Mehanochemical synthesis of calcium oxalate from calcium nitrate

Ovim istraživanjem je prikazana mehanokemijska sinteza kalcijeva oksalata, bez i uz prisutnost otapala (vode), u planetarnom kugličnom mlinu. Sva istraživanja do sada su ponajviše bila usmjerena na sintezu kalcijeva oksalata otopinskom kemijom. Ovim radom nastojalo se opisati drugačiji pristup, kako bi se pridonijelo novim saznanjima o sintezi kalcijeva oksalata, ekološki osvještenijom, mehanokemijskom metodom. Konačni cilj istraživanja jest sinteza, karakterizacija te identifikacija pojedine hidratne faze, dobivene reakcijom kalcijeva nitrata tetrahidrata i natrijeva oksalata. Reakcija je praćena u ovisnosti o vremenu reakcije i brzini mljevenja. Strukturna i termička svojstva uzoraka ispitana su FT-IR spektroskopijom i termogravimetrijskom analizom (TGA). Morfološke osobine kalcijeva oksalata, kao i klasifikacija veličine čestica, određene su optičkom mikroskopijom i metodom dinamičkog raspršenja svjetlosti (DLS).The study presents the mechanochemical synthesis of calcium oxalate, without and in the presence of solvents, in a planetary ball mill. All studies so far have focused mainly on the synthesis of calcium oxalate using solution chemistry. In this paper, we described a different approach that could contribute to new findings in the field of calcium oxalate synthesis using mechanochemical approach. The ultimate goal of the research is synthesis, as well as structural characterization and identification of individual oxalate hydrate phase, gained by the synthesis of calcium salts (of the chlorides, nitrates and sulphates). The reaction is monitored depending on the duration of the synthesis, to determine if the effect of the milling velocity on the reaction exists. Structural and thermal properties of the sample were tested by FTIR spectroscopy and thermogravimetric analysis (TGA). Morphological properties of calcium oxalate as well as particle size distribution are gained by optical microscopy and dynamic light scattering (DLS)

Calcium oxalate and gallic acid: structural characterization and process optimization toward obtaining high contents of calcium oxalate monohydrate and dihydrate

The search for an efficient drug or inhibitor in the formation process of kidney stones has been a promising research topic towards reducing the risks of the formation of disease. However, several challenges have been faced in investigating the most common constituents of kidney stones, calcium oxalate and its hydrate forms (COM, COD and COT). This study focuses on the preparation and structural characterization (TG, XRD, FTIR, SEM) of calcium oxalate hydrates in the presence of gallic acid (GA) and by varying operating parameters such as temperature (25 °C, 36.5 °C and 48 °C), pH (5.6, 6.5 and 7.5) and amount of added GA (ranging from 100 mg to 1000 mg). Response surface methodology was applied in order to evaluate the effects of operating parameters in the formation of COM and COD, and for the process optimization towards maximizing their content in samples. The results indicated that GA inhibited the formation of COM (0–100%) and promoted the formation of COD (0 ≤ 99%), while a medium pH and the amount of added GA showed a significant effect in the process of COD formation. In order to investigate the interactions established in the formation process and the possible adsorption between GA and the formed crystals, electrochemical measurements were performed

Mechanochemical synthesis of calcium oxalate

Ova studija prikazuje mehanokemijsku sintezu kalcijeva oksalata u planetarnom kugličnom mlinu, bez i uz prisutnost otapala. Dosadašnja istraživanja su uglavnom bila usmjerena na otopinsku sintezu kalcijeva oksalata. U ovom radu opisujemo drugačiji pristup, koji će donijeti nova saznanja o sintezi kristala kalcijeva oksalata, a koje su uzrokovane utjecajem mehaničke energije. Cilj istraživanja je sinteza, identifikacija i karakterizacija pojedine oksalatne hidratne faze sintetizirane iz kalcijevih soli (klorida, nitrata i sulfata). Ispitivan je utjecaj brzine mljevenja i praćena je reakcija u ovisnosti o vremenu sinteze. Strukturalna i termička svojstva uzoraka ispitana su FTIR spektroskopijom i termogravimetrijskom analizom (TGA). Morfološke karakteristike kalcijeva oksalata te raspodjela veličine čestica određene su optičkom mikroskopijom i dinamičkim raspršenjem svjetlosti (DLS)

Influence of Aliphatic Chain Length on Structural, Thermal and Electrochemical Properties of n-alkylene Benzyl Alcohols: A Study of the Odd–Even Effect

The century-old, well-known odd–even effect phenomenon is still a very attractive and intriguing topic in supramolecular and nano-scale organic chemistry. As a part of our continuous efforts in the study of supramolecular chemistry, we have prepared three novel aromatic alcohols (1,2- bis[2-(hydroxymethyl)phenoxy]butylene (Do4OH), 1,2-bis[2-(hydroxymethyl)phenoxy]pentylene (Do5OH) and 1,2-bis[2-(hydroxymethyl)phenoxy]hexylene (Do6OH)) and determined their crystal and molecular structures by single-crystal X-ray diffraction. In all compounds, two benzyl alcohol groups are linked by an aliphatic chain of different lengths (CH2)n; n = 4, 5 and 6. The major differences in the molecular structures were found in the overall planarity of the molecules and the conformation of the aliphatic chain. Molecules with an even number of CH2 groups tend to be planar with an all-trans conformation of the aliphatic chain, while the odd-numbered molecule is non-planar, with partial gauche conformation. A direct consequence of these structural differences is visible in the melting points—odd-numbered compounds of a particular series display systematically lower melting points. Crystal and molecular structures were additionally studied by the theoretical calculations and the melting points were correlated with packing density and the number of CH2 groups. The results have shown that the generally accepted rule, higher density = higher stability = higher melting point, could not be applied to these compounds. It was found that the denser packaging causes an increase in the percentage of repulsive H· · · H interactions, thereby reducing the stability of the crystal, and consequently, the melting points. Another interesting consequence of different molecular structures is their electrochemical and antioxidative properties—a non-planar structure displays the highest oxidation peak of hydroxyl groups and moderate antioxidant activit

Precipitation of Calcium Oxalate Monohydrate Under Nearly the Same Initial Supersaturation

Spontaneous precipitation of calcium oxalate monohydrate (COM) in additive-free systems with nearly the same initial supersaturation has been investigated. The influence of thermodynamic parameters such as: temperature (t = 25, 36.5 and 48 °C), calcium concentration range of 5 mmol dm−3 ≤ ci(Ca2+) ≤ 10 mmol dm−3 and pH (5.6, 6.5 and 7.5), on the potential changes in structure, morphology and crystal size of COM have been studied. The values of the initial parameters were varied in a wide range and included values relevant for mimicking the physiological conditions related to those in biological systems and kidney stone formation. The results contributed to the knowledge about the influence of the selected individual parameters as well as their interplay influence on in vitro precipitation of COM. The findings have indicated that COM was the only precipitated phase exhibiting predominant dendritic morphology. The effects on crystal size, structure and morphology are more pronounced at higher temperature, pH and calcium concentration. These results provide basis for future studies of overall mechanism of COM formation and the future studies of kidney stone prevention

Optimization of hydrothermal method towards synthesis of complex metal oxides containing manganese

Sinteza složenih metalnih oksida predstavlja veliki izazov, posebice ako se u jednom konačnom materijalu kombinira više različitih svojstava kao što je to u slučaju multiferoika. Ovim radom istraživani su optimalni uvjeti za sintezu trostrukog perovskita $Sr_{3}Mn_{2}WO_{9}$ hidrotermalnom metodom, koji dosad nije sintetiziran na taj način, niti je poznat kao nanomaterijal. Cilj samoga rada je bio optimizirati uvjete obzirom na temperaturu tijekom reakcije, početne prekursore te puferska sredstva. Tako su sinteze provedene na 150 °C i 200 °C, tijekom 24 h, uz izmjenu manganovih prekursora, $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ te $\left ( CH_{3}COO \right )_{3}Mn$ ∙ $2H_{2}O$, koristeći etanol i limunsku kiselinu kao puferska sredstva. Sintetizirani uzorci kalcinirani su na temperaturi od 950 °C te analizirani termogravimetrijski (TGA) i rentgenskom difrakcijom na prahu (PXRD). Također je elektrokemijski i spektroskopski analizirano ponašanje početnih prekursora otopljenih u vodi, nakon dodatka određene koncentracije mineralizatora NaOH. Najbolje rezultate i poklapanje rentgenskih maksimuma s referentnim $Sr_{3}Fe_{2}WO_{9}$ dao je uzorak koji je sintetiziran pri 150 °C uz manganov prekursor $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ te limunsku kiselinu za pufersko sredstvo.The synthesis of complex metal oxides is a great challenge especially if several different properties are combined into one final material as in the case of multiferroics. This paper investigates the optimal conditions for the synthesis of triple perovskite $Sr_{3}Mn_{2}WO_{9}$ by the hydrothermal method, which has not been synthesized in this way so far, nor it is known as a nanomaterial. The aim of this work was to optimize the conditions with respect to the temperature during the reaction, the initial precursors and buffering agents. Thus, the syntheses were performed at 150 °C and 200 °C for 24 h with exchange of manganese precursors, $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ and $\left ( CH_{3}COO \right )_{3}Mn$ · $2H_{2}O$, using ethanol and citric acid as buffering agents. The synthesized samples were calcined at 950 °C and analyzed by thermogravimetric (TGA) and powder X-ray diffraction (PXRD). The behavior of the initial precursors dissolved in water after the addition of a certain concentration of NaOH mineralizer was also analyzed electrochemically and spectroscopically. The best results and matching of XRD reflections with the reference $Sr_{3}Fe_{2}WO_{9}$ were given by the sample synthesized at 150 °C with manganese precursor $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ and citric acid as a buffering agent

Optimization of hydrothermal method towards synthesis of complex metal oxides containing manganese

Sinteza složenih metalnih oksida predstavlja veliki izazov, posebice ako se u jednom konačnom materijalu kombinira više različitih svojstava kao što je to u slučaju multiferoika. Ovim radom istraživani su optimalni uvjeti za sintezu trostrukog perovskita $Sr_{3}Mn_{2}WO_{9}$ hidrotermalnom metodom, koji dosad nije sintetiziran na taj način, niti je poznat kao nanomaterijal. Cilj samoga rada je bio optimizirati uvjete obzirom na temperaturu tijekom reakcije, početne prekursore te puferska sredstva. Tako su sinteze provedene na 150 °C i 200 °C, tijekom 24 h, uz izmjenu manganovih prekursora, $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ te $\left ( CH_{3}COO \right )_{3}Mn$ ∙ $2H_{2}O$, koristeći etanol i limunsku kiselinu kao puferska sredstva. Sintetizirani uzorci kalcinirani su na temperaturi od 950 °C te analizirani termogravimetrijski (TGA) i rentgenskom difrakcijom na prahu (PXRD). Također je elektrokemijski i spektroskopski analizirano ponašanje početnih prekursora otopljenih u vodi, nakon dodatka određene koncentracije mineralizatora NaOH. Najbolje rezultate i poklapanje rentgenskih maksimuma s referentnim $Sr_{3}Fe_{2}WO_{9}$ dao je uzorak koji je sintetiziran pri 150 °C uz manganov prekursor $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ te limunsku kiselinu za pufersko sredstvo.The synthesis of complex metal oxides is a great challenge especially if several different properties are combined into one final material as in the case of multiferroics. This paper investigates the optimal conditions for the synthesis of triple perovskite $Sr_{3}Mn_{2}WO_{9}$ by the hydrothermal method, which has not been synthesized in this way so far, nor it is known as a nanomaterial. The aim of this work was to optimize the conditions with respect to the temperature during the reaction, the initial precursors and buffering agents. Thus, the syntheses were performed at 150 °C and 200 °C for 24 h with exchange of manganese precursors, $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ and $\left ( CH_{3}COO \right )_{3}Mn$ · $2H_{2}O$, using ethanol and citric acid as buffering agents. The synthesized samples were calcined at 950 °C and analyzed by thermogravimetric (TGA) and powder X-ray diffraction (PXRD). The behavior of the initial precursors dissolved in water after the addition of a certain concentration of NaOH mineralizer was also analyzed electrochemically and spectroscopically. The best results and matching of XRD reflections with the reference $Sr_{3}Fe_{2}WO_{9}$ were given by the sample synthesized at 150 °C with manganese precursor $Mn\left ( NO_{3} \right )_{2}$ ∙ $4H_{2}O$ and citric acid as a buffering agent