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Industrial Automation
Published in Stamatios Manesis, George Nikolakopoulos, Introduction to Industrial Automation, 2018
Stamatios Manesis, George Nikolakopoulos
As an example of an integrated machine, Figure 1.1 depicts the typical production line of an integrated paper machine, where the initial raw pulp is undergoing the sequential processes of pretreatment and grinding, refining, pulp bleaching, and pulp pressing and drying, until it is transformed into the final paper of predefined quality. Figure 1.2 shows the various stages of the papermaking process. During the pretreatment and grinding, in the first stage of the papermaking process, debarked and washed wood logs are preheated in order to become easier to grind and are inserted into large wood log grinders, which produce wood chips. Refining is the second stage of the paper manufacturing process, when the quality of the final product is highly dependent on that specific subprocess. During that stage, the wood chips are being received and transformed into pulp via high energy consumption, water infusion, and addition of chemical compounds. During the next stage of pulp bleaching, the pulp produced by the refining system is fed to the machine that is responsible for the discoloration of the mixture. Bleaching is a chemical process applied to cellulosic materials in order to increase their brightness. The last stage of the paper manufacturing process is the drying and pressing process. During this stage, bleached pulp is dried and pressed in order to form the desired production paper.
Mach–Zehnder Reference Beam Optical Holographic Interferometry
Published in Gregory R. Toker, Holographic Interferometry, 2017
Higher-diffraction-efficiency phase comparison holograms can be obtained after the procedure of bleaching, when the metallic silver grains in the photo emulsion are converted to transparent silver salts. The refraction index of these salts differs from the index of refraction of the gelatin matrix. For example, the indices of refraction of silver bromide and silver chloride8 are 2.25 and 2.07, respectively. Amplitutde holograms with a high optical density would have a good quality—at least D ≥ 2. This bleaching procedure should be performed with definite precautions,8 because some bleaching solutions are hazardous for human health. For a long time, the author used the solution with components indicated in Table 2.1. This bleaching solution is safe, stable, and has a long lifetime. The bleached photo plates are transparent with a light blue undertone.
Chemical Conversion Process for Biodiesel Production
Published in Jay J. Cheng, Biomass to Renewable Energy Processes, 2017
The primary purpose of bleaching is to remove the color pigments from the oil. It also helps to remove remaining soap, trace metals, phosphatides, and sulfur compounds. Bleaching involves mixing bleaching clays consisting of naturally occurring bentonite and montmorillonite with the oil and agitating for 10–30 min. The oil is usually heated to 90°C–120°C. The process is conducted under a slight vacuum to exclude oxygen and the residual water from the neutralization and water washing. The clays are usually activated before use with a mineral acid such as sulfuric acid, removing some of the minerals from the clay and producing a larger volume of micropores and smaller clay particles. The bleaching clays are mixed with the oil, either directly or premixed with a small amount of oil to produce a slurry which is then added to the oil. After the adsorption process reaches equilibrium, the clay is filtered out by self-cleaning filters.
Improvement in the absorbency of ozone bleached cotton fabric by the addition of surfactant
Published in The Journal of The Textile Institute, 2021
Fariha Arooj, Kainat Jamshed, Saif ur Rehman Kashif, Haroon Jamshed, Muhammad Luqman
Textile industry is one the most water intensive industries as it consumes large amount of water in different processes like desizing, scouring, bleaching, dyeing etc and produces highly polluted effluent due to the large amount of toxic chemicals used in these processes (Kant, 2012; Ruuttunen and Vuorinen 2007; Tufekci et al., 2007). Bleaching is an important process required to remove impurities and waxes for subsequent dyeing (Presa & Tavcer, 2008; Shafie et al., 2009). Conventional bleaching of cotton uses hydrogen peroxide along with caustic soda, auxiliary chemicals and high temperature (90-110 °C) operating conditions (Cisneros et al., 2002; Cserhati et al., 2002; Hart & Connell, 2008). Therefore, research is being made to find alternative bleaching methods which consume less water, energy and chemicals (McMullan et al., 2001; Gähr et al., 1994; Correia et al., 1994; Banat et al., 1996; Cheung et al., 2009).
Evolution in the surface modification of textiles: a review
Published in Textile Progress, 2018
Ayoub Nadi, Aicha Boukhriss, Aziz Bentis, Ezzoubeir Jabrane, Said Gmouh
The natural fibre and fabrics even after scouring still contain naturally-occurring colouring substance. This yellowish and brown colouration may be related to flavone pigments of the cotton flower. The climate, soil, drought and frost can also cause various degrees of yellowness. Leaf tips or stalks coming in contact with the moist boll after opening cause dark spots and colouration. These colour changes may also come from dirt, dust, and insects or from harvesting or processing equipment in the form of oils and greases. The aim of bleaching is to produce white fabrics by destroying or rendering soluble the colouring substance. The bleaching agents bring about chemical modification to the colouring substances either by oxidation or reduction. After washing and chemical bleaching, a natural permanent whiteness is obtained which can be further enhanced by the application of optical brighteners.
Evaluation of the sulphate resistance of foamed concrete containing processed spent bleaching earth
Published in European Journal of Environmental and Civil Engineering, 2022
Rokiah Othman, Khairunisa Muthusamy, Youventharan Duraisamy, Mohd Arif Sulaiman, Ramadhansyah Putra Jaya, Nadiatul Adilah Ahmad Abdul Ghani, Sajjad Ali Mangi
SBE is a by-product of the palm oil refining process. Refining of crude palm oil involves several methods such as degumming, bleaching and deodorising. The primary purpose of bleaching is to remove undesirable substances such as soap residues, a trace of heavy metals, a phosphorus compound, as well as coloured matter. It is about 100 000 to 120 000 tons, or more SBE are utilised yearly in the refining process which is commonly disposed at the landfill. In record, some 120 000 tonne (0.8%) SBE was generated from palm oil refining companies based in Malaysia where some 36 000 tonne (30%) of oil is recovered annually from SBE (Loh et al., 2015). With the advancement of technology, the process for regeneration of SBE involves two stages, recovery of oil from SBE for special adsorbents purpose and heat regeneration of de-oiled SBE as a construction material. Overall, the utilisation of SBE in material production can reduce the disposal issue (Eliche-Quesada & Corpas-Iglesias, 2014). It should be noted that SBE can present a potential fire and pollution hazards, because it contains 20 to 40% residual oil by weight, metallic impurities and organic compound upon its disposal. Then, the dumping of SBE in landfill or public disposal sites should be restricted to protect environmentally. In response to these severe issues, SBE disposal has been resolved by removing the oil and colouring materials (Meziti & Boukerroui, 2011). Mostly, the residual oil can be extracted to produce biodiesel (Huang & Chang, 2010) while the deoiled SBE can be reused as an adsorbent in wastewater treatment, as a clay substitute in the bricks, blocks or tile manufacturing process (Beshara & Cheeseman, 2014; Eliche-Quesada & Corpas-Iglesias, 2014) and as filler in asphalts (Sangiorgi et al., 2014).