• Environmental Engineering Research
• /
• v.25 no.4
• /
• pp.579-587
• /
• 2020

Novel silane grafted bentonite was obtained using the natural bentonite as precursor material. The material which is termed as nanocomposite was characterized by the Fourier Transform Infra-red (FT-IR) and X-ray diffraction (XRD) methods. The surface imaging and elemental mapping was performed using Scanning Electron Microscopic (SEM/EDX) technique. The electroanalytical studies were performed using the nanocomposite electrode. The electroactive surface area of nanocomposite electrode was significantly increased than the pristine bentonite or bare carbon paste based working electrode. The impedance spectroscopic studies were conducted to simulate the equivalent circuit and Nyquist plots were drawn for the carbon paste electrode and nanocomposite electrodes. A single step oxidation/reduction process occurred for As(III) having ΔE value 0.36 V at pH 2.0. The anodic stripping voltammetry was performed for concentration dependence studies of As(III) (0.5 to 20.0 ㎍/L) and reasonably a good linear relationship was obtained. The detection limit of the As(III) detection was calculated as 0.00360±0.00002 ㎍/L having with observed relative standard deviations (RSD) less than 4%. The presence of several cations and anions has not affected the detection of As(III) however, the presence of Cu(II) and Mn(II) affected the detection of As(III). The selectivity of As(III) was achieved using the Tlawng river water sample spiked with As(III).

• Korean Journal of Environmental Agriculture
• /
• v.10 no.2
• /
• pp.133-137
• /
• 1991

The inorganic constituents in flay ash such as Ca, Mg, Al and Si were extracted by water and 0.5N-Acetic acid, and changes of the physical properties of the fly ash-treated soils were examined to find out the effect of fly ash on the chemical and physical properties of the soils. The dominant day minerals of fly ash were quartz and mullite. More inorganic constituents were extracted from the fly ash by acetic acid than by water. Si and A1 in fly ash were hardly extracted by water. Addition of fly ash to soil below 10%(W/W) caused improvement in the water permeability and the field moisture capacity of the soil, but did not influence the shrinkage and hardness of the soil. Therefore, it was apparent that the effect of the fly ash on the chemical and physical properties of the soils greatly dependedon soil reaction, the organic acid contents, and the amount of fly ash used in treatment.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.11
• /
• pp.1464-1472
• /
• 2014

The microbial community structures of two continuous stirred tank reactors digesting turkey manure with pine wood shavings as well as chicken and swine manure were investigated. The reactor fed with chicken/swine wastes displayed the highest organic acids concentration (up to 15.2 g/l) and ammonia concentration (up to 3.7 g/l ammonium nitrogen) and generated a higher biogas yield (up to $366ml/g_{VS}$) compared with the reactor supplied with turkey wastes (1.5-1.8 g/l of organic acids and 1.6-1.7 g/l of ammonium levels; biogas yield was up to $195ml/g_{VS}$). The microbial community diversity was assessed using both sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Additionally, methanogens were analyzed using methyl coenzyme M reductase alpha subunit (mcrA) genes. The bacterial community was dominated by members of unclassified Clostridiales with the prevalence of specific clostridial phylotypes in each reactor, indicating the effect of the substrate type on the community structure. Of the methanogenic archaea, methanogens of the genus Methanosarcina were found in high proportions in both reactors with specific methanosarcinas in each reactor, whereas the strict hydrogenotrophic methanogens of Methanoculleus sp. were found at significant levels only in the reactor fed with chicken/swine manure (based on the analyses of 16S rRNA gene). This suggests that among methanogenic archaea, Methanosarcina species which have different metabolic capabilities, including aceticlastic and hydrogenotrophic methanogenesis, were mainly involved in anaerobic digestion of turkey wastes.

• Environmental Engineering Research
• /
• v.22 no.2
• /
• pp.186-192
• /
• 2017

The carbon paste electrode (CPE) was modified with the pristine bentonite and hybrid material (HDTMA-modified bentonite). The modified-CPEs are then employed as working electrode in an electrochemical detection of As(V) from aqueous solutions using the cyclic voltammetric measurements. Cyclic voltammograms revealed that As(V) showed reversible behavior onto the working electrode. The hybrid material-modified carbon paste electrode showed significantly enhanced electrochemical signal which was then utilized in the low level detection of As(V). Moreover, the studies were conducted at neutral pH conditions. The electrochemical studies were conducted with scan rates (20 to 200 mV/s) to deduce the mechanism of redox processes involved at the electrode surface. The anodic current was linearly increased, increasing the concentration of As(V) from 5.0 to $35.0{\mu}g/g$ using the hybrid material-modified electrode. This provided fairly a good calibration line for As(V) detection. The presence of varied concentrations of As(III) in the determination of total arsenic was studied. The influence of several cations and anions viz., Cu(II), Mn(II), Zn(II), Pb(II), Cd(II), Fe(III), $Cl^-$, $NO_3{^-}$, $PO_4{^{3-}}$, EDTA and glycine in the detection of As(V) from aqueous solution was also studied. Further, in an attempt to simulate the real matrix analysis, the tap water sample was spiked with As(V) and subjected for As(V) detection using the modified-CPE.

• Polymer(Korea)
• /
• v.38 no.3
• /
• pp.307-313
• /
• 2014

The physical properties of functionalized graphene sheet (FGS)/poly(ethylene-co-vinyl acetate) (EVA) was examined with various kinds of EVA, having vinyl acetate (VA) contents in the range of 0 to 40 wt%. The compatibility between FGS and EVA was enhanced as the polar VA content of EVA increased. Thus, the dispersion of FGS in EVA became finer, and the decrease of surface resistivity and the increase of tensile modulus by the added FGS became more effective when the VA content of EVA was high. When the VA content was low, the elongation at break was reduced drastically by added FGS due to the poor adhesion of FGS/EVA interface. The crystallization of EVA was generally retarded by the interaction with dispersed FGS. However, when both the VA content of EVA and the added amount of FGS were low, the crystallization of EVA was enhanced, probably due to the predominant nucleating effect by FGS.

• Nuclear Engineering and Technology
• /
• v.51 no.7
• /
• pp.1799-1804
• /
• 2019

The concept of a new method, the CARBEX (CARBonate EXtraction) process, was proposed for reprocessing of spent uranium oxide fuel. The proposed process is based on use of water solutions of $Na_2CO_3$ or $(NH_4)_2CO_3$ and solvent extraction (SE) by the quaternary ammonium compounds for selective recovery and purification of U from the fission products (FPs). Applying of SE allows to reach high degree of purification of U from FPs. Carrying out the processes in poorly aggressive alkaline carbonate media leads to increasing safety of SNF's reprocessing and better selectivity of separation of lanthanides and actinides. Moreover carbonate reprocessing media allows to carry out a recycling and regeneration of reagents. We have been done laboratory scale experiments on the extraction components of simulated voloxidated spent fuel in the solutions of NaOH or $Na_2CO_3-H_2O_2$ and recovery of U from carbonate solutions by SE method using carbonate of methyltrioctylammonium in toluene. It was shown that the purification factors of U from impurities of simulated FPs reached values $10^3-10^5$. The received results support our opinion that CARBEX after the further development can become more safe, simple and profitable method of spent fuel reprocessing.

• Applied Biological Chemistry
• /
• v.38 no.2
• /
• pp.147-150
• /
• 1995

Effects of gelation conditions on physical properties of dover sole skin gelatin prepared by fractional precipitation with ethanol were investigated. The physical properties such as gel strength, melting point and gelling point of both ethanol treated and non-ethanoltreated gelatins were improved as concentration of gelatin was increased. The physical property of 10% ethanol treated gelatin sol reached maximum at pH 6.0, whereas non-treated one showed maximum at pH 5.0. Both ethanol treated and non-treated gelatin gel showed the higher gel strength and melting point at lower temperatures and longer period of time. Generally, the physical properties of ethanol treated gelatin gel was better than those of non-ethanol treated gel.

• Applied Chemistry for Engineering
• /
• v.16 no.1
• /
• pp.101-106
• /
• 2005

Photocurable modified 6 functional polyacrylate(PA-1) were prepared from dipentaerythritol derivatives (DPET) and acrylic acid, and 12 functional polymethacrylate(PA-2) were prepared from dipentaerythritol derivatives (DPET), trimellitic anhydride, and glycidyl methacrylate. And physical properties of photocurable modified poly(meth)acrylate were increased with increasing functionality of (meth)acrylate. Thermal stability of UV cured film obtained by using TGA was shifted to higher temperature as the increasing of functionality. Hardness, abrasion resistance and tensile strength of UV cured film were increased with increasing functionality of (meth)acrylate. Values of yellow index were increased with increasing functionality of (meth)acrylate.

• Applied Chemistry for Engineering
• /
• v.16 no.1
• /
• pp.93-100
• /
• 2005

8 functionality photocurable polyester polyol modified hyperbranched methacrylates of two types were prepared from trimellitic anhydride, glycidyl methacrylate, and 4 functionality polyester polyol of two types. The physical properties of photocurable polyester polyol modified hyperbranched methacrylate were investigated. Thermal stability obtained by using TGA showed that HBMA-2 (hyperbranched methacrylate-2) was superior to the HBMA-1 (hyperbranched methacrylate-1). Hardness, abrasion resistance and tensile strength of HBMA-2 showed that were also superior to the HBMA-1. Value of yellow index of HBMA-2 showed the higher.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.257-257
• /
• 2006

We chose three synthetic polymers, poly(propylene carbonate) (PPC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP), and $Nafion^{(R)}$ that reveal different chemical and physical characteristics, and investigate their biocompatibilities to five different bacteria (that are most notorious for opportunistic and iatrogenic infections) and a human cell (HEp-2). The bacteria chosen in this study found to adhere onto the PPC and Nafion films but not to adhere on the PVFHFP film. On the other hand, both PVFHFP and Nafion films revealed good compatibility to HEp-2 and allowed the growth of the HEp-2 on the film surface but PPC showed poor compatibility to HEp-2. All results will be discussed with taking into account the surface characteristics of the polymers.