• Journal of the Korean GEO-environmental Society
• /
• v.10 no.6
• /
• pp.61-68
• /
• 2009

The main objective of this study was to examine the removal of heavy metals from water by inflated vermiculites. The component of vermiculites was analyzed by XRF, and the concentration of metal ion was measured by ICP-AES. Serial batch kinetic tests and batch sorption tests were conducted to determine the removal characteristics for heavy metals in aqueous solutions. As a result, solution pH values of tests with the inflated vermiculites generally increased and then stabilized. Equilibrium pHs were generally established within 5 hrs. In addition, removal rates of inflated vermiculites were tested at the initial concentration of 3 mg/L. As a result, at equilibrium concentration, except for chromium (36.23%), Most of the heavy metals were effectively removed (96.08~98.54%). Finally, sorption data were correlated with both Langmuir and Freundlich isotherms. The Qmax obtained from Langmuir isotherm were determined to Pb $725.4mg\;kg^{-1}$, Cd $568.8mg\;kg^{-1}$, Zn $540.2mg\;kg^{-1}$, Cu $457.2mg\;kg^{-1}$ Cr $0.9mg\;kg^{-1}$ respectively. The results of the study indicate that inflated vermiculites can be properly used as an adsorbent for various heavy metals because of its outstanding removal rate.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.4
• /
• pp.370-378
• /
• 2005

The characteristics of heavy metal biosorption on the seaweeds were investigated to develop a biological treatment technology for wastewater polluted with heavy metals. The heavy metal biosorption on seaweeds ranked in the tallowing order: U. pinnatifida$\geq$E. stolonifera$\geq$Laminaria sp.>G. amansii. The Pb was biosorbed in the range of $93{\sim}99%$, and the Cu and Cd were biosorbed in the range of $70{\sim}80%$ at the concentration of the heavy metal of $100mg/{\ell}$ respectively. The seaweed which was pretreated with $CaCl_2$ solution improved the biosorption of the heavy metals. The temperature and pH didn't affect the biosorption of heavy metals. The Langmuir isotherm reasonably fit the data of heavy metal biosorption compared to the Freundlich isotherm. The affinity of metals on the biosorption ranked in the following order: Pb>Zn>Cu>Cd. The biosorption efficiency of the heavy metals on the U. pinnatifida decreased in the multi-component rather than the single component. The heavy metals adsorbed on the U. pinnatifida were recovered using 0.3%-NTA. U. pinnatifida among the seaweed used in this work showed the best performance for the biosorption of the heavy metals.

• Korean Journal of Soil Science and Fertilizer
• /
• v.25 no.2
• /
• pp.111-126
• /
• 1992

Silica sorption isotherm belonged to the C-type with weak L-type characteristics according to the classification system of adsorption isotherm. Silica sorption isothem fitted well to the Freundlich and Tempkin equation but not to the Langmuir equation. The color interference probably due to $Fe^{2+}$ during spectrometric silca determination by Molybdenum-blue method affected the sorption isotherm in reduced soils or low pH. Four parameters such as the intercept of Freundlich equation, the slope of Tempkin equation, the "Silica reactivity", and the "C-type slope", where the last two parameters were termed in the current study, were examined to assess treatment effects on silica sorption. Among them the "C-type slope" was found out to be the best parameter. The C-type isotherms showed the same high correlation coefficient as Freundlich and Tempkin equation when regressed to the sorption isothem. Plotting the C-type slope on a logarithmic scale vs. the pH showed high linearity. Using the "C-type slope" as a perameter, the pH and soil type affected the silica sorption while the effect of redox condtion was not significant. All Fe and Al extracted by the various reagents, and OM were highly correlated to silica sorption. Among them $Fe_d$ was identified as the highest influencing soil property. Since there is no equivalent reliable method to discriminate the forms of the soil Al-oxides their likely importance remains unclear.

• Korean Journal of Soil Science and Fertilizer
• /
• v.31 no.2
• /
• pp.95-106
• /
• 1998

To reduce the environmental contamination and to utilize fly ash massively produced from the coal power plant every year, we synthesized the artificial zeolite using fly ash treated with alkaline, and then analyzed the mineralogical and morphological properties by X-ray, IR, and SEM. The amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed by the fly ash and the artificial zeolite were determined with reaction time, amount of adsorbate used, ion concentrations. The results obtained from the pot experiments packed with the top soil, amended with granulated artificial zeolite which was made by treatment of 4% polyvinylalcohol, showed that CEC of the artificial zeolite was $257.7cmol^+kg^{-1}$, that was almost 36 times greater than that of fly ash. The ratio of $SiO_2/Al_2O_3$ decreased but the amount of Na increased. The physico-chemical properties analyzed by X-ray, IT, and SEM represented that the artificial zeolite synthesized had a similar morphological structure to that of the natural zeolite. The structures of the artificial zeolite had a significantly enlarged surface having a lot of pores, while the fly ash looked like spherical smooth shape with having not pores on the surface. Thus, the artificial zeolite was successfully synthesized. The results of adsorption isotherms of fly ash and artificial zeolite showed that the amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed increased as the equilibrium concentration increased, while $NH_4{^+}$ was strongly adsorbed on the surface of fly ash and artificial zeolite than that of $K^+$. The most distinctive growth of Chinese cabbage was found from the top soil(NPK + soils + 20% of granulated artificial zeolite + 5% of compost). Therefore, we concluded that one of the most effective methods to effectively recycle a fly ash was to make the artificial zeolite as we did in this experiment.

• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.581-584
• /
• 2008

The catalyst carriers of the mesoporous layer compounds were prepared to carry out the partial oxidation of methane(POM) to hydrogen. The catalytic activities of POM to hydrogen were investigated over Ru(3)/SPK and Ru(3)/SPM catalyst in a fixed bed flow reactor under atmosphere. In addition, the catalysts and carriers were characterized by BET, TEM, TPR. The BET surface areas of the silica-pillared $H^+-kenyaite$(SPK) and the silica-pillared $H^+-magadite$(SPM) were $760m^2/g$ and $810m^2/g$, repectively, and the average pore sizes were 3.0 nm and 2.6 nm, repectively. The nitrogen adsorption isotherms were type IV with developed hysteresis. The TEM showed that the mesoporous layer compounds were formed well. The Ru(3)/SPK and the Ru(3)/SPM catalyst were obtained high hydrogen yields(90%, 87%), and were kept constant high hydrogen yields even about 60 hours at 973 K, $CH_4/O_2=2$, $1.25{\times}10^{-5}g-Cat.hr/ml$. The TPR peaks of Ru(3)/SPK and the Ru(3)/SPM catalyst showed the similar reducibilities around 453 K and 413 K. It could be suggested that SPK and SPM had the physicochemical properties as oxidation catalyst carries from these analysis data.

• Korean Chemical Engineering Research
• /
• v.55 no.4
• /
• pp.567-573
• /
• 2017

In this work, tungsten oxide ($WO_x$) supported on SBA-15 (mesoporous silica) were prepared and applied for oxidative desulfurization of sulfur compounds in marine diesel containing about 230 ppmw of sulfur concentration. Prepared catalysts were examined by two steps; at first step, oxidation reaction carried out with hydrogen peroxide as oxidant and then the oxidized sulfur compounds were extracted by acetonitrile as solvent. Catalysts were characterized by using X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and $N_2$ adsorption-desorption isotherms. Tungsten oxide exists as monoclinic crystal system on SBA-15 and over about 10 wt% of the $WO_x$ loading took the form of multi-layers on SBA-15. The 13 wt% $WO_x$/SBA-15 catalyst exhibite highest activity, achieving about 76.3% sulfur removal in the reaction conditions, such as catalyst amount of 0.1 g, reaction temperature at $90^{\circ}C$, reaction time for 3 h and O/S molar ratio of 10. One time oxidation reaction is enough oxidize the sulfur compounds in marine diesel completely. The repetition experiment of extraction process indicated that sulfur removal could reach 94.4% after 5 times.

• Applied Chemistry for Engineering
• /
• v.21 no.6
• /
• pp.648-652
• /
• 2010

Catalytic activities of the partial oxidation of methane (POM) to hydrogen were investigated over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK in a fixed bed flow reactor (FBFR) under atmosphere, and the catalysts were characterized by BET, XPS, XRD. The BET surface areas, pore volume and pore width of Horvath-Kawaze, micro pore area and volume of t-plot of Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were $284m^2/g$, $0.233cm^3/g$, 3.9 nm, $30m^2/g$, $0.015cm^3/g$ and $396m^2/g$, $0.324cm^3/g$, 3.7nm, $119m^2/g$, $0.055cm^3/g$, repectively. The nitrogen adsorption isotherms were type IV with hysteresis. XPS showed that Si 2p and O 1s core electronlevels of Ti-SPK and Zr-SPK substituted Ti and Zr shifted to slightly lower binding energies than SPK. The oxidation states of Pd on the surface of catalysts were $Pd^0$ and $Pd^{+2}$. XRD patterns showed that crystal structures of fresh catalyst changed amorphous into crystal phase after reaction. The conversion and selectivity of POM to hydrogen over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were 77, 84% and 78, 72%, respectively, at 973 K, $CH_4/O_2$ = 2, GHSV = $8.4{\times}10^4mL/g_{cat}{\cdot}h$ and were kept constant even after 3 days in stream. These results confirm superior activity, thermal stability, and physicochemical properties of catalyst in POM to hydrogen.