, 2014, 2015). Figure 3.Values of pH iep for the metal oxide systems without and with the ionic polymer.…”
The influence of metal oxide type on the adsorption affinity of anionic polyacrylamide for the solid surface was studied. There were selected three metal oxides: chromium(III) oxide, zirconium(IV) oxide and aluminium(III) oxide. The adsorption behaviour of high-molecular weight polymer containing 30% of carboxyl groups was determined based on the results of spectrophotometric, electrokinetic and turbidimetric measurements. The anionic polymer exhibits the greatest adsorption on the surface of chromium(III) oxide whereas PAM affinity for the aluminium(III) oxide is the lowest. The polymer presence has a pronounced impact on the electrokinetic properties of examined suspensions manifesting in changes in pH pzc and pH iep values of PAM-containing systems compared to those without polyacrylamide. The anionic PAM addition at pH 6 has the greatest effect on the stability of metal oxide aqueous suspensions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
