Dyes synthetic Methylene Blue

Recognition that substrates are oxidized by dehydrogenation is usually attributed to H. Wieland. During the years 1912-1922 he showed that synthetic dyes, such as methylene blue, could be substituted for oxygen and would allow respiration of cells in the absence of Oz- Subsequent experiments (see Chapter 15) led to isolation of the soluble pyridine nucleotides and flavoproteins and to development of the concept of an electron transport chain. 

Ion-pair extraction of an anionic surfactant with a cationic dye such as methylene blue from water into oil is often used for the quantitative analysis of the surfactant in water [57,58]. The surfactant concentration in water is then determined as the dye concentration in the oil or water phase by conventional absorption spectroscopy. Synthetic surfactants such as sulfates and sulfonates completely dissociate in water even at low pH. On the other hand, the association of fatty acid salts (traditional soaps) with H" " depends on the pH. Therefore, the quantitative analysis of surfactants in water is performed by the ion-pair extraction at various pHs. Although quantitative analysis and thermodynamic studies have been already reported for the anionic surfactant/cationic dye extraction, kinetic analysis of the ion-pair extraction has been rarely reported and the extraction mechanism is not discussed in detail. In this section, we describe the kinetic analysis of the extraction of a dodecyl sulfate anion with methylene blue as a typical example using the single microdroplet manipulation and microabsorption methods [59]. In particular, the pH dependence of the ion-pair extraction is discussed. 

The above hypercrosslinked samples have been tested under identical conditions for their ability to extract from aqueous solutions three synthetic organic dyes Malachite Green (MG), Methylene Blue (MB), and Direct Bordeaux (DB) ... 

Synthetic dyes Methylene Blue, Alizarin Red, Eriochrome Black T, Methyl Red, Acid Yellow 1, Acid Blue 22 [20-25]... 

Very recently Zhou et al. used twisted rigid ligands to synthetize compounds based on Keggin clusters with left- and right-handed hehcal chains [148] (see Fig. 3.24). Helical compounds based on HPAs have attracted attention because of their attractive structural features and potential applications, for instance, in asymmetrical catalysis. The chains are further extended to three-dimensional supramo-lecular structures by hydrogen bonds. The methylene blue dye has been photocatalytically bleached in the presence of this solid. Stacking of the chains leads to small pore-size and narrow pore-size distribution which are not beneficial for the photocatalytic activity. 

PVP is a nonionic water-soluble polymer that interacts with water-soluble dyes to form water-soluble complexes with less fabric substantivity than the free dye. Additionally, PVP inhibits soil redeposition and is particularly effective with synthetic fibers and synthetic cotton blends. The polymer comprises hydrophilic, dipolar imido groups in conjunction with hydrophobic, apolar methylene and methine groups. The combination of dipolar and amphiphilic character make PVP soluble in water and organic solvents such as alcohols and partially halogenated alkanes, and will complex a variety of polarizable and acidic compounds. PVP is particularly effective with blue dyes and not as effective with acid red dyes. 

---