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Municipal Wastewater Treatment
Published in Louis Theodore, R. Ryan Dupont, Water Resource Management Issues, 2019
Louis Theodore, R. Ryan Dupont
Chlorine is the disinfectant that has historically been used at wastewater treatment plants. Gaseous chlorine is the most common form used for wastewater disinfection and is applied in a rapid mix chamber at concentrations from 8 to 15 mg/L prior to entering a plug flow chlorine contact chamber to provide contact times of 20–30 minutes so the required disinfection performance can be produced. Chlorine can be toxic to aquatic life, so it is common that a de-chlorination step involving sodium metabisulfite be required to reduce chlorine residual to 0–0.5 mg/L before discharge.
Characterization of the degradation of dipyrone (metamizole) in expired oral pharmaceutical products by Raman spectroscopy and principal component analysis (PCA)
Published in Instrumentation Science & Technology, 2023
Luciana Lopes Guimarães, Leandra Paula Marques de Sousa Rosa Nita, Walber Toma, Marcos Tadeu Tavares Pacheco, Landulfo Silveira
The use of antioxidants and chelating agents as stabilizers for dipyrone in aqueous media reduces the risk of hydrolysis. Sodium metabisulfite, an antioxidant that displays antimicrobial activity,[34] is present in all brand formulations in this study. Chelating agents, such as disodium EDTA, are used in liquid preparations as stabilizers for heavy metals and alkaline earth ions in water. All samples included EDTA in their formulations. Also, the decomposition is not due only to hydrolysis; factors such as oxidation and pH may influence the overall degradation.[35] Dubash and Moore (1972)[35] reported that temperature alone does not affect the decomposition of dipyrone other than to accelerate the rate of oxidative loss and the extent of decomposition is markedly reduced when air is excluded from the sample.
Enzymatic conversion of pistachio (pistacia vera L.) shells for fermentable sugar production
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
DNS assay method was applied to the determination of reducing sugar concentration. The enzyme Cellic CTec2 was supplied by Sigma-Aldrich. 1,416 ml of distilled water, 10.6 g of 3,5-dinitrosalicylic acid, 19.8 g of sodium hydroxide, 306 g of Rochelle salts (sodium potassium tartrate), 7.6 ml of phenol, and 8.3 g of sodium metabisulfite were added to prepare DNS solution. Citrate buffer was prepared with pH 4.8 and 0.05 M. 1 ml of citrate buffer and 0.5 ml of enzymatic supernatant (6-24-48-72 h) were added to tubes. 1.5 ml of citrate buffer was added to blank tube. All the tubes were incubated at 50ºC for 60 min. Then, the tubes were removed from the incubator, were added 3 ml of DNS reagent, and were boiled for 5 min. Then, all tubes were cooled in a cold ice bath. T70 UV–Vis Spectrophotometer (PG Instruments Ltd., UK) was used at 540 nm. The obtained absorbance values were used to determine the reducing sugar concentration (Adney and Baker 2008; Ghose 1987).
Recent progress in the conversion of biomass wastes into functional materials for value-added applications
Published in Science and Technology of Advanced Materials, 2020
Soluble keratin can be obtained by hydrolysis (e.g. alkaline, acid, or enzyme), oxidation or reduction of disulfide bonds, thermal treatment, and steam flash explosion [45]. The yield of keratin through hydrolysis depends on temperature, pH, time, and type and concentration of alkaline, acid, and enzyme. Sinkiewicz et al. [45] used 2.5% NaOH pretreatment and thermo-chemical treatment with different reducing agents (e.g. 2-mercaptoethanol, dithiothreitol, sodium metabisulfite, and sodium hydroxide) to prepare keratin from chicken feathers, and the highest yield was 94%, while the yields of keratin through sodium sulfide and L-cysteine were about 88% and 66% in another study [105]. Ramya et al. [76] extracted keratin from red sheep’s hair using sodium metabisulfite, urea and sodium dodecyl sulfate (SMBS). This method had a yield of 96%, but the high cost for operation and chemicals, highly concentrated agents, long processing time, and potential health and environmental risks limited its application in industrial production. Therefore, Tasaki [77] developed a two-step thermal hydrolysis process without the use of chemicals to extract keratin from hog hair, and the yield was nearly 70%.