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Health Effects
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Much of the available information on acute and chronic effects of SO2 is based on laboratory animal studies conducted at exposure concentrations considerably higher than those found in polluted atmospheres. Because of its solubility in watery fluids, SO2 is efficiently removed in the upper respiratory tract. It forms sulfurous acid (H2SO3), which readily dissociates into bisulfite and sulfite ions that move into the systemic circulation. Less than 1% of inspired SO2 reaches the alveoli. Exposure of the lower airways and alveoli increases during exercise, mouth breathing, and under low ambient SO2 levels. The major physiological effects of SO2 are changes in mechanical function of the upper airways, including an increase in nasal flow resistance and a decrease in nasal mucus flow rate. Animal studies indicate that SO2 exposures can adversely affect pulmonary defense mechanisms such as mucociliary transport, alveolar clearance of particles, and macrophage function. There is some evidence that exposures may cause chronic bronchitis.
Formulation Development of Small-Volume Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Madhav S. Kamat, Patrick P. DeLuca
Morphine in aqueous solution undergoes a pH-dependent oxidative degradation. The rate is slow and constant between pH 2 and 5, where morphine exists in the protonated form as shown in Figure 10.13. However, above pH 5, the oxidation increases with increase in pH [82]. Therefore, morphine can be stabilized by lowering the pH or by adding an antioxidant such as ascorbic acid which will be preferentially and reversibly oxidized between pH 5 and 7. Ascorbic acid, in turn, can act as an antioxidant for hydroquinone because it has a lower oxidation potential and will be preferentially oxidized. Table 10.10 lists some standard oxidation potentials. Salts of sulfur dioxide, including bisulfite, metabisulfite, and sulfite, are the most common antioxidants in aqueous solutions. Irrespective of which salt is added to the solution, the antioxidant moiety depends on the final concentration of the compound and the final pH of the formulation [83]. The metabisulfite is used at low pH values [84]. Some drugs can be inactivated by bisulfites. For example, in the presence of bisulfite, epinephrine forms addition product as epinephrine sulfonate, which is inactive [85]. Ortho- or para-hydroxybenzyl alcohol derivatives such as parabens react in a similar manner.
Heavy Metals/Cyanide Treatment
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
Sodium metabisulfite is used to attain sodium bisulfite. The following reactions occur: Na2S2O5+H2O⇌2NaHSO3NaHSO3+H2O⇌H2SO3+NaOH
The capture of a dilute stream of industrially generated sulfur dioxide in an aqueous solution of the ionic liquid 1-butyl-3-methylimidazolium chloride [bmim][Cl]
Published in Chemical Engineering Communications, 2020
Carlos Carlesi, Nadia Guajardo, Rodrigo Schrebler, Samuel Carrasco
The equilibrium between SO2 and pure water showed that at a pH of 4.5, the maximum amount of dissolved sulfur dioxide exists in the form of bisulfite; below that pH, the equilibria promote the existence of SO2 in a loosely hydrated undissociated form, and above 4.5, there is a combination of sulfite and bisulfite ions.