A new iron-phosphate compound (Fe7P11O38) obtained by pyrophosphate stoichiometric glass devitrification

Iron phosphates are a wide group of compounds that possess versatile applications. Their properties are strongly dependent on the role and position of iron in their structure. Iron, because of its chemical character, is able to easily change its redox state and accommodate different chemical surroundings. Thus, iron-phosphate crystallography is relatively complex. In addition, the compounds possess intriguing magnetic and electric properties. In this paper, we present crystal structure properties of a newly developed iron-phosphate compound that was obtained by devitrification from iron-phosphate glass of pyrophosphate stoichiometry. Based on X-ray diffraction (XRD) studies, the new compound (Fe7P11O38) was shown to adopt the hexagonal space group P63 (No. 173) in which iron is present as Fe3+ in two inequivalent octahedral and one tetrahedral positions. The results were confirmed by Raman and Mössbauer spectroscopies, and appropriate band positions, as well as hyperfine interaction parameters, are assigned and discussed. The magnetic and electric properties of the compound were predicted by ab initio simulations. It was observed that iron magnetic moments are coupled antiferromagnetically and that the total magnetic moment of the unit cell has an integer value of 2 µB. Electronic band structure calculations showed that the material has half-metallic properties.

Pure hydroxyapatite synthesis originating from amorphous calcium carbonate

We report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71 < Ca/P < 1.88), whereas Ca/P = 1.51 leads to pure β-tricalcium phosphate. The ACP phases are precursors for calcium phosphate compounds and may determine the final crystalline phase.

Utilization of bintaro shells as activated carbon to reduce phosphate in laundry wastewater

Laundry wastewater is dangerous if it is immediately disposed into a river without treating it first. One of the chemicals contained in laundry wastewater is a phosphate compound. If laundry wastewater is discharged directly into the river it will increase the phosphate content as a nutrient in river water which can be dangerous for living creatures. The high nutrient in the river will cause eutrophication in the river which will adversely affect aquatic biota. One treatment that can be done is the process of adsorption with activated carbon made from bintaro fruit shells.

Application of Colloidal Dispersions of Bioshell Calcium Oxide (BiSCaO) for Disinfection

Bioshell calcium oxide (BiSCaO) is a scallop-shell powder heated at a high temperature. BiSCaO is composed mainly of calcium oxide and exhibits broad microbicidal properties. The aim of this study is to evaluate the disinfection and decontamination abilities of BiSCaO colloidal dispersions with that of commercially available bioshell calcium hydroxide (BiSCa(OH)2) following the formation of flocculants/precipitates under strongly alkaline conditions (pH 11.5–12.2). Various concentrations of BiSCaO and BiSCa(OH)2 colloidal dispersions were prepared by mixing with Na-polyPO4 (PP) and Na-triPO4 (TP) as flocculating agents. The microbicidal activities, and the degree of flocculation/precipitation of trypan blue, albumin, chondroitin sulfate, heparin, non-anticoagulant heparin carrying polystyrene (NAC-HCPS), and low-molecular-weight heparin/protamine nanoparticles (LMWH/P NPs) were dependent on the pH, the average particle diameter, and the concentration of BiSCaO or BiSCa(OH)2 and of the phosphate compound. BiSCaO (average particle diameter: 6 μm) colloidal dispersions (0.2 wt.%) containing 0.15 wt.% PP or TP exhibited substantially stronger microbicidal activity and flocculation/precipitation under strongly alkaline conditions. These results suggest that BiSCaO colloidal dispersions together with phosphate compounds have practical applicability for disinfection.