• 한국환경보건학회지
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• 제21권4호
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• pp.17-23
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• 1995

As a basic experiment to develope biological pretreatment proces~ in water treatment, the experiments on biodegradability and isothermal adsorption of activated carbon were performed on refractories such as humic acid, $NH_3-N$, phenol and ABS which caused the problems in drinking water treatment. Also, the treatabilities on humic acid were examined in the continuous flow type reactors. The removal efficiencies of humic acid, $NH_3-N$, phenol and ABS in the biodegradable experiments for 5 days were 20.1%, 73.4%, 91.7% and 97.5%, respectively. In the isothermal adsorption test of refractories on activated carbon to be used as a media in the continuous flow type reactors, ABS and phenol are adsorbed easily, but humic acid and $NH_3-N$ are difficult to be done. The removal efficiencies of humic acid in granular activated carbon(GAC) reactor were about 7-8% higher than in biological activated carbon(BAC) reactor. The removal efficiencies of humic acid in biological fluidized bed(BFB) reactor were about 30% in GAC media, but were almost zero in sea sand media.

• Environmental Analysis Health and Toxicology
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• 제13권1_2호
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• pp.11-17
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• 1998

Cadmium, a major aquatic pollutant in many parts of the world, is toxic and readily accumulated in aquatic organisms. It mainly exists in water as complexes with organic ligands such as dissolved organic carbon and this complexation is known to have effects on the aquatic toxicities. In this study, acute toxicity, histology, and bioaccumulation were studied to evaluate effects of humic acid on cadmium toxicity and bioavailability to fish using Oryzias lalipes and Cyprinus carpio. 96h-LC$_{50}$ of cadmium was 6.38mg/L using Oryzias latipes. However, the mortality showed the dose-dependent decrease when humic acid was added to the test solution. When fish were exposed to 5 mg/L of cadmium, histological changes in the exposed organs (caudal fins, gills, kidney, liver, and gut) of C~lprinus carpio were decreased by humic acid, especially in kidney and liver. Bioaccumulation of cadmium also decreased by treatment of humic acid. It seems that the formation of complexes between cadmium and humic acid may decrease bioavailability of cadmium to fish, and thus reduce the toxic effects of cadmium.

• 한국토양비료학회지
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• 제28권2호
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• pp.114-122
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• 1995

토양유기물(土壤有機物)에 의한 중금속(重金屬)의 흡착(吸着)현상을 구명(究明)하기 위하여 이탄토(泥炭土)에서 humic acid를 분리정제(分離精製)하여, humid acid-metal complex 생성반응(生成反應)에 대한 mechanism을 조사(調査)하였다. 1. Humic acid-metal complex의 흡광도(吸光度)는 장파장영역(長波長領域)에서 단파장영역(短波長領域)으로 갈수록 Zn-HA > Cd-HA > Cu-HA의 순(順)으로 증가(增加)하였다. 2. Humic acid의 carboxyl group과 phenolic OH group들이 중금속(重金屬) ion들과 반응(反應)하여 complex를 생성(生成)하였으며 그 생성량(生成量)은 Cu > Zn ≧ Cd의 순(順)이었다. 3. Humic acid-medal complex의 안정도(安定度) 상수(常數)는 pH가 증가(增加)함에 따라 增加하였으며 1차(次) 안정도(安定度) 상수(常數)는 Zn>Cd>Cu 순(順)이었고, 2차(次) 안정도(安定度) 상수(常數)는 Cu>Zn>Cd의 순(順)이었으며, 總安定도 常數는 Cu>Zn>Cd의 순(順)이었다. 4. Humlc acid와 중금속(重金屬)ion들 상호(相互) 간(間)의 평균결합수(平均結合數)는 pH가 증가(增加)함에 따라 Cu>Zn>Cd의 順으고 增加하였다. 5. Humic acid에 의한 중금속(重金屬) ion들의 complex생성과정(生成課程)에서 barboxyl group만이 관여(關與)하는 것과 car-boxyl gruup 및 phenolic OH group이 동시(同時)에 관여(關與)하는 두가지 흡착(吸着)mechanlsm을 제안할 수 있었다.

• 한국물환경학회지
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• 제20권5호
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• pp.520-524
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• 2004

As a feasibility study for the application of carbon nanotubes to the treatment of environmental pollutants, the adsorption characteristics of humic acid on carbon nanotubes has been investigated. The dispersion features of carbon nanotubes in aquatic environment were investigated by measuring the variation of their electrokinetic potentials with pH, and the effects of some dispersants on their dispersion features were also examined. Under the experimental conditions, humic acid was observed to mostly adsorb on nanotubes within a few minutes and reach the equilibrium state within about one hour. The adsorption features of humic acid on nanotubes were found to follow the Freundlich model better than the Langmuir Model. Humic acid adsorbed on carbon nanotubes endothermically and the change of enthalpy in adsorption reaction was estimated to be ca. 18.37kJ/mol at standard state. The entropic change in adsorption reaction for humic acid was ca. 0.0503kJ/mol at standard state and the activation energy for adsorption was also estimated based on the change of rate constants with temperature. FT-IR investigations showed that the functional groups such as alcohol, ester, and aromatics existing in the chemical structure of humic acid might work as the bridge in its adsorption on nanotubes.

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.726-732
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• 1993

A comparative study on cadmium(II) complexation with three well characterized humic acids (SHA: soil humic acid from the Okchun Metamorphic Belt; AqHA: aquatic humic acid from Gorleben underground aquifer, Germany; CoHA: commercially available humic acid from the Aldrich Co.) was carried out in 0.1 M $NaClO_4$ at different solution pH(5.0, 5.5, and 6.0) using the ultrafiltration technique. The maximum binding ability (MBA) of the humic acids for cadmium(II) was observed to vary with their origins and solution pH. The results suggest that 1 : 1 complex predominates within the experimental range, and the conditional stability constants were calculated based on the assumption of cooperative binding, yielding log K values that were quite similar (CoHA: 4.17${\pm}$0.08; AqHA: 4.14${\pm}$0.07; SHA: $4.06{\pm} 0.12\;l\;mol^{-1}$ at pH 6.0) irrespective of humic acid origins or pH. By contrast a nonlinear Schatchard plot was obtained, using the cadmium(II) ion selective electrode speciation analysis method, which indicated that humic acid may have two or more classes of binding sites, with $log\;K_1\;and\;log\;K_2$ of 4.73${\pm}$ 0.08 and $3.31{\pm}0.14\;l\;mol^{-1}$ respectively.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권2호
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• pp.139-148
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• 1998

The charge densities of humic acid and humic extract have been determined by back titration using spectrophotometry as the method of end point detection and several cationic polymers of different charge density(copolymers of acylamide and dimethylaminoethylacrylate and polydiallyidimethylammonium chloride, PDDA), and a cationic indicator o-toluidine blue(o-Tb). The charge densities of humic acid and humic extract obtained depend on the charge densities of cationic polymers used. When the polymers of lower charge density are used, lower apparent charge density values are obtained, but for polymers of high charge density(above 2.5 meq/g), the measured values are almost identical, but also are nearly the same as that obtained for PDDA which has a high charge density(about 6 meq/g). For polymers of lower charge density, it is considered that the optimum dosage does not correspond to 1 :1 charge neutralization between anionic and cationic groups. Polymers of high charge density should be used in order to achieve a complete charge neutralization. As humic acid and humic extract are dissociable acids, their ionization is heavily pH dependent and so higher charge density values are obtaines with increasing pH.

• 한국환경농학회지
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• 제17권3호
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• pp.239-245
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• 1998

부식형성과정에서 nitroaromatics와 그 환원산물들의 구조에 따른 bound residue형성 양상을 밝히기 위하여 nitrotoluene류, nitrophenol류와 그 환원형태의 화합물 및 nitro기를 가진 살충제 parathion과 amino기를 가진 제초제 asulam을 단독으로 또는 부식을 구성하는 humic monomer들이 존재하는 반응 조건에서 laccase와 HRP를 촉매로 사용하여 그 반응 양상을 조사하였다. Laccase와 HRP를 촉매로 하여 반응시킨 경우, humic monomer의 유무, 종류, nitro기의 결합위치와 수에 관계없이 nitrotoluene류와 nitrophenol류는 laccase와 HRP에 의해 거의 전환되지 않았고, aminotoluene류 및 amino-nitrophenol류는 전부 전환되었다. 일부가 환원된 형태인 amino-nitrotoluene류는 humic monomer에 따라 다른 전환율을 나타내는 데, catechol, syringaldehyde와 protocatechuic acid에서 가장 높은 전환율을 나타내었다. Nitro기가 있는 살충제 parathion은 humic monomer가 존재하는 반응 조건에서 거의 전환되지 않았고, 그 분해산물 4-nitrophenol의 경우도 protocatechuic acid를 제외하고는 거의 전환되지 않았다. Amino기가 있는 제초제 asulam의 경우, humic monomer가 존재하지 않는 조건에서는 거의 전환되지 않았지만 catechol, syringaldehyde, protocatechuic acid 및 caffeic acid의 경우, 비교적 높은 전환율을 나타났다.

• 대한화학회지
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• 제12권4호
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• pp.155-159
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• 1968

On the extraction of humic acid from peat, the optimum conditions were studied and the effects of them on the characteristics of humic acid were also examined by means of infrared spectroscopy. 1. Pretreatment of peat with diluted 6-8% HCl solution for 5 hrs. prior to extraction with alcohol-benzol azeotropic mixture have resulted the better yield of humic acid. The water soluble Na-humates were obtained by the subsequent extraction with one hundred times quantity of caustic soda solutieon for 1hr. at 90 $^{\circ}C$. Thus the pure humic acids have been yielded approximately 40% (by wt.) from the raw peat. 2. In characteristics of humic acid, the chemical structure, mainly the contents of such functional groups as -COOH, -OH (phenol type), $-CH_2CO-$, $-CH_2{\cdot}O{\cdot}CH_2-$ and aromatic rings were varied according to the concentration of alkaline solution, temperature and time when the humic acids were extracted with alkali.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.243-245
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• 2002

Brackish water desalination using reverse osmosis(RO) membrane is more useful and economic than sea water to solve the shortage of fresh water supply because of its low total dissolved solid(TDS) contents. Silica and humic acid in brackish water make serious fouling problems and cause the decline of permeate flux and increase of operating pressure. In this study, the experiments for removal of silica and humic acid were conducted with calcite particles to prevent membrane fouling and investigated the effect of pH of feed water Adsorption of silica to calcite was higher at pH=7.5 than 9.5 and removal rate was increased according to increase of initial concentration of silica. The effect of pH on adsorption of humic acid was not significant but at low initial concentration the adsorption of humic acid was enhanced at pH 7.5. The result of this study expect to apply to brackish water desalination experiment of flat-sheet reverse osmosis membrane.

• Applied Biological Chemistry
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• 제9권
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• pp.153-159
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• 1968

강원도(江原道) 춘성군(春城郡) 동산면(東山面) 원창이리(元倉二里) 면내리(面內里)의 화전토양수점(火田土壤數點)을 공시(供試)하여 토양(土壤)의 일반적(一般的) 성질(性質)과 홍법(弘法), 대우(大羽)에 의한 Simon의 수정법(修正法)으로 부식(腐植)의 형태(形態)를 분석검토(分析檢討)하였든바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1) 본화전토양(本火田土壤)은 일반화학성분(一般化學成分)이 보통(普通) 토양(土壤)과 근사(近似)하나 C.E.C.는 크며 유기물(有機物)이 특(特)히 많이 함유(含有)되어 있다. 2) 추출제(抽出劑)에 따른 추출부식(抽出腐植)은 NaOH의 Na-pyrophosphate, NaF.의 순(順)이며 토층(土層)에 따른 추출량(抽出量)은 상층(上層)일수록 많으며 PQ% 역시(亦是) 상층(上層)일수록 크다. 3) 부식화도(腐植化度)는 NaOH. Na-pyrophosphate 추출부식(抽出腐植)은 근사(近似)하나 NaF 추출부식(抽出腐植)은 낮다. 층위별(層位別)로 보면 하층(下層)일수록 높으며 토양(土壤)의 부식화도(腐植化度)의 순위(順位)는 약간 B 토양(土壤)이 높은것 같다. 4) $Mg^{++}$에 의하여 부식산(腐植酸)을 ${\alpha}$ 형(形), ${\beta}$ 형(形)으로 분할(分割)하였으며 NaOH 추출부식산(抽出腐植酸)의 ${\alpha}$ 형(形), ${\beta}$ 형(形) 부식산(腐植酸)이 부식화도(腐植化度)가 높으며 Na-pyrophosphate 추출부식산(抽出腐植酸)의 부식화도(腐植化度)는 낮다. 경작기간(耕作期間)에 따른 부식화도(腐植化度)의 변화(變化)는 별(別)로 찾아 볼 수 없다. 5) ${\alpha}$, ${\beta}$ 형(形) 부식산(腐植酸)의 흡광곡선(吸光曲線)을 보면 추출제(抽出劑)에 따른 변화(變化)는 없고 동일(同一)한 곡선(曲線)이 나타났다.