H2O2 Bleaching Research Articles

Film forming ability of gelatins from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide

Properties of gelatin films from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide (H2O2) at various concentrations (0–8% w/v) were investigated. Tensile strength (TS) and water vapour permeability (WVP) of films decreased, but elongation at break (EAB) increased (p<0.05) as the concentration of H2O2 increased. Among all films, that prepared from gelatin with 2% H2O2 bleaching showed the lowest ΔE∗-value (total colour difference), which was concomitant with the highest L∗-value (lightness). Generally, higher concentration of H2O2 resulted in increased b∗-value (yellowness) of resulting films. Electrophoretic study revealed that α-chains of gelatin in films became lowered with increasing H2O2 concentrations used for bleaching. Thermogravimetric analysis indicated that heat susceptibility and weight loss of different films varied with H2O2 concentrations. Rougher surface was obtained in gelatin films prepared from skin bleached with H2O2 concentrations above 4%. Thus, the concentrations of H2O2 used for bleaching of squid skin prior to gelatin extraction directly affected the properties of corresponding gelatin films.

EFFECTS OF DIFFERENT ACTIVATION PROCESSES ON H2O2/TAED BLEACHING OF Populus nigra CHEMI-THERMO MECHANICAL PULP

Tetra acetyl ethylene diamine (TAED) was used as an activator in H2O2 bleaching to improve bleaching efficiency. The present work was aimed at confirming different activations for various H2O2/TAED bleaching processes, including the addition of acetic anhydride and the step-addition of sodium hydroxide. The results showed that an acetic anhydride dosage of 1%, an acetic anhydride treatment time of 10 min, and an addition time of 45 min were the optimal treatment conditions. The optimum processes of NaOH step-addition treatment in H2O2 bleaching and in H2O2/TAED bleaching also were confirmed, respectively. The o-quinone contents of H2O2 bleached lignin and H2O2/TAED bleached lignin were determined. The results indicated that H2O2/TAED bleached lignin has a lower o-quinone content than H2O2 bleached lignin, which is one of the reasons for the H2O2/TAED bleaching process having better bleaching efficiency than H2O2 bleaching.

The use of lactoperoxidase for the bleaching of fluid whey

Lactoperoxidase (LP) is the second most abundant enzyme in bovine milk and has been used in conjunction with hydrogen peroxide (H2O2) and thiocyanate (SCN–) to work as an antimicrobial in raw milk where pasteurization is not feasible. Thiocyanate is naturally present and the lactoperoxidase system purportedly can be used to bleach dairy products, such as whey, with the addition of very little H2O2 to the system. This study had 3 objectives: 1) to quantify the amount of H2O2 necessary for bleaching of fluid whey using the LP system, 2) to monitor LP activity from raw milk through manufacture of liquid whey, and 3) to compare the flavor of whey protein concentrate 80% (WPC80) bleached by the LP system to that bleached by traditional H2O2 bleaching. Cheddar cheese whey with annatto (15mL of annatto/454kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a standard Cheddar cheesemaking procedure. Various levels of H2O2 (5–100mg/kg) were added to fluid whey to determine the optimum concentration of H2O2 for LP activity, which was measured using an established colorimetric method. In subsequent experiments, fat-separated whey was bleached for 1h with 250mg of H2O2/kg (traditional) or 20mg of H2O2/kg (LP system). The WPC80 was manufactured from whey bleached with 250mg of H2O2/kg or 20mg of H2O2/kg. All samples were subjected to color analysis (Hunter color values and norbixin extraction) and proximate analysis (fat, protein, and moisture). Sensory and instrumental volatile analyses were conducted on WPC80. Optimal LP bleaching in fluid whey occurred with the addition of 20mg of H2O2/kg. Bleaching of fluid whey at either 35 or 50°C for 1h with LP resulted in >99% norbixin destruction compared with 32 or 47% destruction from bleaching with 250mg of H2O2/kg, at 35 or 50°C for 1h, respectively. Higher aroma intensity and increased lipid oxidation compounds were documented in WPC80 from bleached whey compared with WPC80 from unbleached whey. Monitoring of LP activity throughout cheese and whey manufacture showed that LP activity sharply decreased after 30min of bleaching (17.01±1.4 to <1U/mL), suggesting that sufficient bleaching takes place in a very short amount of time. Lactoperoxidase averaged 13.01±0.7U/mL in unpasteurized, fat-separated liquid whey and 138.6±11.9U/mL in concentrated retentate (11% solids). Lactoperoxidase may be a viable alternative for chemical whey bleaching.

SEPARATION AND CHARACTERIZATION OF NEW CELLULOSIC FIBRES FROM THE JUNCUS ACUTUS L PLANT

Cellulose fibres from the Juncus acutus L plant were isolated and characterized. The isolation of the fibres was performed by sequential NaOH treatment and H2O2 bleaching under different extraction conditions. The chemical and surface morphological structures of the Juncus acutus L fibres were characterized with FTIR, SEM, AFM, DSC, surface energy, diameter, density, and lignin content determination. Changes in structure and properties of the obtained fibres were observed by varying the concentration and the treatment time of the applied process. Results revealed that the optimum conditions to remove most of non-cellulosic materials from the Juncus acutus L plant were 7M NaOH, 3h and 100°C for alkaline procedure, and 10 mL.L-1 H2O2, 45 minutes and 95°C for bleaching treatment.

Reinforcement of Hydrogen Peroxide Bleaching of Bamboo Pulp

Magnesium-based alkalis and the Chelants (tetra acetyl ethylene diamine (TAED), Sodium Citrate and Opal) for hydrogen peroxide bleaching of bamboo pulp were investigated in this paper. The results showed that the optimal conditions of hydrogen peroxide bleaching of bamboo pulp were as follows: H2O2 4%, Mg(OH)2:NaOH=25%, Sodium Citrate 1%, Opal 1.5%, TAED:H2O2=0.67, temperature 60°C, and time 90 minutes. Under the optimum conditions, the brightness of bamboo pulp can be enhanced from 41.2% ISO to 78.2% ISO, while the brightness of bleached pulp by using the Mg(OH)2-based alkalis was higher than by using NaOH as the alkali source. It can be seen that Sodium Citrate, Opal, and TAED activated H2O2 bleaching needed lower reaction temperature, shorter time, and got better brightness and alleviated environment pollution, compared with the conventional H2O2 bleaching of the same pulp.

Erratum to: ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp

Erratum to: ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp

Investigation of the Optimum Pretreatment Conditions for the Knitted Fabric Derived from PLA/Cotton Blend

 Abstract— The pretreatment processes prior to dyeing which were the scouring and bleaching, for the knitted fabric of PLA/cotton blend were studied comparing with the 100% cotton and PLA fabrics. These two pretreatment processes were studied in a sequence (scouring followed by H2O2 bleaching) and altogether in the one-bath process. The scouring process of the blended fabric was compared when the different scouring agents were employed (NaOH, Na2CO3 and pectinase enzyme). The two-bath and one-bath scouring/bleaching processes had a signified effect on the strength of the fabrics because the pretreatment processes typically used for cotton are in the alkaline condition which can deteriorate the PLA fiber. Therefore, the pretreatment conditions for the PLA/cotton blended fabric needed to be optimized to avoid fiber damage. From the research, it was observed that the pretreatments for the blended fabric, which was to enter the pale-shade dyeing, were scoured using 10%owf pectinase (60C, 60 min) as it enhanced a satisfactory water absorbency to the fabric without causing any adverse effect on the fabric strength. For deep-shade dyeing, the blended fabric should undergo the one-bath scouring/bleaching with 7%owf H2O2 (100C, 60 min) which yielded a water absorbency and whiteness on the fabric to a standard level and the resulting fabric strength was highest and this one-bath pretreament was the time-saving process. high-CO2 emission and the wastes generated are also difficult to dispose of. Therefore, the researches have focused on an alternative environmental-friendly fiber which has comparable properties and can be used as a substitute of the conventional polyester fiber, poly (ethylene terephthalate) (PET). In 2002, Cargill Dow Polymer LLC, a joint venture between Cargill and Dow Chemical companies opened a production plant to produce a biodegradable polyester fiber, polylactic acid (PLA), with the purpose of replacing the petroleum-based PET fiber. The different structures between

Effectiveness and cytotoxicity of a 35% H2O2 bleaching gel

Effectiveness and cytotoxicity of a 35% H2O2 bleaching gel

Effect of Chemical Pretreatment on Cotton Stalk SCMP Bleaching Properties

Effect of chlorine, potassium permanganate and peracetic acid pretreatment on H2O2 bleaching properties of cotton stalk SCMP was studied in the paper. The results showed that brightness gradually increased with dosage of chlorine, however, the increase is small, and bursting index and breaking length firstly increased and then decreased as dosage of chlorine is great than 1.5%. Brightness of H2O2 bleached pulp decreased for potassium permanganate pretreatment, even change the bleaching sequence. Brightness of PaPP bleaching is the highest with peracetic acid pretreatment. Among the studied reagents, chlorine and peracetic acid can increase brightness of H2O2 bleaching, however, pretreatment with potassium permanganate can not improve bleaching properties. The brightness with CH3COOOH pretreatment is higher than that of chlorine pretreatment.

Study on Bleaching of De-Inked Pulp

FAS bleaching (F) and conventional H2O2 bleaching (P) as well as TAED activated H2O2 bleaching (PT) of wastepaper de-inked pulp (DIP) were studied in this paper. The results showed that the optimum conditions for FAS bleaching of DIP at 10% consistency were FAS 0.6%, NaOH 0.3%, reaction time 30min, temperature 70°C. Under the same conditions of H2O2 3.0%, NaOH 2.0%, Na2SiO3 3.0％, MgSO4 0.05％, the optimum temperature was 80°C and reaction time 90min for conventional hydrogen peroxide bleaching; the optimum TAED dosage was 1.5%, reaction time 60min, temperature 60°C for TAED activated hydrogen peroxide bleaching. Finally a comparison was made between PTF and PF two-stage bleaching for DIP. The performance of PTF was better than PF.

Research on FTIR Analysis of &lt;i&gt;Populus&lt;/i&gt; &lt;i&gt;nigra&lt;/i&gt; L. Lignin Structure Changes in Different Bleaching Processes

To study the bleaching mechanisms of H2O2 bleaching, H2O2 displacement bleaching and H2O2 /TAED bleaching, three kinds of lignin bleached with above processes were obtained. Three types of treated Populus nigra L lignins structure were identified and the functional groups were quantitied by FTIR. In contrast, the deacetylation and the breakage of ester bonds in H2O2/TAED bleaching system was much more significant. The total carbonyl group of H2O2 bleached lignin decreased 6.6% while displacement bleached lignin and H2O2/TAED bleached lignin decreased 9.2% and 15.8% respectively. The PT bleaching process had stronger oxidability to destroy the syringyl units in lignin. The breakage of ether bonds and alcoholic hydroxyl dehydration in side chain increased after bleaching. In contrast, the stronger destroyed effection on guaiacyl dialkyl ether bond with PT bleaching processes. The conclusions obtained may interpret H2O2 displacementbleaching and H2O2/TAED bleaching systems have better bleaching efficiency than H2O2 bleachingsystem.

Gradient Intensified Alkali Extraction of Kraft Pulp by Oxygen-Containing Bleaching Agents

The selectivity of delignification is disappointing in the conventional intensified alkali extraction by oxygen and H2O2. To improve the properties of the conventional intensified alkali extraction, the gradient intensified alkali extraction by oxygen-containing bleaching agents was presented, and effects of treatment conditions on properties of gradient intensified alkali extraction of kraft pulp by oxygen and/or H2O2 were investigated. In DEPD bleaching sequence, the optimal dosage of H2O2 in EP stage is 1.5% with higher brightness and lower loss in viscosity of bleached pulp. The addition time of H2O2 is better after 20 min of alkali extraction in DE/PD sequence to facilitate bleaching function of H2O2. In DP/ED sequence, the brightness is highest when alkali extraction carried through after 20 min of H2O2 bleaching. In EO stage, the optimal dosage of NaOH is 5.0% considering delignification and bleaching efficiency. As to alkali extraction intensified by oxygen and H2O2, the optimum dosage of H2O2 is 1.0%. Gadient intensified alkali extraction with oxygen and/or H2O2 was adopted for further bleaching and delignification, which can increase the brightness and selectivity of delignification by subtly adjusting the parameters.

Process optimization of tetra acetyl ethylene diamine activated hydrogen peroxide bleaching of populus nigra CTMP

To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching.

Bleaching of Wool with Sodium Borohydride

An untreated wool fabric was bleached both with sodium borohydride (SBH) in the presence of sodium bisulphite (SBS) solution and with a commercial H2O2 bleaching method. The concentration effects of SBH and SBS, bleaching time, pH and temperature on SBH bleaching process were investigated. Whiteness, yellowness and alkali solubility results were assessed for both bleaching methods. The results showed that whiteness degrees obtained with SBH bleaching was comparable with that of H2O2 bleaching method; whereas the alkali solubility values of the SBH bleaching was superior to the H2O2 bleaching.

Cytotoxic effect of a 35% hydrogen peroxide bleaching gel on odontoblast-like MDPC-23 cells

This study evaluated transenamel and transdentinal cytotoxic effects of a bleaching gel on the MDPC-23 cell line. Discs obtained from bovine incisors were placed in a metallic device to simulate an in vivo pulp chamber. Groups were formed according to the enamel surface treatment: G1: 35% H(2)O(2) bleaching gel; G2: 35% H(2)O(2) bleaching gel + halogen light; G3: halogen light; and G4: control. Cell metabolism was evaluated by the methyltetrazolium assay and cell morphology by scanning electron microscopy. Cell metabolism decreased by 31.7%, 41.6%, and 11.5% in G1, G2, and G3, respectively. Cytotoxic effects observed in G2 were significantly more severe compared with G3 and G4. In G1 and G2, a smaller number of viable cells with major morphologic alterations remained adhered to dentin. The bleaching gel associated with light presented transenamel and transdentinal cytotoxic effects characterised by direct damage to odontoblasts and decrease of their metabolic activity.

Comparison of enzymatic pretreatments with three xylanases for enhancing H2O2 bleaching of wheat straw chemomechanical pulp

Comparison of enzymatic pretreatments with three xylanases for enhancing H2O2 bleaching of wheat straw chemomechanical pulp

Enzyme and silicone treatments on jute fibre. Part I: Effect on textile-related properties

The present study relates to broad-based assessment of softening of raw jute and selectively pretreated jute fibres under the action of mixed enzymes (cellulase, xylanase and pectinase) and a textile grade aminosilicone softener and to further assess how such selective treatments finally contribute in enhancing some textile-related properties. Application of 4% mixed enzyme on jute fibre at 55°C for 2 h at pH 4.8 offers much finer, softer, cleaner and brighter jute fibre with some lowering of bundle tenacity. However, pretreatment of jute fibre under combined oxidative action of 3% H2O2 and 0.75% K2S2O8 for 2 h at 30°C (pH 11) followed by subsequent treatment with 1% mixed enzyme offers a better balance of textile-related properties covering moisture regain, fineness, bundle tenacity, flexural rigidity, surface reflectance, whiteness index, yellowness index and brightness index. Treatments of jute fibre with 0.5–1% aminosilicone softener under a specified condition also make jute fibre much softer, smoother, brighter and cause noticable reduction in coefficient of friction without much change in bundle tenacity. However, keeping all textile-related properties in view, a preatment of conventional 3% H2O2 bleaching for 2 h at 85°C (pH 11) or an oxidative treatment under combined action of 3% H2O2 and 0.75% K2S2O8 for 2 h at 30°C (pH 11) prior to 1% aminosilicone treatment of jute fibre were found to be much useful for textile purpose.

Preparation and crystalline analysis of high‐grade bamboo dissolving pulp for cellulose acetate

AbstractHigh grade bamboo dissolving pulp for cellulose acetate (named as acetate bamboo pulp) was prepared from bamboo Cizhu (Dendrocalamus affinnis) by oxygen‐alkali pulping, xylanase and DMD (an intermediate product of the reaction of oxone with acetone) delignification treatments, and H2O2 bleaching. Its properties and structures were investigated by different analytical techniques, and compared with those of high grade hardwood dissolving pulp for cellulose acetate (named as acetate wood pulp), viscose bamboo pulp, and bamboo fiber for textile. Most of its properties are comparable with those of acetate wood pulp except ash contents and DCM (dichloromethane) extractive that are slightly high. Crystallinities and crystalline allomorphs of acetate bamboo pulp and the three samples were determined by FTIR spectroscopy, X‐ray diffraction and solid state 13C NMR spectroscopy, and the results obtained by the three methods were coincident. Bamboo cellulose crystalline allomorphs are classified as Iβ‐dominant type, and a higher lateral order index and a larger crystallite size for acetate bamboo pulp were found in spite of its crystallinity similar to acetate wood pulp. Different intermolecular hydrogen bond patterns are likely be responsible for the predominant crystalline fibrils in acetate bamboo pulp. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Molecular Characteristics of Corn Fiber Gum and Their Influence on CFG Emulsifying Properties

ABSTRACTThe molecular characteristics of two purified arabinoxylan fractions derived from corn kernels, corn fiber gum‐1 and ‐2 (CFG‐1 and ‐2), have been studied and correlated with emulsifying properties. CFG‐1 and ‐2 fractions were isolated from different corn fiber sources by 1) a sequential alkaline extraction and H2O2 bleaching to produce CFG‐1; and 2) additional H2O2 treatment of the alkali‐extracted residue at pH 11.5, yielding CFG‐2. Multiangle laser light‐scattering and online viscosity were used to measure the molar mass, polydispersity, structure compactness, and intrinsic viscosity of the generated CFG fractions. Emulsification properties in an oil‐in‐water emulsion system with 10:1 oil‐to‐gum ratio was investigated by measuring turbidity of an aliquot from the bottom of the diluted emulsion over 10 days. The isolated CFG‐2 from each fiber source was higher in weight‐average molar mass (Mw) polydispersity) (Mw/Mn) and structure compactness, and also lower in solution weight‐average intrinsic viscosity (ηw) than the corresponding CFG‐1. Average Mw and ηw values were 244–491 kDa and 1.35–1.84 dL/g, respectively. The emulsion stabilizing capacity of CFG‐2 from each fiber source was superior to the corresponding CFG‐1.

Development of new eco‐friendly options for cotton wet processing

AbstractA new approach was used to search for the optimal conditions for enzymatic scouring with an alkaline pectinase and to investigate the feasibility of performed combined bioscouring and H2O2 bleaching and combined bioscouring and reactive dyeing of unscoured cotton fabrics. The possibility of conducting enzymatic desizing, bioscouring, and H2O2 bleaching of starch‐sized cotton fabrics in a single bath was also examined. The results indicated that changes in the parameters of the bioscouring process, the types and concentrations of the treating bath components, and the sequence of the treatment and addition had pronounced effects on certain properties of the treated cotton substrates (e.g., the residual size, weight loss, wettability, yellowness and whiteness, and dyeability with reactive dyes). The optimal conditions for efficient bioscouring alone and in combination with H2O2 bleaching, reactive dyeing, and enzymatic desizing and H2O2 bleaching were determined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1825–1836, 2004