• Journal of Environmental Science International
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• v.27 no.6
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• pp.401-410
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• 2018

Waste citrus peel-based activated carbon (WCAC) was prepared from waste citrus peels by activation with KOH. The removal of Cu and Pb ions from aqueous solution by the prepared WCAC was investigated in batch experiments. The solution pH significantly influenced Cu and Pb adsorption capacity and the optimum pH was 4 to 6. The adsorption of Cu and Pb ions by WCAC followed pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity calculated by Langmuir isotherm model was 31.91 mg/g for Cu and 92.22 mg/g for Pb. As the temperature was increased from 303 K to 323 K, the ${\Delta}G^{\circ}$ value decreased from -7.01 to -8.57 kJ/mol for Cu ions and from -0.87 to -2.06 kJ/mol for Pb ions. These results indicated that the adsorption of Cu and Pb by WCAC is a spontaneous process.

• Carbon letters
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• v.6 no.3
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• pp.141-147
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• 2005

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of $Pb^{2+}$ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of $Pb^{2+}$ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of $Pb^{2+}$ ions were related to the chemistry of the surface rather than to the textural properties.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1179-1180
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• 2005

To immobilize the pollutants from wastewater in situ, two phosphatic clays collected from different areas in Egypt (eastern and western Sebaia, Aswan-Isna, Upper Egypt) used to remove contaminant ions from industrial wastewater. Obtained results confirmed the strong relationship between phosphatic clay and Pb elimination from wastewater. The sensitivity classification of phosphatic clay toward ions retained as described in three categories: highly sensitive to retain Pb , Al and Cr ; moderately sensitive for Mn; and weakly sensitive for Band Zn. Data suggested that large fraction of Pb removed by phosphatic clays stayed intact under a wide variation in extracting solution pH (3-11). In situ immobilization is considered a promising technique that has the potential to remove contaminant ions from wastewater. Two important factors need to be considered when applying this technique: The first, is the clay must be effective and selective under different composition of wastewater. The second, is the immobilized ions should be stable and non-leacheable under varying water conditions. Phosphatic clays with $Pb^{2+}$ were suitable to achieve these two factors. Possible mechanism for removal $Pb^{2+}$ by phosphatic clays is the formation of fluoropyromorphite through the dissolution of fluoro and hydroxyl apatite by its precipitation from solution, beside, Pb complexation at phosphatic clay surface at P-OH sites.

• Analytical Science and Technology
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• v.12 no.5
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• pp.360-369
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• 1999

In this research, a study of adsorption kinetics of heavy metal ions on the Ulva pertusa and Hizakia fusiformis which is aiming at removing metal ions from water or every kind has been carried out. During the process of this research. Adsorption kinetics of Cd(II) and Pb(II) ions by the Ulva pertusa and Hizakia fusiformis, within five minutes reached at the maximum adsorption amount. The adsorption amoum by Ulva pertusa was more than the other. Adsorption ratio by Ulva pertusa were 15.0~100% of Cd(II) and 39.2~82.5% of Pb(II). Adsorption ratio by the Hizakia fusiformis were 18.3~100% of Cd(II) and 56.4~94.7% of Pb(II). Additionally, recovery ratio or Cd(II) from the Ulva pertusa presents 75.0~83.6% and that of Pb(II) ions presents 79.1~85.5%. Also, recovery ratio of Cd(II) from Hizakia fusiformis fusiformis were 66.7~85.0% of Cd(II) ions and 77.6~83.9% of Pb(II) ions respectively. As a result of this research. adsorption amount of Cd(II) and Pb(II) ions by Ulva pertusa was more than it by Hizakia fusiformis.

• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.146-149
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• 2015

Silicate glasses with different $Nd_2O_3$ concentrations were prepared through conventional melt-quenching methods while PbS quantum dots (QDs) were precipitated through heat treatment. The peak wavelengths of absorption and the photoluminescence of PbS QDs shifted to the short-wavelength side as the concentration of $Nd_2O_3$ increased. The electron energy loss spectroscopy (EELS) indicated that $Nd^{3+}$ ions were preferentially distributed inside the PbS QDs instead of the glass matrix. In addition, there was no significant change in the lifetimes of the $Nd^{3+}:^4F_{3/2}$ fluorescence between the as-prepared glass ($607{\mu}s$) and the heat-treated glass($576{\mu}s$). $Nd^{3+}$ ions were surrounded by oxygen instead of sulfur and the Nd-O clusters probably acted as nucleating centers for the formation of PbS QDs inside the glasses.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.190-195
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• 2015

Here, we demonstrated a $Pb^{2+}$ detecting aptasensor using $Pb^{2+}$-sensitive DNAzyme-conjugated gold nanorods (GNRs). Fluorescent DNA substrates that were initially quenched by GNRs, are released in response to $Pb^{2+}$ ions to give a substantial fluorescence signal. The GNR-tethered DNAzyme is reusable at least three times with a LOD of 50 nM.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.122-128
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• 1994

Macrocyclic ligand has been known to selectively bind with metal ions so that ability applied for the transport of metal ions across the emulsion liquid membrane in this study. The metal ions are transproted from the source phase to the receiving phase by the carrier of the organic phase. Several factors involved in the transport of metal ions acrose the emulsion membrane we reported here and these factors provided the informations for the selective seperation of some metal ion. Stability constants for cation-macrocyclic ligand and metal ion-anion receiving phase interaction are examined as parameters for the prediction of metal ion transport selectivities. $Pb^{2+}$ was transported higher rates than the other metal ions in the mixture solution. The interaction of metal ion to anion in receiving phase is important. $S_2O_3^{2-}$- in replacement of $NO_3^-$ in the receiving phase enhances the transport of $Pb^{2-}$since $Pb^{2-}-S_2O_3^{2-}$interaction is greater than $Pb^{2+}-NO_3^-$ interaction.

• Journal of the Korean Chemical Society
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• v.68 no.3
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.699-702
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• 2001

A series of cleft-type ionophores having two convergent hydroxamic acid functions are prepared and their selective ionophoric properties toward heavy metal and transition metal ions have been investigated. Hydroxamic acids 3 exhibited a prominent selectivity toward heavy metal ions of Hg2+ and Pb2+, and transition metal ions of Cu2+ over other transition metal and alkaline earth metal ions from slightly acidic source phase (pH 6) to an acidic receiving phase (pH 1). Selective ionophoric properties toward Pb2+ and Cu2+ ions over other surveyed metal ions are also confirmed by the FAB-MS measurements.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.357-365
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• 1993

This study was conducted for the efficient utilization of biomaterials such as starch residue, tangerine skin, and green tea residue, which are agricultral by-products discarded in Cheju Province annually, as adsorbents and biomaterials were examined for their removal ability of heavy metal ions in waste water by batch adsorption experiments. The removal efficiency of biomaterials for heavy metal ions was above 80-90% and almost similar to activated carbon and the adsorption ability of those treated with 포르말린 was improved in the green tea residue only for $Pb^{2+}$, $Cu^{2+}$, and $Zn^{2+}$. In the conditions of pH, the removal efficiency of heavy metal ions was high in the range of 5-7. In the solutions which heavy metal ions were mixed, the removal efficiency was similar at $Ag^+$, $Pb^{+2}$ and reduced to about 10% at the other ions, as compared with the solutions they were not mixed. Adsorption isotherm of biomaterials was generally obeyed to Freundlich formular than Langmuir formular and Freundlich constant, 1/n were obtained in the range of 0.1-0.5.