Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation

Abstract

This paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. The precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. Seven compounds were prepared and characterized by thermal analysis, X-ray diffractometry and by surface area measurements. Amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. All these materials present surface area values of >148 m².g-1, determined after heat treatment at 50 °C. The ion exchange behavior of each hydrous zirconium oxide prepared was studied using K+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method

Kinetics of hydrochloric acid leaching of niobium from TiO2 residues

“…A method for separation and pre-concentration of niobium, where an acidic solution is heated to hydrolyse and coagulate niobium, forming niobium oxides has been demonstrated (Marczenko & Kloczko 2000). A similar phenomenon has been observed on other transition metals such as zirconium (Silva et al 2002), nickel (Szymczycha-Madeja 2011), which precipitates as an oxalate at temperatures above 50 o C and titanium, which precipitates as hydrous titanium dioxide at temperatures above 70 o C (Pfaff 2008). For all temperatures investigated, the extraction rate curves show that increasing the residence time above 60 minutes will increase the fraction of niobium extracted in 1.5 M HCl.…”

Nano-crystalline titanium(IV)tungstomolybdate cation exchanger: Synthesis, characterization and ion exchange properties

“…Furthermore, a sharp decrease in IEC is observed as the precipitation temperature is elevated to 120 o C. This may be attributed to the boiling of the synthesized ion exchanger at 120 o C. Our results conquer with the reports made previously [19,29].…”

Metaloxide Nanomaterials and Nanocomposites of Ecological Purpose

“…In this case, unlike heterogeneous deposition, the entire amount of the precipitant appears simultaneously, which prevents local supersaturation in the reaction mixture. The degree of supersaturation depends on the concentration of reagents and the heating temperature, which affects the size of the obtained particles [222]. The sediments obtained by this method are characterized by less polydispersity and greater homogeneity than in the case of the heterogeneous deposition.…”