Bromine—water adsorption

Isotherm I is typical of adsorption in micropores, which occurs, for instance, in zeolites and in activated carbons. Isotherm II represents multilayer physisorption on a flat surface (valid for many nonporous substances). Type HI and V isotherms are characteristics of weak gas-solid interactions (water adsorption on gold and bromine adsorption on silica are good examples). The type IV isotherm is frequently found in the study of heterogeneous catalysts its shape is characteristics... 

Enrichment of Mercury. Due often to very low mercury contents of the samples to be analysed, enrichment procedures are required. Mercury can be extracted with PDDC into MIBK or with dithiazone into chloroform. It can also be electrolysed on the copper or silver cathode. The mercury vapour can be collected in several traps such as various solution traps, gold trap, and active carbon. Adsorption solutions may be nitric acid, bromine water—nitric acid, or potassium permanganate solutions. 

For this reason, the emphasis in this article is directed more towards the simulation of specific adsorption and, in particular, the recent encouraging comparison of electrochemical and UHV data for the interaction of bromine and chlorine with Ag 110 /7, 8/. A brief outline of the conclusions emerging from alkali-water coadsorption experiments is given to illustrate basic modes of ion-solvent interaction on metal surfaces and to discuss future directions of this research. 

The dipole moment of the adsorbed water molecules is estimated to be = 0.22 D (unit of D = 3.36 x 10 ° C m) from the slope of the observed curves shown in Fig. 5-25. Since this dipole moment is nearly one tenth of the dipole moment of gaseous water molecules (m = 1.84 D), the dipole of the adsorbed water molecules on the silver surface is suggested to be aligned almost parallel to the metal surface by forming hydrogen-bonded two-dimensional clusters of water molecules. On the other hand, bromine molecules are in the state of dissociative adsorption on the silver surface, producing adsorbed bromine atoms which receive electrons... 

Fig. 6-25. Relative change in work function, d4>, of a (100) surface of single crystal of silver as a function of adsorption coverage 6 of bromine atoms and water molecules on the clean surface, and of bromine atoms on the surface with pre-adsorbed water molecules. [From Bange-Straehler-Sass-Parsons, 1987.]...

Fig. 6-26. For the hard sphere model on metal electrodes (a) interfacial dipole induced by adsorbed water molecules and (b) interfadal dipole induced by contact adsorption of partially ionized bromine atoms. - 6 = charge number of adsoihed particle (z ). [From Schmickler, 1993.]...

Typically limit to 0.5 ppm total Fe maximum in the cooling water. Above this level, phosphonate can be used to control problems initiated by iron. However, if the total Fe rises to 3.0 ppm, adsorption of the phosphonate onto the iron takes place and a loss of inhibitor function can occur. Iron salts present a serious fouling risk in cooling systems. Dissolved iron quickly oxidizes (especially where chlorine, bromine, or other oxidizing biocides are used) and forms ferric oxide/hydroxide, which acts as a flocculant,... 

Types III (e.g. bromine on silica gel at 352 K) and V (e.g. water vapour on charcoal at 373 K) show no rapid initial uptake of gas, and occur when the forces of adsorption in the first monolayer are relatively small. These isotherms are rare. 

Type 3 Adsorption of bromine on silica gel at 79 C, water on glass... 

Phenylmercuric borate is 0.08 % soluble in water. Mercury is in this compound covalently bound to the phenyl group. It is incompatible with many anions, including halides. However a 0.004 % solution is compatible with up to 0.7 % sodium chloride. The active concentration is 0.002 %, but a concentration up to 0.004 % may be used to compensate losses by adsorption on the membrane filter, etc. Eye drop bottles with chlorine and bromine butyl rubber droppers cannot be used with phenylmercuric salts, because a precipitate will be formed. An alternative is packaging the eye drops in a bottle with a polypropylene dropper (see Sect. 24.4.2). Phenylmercuric borate causes few hypersensitivity reactions, but with prolonged use, there might be a risk of mercury deposition in the lens. 

Surface areas of hydrophilic (hydroxylated) silicas have been measured by adsorption of nitrophenol from water or benzene (79) and phenol from decane or carbon tetrachloride (80, 81). The system must be anhydrous and the solvents dried by molecular sieves. The phenol may be determined by bromine titration or interferometer. Stearic acid is adsorbed from anhydrous methanol and determined by difference by potentiometric titration with alkali. Ttie data given indicate that each stearic acid molecule covers only 20.6 A (82). 

Figure 3.3.42 Typical shapes of adsorption isotherms pA- partial pressure of adsorbate A, p - vapor pressure of liquid A, 0a = coverage relative to monolayer capacity type I Langmuir adsorption, for example, benzene on silica gel, NH3 on charcoal, or H2S on molecular sieve (Figure 3.3.40) type II multilayer BET type of adsorption, for example, water on AI2O3, N2 on silica type III multilayer adsorption, for example, bromine on silica, type IV and V multilayer adsorption and capillary condensation in pores, for example, water on silica or benzene on Fe203 (IV) and water on charcoal (V).

Rajendra Dongre Minakshi Thakur Dinesh Ghugal Jostna Meshram. Bromine pretreated chitosan for adsorption of lead (II) from water. Bull. Mater. Sci. 2012, 35, 875-884. 

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