Thermo-physical properties measurements of hygroscopic and reactive material (zeolite 13X) for open adsorptive heat storage operation

Journal of Thermal Analysis and Calorimetry - The determination of the thermo-physical properties (density, specific heat capacity, and thermal conductivity) of hygroscopic and reactive solid...     

Cationic dyes adsorption onto high surface area ‘almond shell’ activated carbon: Kinetics,equilibrium isotherms and surface statistical modeling

Almond shell agricultural biomass was used to prepare high surface area activated carbon using potassium hydroxide as activating agent. The activated carbon (AC) was characterized using X-Ray photoelectron spectroscopy, X-Ray diffraction, Thermogravimetric and differential thermal analyses, Scanning electron microscopy, Fourier transform infrared, Brunauer–Emmett–Teller surface area and Raman spectroscopy. The AC was found to have a high surface area of 2054 m² g^?1. The influence of various key parameters was evaluated on the adsorption process including contact time, adsorbent dose and solution pH. Isotherm data were modeled using Langmuir and Freundlich models. Langmuir isotherm model presented the best fit to experimental data suggesting homogeneous distribution of adsorption sites. The adsorbent demonstrated high monolayer adsorption capacity of 833.33 and 625.0 mg/g for Methylene Blue and Crystal Violet, respectively. The efficiency of the adsorption process was linked to the micro-mesoporous structure and to the availability of the surface adsorption sites. Response surface methodology was used to optimize the removal efficiency from aqueous solution.     

Synthesis of nanosized TiO2 powder by sol gel method at low temperature

ABSTRACT

Nanotechnology is all about making products from very small constituents, components or subsystems to gain greatly enhanced material properties and functionality. Nanocrystalline anatase TiO₂ was prepared by a facile sol–gel route at a temperature of 50°C under mild conditions. Titanium tetraisopropoxide (TTIP) was used as a titanium precursor, and 2-propanol was used as a solvent. XRD, TEM, SEM, FT-IR and BET were applied to characterize the crystal phase. The Crystalline size of TiO₂ powder has been obtained with diameter < 30 nm for anatase at 500°C using an acid.     

Effects of lutetium doping on the X-ray-excited luminescence properties of the tungstate Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Lu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>WO<Subscript>4</Subscript>

Polycrystalline samples in the lutetium-doped zinc tungstate system Zn_1?x Lu _x WO₄ with 0 ≤ x ≤ 0.08 were synthesized using the coprecipitation method followed by thermal treatment at 1000 °C during 4 h. The polycrystalline samples were characterized by X-ray diffraction analysis, scanning electron microscopy (SEM), infrared spectroscopy, and luminescence analysis under X-ray excitation. Rietveld analyses were performed. The variation of the wolframite structure cell parameters in the range 0 ≤ x ≤ 0.05 were congruent with substitution of Zn²⁺ by Lu³⁺. SEM micrographs of the obtained samples presented improved crystallization with morphology depending on the lutetium fraction. The luminescence spectra obtained under X-ray excitation (E < 40 keV) were in the blue–green region, and their intensity increased with x up to x = 0.05. The differences in the intensities of the X-ray luminescence spectra could be related to additional cation vacancies resulting from substitution of Zn²⁺ by Lu³⁺.