Mongolian Journal of Chemistry 2018-03-09T16:43:08+00:00 Academician J. Temuujin Open Journal Systems <p>Published by the Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences.</p><p>The Mongolian Journal of Chemistry is included on <a title="DOAJ" href="" target="_blank">DOAJ</a> and the <a title="EBSCO" href="" target="_blank">EBSCO Discovery Service</a> and <span>CAS databases</span></p> Preface 2018-02-13T17:06:10+00:00 Temuujin J 2018-02-13T17:06:10+00:00 ##submission.copyrightStatement## Preparation of rare earth oxides from Synchysite oxidized ore by acid leaching 2018-02-13T17:06:13+00:00 Temuujin J Burmaa G Davaabal B D S Kim H J Lee Mixed rare earth oxides have been prepared from synchysite ore from the Lugiin gol rare earth deposit (Mongolia) which contains about 6% of cerium light rare earth elements. Ore powders were leached for up to 60 min using 80-120 g/l sulfuric acids at an acid to powder ratio of 20, agitation was performed by magnetic stirring followed by precipitation and calcination at 700°C for 1h. The highest leaching of REEs equal to 85% of the total REE was observed in the acid solution of 80 g/l. Obtained mixed rare earth oxides represent a layered type structure. 2018-02-13T17:06:13+00:00 ##submission.copyrightStatement## Adsorption of methylene blue from aqueous solutions by pyrolusite ore 2018-02-13T17:06:19+00:00 Nizamettin Demirkıran G D Turhan Özdemir M Saraç M Dardağan In this study, the adsorption of methylene blue dye was examined by using pyrolusite ore as a low-cost alternative adsorbent source. Pyrolusite, which contains mainly MnO<sub>2</sub>, is a manganese ore. The effects of the initial concentration of dye, contact time, initial pH of solution, adsorbent dosage, stirring speed of solution, and average particle size of adsorbent on the adsorption of methylene blue were studied. It was found that the percentage of the adsorbed dye increased with increasing the amount of pyrolusite. While the initial dye concentration, initial pH, contact time, stirring speed, particle size, and adsorbent dosage were 25 ppm, 6, 90 min, 250 rpm, 63 µm, and 12 g/l, respectively, the efficiency of dye adsorption on pyrolusite ore was 99%. The isotherm and kinetic studies relating to this adsorption process were also made. It was found that the equilibrium data followed the Langmuir isotherm model while the kinetic of process could be described by the pseudo-second order kinetic model. 2018-02-13T17:06:19+00:00 ##submission.copyrightStatement## Arsenic occurrence in water bodies in Kharaa river basin 2018-02-13T17:06:25+00:00 Azzaya T Burmaa G S Alen Narangarav T Nyamdelger Sh Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Gold mining activity is one of the anthropogenic sources of environmental contamination regarding As and other heavy metals. In Mongolia, the most productive gold mining sites are placed in the Kharaa river basin. A hundred water samples were collected from river, spring and deep wells in this river basin. Along with total As and its species-As(III) and As(V), examination of concentration levels of other key parameters, 21 heavy metals with pH, total hardness, electric conductivity, anion and cations, was also carried out. In respect to the permissible limit formulated by the Mongolian National Drinking water quality standard (MNS 0900:2005, As10 µg/l), the present study showed that most of samples were found no contamination. In Kharaa river basin, an average concentration of total As in surface water was 4.04 µg/l with wide range in 0.07−30.30 µg/l whereas it was 2.24 µg/l in groundwater. As analysis in surface water in licensed area of Gatsuurt gold mining showed a mean concentration with 24.90 µg/l presenting higher value than that of value in river basin by 6 orders of magnitude and it was 2 times higher than permissible level as well. In Boroo river nearby Boroo gold mining area, As concentration in water was ranged in 6.05−6.25 µg/l. Ammonia pollution may have present at estuary of Zuunmod river in Mandal sum with above the permissible level described in national water quality standard. Geological formation of the rocks and minerals affected to <br />change of heavy metal concentration, especially As and uranium (U) at spring water nearby Gatsuurt-Boroo improved road. 2018-02-13T17:06:25+00:00 ##submission.copyrightStatement## Kinetic study of Mongolian coals by thermal analysis 2018-02-13T17:06:34+00:00 Jargalmaa S Tsatsral G Battsetseg M Batkhishig D Ankhtuya A Namkhainorov J Bat-Ulzii B Purevsuren B Avid B Thermal analysis was used for the thermal characterization of the coal samples. The experiments were performed to study the pyrolysis and gasification kinetics of typical Mongolian brown coals. Low rank coals from Shivee ovoo, Ulaan ovoo, Aduun chuluun and Baganuur deposits have been investigated. Coal samples were heated in the thermogravimetric apparatus under argon at a temperature ranges of 25-1020ºC with heating rates of 10, 20, 30 and 40ºC/min. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were performed to measure weight changes and rates of weight losses used for calculating the kinetic parameters. The activation energy (E<sub>a</sub>) was calculated from the experimental results by using an Arrhenius type kinetic model. 2018-02-13T17:06:34+00:00 ##submission.copyrightStatement## Influence of compressing pressure on macro void formation of carbon monolith for methane adsorption 2018-02-13T17:07:03+00:00 Narandalai B W G Shim M S Balathanigaimani H Moon Carbon monoliths for adsorbed natural gas (ANG) storage were prepared from Mongolian anthracite-based activated carbons using carboxy-methyl cellulose as a binder under different compressing pressures. Nitrogen adsorption/desorption experiments were carried out to obtain the specific surface area, pore volume, and pore size distribution of the monoliths.  Methane adsorption experiments on the carbon monoliths were conducted at different temperatures and pressures up to around 3.5 MPa in a high pressure volumetric adsorption apparatus. As expected, adsorption results indicated that the methane adsorption capacity of the carbon monoliths increased with increasing specific surface area and packing density.  The maximum volumetric adsorption of methane was observed as 163 V/V at 293 K and 3.5 MPa on a carbon monolith sample, PMAC1/2-3-65, that does not have the highest specific surface area but relatively high packing density comparing with other monoliths, which implies that two physical properties contribute contradictorily to the methane adsorption capacity.  Based on experimental results, the carbon monoliths prepared from Mongolian anthracite-based activated carbons can be promising media for ANG storage application. 2018-02-13T17:07:03+00:00 ##submission.copyrightStatement## Synthesis and electrocatalytic activity towards oxygen reduction reaction of gold-nanostars 2018-02-13T17:07:10+00:00 Oyunbileg G Batnyagt G Enkhsaruul B T Takeguchi The oxygen reduction reaction (ORR) is a characteristic reaction which determines the performance of fuel cells which convert a chemical energy into an electrical energy. Aims of this study are to synthesize Au-based nanostars (AuNSs) and determine their preliminary electro-catalytic activities towards ORR by a rotating-disk electrode method in alkaline electrolyte. The images obtained from a scanning electron microscope (SEM) and a transmission electron microscope (TEM) analyses confirm the formation of the star-shaped nanoparticles. Among the investigated nanostar catalysts, an AuNS5 with smaller size and a few branches showed the higher electrocatalytic activity towards ORR than other catalysts with a bigger size. In addition, the electron numbers transferred for all the catalysts are approximately two. The present study results infer that the size of the Au-based nanostars may influence greatly on their catalytic activity. The present study results show that the further improvement is needed for Au-based nanostar catalysts towards the ORR reaction. 2018-02-13T17:07:10+00:00 ##submission.copyrightStatement## Preparation of “Open/closed” pores of PLGA-microsphere for controlled release of protein drug 2018-02-13T17:07:17+00:00 Odonchimeg M S C Kim Y K Shim W K Lee Poly(D,L-lactic-co-glycolic acid)  has been extensively used as a controlled release carrier for drug delivery due to its good biocompatibility, biodegradability, and mechanical strength. In this study, porous PLGA microspheres were fabricated by an emulsion-solvent evaporation technique using poly ethylene glycol (PEG) as an extractable porogen and loaded with  protein (lysozyme) by suspending them in protein solution. For controlled release of protein, porous microspheres containing lysozyme were treated with water-miscible solvents in aqueous phase for production of pore-closed microspheres. The surface morphology of microspheres were investigated using scanning electron microscopy (SEM) for confirmation of its porous microstructure structure. Protein property after release was observed by enzymatic activity assay. The pore-closing process resulted in nonporous microspheres which exhibited sustained release patterns over an extended period. 2018-02-13T17:07:17+00:00 ##submission.copyrightStatement## Chemical compositions of essential oils from two Artemisia species used in Mongolian traditional medicine 2018-02-13T17:07:23+00:00 Javzmaa N Altantsetseg Sh Shatar S Amarjargal A <p>Essential oils of aromatic and medicinal plants generally have a diverse range of activities because they possess many active constituents that work through a several modes of action. <em>Artemisia</em>, the largest genus of the family Asteraceae, has a number of effects against human and plant diseases. The main purpose of the present study was to investigate chemical compositions of essential oils of two <em>Artemisia</em> species,<em> Artemisia</em> <em>palustris</em> L and <em>Artemisia</em> <em>sericea</em> Weber ex Stechm from the Mongolian steppe zone using gas chromatography and gas chromatography-mass spectrometry. The essential oil of<em> A.palustris</em> was characterized by the presence of monoterpene hydrocarbons such as <em> trans-β-</em>ocimene (59.1%),<em> cis-β-</em>ocimene (11.6%) and myrcene (7.1%), while the oil of <em>A.sericea</em> was dominated by the presence of three oxygenated monoterpenoids as 1,8-cineole (25.8%), borneol (22.5%) and camphor (18.8%) which are used for preparation of a fragrance and medicinal products.</p> 2018-02-13T17:07:23+00:00 ##submission.copyrightStatement## Biosorption of lead (II) from an aqueous solution using biosorbents prepared from water plants 2018-02-13T17:07:30+00:00 Tseveendorj E Enkhdul T S Lin Dorj D Oyungerel Sh Soyol-Erdene T.O Due to its toxicity causing serious health problems, persistence in the environment and non-biodegradability, lead (Pb) is considered as one of the most harmful metals on earth. In this study, dried aquatic plants as sorbents including <em>Nymphoides peltata</em> (NP), <em>Typha laxmannii</em> (TL), and <em>Eichhornia crassipes</em> (EC) were examined and compared to discover the best biosorption for Pb. The effect of physical and chemical parameters including pH (2.0–5.5), sorbent dosage (1–5 g/l), metal concentration (20–100 mg/l), and contact time (~240 min) were investigated to determine the optimal condition for Pb(II) biosorption. As a result, the optimum pH, sorbent dosage, and contact time were 5.0, 1 g/l, and 120 minutes, respectively. Pb<sup>2+</sup> biosorption data were found to follow the Langmuir isotherm model while the kinetic biosorption data followed pseudo-second-order model. The maximum biosorption capacity from Langmuir model was calculated as 63.3, 82.9, and 51.9 mg/g for EC, NP, and TL, respectively. All the results showed that biosorption efficiencies of Pb(II) by different biosorbents were in following order NP&gt;EC&gt;TL. 2018-02-13T17:07:30+00:00 ##submission.copyrightStatement## Retraction Notice: Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis 2018-03-09T16:43:08+00:00 Byambasuren O Ulziibayar D Chiibaatar D <p>On 3rd March 2018, the Editorial Board of the Mongolian Journal of Chemistry decided to retract the article entitled "Effect of pretreatment temperature on catalytic performance of the catalysts derived from cobalt carbonyl cluster in Fischer-Tropsch Synthesis" because of an authorship dispute. The article was originally published in Vol.17 No.43 2016 pp.38-41. <br /> DOI: <a href="" target="_self"></a></p> 2018-03-09T00:00:00+00:00 ##submission.copyrightStatement##