Sol-Gel Combustion Synthesis, Crystal Structure and Luminescence of Cr3+ and Mn4+ Ions in Nanocrystalline SrAl4O7

A series of strontium dialuminate SrAl4O7 nanopowders with the grossite-type structure doped with chromium and manganese ions were synthesized by the combined sol–gel solution combustion method with use of two different strontium salts. The Cr3+ and Mn4+ ions concentrations were varied from 0.05 to 5 at.%. Evolution of phase composition, crystal structure, and microstructural parameters of the nanocrystalline materials depending on the synthesis conditions, temperature of thermal treatment, and dopant content were investigated by the X-ray powder diffraction and the scanning electron microscopy techniques. Photoluminescent properties of SrAl4O7 nanophosphors activated with Cr3+ and Mn4+ ions were studied at room temperature. The samples exhibit typical photoluminescence in the deep-red spectral region, corresponding to d-d transitions in Cr3+ or Mn4+ ions. The intensity of this deep-red emission is dependent on the dopant concentration and annealing temperature. Features of the formation of octahedral surroundings around Cr3+ or Mn4+ ions are discussed.

Economic Evaluation of Different Fuels in the Production of La2NiO4 Particles using A Sol-Gel Combustion

Lanthanum nickelate (La2NiO4) is a precursor for producing lanthanum pentanickel (LaNi5) alloys for nickel-metal hydride battery (NiMH; a type of rechargeable battery), which has been developed quite rapidly for many applications, such as Hybrid Electric Vehicles. The purpose of this study was to evaluate the economic feasibility of the production of La2NiO4 with different fuels (i.e., glycine fuel (F-G) and citric acid fuel (F-CA)) using a sol-gel combustion method. Several economic evaluation parameters were analyzed, such as gross profit margin, internal rate of return, payback period, cumulative net present value, and so on. The project was evaluated from the ideal condition to the worst-case conditions, including labor, sales, raw material, utility, as well as external conditions (e.g., tax). The results showed that the production of La2NiO4 is prospective from engineering and economic perspectives. The engineering analysis for both production steps using F-G and F-CA is feasible, and the production can be done even in small-scale production using commercially available apparatus. The economic analysis showed that the process using F-CA is better than that using F-G. From this economic evaluation analysis, the project is profitable and the recovery of the investment is less than seven years for F-G and four years for F-CA. Although this project is feasible to run and profitable, it is not attractive to industrial investors due to the fewer values in some parameters. Thus, since this material is very important to reduce dependence on imports, additional further technologies for improving processes and support from Corporate Social Responsibility (CSR) and government are important for maintaining this project.

Highly Enhanced Adsorption For The Removal of Hg (II) From Aqueous Solution By Co-Polymerized Al2O3 Nanocomposites Fabricated By Improved Sol-Gel Combustion Route: Synthesis, Adsorption Kinetics & Isotherm Modelling

The synthesis, characterization and capacity studies of co-polymerized Al2O3 nanocomposites capable of adsorbing with Hg(II) ions are reported. Al2O3 nanoparticles was fabricated with combustion synthesis using inexpensive mixed fuels. Nanocomposite of poly (aniline-CO-O-anthranilic acid) (PANAA/ Al2O3) was synthesized by chemical oxidative polymerization of anthranilic acid and aniline co-monomers at equimolar ratios (1:1) with the Al2O3 nanostructure. The product was characterized by FT-IR, XRD, SEM and TEM techniques. The adsorption behaviors of the toxic Hg(II) were studied. The equilibrium isotherm, kinetics parameters and the thermodynamics investigations of the adsorption process were calculated. Thermodynamics investigations also confirmed that the adsorption capacity of Hg(II) on each adsorbent was spontaneous and exothermic.

Removal of Malachite Green Dye from Aqueous Solutions by an Efficient Nanosized NiO Fabricated by a Facile Sol-Gel Autocombustion

Nickel oxide nanostructures were synthesized via a sol-gel combustion method using glucose, glycine and tartaric acid fuels. The effect of the fuel type on the formed nanostructures was studied. The as-prepared products were characterized by means of FE-SEM, HR-TEM, XRD, and FT-IR analyses. The results exhibited that the used fuels gave NiO products with different morphologies, and the glucose fuel produced pure NiO nanoparticles with the smallest crystallite size (ca. 8.2 nm). The adsorption properties of the NiO products for the removal of malachite green dye (MG) was examined. Using a batch method, various parameters affecting the adsorption properties were studied. The results revealed that NiO nanostructure generated from the glucose fuel had the highest adsorption capacity