In this study, the effects of deposited gypsum residues on the surrounding environment and radiation exposure in plants and animals were evaluated under various exposure situations. A waste stockyard in a Korean facility (surrounded by mountains and sea) was used to store phosphogypsum, a byproduct of phosphoric acid processes, in a slurry form in a large gypsum storage facility (provided separately on the facility site). The ERICA tool was used to evaluate the impact of radiation on nonhuman environments for mineral processing and waste storage for risk estimation.
View Article and Find Full Text PDFA standard addition (SA) calibration method for determining uranium and thorium in naturally-occurring radioactive materials (NORMs) was studied. Pretreatment method using fusion was established and optimized. The SA method was validated (LOD, LOQ, linearity, selectivity, and accuracy) using certified reference materials (SRM 2709a, RM-ZR, and RM-BX).
View Article and Find Full Text PDFE-wastes comprise complex combinations of potentially toxic elements that cause detrimental effects of the environmental contamination; besides their posing threat, most of the products also contain valuable and recoverable materials (Li, Au, Ag, W, Se, Te, etc.), which make them distinct from other forms of industrial wastes. Most of these value-added elements which are primarily employed in electronic goods are disposed of by incineration and land-filling.
View Article and Find Full Text PDFTransition metal hydroxides (M-OH) and their heterostructures (X|M-OH, where X can be a metal, metal oxide, metal chalcogenide, metal phosphide, etc.) have recently emerged as highly active electrocatalysts for hydrogen evolution reaction (HER) of alkaline water electrolysis. Lattice hydroxide anions in metal hydroxides are primarily responsible for observing such an enhanced HER activity in alkali that facilitate water dissociation and assist the first step, the hydrogen adsorption.
View Article and Find Full Text PDFElectrocatalytic splitting of water is the most convincing and straight forward path to extract hydrogen, but the efficiency of this process relies heavily on the catalyst employed. Here, molybdenum sulphoselenophosphide (MoS Se P ) spheroids are reported as an active catalyst for the hydrogen evolution reaction (HER) and this is the first attempt to study on ternary anion based molybdenum chalcogenides. As-prepared MoS Se P catalyst reveals a unique morphology of microspheroids capped by stretched-out nanoflakes that exhibits excellent electrocatalytic activity ( j-10 mA cm @ 93 mV, Tafel slope of 50.
View Article and Find Full Text PDFA dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters.
View Article and Find Full Text PDFIn a study of hydrogen-producing bacteria, strain T4384 was isolated from rice field samples in the Republic of Korea. The isolate was identified as Enterobacter sp. T4384 by phylogenetic analysis of 16S rRNA and rpoB gene sequences.
View Article and Find Full Text PDFBased on first-principles plane wave calculations, it was shown that boron substituted graphene with Ti metal atom adsorption can be used as a high capacity hydrogen storage material. Boron substitution in graphene enhances the Ti metal adsorption energy, which is much larger than that in the case of pure graphene, and than the Ti cohesive energy. The Ti metal atom can be well dispersed on boron-substituted graphene and can form a 2 x 2 pattern because the clustering of the Ti atoms is hindered by the repulsive Coulomb interaction between them.
View Article and Find Full Text PDFA three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e.
View Article and Find Full Text PDFIn this study, a three-zone carousel process based on a proper molecular imprinted polymer (MIP) resin was developed for continuous separation of Cu(2+) from Mn(2+) and Co(2+). For this task, the Cu (II)-imprinted polymer (Cu-MIP) resin was synthesized first and used to pack the chromatographic columns of a three-zone carousel process. Prior to the experiment of the carousel process based on the Cu-MIP resin (MIP-carousel process), a series of single-column experiments were performed to estimate the intrinsic parameters of the three heavy metal ions and to find out the appropriate conditions of regeneration and re-equilibration.
View Article and Find Full Text PDFIn the present study, silver-doped silica thin films were successfully prepared by sol-gel method to apply for antibacterial materials. The starting solution was prepared from 1:0.24:3.
View Article and Find Full Text PDFJ Colloid Interface Sci
June 2000
In this study, Y(2)O(3):Eu luminescent nanoparticles were prepared by precipitation of aqueous yttrium nitrate/europium nitrate solution using ammonium hydroxide in the reverse microemulsions based on polyoxyethylene (5) nonylphenyl ether/polyoxyethylene (9) nonylphenyl ether, cyclohexane, and water. With Eu-doped Y(2)O(3) nanoparticles obtained, particle size, shape, chemical composition, crystalline formation rate, crystallinity, and photoluminescence were measured and compared with those of particles formed by a bulk precipitation method. The nanoparticles synthesized in microemulsion showed a narrow size distribution, spherical shape, fast crystalline formation rate, high crystallinity, and strong photoluminescence.
View Article and Find Full Text PDF