“…In addition, a peak around ∼2.3 Å was attributed to calcite (marked with *), which may have formed owing to the high calcium concentration and high pH conditions in the calcium bath (Spectra 1 and 3 in Figure B). These results are similar to those recently reported by Solonenko et al, who studied precipitation in an aqueous system containing Ca–Si–P for application as a bioceramic material for bone regeneration . Interestingly, instead of tobermorite, they reported clear calcite XRD peaks as the result of Si incorporation.…”
Section: Resultssupporting
confidence: 91%
“…This suggests that the 10 mM P + 10 mM Si mineral seeds were formed through coprecipitation of CaP and CSH during calcium alginate hydrogel formation. The elemental composition of the mineral seed formed in this study was similar to that of the mineral aggregates precipitated from a Ca–Si–P system reported by Solonenko et al With regards to the mineral aggregate size, however, they reported that, regardless of silicate content, their mineral precipitates were comprised of aggregates sized from 3 to 100 μm. On the other hand, the CaP mineral seeds in our work were largely spherical single particles with submicrometer sizes.…”
Section: Resultssupporting
confidence: 86%
“…These results are similar to those recently reported by Solonenko et al, who studied precipitation in an aqueous system containing Ca−Si−P for application as a bioceramic material for bone regeneration. 30 Interestingly, instead of tobermorite, they reported clear calcite XRD peaks as the result of Si incorporation. In our study, we mainly observed peaks associated with tobermorite (Spectra 1 and 2 in Figure 1B).…”
Effectively
recovering phosphate from wastewater streams and reutilizing
it as a nutrient will critically support sustainability. Here, to
capture aqueous phosphate, we developed novel mineral–hydrogel
composites composed of calcium alginate, calcium phosphate (CaP),
and calcium silicate hydrate (CSH) (CaP + CSH/Ca-Alg). The CaP + CSH/Ca-Alg
composites were synthesized by dripping a sodium alginate (Na-Alg)
solution with ionic precursors into a calcium chloride bath. To change
the mineral seed’s properties, we varied the calcium bath concentrations
and the ionic precursor (sodium dibasic phosphate (NaH2PO4) and/or sodium silicate (Na2SiO3)) amounts and their ratios. The added CSH in the mineral–hydrogel
composites resulted in the release of calcium and silicate ions in
phosphate-rich solutions, increasing the saturation ratio with respect
to calcium phosphate within the mineral–hydrogel composites.
The CSH addition to the mineral–hydrogel composites doubled
the phosphate removal rate while requiring lesser initial amounts
of Ca and P materials for synthesis. By incorporating both CSH and
CaP mineral seeds in composites, we achieved a final concentration
of 0.25 mg-P/L from an initial 6.20 mg-P/L. Moreover, the mineral–hydrogel
composites can remove phosphate even under CaP undersaturated conditions.
This suggests their potential to be a widely applicable and environmentally
sustainable treatment and recovery method for nutrient-rich wastewater.
“…In addition, a peak around ∼2.3 Å was attributed to calcite (marked with *), which may have formed owing to the high calcium concentration and high pH conditions in the calcium bath (Spectra 1 and 3 in Figure B). These results are similar to those recently reported by Solonenko et al, who studied precipitation in an aqueous system containing Ca–Si–P for application as a bioceramic material for bone regeneration . Interestingly, instead of tobermorite, they reported clear calcite XRD peaks as the result of Si incorporation.…”
Section: Resultssupporting
confidence: 91%
“…This suggests that the 10 mM P + 10 mM Si mineral seeds were formed through coprecipitation of CaP and CSH during calcium alginate hydrogel formation. The elemental composition of the mineral seed formed in this study was similar to that of the mineral aggregates precipitated from a Ca–Si–P system reported by Solonenko et al With regards to the mineral aggregate size, however, they reported that, regardless of silicate content, their mineral precipitates were comprised of aggregates sized from 3 to 100 μm. On the other hand, the CaP mineral seeds in our work were largely spherical single particles with submicrometer sizes.…”
Section: Resultssupporting
confidence: 86%
“…These results are similar to those recently reported by Solonenko et al, who studied precipitation in an aqueous system containing Ca−Si−P for application as a bioceramic material for bone regeneration. 30 Interestingly, instead of tobermorite, they reported clear calcite XRD peaks as the result of Si incorporation. In our study, we mainly observed peaks associated with tobermorite (Spectra 1 and 2 in Figure 1B).…”
Effectively
recovering phosphate from wastewater streams and reutilizing
it as a nutrient will critically support sustainability. Here, to
capture aqueous phosphate, we developed novel mineral–hydrogel
composites composed of calcium alginate, calcium phosphate (CaP),
and calcium silicate hydrate (CSH) (CaP + CSH/Ca-Alg). The CaP + CSH/Ca-Alg
composites were synthesized by dripping a sodium alginate (Na-Alg)
solution with ionic precursors into a calcium chloride bath. To change
the mineral seed’s properties, we varied the calcium bath concentrations
and the ionic precursor (sodium dibasic phosphate (NaH2PO4) and/or sodium silicate (Na2SiO3)) amounts and their ratios. The added CSH in the mineral–hydrogel
composites resulted in the release of calcium and silicate ions in
phosphate-rich solutions, increasing the saturation ratio with respect
to calcium phosphate within the mineral–hydrogel composites.
The CSH addition to the mineral–hydrogel composites doubled
the phosphate removal rate while requiring lesser initial amounts
of Ca and P materials for synthesis. By incorporating both CSH and
CaP mineral seeds in composites, we achieved a final concentration
of 0.25 mg-P/L from an initial 6.20 mg-P/L. Moreover, the mineral–hydrogel
composites can remove phosphate even under CaP undersaturated conditions.
This suggests their potential to be a widely applicable and environmentally
sustainable treatment and recovery method for nutrient-rich wastewater.
“…Then, for the 7 days of immersion, the presence of oval and spherical grains and the formation of sub-micrometric spherical agglomerates is evident on the surface (Fig. 5 b) 46 , 47 . Figure 5 SEM images of the samples treated at different calcination temperatures and after soaking in SBF during ( a ) 3 days and ( b ) 7 days.…”
Biogenic hydroxyapatite (BHAp) is a widely used material in the biomedical area due to its similarities with the bone tissue mineral phase. Several works have been spotlighted on the thermal behavior of bone. However, little research has focused on determining the influence of calcination temperature in the physicochemical and bioactive properties of BHAp. In this work, a study of the physicochemical properties’ changes and bioactive response of BHAp produced from porcine femur bones using calcination temperatures between 900 to 1200 °C was conducted. The samples’ structural, morphological, and compositional changes were determined using XRD, SEM, and FTIR techniques. XRD results identified three temperature ranges, in which there are structural changes in BHAp samples and the presence of additional phases. Moreover, FTIR results corroborated that B-type substitution is promoted by increasing the heat treatment temperature. Likewise, samples were immersed in a simulated biological fluid (SBF), following the methodology described by Kokubo and using ISO 23317:2014 standard, for 3 and 7 days. FTIR and SEM results determined that the highest reaction velocity was reached for samples above 1000 °C, due to intensity increasing of phosphate and carbonate bands and bone-like apatite morphologies, compared to other temperatures evaluated.
“…Calcium silicate hydrate-based electrical conductive material was prepared when copper powder was incorporated [ 5 ]. A new type of bioceramic was prepared by compaction of weakly crystallized calcium phosphate and calcium silicate hydrates [ 10 ]. Udawatte et al [ 11 ] used the hydrothermal hot pressing method to solidify calcium silicate hydrate powders to prepare artificial wood, where the reinforcement substance was chitosan, while the authors used the contact-hardening method to produce artificial wood from a mixture of amorphous calcium silicate hydrate powder, polypropylene fiber and latex [ 12 ]..…”
Carbon fiber dispersion has a substantial influence on the properties of amorphous calcium silicate hydrate-based contact-hardening composites. In this study, a mixture of carbon fiber and calcium silicate hydrate powder was compressed into solid composites at 40 MPa for one minute. The mechanical properties and electrical resistivity of the solid materials were measured, and the dispersion of carbon fibers was quantitatively evaluated by digital image processing technology. The Taipalu model was used to build the correlation between the electrical resistivity of the composites and the carbon fiber dispersion. The results of the electrical resistivity showed that the down threshold of carbon fiber content in the contact-hardening composites was 1.0 wt.% and the electrical resistivity was 30,000 Ω·cm. As the fiber content increased to 2.0 wt.%, the electrical resistivity dropped to 2550 Ω·cm, which was attributed to the increase in fiber dispersion uniformity in the solid composites, and the value of the fiber distribution coefficient reached a maximum value of 0.743. A subsequent decrease in the uniformity of the fiber dispersion was observed at a high fiber content. In addition, the carbon fiber content showed a slight influence on the fiber orientation in the contact-hardening composites.
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