• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.379-381
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• 2003

Metal sorption onto the ICS (Iron oxide coated sand) was studied in batch experiments. Heavy metal cations such as Cd, Pb, and Cu, and a metal anion, As, which sporadically exist in mine sites, were tested for the sorptive removal by ICS. In low pH conditions As showed the highest removal efficiency compared to the other metal cations. And the sorption removal of As was apparently pH-independent reaction. However, removal of metal cations increased with pH and above pH 7 most metal cations showed very low soluble concentrations after treatment. Such a high removal ratio of metal cations above the neutral pH appeared predominantly due to precipitation.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.114-122
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• 1995

Complexation experiment between humic acid and heavy metal cations was conducted to clear information on heavy metal adsorption by soil organic constituent. The absorbance of UV-visible light of humic acid-metal complexes increased with increasing wavelength, and the order of their absorbance was in the order of Zn->Cd->Cu- saturated humic acid. Carboxyl and phenolic OH groups participated in the complex formation between heavy metal cations and functional groups of humic acid, and the amounts complex was in the order of $Cu^{+{+}}$ > $Zn^{+{+}}$ $\geq$ $Cd^{+{+}}$. The stability constants of humic acid-metal complexes increased with increasing pH, and the order of first stability constants was $Zn^{+{+}}$ > $Cd^{+{+}}$ > $Cu^{+{+}}$, and those of second and overall stability constants were $Cu^{+{+}}$ > $Zn^{+{+}}$ > $Cd^{+{+}}$. With increasing pH, the average binding numbers betwen heavy metal cations and functional groups of humic acid increased the order of $Cu^{+{+}}$ > $Zn^{+{+}}$ > $Cd^{+{+}}$. It was postulated that two types of complexations between heavy metal cations and functional groups of humic acid. One was the reactions in which only carboxyl groups participated to form complexes, and the other was those in which both carboxyl and phenolic OH groups simultaneously participated.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.231-241
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• 1995

It is well known that hydroxyapatite [$Ca_{10}(PO_4)_6(OH)_2$] have an exchangeability for various heavy metal ions in aqueous solution. To evalute the feasibility of employing the synthetic hydroxyapatites as an eliminatable exchanger for environmentally noxious caions in waste water, the adsorption properties, the removal capacities and the selectivity of the apatites for various cations were investigated in more detailed. The heavy metal cations have been exchanged in calcium part of hydroxyapatite. The order of the degree of amount exchanged of the investigated cations is $Pb^{2+}>Cd^{2+}>Zn^{2+}>Ba^{2+}$. The molar ratios between released $Cd^{2+}$ ions and remeved divalent metal cations in the reacted solution with hydroxyapatite are roughly close to an integer 1.0, suggesting that an ion-exchange reaction could have played a major role in the removal of heavy metals rather then an adsorption effect. The exchangeability of the hydroxyapatite powder of Ca/P molar ratio 1.67, which have specipic surface area of $104.5m^2g^{-1}$, appeared to be better then $237.6{\mu}g$ per g for $Pb^{2+}$ ions. The removal capacity of the heavy metal ions varies directly as particle size of hydroxyapatites. All evidences obtained indicate that the synthesized hydroxyapatite powders by precipitation reaction method can be employed as an effective cation exchanger for eliminating noxious ions in waste water even in some improvemental.

• Applied Biological Chemistry
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• v.41 no.8
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• pp.587-594
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• 1998

The objective of this research was to characterize effects of Cu or Cd additions on chemistry of soil quality indices, such as pH, EC, cation distribution and buffering capacity. Metals were added at rates ranging from 0 to 400 mg $kg^{-1}$ of soil. Soil solution was sequentially extracted from saturated pastes using vacuum. Concentrations of Cu or Cd remaining in soil solutions were very low as compared to those added to the soils, warranting that most of the added metals were recovered as nonavailable fractions. Adsorption of the added metals released cations into soil solution causing increases of ionic strength of soil solution. At metal additions of $200{\sim}400\;mg\;kg^{-1}$, EC of soil solution increased to as much as $2{\sim}4\;m^{-1}$; salinity levels considered high enough to cause detrimental effects on plant production. More divalent cations than monovalent cations were exchanged by Cu or Cd adsorption. The nutrient buffering capacity of soils was decreased due to the metal adsorption and release of cations. pH of soil solution decreased linearly with increasing metal loading rates, with a decrement of up to 1.3 units at 400 mg Cu $kg^{-1}$ addition. Influences of Cu on each of these soil quality parameters were consistently greater than those of Cd. These effects were of a detrimental nature and large enough in most cases to significantly impact soil productivity. It is clear that new protocols are needed for evaluating potential effects of heavy metal loading of soils.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.05a
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• pp.8-11
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• 1997

Current methods of evaluating soil contamination by heavy metals rely on analyzing samples for total contents of metals or quantities recovered in various chemical extracting solutions. Results from these approaches provide only an index for evaluation because these methodologies yield values not directly related to bioavailability of soil-borne metals. In addition, even though concentrations of metals may be less than those required to cause toxic effects to biota, they may cause substantial effects on soil chemical parameters that determine soil quality and sustainable productivity. The objective of this research was to characterize effects of Cu or Cd additions on soil solution chemistry of soil quality indices, such as pH, EC, nutrient cation distribution and quantity/intensity relations (buffer capacity). Metals were added at rates ranging from 0 to 400 mg/kg of soil. Soil solution was sequentially extracted from saturated pastes using vacuum. Concentrations of Cu or Cd remaining in soil solutions were very low as compared to those added to the soils, warranting that most of the added metals were recovered as nonavailable (strongly adsorbed) fractions. Adsorption of the added metals released cations into soil solution causing increases of soluble cation contents and thus ionic strength of soil solution. At metal additions of 200~400 mg/kg, EC of soil solution increased to as much as 2~4 dS/m; salinity levels considered high enough to cause detrimental effects on plant production. More divalent cations (Ca+Mg) than monovalent cations (K+Na) were exchanged by Cu or Cd adsorption. The loss of exchangeable nutrient cations decreased long-term nutrient supplying capacity or each soil. At 100 mg/kg or metal loading, the buffering capacity was decreased by 60%. pH of soil solution decreased linearly with increasing metal loading rates, with a decrement of up to 1.3 units at 400 mg Cu/kg addition. Influences of Cu on each of these soil quality parameters were consistently greater than those of Cd. These effects were of a detrimental nature and large enough in most cases to significantly impact soil productivity. It is clear that new protocols are needed for evaluating potential effects of heavy metal loading of soils.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.105-113
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• 1995

Adsorption experiments of heavy metal cations by Fe- and Al-hydroxides was conducted to obtain clear information on their adsorption mechanisms. The adsorption isothermal curves of heavy metal cations by Fe- and Al-hydroxides conformed to Langmuir's equation. Increasing the crystallinity degree of Fe- and Al-hydroxides tended to decrease the adsorption capacity and binding energy of heavy metal cations. At the same crystallinity degree, Al-hydroxide showed higher adsorption capacity and energy for the heavy metal cations than Fe-hydroxide. The adsorption capacity and energy of heavy metal cations were directly related to CEC, specific surface area and charge density of hydroxides, and the sequence was in the order of $Cu^{+{+}}$ > $Zn^{+{+}}$ > $Cd^{+{+}}$. The adsorption mechanism of $M^{+{+}}$ form of heavy metal could be presumed as the specific adsorption of $M^{+{+}}$ and the desorption of two $H^+$ from the surface aquo($OH_2$) and/or hydroxo(-OH) group for each mole of $M^{+{+}}$ adsorbed. A ring structure between $M^{+{+}}$ and two surface aquo and/or hydroxo groups was postulated. Nonspecific adsorption involved the adsorption of $MCl^+$ and the desorption of one H+ from the surface aquo and/or hydroxo groups for each mole of $M^{+{+}}$ adsorbed. A single bond structure in which $MCl^+$ replaced one $H^+$ from the surface aquo and/or hydroxo groups was postulated. The ratio of specific to nonspecific adsorption increased with increasing pH.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.130-131
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• 2016

Although many metals contaminated sediment from coastal area contain both anionic and cationic heavy metals, the current remediation technologies are not effective for stabilize heavy metals of both anionic and cationic elements from contaminated coastal region. the present work investigated the efficiency and mechanism of immobilization of Fe, Zn, Cr, Cu, Pb and Cd metal solutions in modified zeolite based biostimulant ball. Biostimulant ball containing acetate, nitrate and sulphate which are enhance the activity of marine microorganisms and it can act as electron donors and electron acceptors. Modified zeolite and chelating agent is greatly enhance the metal stabilization due to increased immobility of the analysed metals. The XRD, FT-IR and SEM of modified zeolite which cheating agents containing heavy metals were investigated. The results indicated that heavy metals could be effectively immobilized in modified zeolite and chelating agents in BSB added sediment. The immobilization of heavy metals in modified zeolite and chelating agents along with BSB could be due to stabilize of heavy metal cations. Immobilization of heavy metals using BSB with modified zeolite and chelating agent has lower cost effect and enhance the sediment quality.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.151-158
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• 2009

The objective of this study was to determine on optimum ratio of oxidant and catalyst and to evaluate affecting factors such as anions and cations on persulfate oxidation of organic pollutant. Fe(II) activated the persulfate anion to produce a sulfate free radicals and thus effectively used to degrade the target organic pollutant in aqueous system. The chloride ions reacted with sulfate radical produced the $Cl^{\cdot}$ atom and had positive effects on the oxidation of organic pollutant at the initial stage. However, it was observed that chloride ions had the scavenging effects on the rate of oxidation of organic pollutant. Cations and some heavy metals were partly able to activate the persulfate anion to generate a sulfate free radical. However, high levels of cations inhibited the oxidation of organic pollutant.

• Korean Journal of Environmental Agriculture
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• v.7 no.2
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• pp.96-101
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• 1988

It is important to assess the effects of ionic strength and type of anions when studying the adsorption of heavy metals on zeolite because the background salt may complex with heavy metals and compete for adsorption sites. This experiment was carried out to determine the effect of ionic strength and anion species($Cl^-$, $SO^{2-}\;_4$, and $ClO^-\;_4$) on heavy metal adsorption. Heavy metal adsorption by zeolite from solutions in the range of 10 to 50ppm was studied in the presence of NaCl, $Na_2SO_4$ and $NaClO_4$, with different concentrations. The ionic strength ranged from 0.01 to 1.00. Adsorption of heavy metal cations could be described by the Freundlich isotherm equation. Increasing the ionic strength of equilibrium solutions, the amounts of heavy metal adsorbed on the zeolite surfaces decreased in all three of the anion systems. This fact could be attributed to the competition of background salt cation and the decrease in initial activity of heavy metal cations. In the presence of Cl anion, less adsorption resulted than in the presence of $SO_4$ or $ClO_4$ anions of the same ionic strength, indicating the presence of uncharged and negatively charged complexes of heavy metal with Cl ligands.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.129-136
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• 2004

Titanium and [titanium+Na(K)] substituted 11${\AA}$ tobermorites solids synthesized under hydrothermal conditions at 180$^{\circ}C$ exhibit cation exchange properties toward heavy transition metal cations, such as Fe$^{2+},\;Zn^{2+},\;Cd^{2+}\;and/or\;Pb^{2+}$. The amount of heavy metal cations taken up by these solids was found in the order: Fe$^{2+}>Zn^{2+}>Cd^{2+}>Pb^{2+}$, and reached maximum at 10% [Ti+K]-substituted tobermorite. The total cation exchange capacity of the 10% Ti+Na (K) - substituted tobermorites synthesized here range from 71 to 89 meq/100 g, and 50-56 meq/100g for Ti-substituted only. Results indicated that 10% [Ti+K] substitution exhibit cation exchange capacity more 2.4 times than the unsubstituted-tobermorite. This is due to the increase of the number of active sites on the exchangers. The incorporation of Ti and/or [Ti+Na(K)] in the lattice structure of synthesized tobermorites is due to exchange of Ti$^{4+}{\Leftrightarrow}2Ca^{2+}\;and/or\;Ti^{4+}+2Na^+(K^+){\Leftrightarrow}3Ca^{2+}$, respectively. The mechanism of Ti and [Ti+Na(K)] incorporations in the crystal lattice of the solids during synthesis and the heavy metal cations uptaken by these solids is studied.