• Food Science and Preservation
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• v.15 no.3
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• pp.332-339
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• 2008

This study was performed to investigate the sorption characteristics and shelf-life of coated ascorbic acid Stability of ascorbic acid, which oxidizes easily during storage and processing, was achieved by applying a fluidized bed coating using Zein-DP and HPMC-FCC as covering materials. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than when calculated using the BET equation. The fit to the isotherm curve was in the order of Halsey, Caurie, Oswin and Khun. The equilibrium relative humidity prediction model was established in terms of time and water activity, it had higher significance. The stability of the coated ascoribic acid during storage was investigated in terms of radical-scavenging activity, which decreased with increasing time of storage and was more affected at higher storage temperatures. The quality reduction rate constant (k) was calculated by a first-order reaction rate. The reaction rate constant increased with increasing storage temperature. The shelf-life of Zein-DP-coated ascorbic acid was estimated to be 45.83 days at 20C and 63.19 days at 10C, and the shelf-life for HPMC-FCC-coated ascorbic acid was estimated to be 28.84 days at 20C and 36.14 days at 10, the ascorbic acid was 24.52 days at $20^{\circ}C$ and 27.22 days at $10^{\circ}C$, respectively. Therefore, the fluidized bed coating effectively increased the stability of ascorbic acid.

• Food Science and Preservation
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• v.16 no.6
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• pp.797-803
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• 2009

The effects of drying methods on the browning and moisture sorption characteristics of Rubus coreanus were studied. Fruits were steamed for 5 min at $100^{\circ}C$, dried by sun drying, infrared drying, or freeze drying, and powdered to a size of 20 mesh. Color values were measured and equilibrium moisture contents (EMC) were determined at $20^{\circ}C$, over a range of water activity ($a_w$) from 0.11 to 0.90. The browning indices $L^*$ and $a^*$ values were higher and lower, respectively, in freeze-dried Rubus coreanus compared with other samples. The $b^*$ value was greatest in freeze-dried Rubus coreanus. EMC tended to increase with increasing $a_w$ values, and a particularly sharp increment was observed above 0.75 $a_w$. The EMC of freeze-dried Rubus coreanus was significantly higher compared with the EMC of sun-dried and infrared-dried fruit at constant aw. The moisture sorption isotherms showed a typical sigmoid shape, and the Halsey, Kuhn, and Oswin models were the best fits for the sun-dried, infrared-dried, and freeze-dried powder isotherms, respectively. With respect to monolayer moisture content, the Guggenheim-Anderson-Boer (GAB) equation showed that the various drying methods yielded very different results, with monolayer moisture contents of 0.005 g $H_2O/g$ dry solid in infrared-dried and 0.019 g $H_2O/g$ dry solid in sun- and freeze-dried powders, respectively. These results indicate that the drying method affects the browning and moisture sorption characteristics of Rubus coreanus.

• Journal of Environmental Science International
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• v.15 no.3
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• pp.211-219
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• 2006

An experimental study on the removal of VOCs gas using a biomembrane reactor were carried out at various inlet gas concentration, specific loading rate, retention time and gas flow rate of volume. The variations of efficiency and various parameters, which are relevant to gas removal, with mixing of soluble gas and without have been discussed. More than 95% of the toluene and methanol present in the feed was successfully removed in each study. The elimination of methanol with mixture of soluble compound of about 300 mg/h corresponds to a portion of 21% if there is a feed stream of 1400 mg/h. On the contrary the maximum efficiency of about 72% of toluene was reached. This is to be rated as a treatment of sorption that the limiting factor of the dismantling speed could be represented by this difficult degradable component. Nevertheless the elimination capacities for this reactor for toluene were on a very high level. For substances which show a very high solubility in silicon rubber an advantage of a bio membrane is clearly shown. Therefore a similarly good result is expected for n-hexane, because of its relatively good permeability which was distinguished during permeation experiments.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.2
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• pp.25-34
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• 1994

In this research, investigations were made on the effect of type and load of organic substrate on phosphorus release. Reactors of three different sizes were operated, being fed on five kinds of organic substrates. The quantitative analyses were made on phosphorus release and substrate utilization under anaerobic condition. The molar ratios of the uptaken organic substrate to the released phosphorus were 0.5 with acetate, 0.6 with glucose, 0.8 with glucose/acetate, and 1.2 with glucose/acids, respectively. The phosphorus release was inhibited at the higher organic load than the normal at stead state. Both acetate and acids/glucose enhanced phosphorus release- as well as uptake-rate, however, the complete phosphorus removal was achieved after the microbial adaptation to the new environment. In case with acetate, operation was hampered by the poor sludge settleability and phosphorus uptake was not enough although the phosphorus release was active. But with milk/starch, the phosphorus release and uptake was well developed even though phosphorus release was not comparatively high. From this study, it was concluded that organic substrates, such as glucose seemed to be converted fatty acids after fast bio-sorption, followed by concurrent uptake of these acids by excess phosphorus removing bacteria.

• Advances in environmental research
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• v.7 no.3
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• pp.225-237
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• 2018

The sorption of metal ions with low-cost adsorbents plays an important role in sustainable development. In the present study, the efficacy of sugarcane bagasse, rain tree fruits (samaneasaman), banana stem and their mixtures, used as bio-sorbents, in the removal of Cu(II) and Pb(II) ions from aqueous solution is evaluated. Batch studies are conducted, and residual ions were measured using Inductively Coupled Plasma (ICP)-atomic spectrometer. Effect of pH, initial metal ion concentration, reaction time and adsorbent dosage are studied. The Pb(II) removal efficiency was observed to be 97.88%, 98.60% and 91.74% for rain tree fruits, banana stem and a mixture of adsorbents respectively. The highest Cu(II) ion removal was observed for sugarcane bagasse sorbent with an efficiency of 82.10% with a pH of 4.5 and a reaction time of 90 min. Finally, desorption studies were carried out to study the leaching potential of adsorbent, and it was found that the adsorbent is stable in water than the other leaching agents such as HCl, ammonium acetate, Sodium EDTA. Hence, these adsorbents can be effectively used for the removal of these heavy metals.

• Journal of the Korean Wood Science and Technology
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• v.41 no.3
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• pp.173-180
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• 2013

This study was carried to provide basic data for the research of the effect of PEG impregnation on preventing wood from cracking during heat treatment. Three popular softwood species were selected for investigating the PEG penetration rate and retention depending on PEG molecular weight, PEG retention after heat treatment and their EMCs. The average retentions of PEG400 were reversely proportional to the basic densities of three species and those of the other PEGs showed similar behaviour as well. It is obvious that PEG retention decreased as PEG molecular weight increased with a species. PEG impregnation increased or decreased the moisture contents of the specimens within 2%, and increased their basic densities by 16.8% as a maximum. The Weight Percentage Losses of PEG400 during heat treatment were the largest among three PEG levels, which implied that lower molecular weight PEG leached more than the highers. There was less difference in EMC between PEG impregnated and control specimens at low RH, but their difference increased at high RH.

• Food Science and Preservation
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• v.16 no.5
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• pp.719-725
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• 2009

We investigated the absorption characteristics of protein-bound polysaccharide powders of various molecular weights isolated from the mushroom Agaricus blazei Murill. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than did the BET equation. The higher the water activity, the lower the isosteric heat of sorption. The fitness of the isotherm curve was shown to be in the order of the Khun, Oswin, Caurie and Henderson models. The prediction model equations for moisture content were established by use of ln(time), water activity, and temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.413-420
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• 2015

Objective of this study was to investigate adsorption characteristics and kinetic models of $NH_4-N$ to biochar produced from rice hull in respective to mitigation of greenhouse gases. $NH_4-N$ concentration was analyzed by UV Spectrophotometer. For the experiment, the soil texture used in this study was sandy loam soil, and application rates of chemical fertilizer and pig compost were $420-200-370kgha^{-1}$ (N-P-K) and $5,500kgha^{-1}$ as recommended amount after soil test for corn cultivation. Biochar treatments were 0.2-5% to soil weight. Its adsorption characteristic was investigated with application of Langmuir isotherm, and pseudo-first order kinetic model and pseudo-second order kinetic model were used as kinetic models. Adsorption amount and removal rates of $NH_4-N$ were $39.3mg^{-1}$ and 28.0% in 0.2% biochar treatment, respectively. The sorption of $NH_4-N$ to biochar was fitted well by Langmiur model because it was observed that dimensionless constant ($R_L$) was 0.48. The maximum adsorption amount ($q_m$) and binding strength constant (b) were calculated as $4.1mgg^{-1}$ and $0.01Lmg^{-1}$ in Langmuir isotherm, respectively. The pseudo-second order kinetic model was more appropriate than pseudo-first order kinetic model for high correlation coefficient ($r^2$) of pseudo-second order kinetic model. Therefore, biochar produced from rice hull could reduce $N_2O$ by adsorbing $NH_4-N$ to biochar cooperated in sandy loam soil.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.47-56
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• 2008

Temporal changes of metal solubility have been repeatedly observed in soils equilibrated with metal salt solutions. This phenomenon is known as aging, yet factors that affect the degree of metal aging remain largely unexamined. In this study, we compared the extent of aging on metal partitioning depending on soil, metal, and metal loading. Five soils spiked with four levels of Cd (2.5-20 mg ${kg}^{-1}$), Cu, and Zn (50-400 mg ${kg}^{-1}$) salt solutions were aged in the laboratory up to 1 year. The partitioning coefficient ($K_d$) of each metal was calculated from the ratio of total to dissolved metal concentration in samples collected at times ranging from 1 day to 1 year. The highest $K_d$ values for Cd, Cu and Zn were recorded in a Histosol, Andisol, and fine-textured Alfisol, respectively, whereas the lowest $K_d$ was recorded for an Oxisol and coarsetextured Alfisol. For all soils, a pattern of increasing Kd with aging was evident for Cd and Zn, but not Cu. Rapid Cu sorption was limited when dissolved organic matter was high in soils. In highly-retentive soils, $K_d$ values seemed to be insensitive to metal loading, although a longer period was required for the higher metal loadings to reach the same degree of metal aging as the lower loadings. In soils with low sorption capacity, the $K_d$ values were determined more by metal loading than by aging. Therefore, marked differences can be expected in the degree of metal aging in spiked soils by the soil type, metal and amount of metal added.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.3
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• pp.60-67
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• 2015

Objective of this study was to investigate adsorption characteristics of $PO_4-P$ to biochar produced from oak tree in respective to reduce eutrophication from runoff water in the cropland. For adsorption experiment, input amount of biochar was varied from 4 to 20 g/L with 30 mg/L $PO_4-P$ solution. Adsorption amounts and removal rates of $PO_4-P$ was increased at 3 times in 4~14 g/L, and increased at 28.6% in 4~16 g/L, respectively. The maximum adsorption amount ($q_m$) and binding strength constant(b) were calculated as 0.10 mg/g and 0.06 L/mg, respectively. The sorption of $PO_4-P$ to biochar was fitted well by Langmuir model because it was observed that dimensionless constant($R_L$) was 0.37. It was indicated that biochar is favorably adsorbed $PO_4-P$ because this value lie within 0 < $R_L$ < 1. Therefore, biochar produced from oak tree could be used as adsorbent for reduce eutrophication from runoff water in the cropland.