SYNTHESIS, MORPHO-STRUCTURAL CHARACTERIZATION AND ELECTROPHORETIC DEPOSITION OF AEGIRINE OBTAINED BY A HYDROTHERMAL METHOD IN THE Si-Fe-Na-H2O SYSTEM

Aegirine belongs to a group of minerals known as inosilicates. In this study, a fast and efficient procedure is proposed for the synthesis of aegirine nanoparticles by means of the hydrothermal process, starting from a suspension of simple hydroxide/silicate precursors. Structural properties of the obtained mineral were assessed by the XRD technique. It was found that aegirine was the only crystalline phase present. The expected needle-like morphology, characteristic of inosilicates, was confirmed by scanning electron microscopy (SEM). Through an appropriate selection of solvents and dispersants, an electrophoretic deposition and immobilization of aegirine on stainless steel was achieved. Native layers of aegirine displayed a very smooth morphology, while after calcination, a detachment of the layers from the stainless steel substrate and the appearance of cracks in the coating was observed. This phenomenon could be prevented by the use of appropriate additives. SINTEZA, MORFO-STRUKTURNA KARAKTERIZACIJA I ELEKTROFORETSKA DEPOZICIJA EGIRINA DOBIJENOG Si-Fe-Na-H2O SISTEMA HIDROTERMALNIM POSTUPKOMEgirin je mineral inosilikatnog tipa. U ovom radu je opisan brz i efikasan hidrotermalni postupak za sintezu nanočestica egirina, polazeći od suspenzije jednostavnih hidroksida/silikata kao prekursora. Strukturne karakteristike dobijenog minerala su proučavane XRD metodom (rendgenska difrakcija praha), pri čemu je utvrđeno da se on sastoji isključivo od kristalne faze. Primenom SEM  metode (skenirajuća elektronska mikroskopija), potvrđena je igličasta struktura minerala, karakteristična za inosilikate. Odabirom odgovarajućeg rastvarača i desperzanta, izvršena je elektroforetska depozicija i imobilizacija egirina na nerđajućem čeliku. Nativni slojevi egirina su posedovali glatku morfologiju, međutim, nakon kalcinacije uočeno je odvajanje prevlake od nosača od nerđajućeg čelika i pojava naprslina. Ovo se može sprečiti upotrebom odgovarajućih aditiva. HIGHLIGHTSFast and efficient synthesis of inosilicate aegirine nanoparticles by a hydrothermal process from hydroxide/silicate precursors was herein proposedStructural properties of the obtained mineral were studied by XRD and SEM techniquesElectrophoretic deposition and immobilization of aegirine on stainless steel was achievedNative layers of aegirinedeposits on stainless steel had a very smooth morphologyThe addition of additives prevented detachment of the layers from the substrate and the appearance of crack

Physicochemically modified peat by thermal and oxidation processes as an active material for purification of wastewaters from certain hazardous pollutants

The physicochemical modification of peat through thermal and oxidation processes was carried out, in order to obtain new, inexpensive and active material for purification of different types of waters. During the modification, surface chemical compounds of Shilov type were formed. Batch adsorption properties and suitability of physicochemically modified peat (PCMP) for odor removal were tested in aqueous solutions of H2S and colloidal sulphur. Additionally, PCMP was tested in the removal of As(V) which is hazardous ingredient in contaminated waters. Possible mechanisms of pollutants binding include interactions, which lead to formation of adducts and clathrates. All these processes are elucidated in detail. The results showed that the obtained material can be used for the removal of sulphide, colloidal sulphur and As(V) from different types of waters