• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.1
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• pp.65-73
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• 2012

Nowadays, the concern on the environmental load of bleaching process gave rise to the process of ECF(elemental chlorine free) and TCF(total clorine free). These sequences are based on oxygen-derived compounds such as oxygen, ozone, and hydrogen peroxide which is used as a typical eco-friendly bleaching agent. In this study, paper mulberry pulp was bleached with hydrogen peroxide and some bleaching process were accompanied with ultrasonication in order to increase the bleaching efficiency. The best bleaching efficiency of paper mulberry pulp was obtained in the condition of hydrogen peroxide and ultrasonication(20 kHz) bleaching system at $45^{\circ}C$ for 30 min. The brightness and kappa number of paper mulberry pulp were gained to 5.09% and 3.52 respectively. and yield was slightly loosed to 2%. Therefore, the efficiency of hydrogen peroxide and ultrasonication bleaching system of paper mulberry pulp was superior to the conventional hydrogen peroxide bleaching system. Magnesium sulfate acted as a bleaching stabilizer for the increasement of yield. As a result, the yield and viscosity were increased to 2.2% and 12% respectively.

• Korean Journal of Optics and Photonics
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• v.2 no.2
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• pp.89-95
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• 1991

High diffraction efficiency holographic gratings in silver halide emulsion were fabricated by using reversal bleaching process. The diffraction efficiencies of gratings were improved greatly by applying rapid drying procedure with isopropyl alcohol after bleaching with optimized developers. The dependency of diffraction efficiencies on the different groups of developers, the concentration of bleaching solutions, and the drying methods are investigated experimentally and the results were analyzed theoretically. Same as usual reversal bleaching process, the fabricated gratings showed very low scttering compared to those made by conventional bleach process. The maximum diffraction efficiency was 88%.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.66-74
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• 2015

DIP(deinked pulp) was bleached by FAS, $Na_2S_2O_4$ and $H_2O_2$, which are widely used in DIP bleaching process, in order to improve optical properties of DIP, and the bleaching efficiencies of DIP and environmental loads of waste water were compared, depending on bleaching chemical dosages. With the application of different bleaching chemicals, some positive improvements were shown in optical and physical properties of bleached pulp. However, the physical properties of bleached DIP and their characteristics of wastewater were remarkably different, depending on dosages and bleaching reagents. DIP chemicals with FAS and $Na_2S_2O_4$ have higher improvement in optical and physical properties than $H_2O_2$. Also, environmental loads such as pH, turbidity, SCODcr and cationic demand were decreased in reductive bleaching process. Despite of higher effectiveness of reductive bleaching process, there were some environmental problems caused by sulfur ions from FAS and $Na_2S_2O_4$. With the method of sulfur ion controls, it would be more effective than $H_2O_2$ bleaching process.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.7 no.1
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• pp.6-17
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• 1998

Tooth bleaching was being done more than 100 years ago, but the standard for vital tooth bleaching for the last quarter century has been the use of hydrogen peroxide with heat or with a combination of heat and light. The major disadvantages of this process are high cost, unpredictability of results, and patient discomfort. In March, 1989, the dental world was introduced to a new vital tooth bleaching process by Haywood and Heymann in their article "Nightguard vital bleaching(NGVB)." Interestingly enough, this simple technique could have been developed years ago if we had known about the chemical effects of carbamide peroxide on tooth structure. NGVB has created a resurgence in the area of bleaching, primarily because of its relative ease of application, the safety of the materials used, low cost, and the high percentage of successful treatments. This article was to explain simply about all around NGVB(etiology of stains, bleaching chemicals and mechanisms, bleaching effectiveness, side effect, documentation, indications, treatment therapy, laboratory procedure, case reports)

• Journal of Fashion Business
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• v.10 no.1
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• pp.94-105
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• 2006

Hair bleaching is a treatment process in which the melanic pigment is oxidized by hydrogen peroxide. With the increase of the number of treatments, $1{\sim}10$ levels of various colors develop, the hair luster diminishes, and the appearance becomes very rough. In this study, by changing the number of hair bleaching and bleaching conditions, the changes in the degree of hair damage and its process were observed through the use of scanning electron microscopy. The color changes were also compared through the use of spectrophotometer. In order to study the physical changes of the bleached hairs and to search for the optimum conditions to keep the hair damages minimum during bleaching, tensile properties were measured and reviewed. By increasing the number of hair bleaching and by the severe conditions, the scales became eroded and the protection layers were decreased, and the oxidation reached the inner sectors resulting in rough surface and fibrillation. The surface of the hairs became bright yellowish and transparent by the bleaching of melanic pigments or by the destruction of pigments. With the increase of bleaching degree, in terms of physical changes, the breaking strength decreased while the elongation increased a little.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.195-206
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• 2010

Xylan can be applied to improve the strength properties of paper; however the optical properties, such as brightness, are decreased significantly. To solve that problem, an applicable bleaching process is therefore desired. The aim of this research was to investigate the impact of hydrogen peroxide bleaching on hardwood kraft pulp pretreated with birchwood xylan by measuring optical properties (whiteness, brightness, opacity) as well as physical properties (tensile index, tearing index, bulk) of handsheets made from the bleached pulp. Hydrogen peroxide bleaching, as a kind of totally chlorine free (TCF) bleaching method, is quite important industrially for chemical pulp. In our work, the process variables of peroxide bleaching including bleaching temperature, time, initial pH and $MgSO_4$ dosage were studied. The results showed that both good mechanical properties and optical properties could be achieved when the operating parameters were controlled properly and therefore hydrogen peroxide bleaching was proved to be a suitable method for bleaching hardwood kraft pulp with adsorption of birchwood xylan.

• Preventive Nutrition and Food Science
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• v.3 no.4
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• pp.374-378
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• 1998

The objectives of this study are to determine the optimum process conditions of Korean beeswax and discuss the parameter of adsorption . Purification conditions, such as time, temperature and the type of adsorbents were investigated using the relationship between the properties of refined products and process conditions and theiptimum bleaching condition of Korean beeswax were determined for the first time. The various bleaching conditions were examined by observing the result of Lovibond color, photometric color, methods provided by the American Oil Chemists '(A.O.C.S).The iptimum bleaching temperature was 8$0^{\circ}C$ and the bleaching agents (5% of the weight of beeswax) which consisted of activated clay and activated carbon and a vacuum system were also necessary.

• Korean Journal of Poultry Science
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• v.34 no.2
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• pp.99-104
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• 2007

Studies were conducted to evaluate spent bleaching clay as a feed resource. Raw spent bleaching clay from the soybean refining process in a rotary reactor is rich in crude fat (26.0%) and crude ash (68.3%) but low in moisture (5.2%) and crude protein (0.5%). The peroxide value of spent bleaching clay was significantly higher than soybean oil (P<0.05). Also the acid value of spent bleaching clay and soybean oil were 9.72 and 0.001, respectively, it was significantly different(P<0.01). It is possible that the acidification of spent bleaching clay was prevented by artificial method. On the feeding experiment, 2.0 to 4.0% of dietary spent bleaching clay were improve body weight gain, feed intake and feed/ gain. Results indicate that spent bleaching clay may be used at 2.0 to 4.0% for broiler diets without deleterious effects on performance.

• Analytical Science and Technology
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• v.12 no.4
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• pp.318-325
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• 1999

Sludges from the wastewater of hanji production were analysed to see that sludges from the bleaching process, the bleach washing process, and the paper preparation process were fibrous, while sludges from the process cooking with NaOH and the process of final chemical and microbiological treatment were non-fibrous. Sludge solution from the bleaching process had the most amount of solid matters. Sludges from the bleaching process, the bleach washing process, and the final chemical and microbiological treatment process contained about 80-90 %(w/w) moisture. Owing to hypochlorite ion, pH of sludge from the bleaching process was higher than any other sludge samples. The inorganic components of sludges were determined by ICP-AES. The major inorganic component of sludge from the process cooking with NaOH was Na, while the sludge from the bleaching process had Na and Ca, major components in the final chemical and microbiological treatment process were Ca and Al. Trace amount of Mg, Fe, K, P, Mn and Ti were observed in sludges. Sludge from the bleaching process had ashes more than any other sludges. Shape of sludges observed by SEM was appeared to fibrous or crystalline, and the breadth of fibrous sludge was $5{\sim}50{\mu}m$. The sludge from the bleaching process had the most amount of matters soluble by cold and hot water and by alcohol-benzene.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.2 s.150
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• pp.338-347
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• 2006

Due to the complex environment in the ground, most of excavated costumes undergo deterioration and color change. To reduce the extent and intensity of the staining and to recover the original color or gray fabrics of excavated costumes, bleaching would be required. Excavated historical costumes are very delicate in nature, therefore, special care is needed in bleaching process. Several bleaching agents were selected and applied to the control cotton fabric and pre-deteriorated cotton fabrics to examine the change of color and physical properties after bleaching. A dual bleaching using hydrogen peroxide and sodiumborohydride showed the superior bleaching effect to the other bleaching agents. The strength of pre-deteriorated fabrics slightly increased after dual bleaching. The six historical costumes which belonged to General Duk-Ryung Kim's nephew's wife were dual bleached. They became remarkably cleaned and brightened. The treatments improved the appearance of costumes. By microscopic investigation, it is found that costumes did not show the damage after treatment. In conclusion, it is possible to bleach historical textiles without damage using appropriate bleaching agents like hydrogen peroxide and sodiumborohydride.