Hydrogen Peroxide Bleaching

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Hydrogen peroxide is a very effective bleaching chemical if applied under appropriate conditions. It decomposes to give water and oxygen only, so it is ideally suited to applications in which the effect on the environment of effluents has to be minimal. In chemical pulp bleaching, hydrogen peroxide is used mostly as a reinforcement to existing bleaching stages. The extraction process reinforced with atmospheric peroxide has gained notability due to its good effectiveness and low capital requirement for implementation. However, peroxide reinforcement can be more effective when pressurized in the so-called PHT-stage technology. The most common types of alkaline extractions today are those reinforced with oxygen and peroxide, partially pressurized alkaline extraction with oxygen and hydrogen peroxide (EOP) or pressurized all the way, the so-called (PO) stage. Use of hydrogen peroxide in the extraction stage results in more reduction in chlorine chemicals and also decreases the color of mill effluent. Other advantages of alkaline extraction with peroxide include improvement of environmental parameters such as color COD, BOD, and AOX. Significant reduction in effluent color is the greatest benefit of H2O2 addition in the extraction stage. It is common to use the alkaline extraction reinforced with oxygen (EO) or hydrogen peroxide (EP, PHT), or both (EOP, PO), to compensate for lower chlorine dioxide availability and also to make possible the bleaching in short sequences. Bleach plants that have a low availability of chlorine dioxide and require high peroxide dosages (0.8–1.0%) need more severe conditions for peroxide consumption. In these cases, pressurized peroxide stages such as (PO) or PHT are recommended because they allow use of high temperatures. A very significant increase in brightness is achieved when peroxide is applied to the alkaline extraction. Another positive effect is the peroxide effectiveness to bleach shives; even when they are not completely bleached, they are lighter and less visible. H 2 O 2 can also be used in the second alkaline extraction stage to counteract pulp darkening to reduce chlorine dioxide consumption. Use of pressurized peroxide stages (PO) makes possible to achieve a high final brightness in totally chlorine-free (TCF) bleaching. In sequences with chlorine dioxide (ECF bleaching), a powerful peroxide stage will reduce the consumption of chlorine dioxide or even replace one chlorine dioxide stage. A hot, pressurized peroxide stage operates at temperatures above 100 °C with a small amount of oxygen added. A prerequisite for successful peroxide bleaching is that the content of metal ions, for example, manganese, copper, and iron, is low. Several mills around the world are using peroxide for bleaching.

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... Peroxides are used to eliminate the color and to improve the brightness of the pulp, but depending on the reaction condition it can also degrade the cellulose fiber. There are some works in the literature showing the degeneration and discussion mechanism of the reactions that take place [30,31]. The alkaline treatment sequence using NaOH treatment and the bleaching treatment using NaOH/H 2 O 2 , under appropriate condition, can promote the removal of the majority of the amorphous constituents, such as hemicellulose, pectin, lignin, ashes, waxes, oils, from the vegetal fiber and therefore, increase the purity of the cellulose fibers. ...
Recently, the growing environmental concerns and economic demands have driven the need to develop effective solutions for the treatment of vegetal fibers to be used as renewable source for various industrial applications. The present study aimed to explore pineapple crown fibers (PCs) as an alternative source of cellulose. The three treatments (alcohol-insoluble residue (AIR), alkaline (AT), and organosolv) evaluated promoted chemical and morphological changes to the PCs. Fresh and treated PCs were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), thermogravimetric analysis (TG), and chemical composition. The XRD results showed that the Cellulose-I allomorph was not altered during extraction, and that the crystallinity index of the fibers treated with AT, first bleaching step, second bleaching step, and the second bleaching step followed by KOH treatment (2B_KOH) increased to 77.8; 83.2; 83.5 and 86% when compared with fresh PC (62.3%). Results from the thermal analysis revealed that thermal stability increased for the isolated cellulose, and the maximum degradation for (2B_KOH) is 350°C. Chemical composition results showed a decrease in the content of hemicellulose, lignin and other soluble materials after alkaline treatment, suggesting high-quality 2B_KOH with 74.6% of cellulose. SEM revealed changes in the morphological structure on fibers. Alkaline treatment followed by H2O2 bleaching is an excellent alternative for the removal of non-cellulosic material and facilitates the isolation of cellulose. These results suggested that there is a potential to isolate cellulose from PC via the sequence of treatment of a methodology by chlorite-free.
... The reactivity of HO -. and O2 -. toward aromatic lignin (phenolic structures) is only slightly higher than that with cellulose. Therefore, if H2O2 decomposes too fast and the concentrations of HO -. and O2 -. become too high, selectivity toward lignin is lost and cellulose degradation occurs, as well as lignin degradation (Bajpai 2012). In addition, a slow H2O2 decomposition rate will provide a longer duration for pulp exposure to HOOanions. ...
The brightness of bleached bamboo chemo-mechanical pulp (CMP) is often too low to be used as a furnish in value-added paper products. In this study, preliminary optimization of various parameters of a modified hydrogen peroxide (H 2 O 2 ) bleaching procedure for bamboo CMP pulps was performed using the inclusion of ethanol in the bleaching medium (IEBM). Compared with a conventional bleaching method, this modified process is aimed at improving bleaching efficiency and brightness ceiling of bamboo CMP with the proper usage of chemicals. The CMP was bleached to a brightness of 74.2% ISO at the usage level of 12% H 2 O 2 , which shows it increased by 7.4% ISO compared with the conventional method. For a brightness target of 72.0% ISO, bleaching with the IEBM method reduced the H 2 O 2 consumption by approximately 60%. In addition, a higher activation energy of H 2 O 2 for the IEBM method was calculated to be 23.3 kJ/mol, which was increased by 3.3 kJ/mol compared with the conventional method.
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Cotton fiber contains natural impurities on its' surface. To remove those impurities, cotton is treated with several types of bleaching agents based on industrial practice. The study investigated pre-post behaviors of single jersey knit after the bleaching treatments. Two types of bleaching chemicals were used to perform the study: such as (a) reductive, and (b) oxidative bleaching agents. The specimens were subjected to weight loss, absorption, color measurement, and bursting strength tests at the pre-post stages of the bleaching. Results from the statistical analysis revealed that the bleaching treatments significantly impacted on the behaviors of cotton knits. The findings also disclosed that hydrogen peroxide bleaching in the alkaline medium had the superior bleaching performance in cotton fabrics.
One of the most popular ways to carry out the re-use of wastes from agriculture is the pulping, refining and bleaching of those residues for papermaking. Spain annually produces more than 300 thousand tonnes of Citrus sinensis (orange tree) trimmings, crops being concentrated in the East and the South of the country. Their chemical composition is similar to that of common hardwoods. This work aims to show the suitability of ethanolamine cooking when applied to orange tree trimmings , and to study the effect of peroxide bleaching and refining on some key properties. As for bleaching, we used a design of experiments to discuss the influence of peroxide concentration, time and temperature on the yield, brightness, viscosity, kappa number of pulps and mechanical properties of paper sheets. Refining was studied by analysing the diminishment in freeness and the mechanical properties of paper sheets formed. Results showed that even a mild bleaching process gives out a high relative brightness gain, but a multiple-step process is necessary to achieve enough brightness for printing paper. Mechanical properties of non-refined pulps were found to be too low for paper of any grade, but they were greatly improved by refining.
The experimental research, process design principles, and engineering practice of a bagasse pulp production line that could run both totally chlorine-free (OP)Q(PO) and elemental chlorine-free (OP)D(EOP) bleaching sequences are discussed in this paper. Under specified process conditions, the oxygen delignification rate was up to 50% and the brightness of unbleached pulp increased. The (OP)Q(PO) sequence bleached pulp had a brightness of 83.1% ISO and an intrinsic viscosity of 888 mL/g, and the (OP)D(EOP) sequence bleached pulp had a brightness of 85.7% ISO and an intrinsic viscosity of 905 mL/g. Pulp quality produced from both bleaching sequences was better than pulp bleached by the chlorination, alkaline extraction, and hypochlorite (CEH) sequence. The wastewater was discharged only from the Q or D stage, and the chemical oxygen demand (COD) of Q or D stage was about 650 mg/L or 1100 mg/L, respectively. It was easy to alternate between these two bleaching sequences, and the bleached pulp quality from these sequences was stable.
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