China
Africa
Explore chapters and articles related to this topic
Atmospheric Pollution and Pollutants
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Organic acids are characterized by one or more carboxyl groups (−COOH). Organic acids commonly used in industry include acetic and formic acids. Although emissions are limited, organic acids are common in the atmosphere in the gas phase. Acetic acid is found in urban areas in the low ppbv range. A variety of dicarboxylic acids (two −COOH groups) have been observed in urban areas. These include oxalic, succinic, and malonic acids. They are produced from the photochemical oxidation of organic compounds in the atmosphere. Because of their low vapor pressures, dicarboxylic acids and other organic acids are predominantly found in or on aerosol particles. Organic acids are removed from the atmosphere by reaction with OH and by wet and dry deposition processes.
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Organic acid is a hydrocarbon derivative family. They can be flammable and toxic and all are corrosive. In chemistry, there are two general types of acids: organic and inorganic. Inorganic acids do not burn, but they can be oxidizers and support combustion. Some organic acids burn, whereas others do not. If a flammable placard is found on an acid container or the MC 312/DOT 412 acid tanker, it is an organic acid. Organic acids are polar; in fact, of all the hydrocarbon derivatives, they are the most polar. They have both the carbonyl structure CO like the ketones, aldehydes and esters and the OH structure like the alcohol. The formula for a generic organic acid is COOH. One radical is attached and the name comes from the radical with an “ic” added and with the ending word “acid.” Acetic acid is formed when a methyl radical is attached to the generic COOH of the organic acid. This does not follow the naming conventions of other derivatives, however, the reasons why are not important in terms of Applied Chemistry. It can be found in varying concentrations from strong, as in glacial acetic acid which is the pure compound (99.8%), to weak solutions known as vinegar. Acetic acid is a clear, colorless liquid with a pungent odor. It is one of the organic acids that are flammable, and are toxic by inhalation and ingestion in higher concentrations, with a TLV of 10 ppm in air. Other types of common organic acids include formic acid, acrylic acid, butric acid and propionic acid.
Properties and Conversion Technologies of Biomass
Published in Jacqueline A. Stagner, David S-K. Ting, Green Energy and Infrastructure, 2020
Yaning Zhang, Wenming Fu, Pingfei Xu, Bingxi Li, Baocheng Jiang
Organic acids are mainly produced through homolactic fermentation and heterolactic fermentation (Wikipedia, 2018): Homolactic:C6H12O6→2CH3CHOHCOOHHeterolactic:C6H12O6→CH3CHOHCOOH+C2H5OH+CO2
Identification, characterization and optimization of culture medium conditions for organic acid-producing lactic acid bacteria strains from Chinese fermented vegetables
Published in Preparative Biochemistry & Biotechnology, 2023
Charles Obinwanne Okoye, Lu Gao, Yanfang Wu, Xia Li, Yongli Wang, Jianxiong Jiang
Organic acids and other metabolites enhance flavor development in food and animal feed and prevent spoilage and are thus very useful in many industrial applications, especially in the feed and livestock industry.[1,7,10,11] The safety of fermented food products for human and animal consumption may be improved due to the inhibition of pathogenic microorganisms by several organic acid-producing LAB. These LAB species have the ability to inhibit harmful microorganisms during fermentation.[5,12] However, under unfavorable conditions, most LAB species hasten the decrease in pH but cannot inhibit the effect of pathogens. This is because they are usually short-lived and unable to sustain prolonged fermentation. Many LAB strains have proven to produce different organic acids other than LA, indicating that those strains may be more beneficial for silage production. Present studies have undergone the molecular characterization of distinct LAB species such as Lactobacillus sp., Weissella sp., Enterococcus sp., and Pediococcus sp. as potential sources of microbial metabolites and organic acids.[13–15]
A Comprehensive Review on Cobalt Bioleaching from Primary and Tailings Sources
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Alex Kwasi Saim, Francis Kwaku Darteh
Several organic acids are released by fungi, which include oxalic, gluconic, citric, malonic, lactic, acetic, succinic, pyruvic and formic acids. The acidity of organic acids comes from the presence of carboxyl, hydroxyl, and carbon double bond functional groups. These organic acids maintain a low pH in order to maximize Co bioleaching. The acids also give the necessary protons to decrease access of anions to cations in metal compound reactions, improving Co solubility. In addition, as illustrated in Figure 2, organic acids (as natural chelating agents) have a role in complexolysis to stabilize Co2+ ions that have been solubilized by acidolysis. Fungi species can also recover metals through bioaccumulation within the fungal biomass. It should be noted that acidophilic bioleaching is often linked to the process of acidolysis and redoxolysis, while acidolysis and complexolysis are often linked to bioleaching by fungi. Reactions 6–8 indicate how the organic acid metabolites of fungi aid in Co dissolution (Biswal et al. 2018).
Mutual Separation of Ln and an Using TODGA and DTBA with High Organic Acid Concentrations
Published in Solvent Extraction and Ion Exchange, 2022
Yuji Sasaki, Masashi Kaneko, Masahiko Matsumiya, Masahiko Nakase, Kenji Takeshita
Before the solvent extraction experiments, the pH values of the organic acid solutions were measured, and the results obtained are summarized in Table 1. The organic acids in this study were: glycolic, lactic, citric, tartaric, malonic, maleic, malic, propionic, and glutaric acids. These organic acids have high solubility in water, and their solutions can be prepared to have high concentrations (e.g., 1–5 M). Table 1 shows that the maximal concentrations for citric, maleic, and glutaric acids is 3 M, while that for glycolic, malic, and propionic acids is 4 M, and that for lactic, tartaric, and malonic acids is 5 M. Higher organic acid concentrations resulted in lower pH values, and the pH values of the different solutions depend on their dissociation constants. The pKa values organic acids corresponding to their 1st order dissociation (HL ⇄ H+ + L−) varied in the order: propionic acid > glutaric acid > lactic acid > glycolic acid > malic acid > citric acid > tartaric acid > malonic acid > maleic acid, is shown in Table S1.[49] The order of the pH values in the acids to be 1 M as shown in Table 1 is almost the same as their dissociation constants. Reportedly, a pH value of 1–2 is suitable for An/Ln separation using DTPA and DTBA[34,40;] thus, organic acids with low pH values (approximately zero) were not used. From this point of view, 5 M malonic or tartaric acids were hard to use, given that higher pH values were required.