• Resources Recycling
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• v.29 no.5
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• pp.28-37
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• 2020

In this study, the effect of precipitation temperature, ammonium chloride amount and addition method, vanadium and sodium hydroxide content of the solution on the precipitation of ammonium metavanadate were examined by using the sodium vanadate(NaVO₃) solution in alkali region as a starting material. As the pH of solution decreased, the addition amount of ammonium chloride and the vanadium content of the solution increased, the precipitation rate of ammonium metavanadate increased. In this research condition, the basic conditions for obtaining more than 90% of precipitation yield were 10,000mg/L of vanadium content, 2equivalents of ammonium chloride addition, room temperature, and 2 hours of precipitation time. The size of precipitated particles decreased with increasing precipitation rate. Especially when liquid ammonium chloride was injected into the solution, the precipitation rate was the slowest and the particle size of the precipitate was the largest. After the primary precipitation by adding ammonium chloride as a solid, the secondary precipitation was carried out by adding new reactants. At this time, the precipitation with added ammonium chloride solid was not affected by the precipitates present in the solution. However, when liquid ammonium chloride was added, new precipitate was deposited on the surface of the precipitate present in the solution, increasing its size. Due to the difference in ammonium metavanadate solubility to temperature, the precipitation temperature at the vanadium content of 10,000mg/L in the solution affected the precipitation rate of ammonium metavanadate and the precipitation temperature did not affect the precipitation rate at a high concentration of more than 30,000mg/L vanadium content in the solution.

• Resources Recycling
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• v.28 no.5
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• pp.42-50
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• 2019

In this study, the precipitation reaction of vanadium and ammonium chloride in aqueous solution was investigated in order to recover vanadium. Ammonium metavanadate having a crystal structure of [$NH_4VO_3$] was precipitated from aqueous solution containing vanadium at pH 9.2 ~ 9.4, and ammonium polyvanadate having a crystal structure of [$(NH_4)_2V_6O_{16}$] was precipitated when the pH of the aqueous solution containing vanadium was adjusted with sulfuric acid. Ammonium polyvanadate [$(NH_4)_2V_6O_{16}$] precipitated at a temperature of $80{\sim}90^{\circ}C$ and pH 2, and at a temperature of $40^{\circ}C$ and pH 6 ~ 8 of aqueous solution. In the acidic region of aqueous solution pH 2, the vanadium content of the aqueous solution should be at least 3,000 mg/L and the precipitation temperature should be maintained at $80^{\circ}C$ or higher in order to obtain a precipitation ratio of 99% or more. When the ammonium vanadate was precipitated in the alkaline region, the vanadium content was more than 10,000 mg/L and the precipitation temperature was maintained at $40^{\circ}C$ to increase the precipitation ratio. Aluminum was not precipitated regardless of the vanadium content and pH of the aqueous solution. However, the iron component reacts with ammonium chloride to precipitate into ammonium jarosite. Therefore, Fe component must be preferentially removed in order to increase the recovery of vanadium.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.365-369
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• 2001

EAF's dust has been treated mainly by pyrometallurgical reduction process in rotary kiln furnace to recover valuable metal elements such as Zn and to avoid the disposal of hazardous materials to waste. Recently, hydrometallurgical eletrowinning of zinc from a zinc-amino chloride solution obtained by the leaching of EAF's dust was developed to recover high grade zinc metal from EAF’s dust. But there are some disadvantages in each process such as difficulty of operation condition control and sticking problem in kiln process and low extractability and recovery of zinc owing to insoluble zinc-ferrite in electrowinning process. We propose a new combined process of pyrometallurgical one and hydrometallurgical one to treat EAF's dust efficiently and economically. In this study, ammonium chloride solution leaching of crude zinc oxide recovered from reduction of EAF's dust was carried out to find out the efficiency of zinc extraction from it and the possibility for performance of eletrowinning in the proposed process. Effects of various leaching variables ruck as leaching temperature, concentration of leaching solution and leaching time were investigated. And the leaching results of the crude zinc oxide were compared with those of EAF's dust. The extraction percents of zinc in ammonium chloride solution leaching of the crude zinc oxide recovered from reduction of EAF's dust were above 80% after 60 minutes of leaching under the leaching condition of 4M NH$_4$CI concentration and above leaching temperature of 7$0^{\circ}C$. And the concentrations of zinc in the leached solution were obtained above 50g/$\ell$. The activation energy calculated for zinc extraction in NH$_4$CI leaching was 58.1 KJ/㏖ for EAF's dust and 15.8 KJ/㏖ for the crude zinc oxide recovered from reduction of EAF's dust.

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.1009-1014
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• 2001

In aqueous mixtures of cationic OTAC (octadecyl trimethyl ammonium chloride) and anionic ADS (ammonium dodecyl sulfate) surfactants, mixed micelles were formed at low (< 0.2 wt %) total surfactant concentrations. For these mixtures mixed micelliza tion and interaction of surfactant molecules were examined. Mixed critical micelle concentration (CMC), thermodynamic potentials of micellization, and minimum area per surfactant molecule at the interface were obtained from surface tensiometry and electrical conductometry. The mixed micellar compositions and the estimation of interacting forces were determined on the basis of a regular solution model. The CMCs were reduced, although not substantial, and synergistic behavior of the ADS and OTAC in the mixed micelles was observed. The CMC reductions in this anionic/cationic system were comparable to those in nonionic/anionic surfactant systems. The interaction parameter $\beta$ of the regular solution model was estimated to be -5 and this negative value of $\beta$ indicated an overall attractive force in the mixed state.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.47-48
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• 2015

Recycled aggregate used in a site is strong alkali due to calcium hydroxide attached on its surface. Accordingly, many environmental problems arise. Therefore, as basic research to reduce pH of recycled aggregate, this study tries to reduce the strong alkalinity of recycled aggregate by using mixture solution based on sodium phosphate and ammonium chloride. As a result, original aggregate has the strong alkalinity of pH 11.23, whereas pH of recycled aggregate immersed in mixture solution decreased as more mixture rate increased, and mostly pH 9.8 or less was found.

• Journal of the Korean institute of surface engineering
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• v.19 no.1
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• pp.13-19
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• 1986

Manganese in the Anode slime and the paste-positive material of waste-dry cell was recovered by leaching with the hydrochloric acid solution. The impurities (Zn, Fe, Pb), co-leached with manganese were removed from the leached solution prior to electrolysis by hydrometallurgical techniques such as the neutralization with ammonium hydroxide and cementation on manganese powder. The electrodeposition of manganese from the purified chloride solution with sodium selenate was performed. Cathode current efficiency was found to be affected significantly by the concentration of sodium selenate and ammonium chloride salt, bath temperate, current density and PH. The current efficiency of about 88.7% was obtained by electrolysis manganese chloride solution with sodium selenate (0.1/g) at 10$^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.21 no.4
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• pp.168-175
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• 1988

The nickel0zinc allot depositions have been studjen in ammonium chloridw added chloride baths to fine out the effects of ultrasonic irradiation for the electrodeposition processes. The compositions of deposited alloys, the current efficiencies, corrosion resistance and brightness in various conditions of electrodeposition were investigated, in the range of ultrasonic irradiation of 50,500 and 1,000kc/s respectively. The results obtained are as follows; 1. the ratio of nikel to zinc in the deposit increased according 시 the ammonium chloride concentration in irradiated baths. 2. The current efficiencies became also higer in the irradiated bath. 3. Ammonium ions in solution seem to retard formation of zinc hydroxide. 4. The corrsion resistance and brightness of the deposits are dependent upon nickel content of deposits which ranges 10-18%(wt)nickel in the irradiated baths and 11-15%(wt)in ninirradisted baths. 5. The corrosion resistance and brightnes of the deposited are appreciably better in the irradiated baths than in non-irradiated bath with the mole ratio of 3.4(NH+4/Ni+++Zn++).

• Textile Coloration and Finishing
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• v.31 no.4
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• pp.276-287
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• 2019

In this study, cotton fibers were coated with a different weight percentage of octadecyl dimethyl(3-triethoxy silylpropyl) ammonium chloride(ODDMAC) to improve antimicrobial and water repellent properties. First, the ODDMAC dissolved in ethanol to prepare a solution. Then the cotton fibers were immersed in the ODDMAC/ethanol solution for 10 minutes at ambient temperature and dried at 80℃ for 3 minutes followed by curing. The treated cotton fibers were characterized by scanning electron microscopy(SEM) and x-ray photoelectron spectroscopy(XPS). The treated cotton fibers revealed sufficient antimicrobial activity against Klebsiella pneumoniae(ATCC 4352) and Staphylococcus aureus(ATCCBAA-1707). The hydrophobic nature of the treated cotton fibers was characterized by contact angle measurement. The results showed that the cotton fibers treated with the ODDMAC showed excellent hydrophobic properties which improved to 121°.

• Journal of the Korean Electrochemical Society
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• v.5 no.2
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• pp.57-61
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• 2002

In this study, the effect of ammonium chloride on the electrodeposition of CoP magnetic alloy film was investigated. The correlation between the electrodeposition condition and the magnetic properties was tried to elucidate by the electro- analytical tests such as cyclic voltammetry. It was observed that the magnetic properties of the films were varied extensively with the ammonium chloride contents in the solution. The reason why the magnetic properties of the films were varied with the addition of ammonium chloride was thought that the addition of ammonium chloride controlled the electrocrystallization of CoP kinetically by charge transfer and increased the grain size and the orientation factor. This may cause the variation of the magnetic properties of CoP films.

• Textile Coloration and Finishing
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• v.12 no.3
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• pp.166-173
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• 2000

Various kinds of water soluble N,N,N-trimethylchitosan ammonium chloride(TMC) with different molecular weights were synthesized to examine the antimicrobial activity against Methicillin Sensitive Staphylococcus aureus(MSSA) and Methicillin Resistant Staphylococcus aureus(MRSA), which causes serious hospital infection, and to apply them to antimicrobial finishing agents for textiles. Chitosan samples were highly deacetylated with sodium hydroxide solution and degraded with hydrogen peroxide to control the molecular weight. TMC has the antimicrobial activities against MRSA and MSSA. TMC showed an excellent antimicrobial activity below the molecular weight of 70,000, especially at 40,000. The minimum inhibitory concentration (MIC) of TMC with optimum molecular weight against MRSA and MSSA was 250ppm. Because MRSA did not resist TMC in the subculture test of bouillon medium, it was expected that the successive use of TMC against MRSA was possible.