PROSJEČNA TOPIVOST MONONATRIJEVIH FOSFATA FIZIKALNO-KEMIJSKA PROCJENA FOSFATA KRMIVA KAO KRITERIJ ZA NJIHOVU KLASIFIKACIJU

Chemical composition of 341 charges – samples of fodder phosphates, their physico-chemical properties (solubility in different solvents), harmful elements content, phase composition and thermal analysis of 150 selected samples of phosphates were determined. Average solubility of monocalcium phosphates (% P2O5 in relation to total P2O5) (in%) amounted to: in water 74.8 – 82.1; in 2% citric acid from 96.6 to 98.3; in 0.4% HCl 94.8 – 98.8 and in neutral ammonium citrate 93.6 – 97.1. Solubility of dicalcium phosphates amounted to (in %): in water from 1.4 to 7.4; in 2% citric acid 50.9 – 98.5; in 0.4% HCl 78.7 – 92.3 and in neutral ammonium citrate 70.3-85.1. Average solubility of monosodium phosphates amounted to (in %): in water 0.1-89.6; in 2% citric acid 25.0 – 90.0; in 0.4% HCl 26.9 – 47.7 and in neutral ammonium citrate 27.7 – 90.2. Solubility of the remaining groups of phosphates (tricalcium, calcium-magnesium and sodium-calcium phosphates) amounted to (in %): in water from 0.1 to 25.8; in 2% citric acid from 25.1 to 95.7; in 0.4% HCl from 26.9 to 56.2 and in neutral ammonium citrate from 23.1 to 79.3. Hydrated monocalcium phosphates with admixture of both hydrated and dehydrated dicalcium phosphate were characterized by the highest solubility in water. In the group of dicalcium phosphates the lowest solubility in 0.4% HCl was stated for dehydrated forms, while the highest solubility was observed in hydrated phosphates. Solubility in water or in 0.4% hydrochloric acid together with the roentgenographical and thermogravimetrical investigations as well as solubility in 2% citric acid and in neutral ammonium citrate are good and cheap methods for identifying by precise the quality of phosphates.Određen je kemijski sastav 341 uzorka fosfata krmiva, njihova fizikalno-kemijska svojstva (topivost u raznim otopinama), sadržaj štetnih elemenata, fazni sastav i termalna analiza 150 odabranih uzoraka fosfata. Prosječna topivost monokalcijevih fosfata (%P2O5 u odnosu na ukupno P2O5) (%) iznosila je u vodi 74,8 - 82,1; u 2% limunskoj kiselini od 96,6 do 98,3; u 0,4% HCI 94,8 - 98,8 i u neutralnom amonijevom citratu 93,6 - 97,1. Topivost dikalcijevih fosfata iznosila je (u %) u vodi od 1,4 do 98,5; u O4%HCI 78,7 -92,3 i u neutralnom amonijevom citratu 70,3 - 85,1. Prosječna topivost mononatrijevih fosfata iznosila je (u%) u vodi 0,1 - 89,6; 2% limunskoj kiselini 25,0 - 90,0; u 0,4% HCI 26,9 - 47,7 i u neutralnom amonijevom citratu 27,7 - 90,2. Topivost ostalih skupina fosfata (trikalcij, kalcijev magnezij i natrijevi-kalcijevi fosfati) iznosila je (u %) u vodi od 0,1 do 25,8; u 2% limunskoj kiselini od 25,1 do 95,7; u 0,4% HCI od 26,9 do 56,2 i u neutralnom amonijevom citratu od 23,1 do 79,3. Hidratni monokalcijevi fosfati s primjesom hidratog i dehidratnog dikalcijevog fosfata obilježila je najviša topivost u vodi. U skupini dikalcijevih fosfata najniža topivost u 0,4% HCI ustanovljena je za dehidrirane oblike, ali je najviša topivost primijećena u hidratnim fosfatima. Topivost u vodi ili u 0,4% hidroklornoj kiselini zajedno s rendgenografskim i termogravimetrijskim ispitivanjima kao i topivost u 2% limunskoj kiselini i neutralnom amonijevom citratu dobre su i jeftine metode za precizno identificiranje kakvoće fosfata

Hydroxyapatite/Silver Nanoparticles Powders as Antimicrobial Agent for Bone Replacements

This paper reports a superficial morphological modification of the hydroxyapatite grains obtained by in situ deposition of Ag nanoparticles on natural origin calcium phosphate powder. Ceramic material was prepared in three stage bone treatment, including hydrolysis with a lactic acid, pre-calcination, and proper calcination. Subsequently, the Ag nanoparticles were synthesized by chemical reduction of Ag+ by sodium borohydride in a solution of polyvinylpyrrolidone and in presence of hydroxyapatite. Such-prepared materials were investigated with X-ray diffraction, Fourier-transformed infrared spectroscopy, atomic absorption spectrometry and scanning electron microscopy with energy dispersive spectroscopy. Furthermore, Ca/P molar ratio was calculated and microbiological tests were performed to investigate materials antimicrobial activity. The appearance of Ag nanoparticles located on phosphate surface was confirmed by SEM analysis, and no chemical bonding with hydroxyapatite was recorded by IR and XRD techniques. Additionally, the biological assessment revealed bactericidal effect on Escherichia coli and Staphylococcus aureus, while slightly affected on Enterococcus faecalis viability. This work is licensed under a Creative Commons Attribution 4.0 International License

Propolis – beekeeping medicinal product

The paper presents the healing properties and biological activity of propolis, commonly known as bee glue. Propolis is a natural product collected by bees from buds of plants and bark of trees, then moistened with bee enzymes. Propolis is widely used for general treatment, skin affections, and as an anti-inflammatory agent for ulcers and hard-to-heal wounds. Propolis, due to its properties, is called an antibiotic of the 21st century

Distributed generation power systems in wastewater management

The article concerns the energy security of a wastewater treatment process caused by unforeseen situations related to the risk of electrical power outages. In this case, renewable energy sources based on distributed generation power systems can solve this problem in each wastewater treatment plant. The article highlights e related challenges and proposes the direction of solutions in this regard based on Czech conditions. The first part of the paper deals with the consequences of long-term outage of wastewater treatment plants on the population and the environment. There are several solutions presented for blackout conditions, and model calculations are made based on data from a Czech wastewater treatment plant. Diesel engine-generators, biogas as a cogeneration source of heat and electricity, solar panels with storage systems and combined biogas and solar systems were considered as approaches to provide energy autonomy during a blackout in a wastewater treatment plant. Special attention was paid to a combination of CHP units with solar panels and batteries. The results were evaluated for three different locations for this combination. It was concluded that biogas combustion in the CHP unit was the most profitable option, allowing the production of electricity independently of the grid for its own consumption and possibly for other operations. The last part of the paper deals with the transition to island operation, which must occur during a blackout. This transition is more difficult for both solar panels and cogeneration units if they were to supply electricity to the grid before a blackout. The transition to energy island operation could be ensured by frequency relay and processor devices to control the circuit breaker. Then, to maintain island operation, it would be necessary to have an automatic load shedding/application system.Web of Science1517art. no. 628

Preparation of hydroxyapatite from animal bones. Acta of Bioengineering and Biomechanics

This paper presents the method of obtaining hydroxyapatite from animal bones. Bone sludge and calcined products were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Calcium concentration was determined with titration, and phosphorus -spectrophotometrically. Making use of the AAS and ICP methods the content of microelements was determined. In all the products, hydroxyapatite was the only crystalline phase indicated. The FT-IR spectra confirmed that calcination removed the total of organic substances. Calcium and phosphorus contents were 38% and 18%, respectively, which corresponded to the Ca/P molar ratio of nonstoichiometric hydroxyapatite. The specific surfaces of products were measured by BET method. The volume of micro-and mesopores was determined

Sustainable Management of Calcite Contaminated with Waste Toner Powder in the Construction Industry

Due to the highly explosive nature of toners, absorbers are used in toner processing plants to prevent the explosion of toner dust suspension in the air. Usually, finely divided calcite (in the form of a dust) is used. The mixture of toner-calcite is treated as waste and landfilled. The main aim of this study was to investigate the possibility of using toner-contaminated calcite as an additive to concrete. Materials originating from the toner processing plant were analyzed by using TGA, AAS, XRD, FTIR and SEM techniques. Calcite-waste toner powder mixture in amounts 0%, 1%, 5%, 10%, 15% and 20% were used to produce concrete. The results of the study showed that an increase in the amount of calcite contaminated with toner to 20% causes a decrease in compressive strength of concrete by 24–51% depending on material sample. The addition of calcite in amounts up to 5% can be a suitable method of its management

The impact of reagents concentration on the efficiency of obtaining high-purity magnesium hydroxide

The work presents the impact of reagents concentration and the drying process on the efficiency of obtaining magnesium hydroxide and its specific surface area. Magnesium sulphate(VI) within the concentration range of 0.7–2.0 mol/dm3 was used in the research as magnesium feedstock and sodium hydroxide was used as a precipitating agent within the same concentration range. The process of obtaining magnesium hydroxide was carried out with a 25% excess of the precipitating agent in relation to the reaction stoichiometry. The obtained suspension was separated by way of multi-stage sedimentation with the use of acetone and freezing samples. Depending on the concentration of reagents the efficiency of obtaining magnesium hydroxide fell within the range of 88–99%, whereas the specific surface area – within 115–609 m2/g, while the high purity of samples above 99% of magnesium hydroxide was maintained

The impact of reagents concentration on the efficiency of obtaining high-purity magnesium hydroxide

The work presents the impact of reagents concentration and the drying process on the efficiency of obtaining magnesium hydroxide and its specific surface area. Magnesium sulphate(VI) within the concentration range of 0.7–2.0 mol/dm3 was used in the research as magnesium feedstock and sodium hydroxide was used as a precipitating agent within the same concentration range. The process of obtaining magnesium hydroxide was carried out with a 25% excess of the precipitating agent in relation to the reaction stoichiometry. The obtained suspension was separated by way of multi-stage sedimentation with the use of acetone and freezing samples. Depending on the concentration of reagents the efficiency of obtaining magnesium hydroxide fell within the range of 88–99%, whereas the specific surface area – within 115–609 m2/g, while the high purity of samples above 99% of magnesium hydroxide was maintained