• Resources Recycling
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• v.15 no.3 s.71
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• pp.58-65
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• 2006

The applicability of the waste pulp which produced in the paper recycling process as an adsorbent for the treatment of $Ni^{2+}$ ion in wastewater has been investigated taking the initial concentration of adsorbate, temperature, the amount of adsorbent, and solution pH as the experimental variables. In addition, the effect of the concentration of coexisting solute and pre-treatment of adsorbent on the adsorbability of $Ni^{2+}$ ion were also examined. The electrokinetic potential of waste pulp was observed to be positive below pH 7.8 and negative above this pH. The adsorption reaction of $Ni^{2+}$ ion reached its equilibrium within 4 hours after the reaction was initiated and the adsorbed amount of adsorbate was found to increase with its initial concentration. The adsorbability of $Ni^{2+}$ was raised with temperature so that its adsorption reaction was considered to be exothermic, which was substantiated by thermodynamic calculation. Also, the adsorbed amount of $Ni^{2+}$ was raised with the amount of waste pulp and with pH in the range of pH $3{\sim}6$. This behavior of the adsorption of $Ni^{2+}$ according to the solution pH was well agreed with the electrokinetic characteristics of waste pulp in solution. The amount of coexisting solute was observed to reversely affect on the $Ni^{2+}$ adsorption onto waste pulp under the experimental conditions. With regard to the pre-treatment of adsorbent with NaOH, the adsorbability of $Ni^{2+}$ was increased with the concentration of NaOH to a certain extent. However, it was found to decrease contrarily when the concentration of NaOH became too high.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.24-24
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.100-100
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• 1999

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.614-622
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• 1996

Efficient removal of nickel from the ferric chloride etching solution has been studied. At first, $Fe^{3+}$ was reduced to $Fe^{2+}$ by the electrolytic iron flake or the waste shadow mask iron plate. And then, $Ni^{2+}$ was removed from the solution by electrolytic iron powder. Under the optimum conditions the reduced rates of nickel were 99 % and 98%, respectively at the initial $Ni^{2+}$ concentrations of 1.0% and 0.1%. Sludge formed during reduction of $Fe^{3+}$ in the solution were analyzed by XRD and SEM.

• Korean Journal of Materials Research
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• v.33 no.10
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• pp.385-392
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• 2023

A solution combustion process for the synthesis of hollandite (BaAl₂Ti₆O₁₆) powders is described. SYNROC (synthetic rock) consists of four main titanate phases: perovskite, zirconolite, hollandite and rutile. Hollandite is one of the crystalline host matrices used for the disposal of high-level radioactive wastes because it immobilizes Sr and Lns elements by forming solid solutions. The solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between a nitrate and organic fuel, generates an exothermic reaction and that heat converts the precursors into their corresponding oxide products in air. The process has high energy efficiency, fast heating rates, short reaction times, and high compositional homogeneity. To confirm the combustion synthesis reaction, FT-IR analysis was conducted using glycine with a carboxyl group and an amine as fuel to observe its bonding with metal element in the nitrate. TG-DTA, X-ray diffraction analysis, SEM and EDS were performed to confirm the formed phases and morphology. Powders with an uncontrolled shape were obtained through a general oxide-route process, confirming hollandite powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using these methods.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.245-256
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• 2004

The extraction of three kinds of amido podands, N,N,N'N'-tetrabutyl-3-oxa-pentanedi- amide (TBDGA), N,N,N'N'-tetra-isobutyl-3-oxa-pentanediamide(TiBDGA) and N,N,N'N'-tetra- butyl-3,6-dioxa-oct-anediam- ide(TBDOODA) on U(VI),Pu(IV), Am(III), Eu(III) and other metal ions is studied in nitric acid solutions. 40%octanol-kerosene is chosen as diluents to eliminate third phase and emulsion. TBDGA and TiBDGA show extraction selectivity to An(III) and Ln(III) much higher than to U(VI) and Pu(IV). Fe, Ru and Mo is poorly extracted by the three kinds of amid podands in 2~3mol/L $HNO_3$ solutions. Aiming to eliminate interface crude when using simulated HLLW solution in the system of 0.2mol/L TBDGA/Octanol＋kerosene, acetohydroxyamic acid was adapted. Distribution ratio of zirconium was decreased when adding acetohydroxyamic acid in aqueous solution, and interface crude disappeared as mixing extractant with HLLW. The counter-current extraction test is carried out in a set of miniature mixer-settler, with 0.2mol/L TBDGA/ 40% octanol-kerosene as extractant to separate U(VI), Pu(IV), Am(III) and Eu(III) from simulated high level liquid waste(HLLW) solution. In battery A, lanthanides and actinides are coextracted into organic phase with the recovery of 99.98% for U(Ⅵ), >99.99% for Pu(IV), and >99.99% for Am(III) and Eu(III) respectively. In battery R1, 99.99% U, 86.2% Pu and a part of Am or Eu are stripped into aqueous phase by 0.2mol/L acetohydroxyamic acid (AHA) in 0.01mol/L $HNO_3$ solution. In battery $R_2$, Am, Eu and remained Pu are completely back-extracted by 0.2mol/L AHA. This separation process contains no salt reagent, and it is not necessary to dilute HLLW feed.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.259-263
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• 2001

There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove damaged layer caused In the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. At present, the waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP(Tri-butyl phosphate) as an extractant. Finally hydrofluoric acid is separated with the TBP solvent extraction. The expected recovered acids in this process are 2㏖/l acetic acid, 6㏖/1 nitric acid and 6㏖/l hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.847-856
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• 2014

Spent resin waste containing a high concentration of $^{14}C$ radionuclide cannot be disposed of directly. A fundamental study on selective $^{14}C$ stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive $HCO_3{^-}$ ion, as the chemical form of $^{14}C$, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of $NO_3{^-}$ > $HCO_3{^-}{\geq}H_2PO_4{^-}$. Thus the competitive adsorption affinity of $NO_3{^-}$ ion in binary systems appeared far higher than that of $HCO_3{^-}$ or $H_2PO_4{^-}$, and the selective desorption of $HCO_3{^-}$ from the resin was very effective. On one hand, the affinity of $Co^{2+}$ and $Cs^+$ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of $Cs^+$ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, $NH_4H_2PO_4$ solution was preferable for the stripping of $^{14}C$ from the spent resin.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.237-246
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• 2001

In this paper we introduce a solution to improve the unfairness problem and to remove the waste of bandwidth in the distributed queue dual bus system. This solution requires only a minor modification of the current protocol and further shows no bandwidth wastes when we try to resolve the unfairness problem occurred in current DQDB protocol. There has been many problem in DQDB system in terms of fairness of sending message in each node. In order to solve this problem, Bandwidth Balancing technic and proportional assignment technic have been introduced. It is, however, to note that the waste of bandwidth problem is still existing in those technics, even though there has been significant improvement as to the fairness problem. In this paper we introduce a new solution to remove the waste of bandwidth problem while we are still obtaining the improved fairness of the network. By following this new solution, the simulation result shows higher throughput and lower message delay than previously proposed technics.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.332-339
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• 2005

The environmental regulations in the world has been reinforced and many nations has devoted themselves to the development of cost-effective technology. Selective catalyst reduction(SCR) and selective non-catalyst reduction (SNCR) processes are mainly used to treat nitrogen oxidants generated from fossil-fuel combustion. One of these typical technologies for reduction of do-NOx is SNCR process has increased continuously because of the low cost for building and maintenance. Nevertheless the researches on the application to real scale plant by the reductant like Urea are rarely studied. In this paper, an experimental investigations were performed on the SNCR process in the industrial waste incineration plant. With no reducing agent, the concentration of NOx stayed in around 180 ppm $(O_2\;12\%)$ with the exhausting temperature of $950^{\circ}C$ and changed within the range of 20 ppm to remain relatively consistent. When $10\;wt\%)$ of a solution was added, the efficiency of denitrification reached above $61.4\%$ with the NSR of 2.0 and the exhausting temperature of $950^{\circ}C.$ When the concentration of the urea solution was set to $10\;wt\%$ and the sprinkling to four nozzles, the reaction temperature was reduced to about $50~100^{\circ}C$ with a mixture of $10\;wt\%\;CH_3OH\;and\;5wt\%\;Na_2CO_3$ in $40\;wt\%$ of the solution. The NOx removal efficiency increased to $78.4\%,$ achieving a broader and expansive range of reaction temperatures than the addition of an unmixed pure solution.