• Journal of Environmental Science International
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• v.21 no.9
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• pp.1043-1051
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• 2012

Coagulation, flocculation, and dissolved air flotation (DAF) experiments were performed with humic acid to evaluate the influence of operational conditions on removal efficiencies. We investigated coagulation, flocculation, and flotation conditions of humic acid removal using a laboratory-scale DAF system. This paper deals with coagulant type (aluminum sulfate and PSO-M) and the most relevant operational conditions (velocity gradients for coagulation and flocculation, retention time and recycle ratio and flotation time). Results showed that optimal conditions for removing humic acid, yielding CHA removal efficiencies of approximately 85 %, are a recycle ratio of 40 %, coagulant dosages of 0.15 - 0.20 gAl/gHA as aluminum sulfate and 0.03 - 0.12 gAl/gHA as PSO-M, coagulation($400s^{-1}$ and 60s), flocculation($60s^{-1}$ and 900s or more), and flotation(490 kPa or more and at least 10 min).

• Journal of Industrial Technology
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• v.18
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• pp.417-423
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• 1998

Experiments were performed to evaluate UV/VIS absorbance and TOC of humic acid solutions which were ozonated at different pH values. The optimum conditions for ozonation of humic acid from this study are pH 9 (buffered) and 0.84 ($H_2O_2/HA$, w/w) for $H_2O_2$ dosage.

• Journal of Environmental Science International
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• v.13 no.3
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• pp.279-288
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• 2004

This study aimed at improving the $TiO_2$ photocatalytic degradation of HA. A set of tests was first conducted in the dark to study the adsorption of HA at different coexisting material concentration. Adsorption rate increased with adding cation ion but decreased with adding bicarbonate ion. The photodegradation of HA in the presence of UV irradiation was investigated as a function of different experimental condition: initial concentration of HA, $TiO_2$ weight, pH, air flow rate and coexisting material. It was increased either at low pH or by adding cation ion. The increase of cation strength in aqueous solution could provide a favorable condition for adsorption of HA on the $TiO_2$ surface and therefore enhance the photodegradation rate. It was found that bicarbonate ions slowed down the degradation rate by scavening the hydroxyl radicals.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.28-33
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• 2004

This study was conducted to how the effect of lime and humic acid on cadmium availability and ie uptake by plant grown in contaminated paddy soils with heavy metal. The treatment levels of lime were 2.5 and 5.0 ton/ha and that of humic acid were 1 and 2%. The contents of 0.1N HCl extractable Cd were reduced with lime and humic acid and were negatively correlated with CEC as well as soil pH. The sequential extraction procedure was used to fractionate the heavy metals in soils into the designated from exchangeable (0.5 M $KNO_3$) water soluble ($H_2O$), organically bound (0.5 M NaOH), carbonate (0.05 M $Na_{2-}$ EDTA) and sulfide/residual (4 M $HNO_3$). In soil amended with 2.5 ton/ha lime and 1% humic acia che- mical forms of Cd at tillering stage were predominant exchangeable + water soluble extractable Cd, whereas that at harvesting stage were predominant carbonate + sulfide/residual extractable Cd. The exchangeable forms of Cd in soil with lime and humic acid were negatively correlated with soil pH during the harvesting period. Total absorbed Cd of paddy rice tended to occur in the order of root > stem > leaf > brown rice. Cd contents of brown rice with lime and humic acid treatment were 0.09 and 0.08 mg/kg, respectively. That were lower than control, 0.20 mg/kg. It could be that treatment of lime and humic acid in polluted soil by heavy metals would reduce the uptake of heavy metals by piano and be a temporary method of reclamation at the highly heavy Metal contaminated soils.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.42-51
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• 2004

Peat humin(p-Humin), humic acid(p-HA) and fulvic acid(p-FA) were isolated from Canadian Sphagnum peat moss by dissolution in 0.1M NaOH followed by acid precipitation. After purification cycles, they are characterized for their elemental compositions and, acid/base properties. Functionalities and carbon structures of the humic fractions were also characterized using FT-IR and solid state $^{13}C$-NMR spectroscopy. Those results are compared with one another and with soil humic substances from literatures. Main purpose of this study was to present a chemical and spectroscopic characterization data of humic substance from peat moss needed to evaluate its environmental applicability. The relative proportions of the p-Humin, p-HA and p-FA in the peat moss was $76\%,\;18\%,\;and\;3\%$, respectively, based on the total organic matter content ($957{\pm}32\;g/kg$). Elemental composition of p-Humin were found to be $C_{1.00}H_{1.52}O_{0.79}N_{0.01}$ and had higher H/C and (N+O)/C ratio compared to those of p-HA($C_{1.00}H_{1.09}O_{0.51}N_{0.02}$) and p-FA($C_{1.00}H_{1.08}O_{0.65}N_{0.01}$). Based on the analysis of pH titration data, there are two different types of acidic functional groups in the peat moss and its humic fractions and their proton exchange capacities(PEC, meq/g) were in the order p-FA(4.91) >p-HA(4.09) >p-Humin(2.38). IR spectroscopic results showed that the functionalities of the peat moss humic molecules are similar to those of soil humic substances, and carboxylic acid(-COOH) is main function group providing metal binding sites for Cd(II) sorption. Spectral features obtained from $^{13}C$-NMR indicated that peat moss humic molecules have rather lower degree of humification, and that important structural differences exist between p-Humin and soluble humic fractions(p-HA and p-FA).

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.5-14
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• 2017

Humic acid was used soil amendment or functional fertilizer in Korean agriculture, and its cation exchangeable capacity was high enough to increase soil buffering from plant toxicant. This study was conducted to evaluate effects of humic acid powder (HA) on composting of livestock manure (LM) and of its application on growth of lettuce. Treatments were designed as follows; livestock manure compost (LM+sawdust+bark+castor meal; Control), control+0.1% HA (0.1% HA), control+0.5% HA (0.5% HA), control+1.0% HA (1.0% HA), control+3.0% HA (3.0% HA), and control+5.0% HA (5.0% HA). The changes of temperature, water content, organic matter content, total nitrogen and ratio of organic matter and nitrogen in HA treatments were similar to those of control. Although pH of 3.0% HA and 5.0% HA blending with HA and LM was lower than those of others, it unaffected by HA blending during composting. Humic acid content of HA treatments was increased by 1.7~4.4 folds than that of control. As compared with odor index, 3.0% HA and 5% HA were decreased than control for composting time. Application of 3.0% HA increased the dry weight of lettuce by about 7% than that of control.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.454-459
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• 2009

In this paper, we have performed an experimental study to simultaneously remove humic acid (RA) and heavy metals (Cu, Mn, and Zn) from the river water using potassium ferrate(VI), a multi-purpose and environment-friendly chemical. In the experiments for treating three 0.1 mM single heavy metals using 0.03${\sim}$0.7 mM (as Fe) ferrate, the removal efficiencies ranged 28${\sim}$99% for Cu, 22${\sim}$73% for Mn, and 18${\sim}$100% for Zn. In addition, humic acid and heavy metals could be very efficiently removed at the same time using 0.03${\sim}$0.7 mM (as Fe) ferrate: for example, 49${\sim}$81% (humic acid), 93${\sim}$100% (Cu), 22${\sim}$86% (Mn), and 20${\sim}$100% (Zn). The removal efficiencies of humic acid and heavy metals in the mixture of humic acid and heavy metals were higher than that in the solution of single humic acid or heavy metal. It can be explained by the fact that, before adding ferrate to the mixed solution, part of solutes were already removed by the complexation between the negatively-charged functional groups of humic acid and heavy metal cations.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.21-26
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• 2001

In this study, the effects of crystalinity, composition and particle size of $TiO_2$ catalysts on the degradations of humic acid in aqueous solution was assessed using the commercially avaliable $TiO_2$ particles. Photocatalytic oxidations of humic acid (HA, Aldrich Co.) solution were carried out in case of adding different types of $TiO_2$ catalysts and their decomposition efficiencies were analyzed with respect to pH, DOC and UV absorbances values for the HA solutions and compared one another. The experimental results showed that $TiO_2$ particles(Degussa P-25) mixed with anataze and rutile gave the highest degradation efficiencies, respectively and much lower degradation efficiency in $TiO_2$ paticles of rutile only type. In comparing among ST series of anataze types, it was observed that the degradation efficiencies generally were increased with increasing $TiO_2$ contents and surface area of the particles. Higher degradation efficiency of HA was also found in zeolite type(D-TZ) of $TiO_2$ paticles compared with hydroxyapatite type (D-TH) of $TiO_2$ particles.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.165-172
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• 2003

Humic acids present in the soils at the vicinity of domestic atomic power plants(NPPs), located in Yeongkwang(YK), Uljin(UJ), Kori(KR), Koseong(KS), Wolseong(WS) area were isolated, and characterized using elemental analysis and UV/Vis, IR, CPMAS $^{13}C$ NMR spectroscopic methods. The characteristics were compared with one another and with commercial humic acid (Aldrich Co.). Molecular size distributions of the humic acids were determined using a stirred cell ultrafiltration technique. The results of elemental analysis showed that soil humic acid from UJ contains higher oxygen content than humic acids from KR and KS (O/C ratios: 0.51 (UJHA) us. 0.45(KRHA), 0.43(KSHA)). The molecular size distribution revealed that the soil humic acids of UJ and YK contained a higher percentage of larger molecules of > 30,000 daltons, compared to those of KR and KS. The spectral features obtained from UV/vis., IR and CPMAS $^{13}C$ NMR showed that the aromatic character and oxygen containing functional groups in the humic acids from UJ and YK were relatively higher than those of KR and KS. These results indicate that the soil humic acids from UJ and YK were in a higher degree of humification, which may suggest higher affinity of the humic acids with radionuclides released in the soil environments.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.3
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• pp.242-247
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• 2017

Humic acid (HA) is a complex organic matter found in the environments, especially in grassland soils with a high density. The bioactivity of HA to promote plant growth depends largely on its extraction sources. The quality-control of HA and the quality improvements via an artificial synthesis are thus challenging. We recently reported that a polymeric product from fungal laccase-mediated oxidation of catechol and vanillic acid (CAVA) displays a HA-like activity to enhance seed germination and salt stress tolerance in a model plant, Arabidopsis. Here, we examined whether HA or CAVA enhances the growth of Italian ryegrass seedling. Height and fresh weight of the plant with foliar application of HA or CAVA were bigger than those with only water. Interestingly, enhanced root developments were also observed in spite of the foliar treatments of HA or CAVA. Finally, we proved that HA or CAVA promotes the regrowth of Italian ryegrass after cutting. Collectively, CAVA acts as a HA mimic in Italian ryegrass cultivation, and both as a biostimulant enhanced the early growth and regrowth after cutting of Italian ryegrass, which could improve the productivity of forage crops.