• Journal of Environmental Science International
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• v.17 no.3
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• pp.335-342
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• 2008

This study based on electro-coagulation & oxidation reaction is applied to wastewater treatment. Electro-oxidation reaction is used to remove cyanide(CN) which is contained in plating wastewater. Cyanide is transferred by gases such as $NH_3,\;NO_x,\;CO_2$. Analysis result and removal efficiency of Cyanide which is contained in heavy metal wastewater of plating plant, are shown as following paragraph. In electrode arrangement experiment, removal efficiency of carbon electrode(-)/STS316L electrode(+) arrangement method is superior to carbon electrode(-)/carbon electrode(+) arrangement method. Removal efficiencies of cyanide in different HRT such as 30 min, 45 min, 60 min, 75 min and 90 min are 85.5%, 93.1%, 98.0%, 98.7% and 99.4% respectively in carbon electrode(-)/STS316L electrode(+) arrangement method. Finally we can estimate the critical point at HRT of 60 min which the variation of removal efficiency is decreased and HRT to obtain removal efficiency of less than 1 mg/LCN is minimum 90 min.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.165-168
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• 2010

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.168.2-169
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• 2003

Hydrogen cyanide is one of the toxic agents with carbon monooxide in fire victims and is released by combustion of nitrogen-containing organic material such as plastic and wool. Until now there are few reports about blood cyanide concentrations in fatalities by fire in Korea. So in this study we examined blood cyanide concentration in 12 cases of fire fatalities. (omitted)

• Resources Recycling
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• v.11 no.2
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• pp.3-13
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• 2002

The characteristics of cyanide decomposition in aqueous phase by hydrogen peroxide have been explored in an effort to develop a process to recycle waste water. The self-decomposition of $H_2O$$_2$at pH 10 or below was minimal even in 90 min., with keeping about 90% of $H_2O$$_2$undissociated. On the contrary, at pH 12 only 9% of it remained during the same time. In the presence of copper catalyst at 5 g Cu/L, complete decomposition of $H_2$O$_2$was accomplished at pH 12 even in a shorter time of 40 min. The volatility of free cyanide was decisively dependent on the solution pH: the majority of free cyanide was volatilized at pH 8 or below, however, only 10% of it was volatilized at pH 10 or above. In non-catalytic cyanide decomposition, the free cyanide removal was incomplete in 300 min. even in an excessive addition of $H_2$$O_2$at a $H_2$$O_2$/CN molar ratio of 4, with leaving behind about 8% of free cyanide. On the other hand, in the presence of copper catalyst at a Cu/CN molar ratio of 0.2, the free cyanide was mostly decomposed in only 16 min. at a reducedH202/CN molar ratio of 2. Ihe efnciency of HBO2 in cyanide decomposition decreased with increasing addition of H2O2 since the seu-decomposition rate of $H_2$$O_2$increased. At the optimum $H_2$$O_2$/mo1ar ratio 0.2 of and Cu/CN molar ratio of 0.05, the free cyanide could be completely decomposed in 70 min., having a self-decomposition rate of 22 mM/min and a H$_2$$O_2$ efficiency of 57%.

• Clean Technology
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• v.19 no.4
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• pp.487-491
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• 2013

To efficiently desorb gold and copper-cyanide complexes adsorbed onto Dowex21K XLT resin, the mixed solvent with HCl and acetone which is a kind of dipolar aprotic solvent was used as a desorbing agent. The desorption efficiency for gold-cyanide complex was the highest as about 94% when the mixing ratio of HCl and acetone based on volume was the 7:3, however, the value decreased as the ratio of acetone increased. In the case of copper-cyanide complex, most of them was desorbed when the amount of HCl was relatively higher than that of acetone, however, desorption efficiency decreased as the ratio of acetone increased. The desorption efficiency for gold and copper-cyanide complexes was the 94 and 100%, respectively at the 0.6 M of HCl with the 7 (HCl) : 3 (Acetone) of mixing ratio and desorption efficiency for gold-cyanide complex not increased any more even though higher HCl concentration was used. And the desorption efficiency for gold and copper-cyanide complexes was about 100% at the S/L raio ${\leq_-}1.0$ whereas desorption efficiency for gold-cyanide complex was very low as about 20-29% at the S/L ratio > 1.0. Also, most of desorption process for gold and copper-cyanide complexes was completed within 120 min.

• Analytical Science and Technology
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• v.13 no.6
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• pp.699-704
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• 2000

A study has been made for the electrochemical destruction of cyanide ions and removal of zinc ions from a simulated electroplating wastewater by the use of a platinum platized-titanium anode and a stainless steel cathode. Several experimental parameters, including electrolysis time, cell current, additives, and chloride concentration, have been investigated and used for efficient destruction of cyanide waste and removal of zinc ions from aqueous solutions. It was found that cell current and type of additives gave great effects on the destruction of cyanide ions and removal of zinc ions. The optimized conditions (electrolysis time: 1hr, current: 12A, additive: 0.5 M NaCl) have been defined to destroy cyanide ions and remove zinc ions with high efficiency and low operation cost. The proper reaction mechanism leading to the destruction of cyanide on the anode has also been discussed.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.460-468
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• 2022

Due to its high electrical conductivity, low contact resistance, good weldability and high corrosion resi-stance, gold is widely used in electronic components such as connectors and printed circuit boards (PCB). Gold ion salts currently used in gold plating are largely cyan-based salts and non-cyanic salts. The cya-nide bath can be used for both high and low hardness, but the non-cyanide bath can be used for low hardness plating. Potassium gold cyanide (KAu(CN)₂) as a cyanide type and sodium gold sulfite (Na₃[Au(SO)₃]₂) salt as a non-cyanide type are most widely used. Although the cyan bath has excellent performance in plating, potassium gold cyanide (KAu(CN)₂) used in the cyan bath is classified as a poison and a toxic substance and has strong toxicity, which tends to damage the positive photoresist film and make it difficult to form a straight side-wall. There is a need to supplement this. Therefore, it is intended to supplement this with an eco-friendly process using sodium sulfite sodium salt that does not contain cyan. Therefore, the main goal is to form a gold plating layer with a controllable hardness using a non-cyanide gold plating solution. In this study, the composition of a non-cyanide gold plating solution that maintains hardness even after annealing is generated through gold-palladium alloying by adding thallium, a crystal regulator among electrolysis factors affecting the structure and hardness, and changes in plating layer structure and crystallinity before and after annealing the correlation with the hardness.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.93-101
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• 1997

A modified procedure for electroplating wastewater treatment using formaldehyde and hydrogen peroxide can destroy free cyanide. The representative diagram which is quite sensitive on reaction temperature is showed for this kinds of treatment. Principally free cyanide and some kinds of cyanide complex should be treated first, and then toxic heavy metals can be removed because cyanide component will be inhibited to remove other pollutants, if it is not destroyed perfectly. Formaldehyde and hydrogen peroxide are added in controlled amounts to cyanide treatment tank. Reasonable amounts of these chemicals are (HCHO/CN)=0.9 and ($H_2O_2/CN$)=1.1 in molar ratios, it is also variable on reaction temperature. Of course, actual treatment processes depending on plating material and chemical are good applicable, also to systematize operation manual for treating electroplating wastewater process, further works are desirable.

• Analytical Science and Technology
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• v.14 no.6
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• pp.540-544
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• 2001

Determination of cyanide ion has been studied by adsorptive stripping voltammetry using hanging mercury electrode. Cyanide ion complexed with copper ion is adsorpbed on the electrode and oxidised at the positive potential scan. Optimal conditions of CN determination were found to be ; supporting electrolyte solution ; 0.1 M NaCl of ammonium buffer at pH 10, accumulation potential; -800 mV vs Ag/AgCl, accumulation time ; 300 s, scan rate ; 50mV/s. The linear concentration of cyanide ion was observed in the range $1{\times}10^{-8}$, $1{\times}10^{-7}M$. The detection limit(n/s=3) was $0.13{\mu}g/L$($5{\times}10^{-9}M$) with 3.5% RSD.

• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.130-135
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• 2010

Picrate, enzyme-picrate and instrumental analysis methods using IC (Ion Chromatography) and HPLC (High Performance Liquid Chromatography) were compared for their effectiveness in determining cyanide in extracts of Maesil, which is classified as a harmful substance. First, the picrate method showed the shortest analysis time (about 5 hr). The color of picrate paper changed at 0.01 mg/$200\;mL\;CN^-$. However, it was difficult to detect cyanide from amygdalin of glucosides. Second, we performed a qualitative analysis for total cyanide (free cyanide and cyanide from amygdalin) by the enzyme-picrate method using $\beta$-glucosidase and a quantitative analysis by spectrophotometry. Finally, analysis of cyanide by IC and HPLC required the longest determining time (about 17 hr) as well as pretreatment for each free cyanide and amygdalin. These results suggest that enzyme-picrate is the most effective analysis method for the detection of cyanide in Maesil extracts.