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Polyvinyl Alcohol and Polyvinyl Acetate
Published in Abdullah Al-Mamun, Jonathan Y. Chen, Industrial Applications of Biopolymers and their Environmental Impact, 2020
PVAc is used in the coatings for wires. It has an amazing function in seizing the colors on the surfaces such as wires, bill boards, and advertisement boards. The theory of color seizing is that the PVAc has a viscosity which performs well in color stablizing. In its most important application, polyvinyl acetate serves as the film-forming ingredient in water-based paints.
Filling Data Gaps by Correlation and Prediction
Published in David A. Palmer, Handbook of Applied Thermodynamics, 2019
Organic acids form such strong dimers in the gas phase that the VLE cannot possibly be modeled without taking them into account. In fact, VLE data look thermodynamically inconsistent if an ideal gas phase is assumed. The organic acids cannot be ignored, as is done by some authors, because these acids have considerable importance in the chemical industry. Acetic acid is used in manufacture of acetate fibers and is the solvent used in production of terephthalic acid, the main building block for polyester. Further, it is such a good solvent that it is used as a reaction medium in many other situations. For this reason, DIPPR established a special project just to measure its PVT properties and VLE in mixtures with water up to and including reaction pressures. Hydrogen fluoride forms hexamers which can be treated with the same approach.
Preparation, Properties, and Bonding Utilization of Pyrolysis Bio-oil
Published in Zhongqi He, Bio-based Wood Adhesives, 2017
An Mao, Zhongqi He, Hui Wan, Qi Li
Commonly used separation methods are solvent extraction and distillation (Garcia-Perez et al., 2007; Effendi et al., 2008; Zilnik and Jazbinsek, 2012). In solvent extraction, the separation of lignin fraction is based on the lignin’s good solubility in organic solvents and poor solubility in water (Chum and Black, 1990). Ethyl acetate is a common organic solvent. The lignin and neutral fractions of bio-oil are soluble in ethyl acetate, while the other components derived from cellulose and hemicellulose are much more soluble in water (Sukhbaatar et al., 2009). As described in a patent (Chum and Kreibich, 1992), by mixing bio-oil and acetate, a fraction with lignin and neutral was obtained. This ethyl acetate-soluble fraction was separated and washed with water and sodium bicarbonate solutions to remove organic acids. A lignin fraction was obtained after the evaporation of ethyl acetate. Dobele et al. (2010) used a simple solvent, water, to extract pyrolytic lignin from bio-oil. The bio-oil was obtained from fast pyrolysis of alder, ash-tree, and aspen mixture in a laboratory scale reactor. When water was added into bio-oil, precipitation occurred. The water-insoluble fraction was separated and dried to obtain pyrolytic lignin fraction. The content of phenolic compounds in this fraction was between 75%-83%. The authors (Dobele et al., 2010) also proposed another procedure to separate monomeric phenol from bio-oil using methyl tert-butyl ether (MTBE) as organic solvent (Fig. 2).
Pervaporation separation of ethylacetate-ethanol mixtures using zeolite 13X-filled poly(dimethylsiloxane) membrane
Published in Chemical Engineering Communications, 2022
Sebnem Senol, Buket Kaya, Inci Salt, Berk Tirnakci, Yavuz Salt
Ethyl acetate is an important chemical compound in many areas such as adhesives, leather varnishes, inks, fast-drying paints, photo films, transparent paper production, varnishes, pharmaceutical and organic syntheses. It can be produced from ethanol and acetic acid in either continuous or batch processes by the Fischer esterification reaction and the ethanol dehydrogenation method, respectively. Ethanol and ethyl acetate form an azeotropic mixture, that is difficult to separate using conventional methods (Zhang et al. 2017; Alamaria et al. 2019). Pervaporation (PV) method in which the transport mechanism through a non-porous membrane is based on the solution-diffusion model is recognized as an efficient membrane separation process that can be used for the separation of azeotropic systems or the mixtures containing components with similar boiling points (Lipnizki et al. 1999; Baker 2004; Uragami et al. 2010).
The technique of electrospinning for manufacturing core-shell nanofibers
Published in Materials and Manufacturing Processes, 2018
Zhao-Xia Huang, Jia-Wei Wu, Shing-Chung Wong, Jin-Ping Qu, T. S. Srivatsan
Similar to coaxial electrospinning, hollow nanofibers can be produced by selectively removing the core fiber from electrospun fibers having a core-shell nanostructure that was engineered using the technique of emulsion electrospinning. Hsieh and coworkers [112, 115] prepared nanofibers from: (a) PAN/cellulose acetate (CA), (b) PAN/PEO and (c) PAN/PMMA using the technique of emulsion electrospinning by dissolving PAN/CA, PAN/PEO and PAN/PMMA into an DMF liquid with the intent of form a working liquid. Subsequent to emulsion electrospinning, the CA, PEO and PMMA were carefully removed by an immersion of nanofibers in the following: acetone at 30°C for 2 h,di-water at 70°C for 10 min,chloroform at laboratory temperature for 1 h.
One- and two-stage anaerobic co-digestion of cucumber waste and sewage sludge
Published in Environmental Technology, 2020
Taylor B. Lowe, Benjamin T. Hatch, Chad Antle, Steven Nartker, Michelle L. Ammerman
The four stages of AD include hydrolysis, acidogenesis, acetogenesis and methanogenesis. In the first, stage hydrolytic bacteria secrete enzymes that hydrolyse polysaccharides into smaller units. In acidogenesis, the sugars, long chain fatty acids, and amino acids produced into the first stage are substrates for fermentative, bacteria that produce organic acids. Although some acetate is produced through direct fermentation the majority is produced by acetogenic bacteria that convert intermediates (such as propionate and butyrate) to acetate under anaerobic conditions. The rate-limiting step of AD is when methanogenic archaea use different substrates to produce methane [14]. AD can be performed in a single-stage or two-stage system, and under mesophillic or thermophillic conditions. All reactions in a single-stage digester take place in one reactor and environmental conditions are maintained at levels that suit all of the bacteria and archaea involved in the process. Traditional one-stage digesters require less space and construction but provide less stability than two-stage digesters. The two-stage digesters separate the hydrolysis and acidogenesis processes from acetogenesis and methanogenesis. In the first stage, digestion is limited by the rate of hydrolysis especially of cellulosic materials; the second stage is typically limited by the rate of microbial growth [15]. Physically separating the acidogens from the methanogens can result in a higher methane production and chemical oxygen demand (COD) removal efficiency at a shorter hydraulic retention time (HRT) as compared to conventional single-stage digesters [16,17]. It has been reported that augmenting the first hydrolysis stage could stimulate the acidogens to produce more specific enzymes that result in more extensive degradation of substrates [18,19].