In this study, the removal of Cr(VI) from aqueous solution by modified zeolite with 3-aminopropyltriethoxysilane was investigated. The effect of various parameters such as pH, contact time, temperature, initial concentration of Cr(VI) ion, common cations, and anions on the adsorption of Cr(VI) was studied. The modified zeolite was characterized by following instrumental analysis of XRD, SEM/EDS, BET, and FT-IR. Based on calculated thermodynamic parameters values (∆G 0 < 0, ∆H 0 > 0, and ∆S 0 > 0) and kinetic properties of the adsorption of Cr(VI) by modified zeolite, it was concluded that the ratelimiting step of the process is a second-order chemical reaction. The results of the adsorption isotherm study confirmed that the adsorption follows the Langmuir isotherm model. The maximum adsorption capacity was 13.5 mg/g.

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Abstract:The silicon organic polymer containing PSOT-3 (dioxothiocarbamide groups) has been synthesized and characterized, and the adsorption of Au(III) on PSOT-3 was investigated. The results showed that PSOT-3 had good adsorption capacity for Au(III), and the adsorption of Au(III) was found to be the most effective in 0.1~0.3 mol/dm 3 hydrochloric acid solution. The adsorption is physical and the process is endothermic, and Freundlich isotherm fits the data better than the Langmuir isotherm. The adsorption can be generally described by electrostatic interaction (Coulomb's force) between the adsorbent and the adsorbate. The high adsorption capacity of this sorbent has significant potential for gold recovery from aqueous solutions.

In the research, we show that suboxidic Ti7O13 and rutile TiO2 phases formed in addition to the general Ti3O5 phase when the sintering temperature was set at constant argon gas flow rate. Suboxidic Ti7O13 and rutile TiO2 phases were removed by tuning the flow rate of argon gas at constant sintering temperature. At the 1300°C temperature, the smallest Ti3O5 nanocrystals with a size of ~9 nm were produced. Flat shaped particles of Ti3O5 crystals were observed in SEM measurements.

In this research work, a new type of absorbent material was obtained using kaolin which is produced by clay of the "Tsogt-Ovoo" deposit in Umnogovi province. The kaolin was produced by removing its mechanical impurities from clay and treating it to acid and heat treatment. When producing a chitosan based new absorbent bead, pure chitosan and mixtures of chitosan and kaolin (8:1, 8:2 and 8:3) with certain ratios were subjected to chemical processing. It was determined that the absorption capacity of chromium ion (Cr(VI)) was the highest when chitosan and kaolin mass ratio was 8:2. The adsorption activity of Cr(VI)in chitosan-based adsorbent was studied depending on the pH of the solution, time, temperature, initial concentration of chromium ion solution and mass of adsorbent material. The degree of absorption was the highest (80.25%) when initial concentration of thechromium ion solution is 50 mg/l, temperature is 250C, contact time is 3h and the mass of the adsorbent material is 0.1 g. It shows that this chitosan based adsorbent bead can be used for the separation of chromium (Cr(VI)) from aqueous solutions. Читосан суурьтай шинэ материалын +6 валенттай хром шингээх идэвхийн судалгаа Хураангуй: Тус судалгааны ажлын хүрээнд Өмнөговь аймгийн нутагт орших “Цогт-Овоо” ордын шаврын дээжийг механик хольцоос салган, хүчлийн ба дулааны боловсруулалтад оруулж бэлтгэсэн каолиныг ашиглан шинэ төрлийн шингээгч материал гарган авав. Читосан суурьтай, үрэл хэлбэрийн шинэ төрлийн шингээгч материалыг гарган авахдаа цэвэр читосан болон тодорхой харьцаа бүхий читосан ба каолины (8:1, 8:2 ба 8:3) хольцыг химийн боловсруулалтад оруулж гарган авсан. Туршилтаар 8:2 массын харьцаа бүхий читосан ба каолинын хольцыг ашиглан гарган авсан үрэл хэлбэрийн шингээгч материалын +6 валенттай хром (Cr(VI)) шингээх шингээлтийн багтаамж хамгийн өндөр болохыг тогтоов. Читосан суурьтай шинэ төрлийн шингээгч материалын усан уусмалаас Cr(VI) шингээх идэвхийг уусмалын рН, хугацаа, температур, хромын уусмалын анхны концентраци ба шингээгч материалын массаас хамааруулан судалж үзэхэд уусмалын орчин pH 3, шингээлтийн хугацаа 3 цаг, шингээлтийн температур T= 25℃, хромын уусмалын анхны концентраци 50 мг/л, шингээгч материалын масс 0.1 г байх нөхцөлд шингээлтийн зэрэг хамгийн өндөр буюу 80.25% байна. Энэхүү шинэ материалыг усан уусмалаас хромыг (Cr(VI)) ялгахад ашиглах боломжтой гэж үзэж байна. Түлхүүр үг: адбсорбент, металлын ион, усан орчин, шингээлтийн багтаамж