• Bulletin of the Korean Chemical Society
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• v.15 no.7
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• pp.581-584
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• 1994

A comparative investigation of the complexations of divalent metal ions (Cd, Cu, and Pb) by a well characterized soil humic acid (HA) from Okchun Metamorphic Belt was carried out in 0.05 M $KNO_3$ and pH of 4.5 using ion selective electrodes. A continuous distribution model based on the Scatchard Plot was used to determine the stability constants, because the constants obtained by this modeling technique takes the variations in binding energies into consideration without regards to the manner in which M(II) ion is bound on HA. The mean value of log $K_i$ were $4.05{\pm}0.60,\;4.92{\pm}0.36,\;and\;5.63{\pm}0.34\;{\ell}\;mol^{-1}$ for Cd(II)-, Pb(II), and Cu(II)-humate complexes respectively. The values of intrinsic constant (log $K_{int}$; binding at strongest site) were $7.12{\pm}0.30,\;6.59{\pm}0.32,\;and5.07{\pm}0.56\;{\ell}\; mol^{-1}$ in the order Cu(II) > Pb(II) > Cd(II) ion.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.67-73
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• 1996

This study was conducted to determine the effect of treatment with the plant-growth-promoting bacteria on the growth of red pepper(Capsicum annuum L.).The eight plant-growth-promoting bacteria were isolated from the humic soil in the forest region. The isolated bacteria(IB) was identified by the method of the biochemical test(API kit) and the composition of the fatty acid(MIDI system).The IBs were inoculated by spray of 17ml at 72 cell tray filled with peatmoss every week. respectively, with mixed liquid eulture of eight strains. The IBs were identified as Micrococcus sp.. Bacillus subtilis. Enterobacter agglomerans, Bacillus megaterium, Pseudomonas putida. Pseudomonas fluorescens, Xanthomonas maltophilia and Staphylococcus xylosus by API kit and MIDI system. The plant height number of leaves and leaf length of red pepper grown on peatmoss treated with the IB were better than those of nontreatment at the 10th day after inoculation.

• Membrane Journal
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• v.21 no.1
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• pp.46-54
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• 2011

In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.146-152
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• 2019

In order to study the transport behavior of tripolyphosphate (TPP) in aqueous solutions, the adsorption process of TPP on synthetic goethite, which exists stably in supergene environment, has been systematically studied. The adsorption properties under different conditions (pH, electrolyte presence, and temperature) were investigated. The adsorption of TPP in the presence of humic acid (HA)/fulvic acid (FA) has also been discussed in this paper. The results indicated that the adsorption capacity quickly increased within the first hour and equilibrium was reached within 24 h. The adsorption capacity decreased from 1.98 to 0.27 mg·g^-1 upon increasing the pH from 8.5 to 11.0, whereas the adsorption of TPP on goethite hardly changed with increasing electrolyte concentration. The results of analysis of the kinetic and isothermal models showed that the adsorption was more in accord with the pseudo second-order equation and Freundlich model. The adsorption capacity decreased obviously regardless of the order of addition of TPP, HA, and goethite. Subsequent addition of FA led to a large increase in the adsorption capacity, which might be attributed to the adsorption ability of FA. According to the predictions of the kinetic and isothermal models and the spectroscopic evidence (X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM)), the adsorption mechanism may be mainly based on surface complexation and physical adsorption.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.445-451
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• 2010

$TiO_2$ shows considerably efficient photoreaction activity under the ultraviolet range but it has disadvantage that there is no activity in the visible light range. In this study, it was tried to find a solution for the problem of this kind of photocatalyst by utilizing transition metal, which can show electronic transition with $TiO_2$ in the visible light area. Photocatalyst was prepared, which can have photocatalytic activity in the wide wavelength range, not only ultraviolet region but also visible light area and prevent the combination of electron and hole hindering the photoreaction. For this purpose, by using the ion exchange method, $TiO_2$ precursor and transition metal precursor were dipped into H typed strong acid ion-exchange resin. And two kind photocatalysts (Ti-M-SCM) in which transition metal and titanium dioxide coexist through the carbonization/activation process was prepared. Moreover, photolytic reaction under the wavelength 254 nm and 365 nm was performed for humic acid (HA) in the continuous reactor in order to estimate the efficiency of produced Ti-M-SCM.

• Environmental Engineering Research
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• v.16 no.3
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• pp.137-148
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• 2011

In this study, a series of experiments was conducted on the relative degradation of commonly known endocrine-disrupting compounds such as bisphenol A (BPA) and $17{\alpha}$-ethinyl estradiol (EE2) in a single-component aqueous solution using 28 and 580 kHz ultrasonic reactors. The experiments were conducted with three different types of model water: deionized water (DI), synthetic brackish water (SBW), and synthetic seawater (SSW) at pH 4, 7.5, and 11 in the presence of inert glass beads and humic acids. Significantly higher sonochemical degradation (93-97% for BPA) occurred at 580 kHz than at 28 kHz (43-61% for BPA), regardless of water type. A slightly higher degradation was observed for EE2 compared to that of BPA. The degradation rate of BPA and EE2 in DI water, SBW, and SSW after 30 min of ultrasound irradiation at 580 kHz increased slightly with the increase in pH from 4 (0.073-0.091 $min^{-1}$ for BPA and 0.081-0.094 $min^{-1}$ for EE2) to 7.5 (0.087-0.114 $min^{-1}$ for BPA and 0.092-0.124 $min^{-1}$ for EE2). In contrast, significant degradation was observed at pH 11 (0.149-0.221 $min^{-1}$ for BPA and 0.147-0.228 $min^{-1}$ for EE2). For the given frequencies of 28 and 580 kHz, the degradation rate increased in the presence of glass beads (0.1 mm and 25 g) for both BPA and EE2: 0.018-0.107 $min^{-1}$ without beads and 0.052-0.142 $min^{-1}$ with beads for BPA; 0.021-0.111 $min^{-1}$ without beads and 0.054-0.136 $min^{-1}$ with beads for EE2. A slight increase in degradation of both BPA and EE2 was found as the concentration of dissolved organic carbon (DOC, humic acids) increased in both SBW and SSW: 0.107-0.115 $min^{-1}$ in SBW and 0.087-0.101 $min^{-1}$ in SSW for BPA; 0.111-0.111 $min^{-1}$ in SWB and 0.092-0.105 $min^{-1}$ in SSW for EE2. After 30 min of sonicating the humic acid solution, DOC removal varied depending on the water type: 27% (3 mg $L^{-1}$) and 7% (10 mg $L^{-1}$) in SBW and 7% (3 mg $L^{-1}$) and 4% (10 mg $L^{-1}$) in SSW.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• Membrane Journal
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• v.21 no.2
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• pp.201-211
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• 2011

The effects of humic acid (HA), photo-oxidation and adsorption were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. UF, photocatalyst, and UV radiation processes were investigated in viewpoints of membrane fouling resistance $(R_f)$, permeate flux (J), and total penneate volume $(V_{\Upsilon})$ at 2 and 4 mg/L of HA respectively. As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_{\Upsilon}$ was the highest at 2 mg/L HA. Average treatment efficiencies of turbidity decreased as increasing HA, but treatment efficiency of HA was the highest at 4 mg/L HA. It was because most of HA was removed by membrane and some HA passing through the membrane was adsorbed or photo-oxidized by photocatalyst at low HA, and therefore treated water quality was almost same at 2 and 4 mg/L HA, but feed water quality was higher at 4 mg/L. At effect experiment of photo-oxidation and adsorption, J of UF + $TiO_2$ + UV process was maintained at the highest, and ultimately $(V_{\Upsilon})$ after 180 minutes' operation was the highest. As results of comparing the treatment efficiencies of turbidity and HA, photocatalyst adsorption had more important role than photo-oxidation when HA increased from 2 to 4 mg/L.

• Korean Journal of Environmental Agriculture
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• v.11 no.3
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• pp.243-252
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• 1992

This research was conducted to investigate the influence of kind and concentration of organic ligands such as humic (HA) or fulvic acid (FA) on the removal of Cu or Pb from the aqueous solution employing the principles in metal-ligand complexation. Increasing HA concentration enhanced the efficiency of Cu or Pb removal, but there existed upper critical concentrations capable of forming maximum HA-metal complex. which ranged 53-289 and 42-315mg/L for Cu and Pb, respectively. At these concentrations. efficiency of removal was 70 to 95 % for Pb, but 13 to 65 % for Cu. Amounts of Cu and Pb which complexed with 100mg HA were estimated to be 7.5 and 34.1mg, respectively. FA-metal complex forming reactions were fitted significantly to the empirical models of Freundlich for Cu and Langmuir for Pb. Fulvic acid precipitated nearly 100% of Pb in solution, but formed precipitates with Cu in only 13 to 29%. Comparing organic ligands. HA had a higher removal efficiency for Cu but FA had such for Pb. Metalligand complex formation was differed from kinds and concentrations of corresponding ligands and metals. Results demonstrated that this principle has a strong potential to be employed for treating heavy metals in aqueous solution.

• Membrane Journal
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• v.22 no.3
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• pp.171-177
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• 2012

Effect of humic acid (HA), photo-oxidation and adsorption with periodic $N_2$ back-flushing was investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous result at water back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_T$ was the highest at HA 2 mg/L. As HA concentration increased from 2 to 10 mg/L, the membrane fouling resistance after 180 mins' operation ($R_{f,180}$) improved 0.8 times more than that of water back-flushing. Therefore, HA concentration should affect on the membrane fouling at $N_2$ back-flushing than water back-flushing. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 2 mg/L. This means that adsorption and photo-oxidation of photocatalyst beads could removed HA at HA 2 mg/L, but it was not enough at 4 mg/L. Beyond HA 6 mg/L, UF could effectively treat HA by thick cake layer on membrane surface and severe inner membrane fouling.