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Published in Francisco Javier Rubio Rincon, Effect of Sulphide on Enhanced Biological Phosphorus Removal, 2017
On the other hand, it has been demonstrated that one of the effects of sulphide in the microbial process it is the deprotonation of dihydrogen sulphide inside the cell membrane (Comeau et al., 1986; Koster et al., 1986). Past research has suggested a similar inhibition pattern by nitrous acid than dihydrogen sulphide on the metabolism of PAOs (Saad et al., 2013). On the other hand, nitrous acid can be used to enhance the hydrolysis of anaerobic digesters, which is normally the limiting process for biogas production (Wang et al., 2013). Thus, as sulphide could be produced in the anaerobic zones of the wastewater treatment plant, it is interesting to asses if it could be used in a similar way that nitrous acid to enhance the hydrolysis in anaerobic digesters or pre-acidification units.
Advances in the synthesis and chemical transformations of 5-acetyl-1,3,4-thiadiazolines
Published in Journal of Sulfur Chemistry, 2021
Samir Bondock, Tallah Albarqi, Mohamed Abboud
In a similar manner, treatment of 1,1′-([1,1′-biphenyl]-4,4′-diylbis(5-imino-4,5-dihydro-1,3,4-thiadizole-2,4-diyl))bis(ethan-1-one) (7) with two equivalent amounts of each acetyl chloride and benzoyl chloride in pyridine furnished the N,N′-([1,1′-biphenyl]-4,4′diylbis(5-acetyl-1,3,4-thiadiazole-3(3H)-yl-2(3H)-ylidene))diacetamide (136) and N,N′-([1,1′-biphenyl]-4,4′diylbis(5-acetyl-1,3,4-thiadiazole-3(3H)-yl-2(3H)-ylidene))dibenzamide (137), respectively. Nitrosation of 7 with nitrous acid, generated in situ from treatment of a cold solution of sodium nitrite with acetic acid, afforded the corresponding 1,1′-([1,1′-biphenyl]-4,4′-diylbis(5-nitrosoimino-4,5-dihydro-1,3,4-thiadizole-2,4-diyl))bis(ethan-1-one) (138) (Scheme 33) [25].
Benzophenone based disperse dyes for UV protective clothing: synthesis, comparative study of UPF, light fastness and dyeing properties and computational study
Published in The Journal of The Textile Institute, 2021
Suvidha Shinde, Smita Prasad Bait, Ravindra Adivarekar, Nagaiyan Sekar Nethi
The diazotization method used for the preparation of (6a–6c) (7a–7c) and (8a–8c) dyes (Bhide et al., 2016). A solution containing amine (3.3 mmol), conc. HCl (3 ml, 35 mmol) was cooled to 0 °C. The acidity of the solution was checked by means of congo red paper. Sodium nitrite (0.25 g, 3.6 mmol) solution was steadily added to the above solution with stirring maintaining the temperature below 5 °C. After complete addition, the solution was further stirred for 40 min at 5 °C. Starch iodide paper was used to check presence of nitrous acid and urea was added to destroy the excess nitrous acid. Meanwhile, the coupler solution containing benzophenone (0.5 g, 3.3 mmol), sodium hydroxide (0.16 g, 0.4 mmol), sodium carbonate (1.06 g, 10 mmol) and 50 ml water was cooled to 0 °C. With continuous stirring, the diazonium salt solution was gradually added to the coupler solution maintaining the temperature below 5 °C. After complete addition, pH of the solution maintained using Na2CO3 (10% w/v) solution to avoid further decrease in pH and was maintain in between 7.5 and 8 (Dixit et al., 2007). The mixture was further stirred for 3 h. The precipitated crude dye was filtered and further recrystallized using 75% methanol solution and finally dried.
Novel design and optimisation of a nitritation/anammox set-up for ammonium removal from filtrate of digested sludge
Published in Environmental Technology, 2018
Yury Nikolaev, Anna Kallistova, Marina Kevbrina, Alexander Dorofeev, Anton Agarev, Andrey Mardanov, Nikolay Ravin, Michail Kozlov, Nikolay Pimenov
Anammox bacteria are characterised by high affinity to their major substrates (ammonium and nitrite); however, high concentrations of nitrite inhibit the process. The NO2– threshold concentrations vary within a wide range (from 40 to 400 mg NO2-N/l) and apparently depend on the type of biomass (suspended, granular, or biofilm). Granular biomass appears to be more resistant to nitrite inhibition, while suspended biomass is the most sensitive [9,11]. The mechanisms of nitrite inhibition are yet unknown and it can be suggested that ionised nitrite is a substrate inhibitor, and free nitrous acid (FNA) is a noncompetitive inhibitor of the anammox process. The negative effect of FNA (in concentrations above 0.1 mg HNO2-N/l) is more pronounced at pH values <7.1, whereas ionised nitrite is acting as an inhibitor of the anammox process at higher pH values [45]. Thus, it is highly important for the technology to maintain the proper nitrite concentration.