four different alkaline earth metal oxides i.e. mgo, cao, sro and bao were used as heterogeneous catalysts for biodiesel production from palm oil. effects of critical process variables i.e. reaction time, methanol to oil ratio and temperature were investigated. the results were then fitted to a historical design to study the analysis of variance (anova), to characterize interactions between var...

In concentration of hydrogen peroxide, first, the solution should be quite pure, and then, it concentrate with methods such as vacuum distillation and cooling crystallization, because impurities in the hydrogen peroxide solution in high concentrations are causing decomposition of this substance; that is very dangerous. The purpose of this article is separation of chromium and magne...

Background: There are great resources of natural zeolite in Iran. Zeolite, an inorganic ion-exchanger, may be used as a suitable technical-economical solution for water treatment in many regions of Iran. In this study, the characterization of natural zeolite natrolite and the feasibility of removing hardness, cations, and anions were investigated. Methods: First, zeolite composition and type...

the complexation reaction between hydroxyl ammonium (honh3+ ) cation with 18-crown-6 (18c6) ligand was studied in dimethylsulfoxide – water (dmso-h2o), methanol – water (meoh-h2o) and dimethylformamid – methanol (dmf-meoh), binary solutions at different temperatures using conductometric method. the obtained results show that the stoichiometry of the complex formed between honh3+ cation with (18...

A range of complexes based on the high-nuclearity [W36] isopolyoxotungstate cluster, [H12W36O120]12-, with a triangular topology has been isolated by using the organic cation, protonated triethanolamine. In analogy to an 18-crown-6 crown ether with six oxygen donors on a ring, the cluster can form alkali and alkaline earth metal complexes [M within W36] (M = K+, Rb+, Cs+, NH4+, Sr2+ and Ba2+, 1...

Theoretical reasons for metallic behavior among diverse Zintl phases have generally not been pursued at an advanced level. Here, the electronic structure of Ca5Ge3 (Cr5B3 type), which can be formulated (Ca+2)5(Ge2-6)Ge-4 in oxidation states, has been explored comparatively by means of semiempirical and first-principles density functional methods. The FP-APW calculations show that alkaline-earth...

As a contribution to the study of alkaline iron (III) monophosphates, we recently investigated the A3PO4-M3(PO4)2FePO4 (A: alkali metal; M: divalent cation) using both the flux method and the solid state reaction. This investigation led to the synthesis and structural characterization of twelve new compounds. Their structural analysis showed them to be constructed by PO4 tetrahedra and FeOx pol...

The fresnoite-type compound Sr2TiO(Si2O7), distrontium oxidotitanium disilicate, has been prepared by high-temperature solid-state synthesis. The results of a Rietveld refinement study, based on high-resolution synchrotron X-ray powder diffraction data, show that the title compound crystallizes in the space group P4bm and adopts the structure of other fresnoite-type mineral samples with general...

The observed rates of ribozyme cleavage reactions are strongly dependent on the nature of the metal ion present. Metal ions can thereby exhibit a stronger inhibiting or accelerating effect compared to Mg(2+), which is usually considered the natural cofactor. Alkaline, alkaline earth, transition, d(10), and other metal ions are applied either to gain a spectroscopic handle on the metal center, a...