Adsorption of phosphorus

Ramsier RD, Henriksen PN, Gent AN (1988) Adsorption of phosphorus acids on alumina. Surf Sci 203 72-88... 

Cabrera et al. [95] determined total dissolved and suspended phosphorus in natural waters by a method involving digestion with hydrogen peroxide and sulphuric acid, errors may be caused by adsorption of phosphorus on hydrous iron and aluminium oxides formed during neutralization prior to filtration. It is proposed that this can be prevented by adding extra sulphuric acid after neutralization, to dissolve such oxides and release the adsorbed phosphorus into solution. 

To understand the complex interaction of phosphorus-containing species with alumina and with the other elements (molybdenum, cobalt, or nickel) introduced in the catalyst formulations, it is important to examine the chemistry involved in the preparation steps. In this section, adsorption of phosphorus-containing species on alumina is discussed. 

Han et al (61) reported that the Al2(Mo04)3 phase on alumina is easily hydrated by moisture in air and transforms into amorphous M0O3, whereas AIPO4 only shghtly reacts with water. Further addition of phosphorus decreases the formation of Al2(Mo04)3 since competitive adsorption of phosphorus and molybdenum oxo-species occurs on the alumina surface. Phosphorus inhibits the formation of Al2(Mo04)3 in the presence of nickel (62). The number of deposited polymeric phosphorus-oxo compounds decreases in the presence of molybdenum, probably through the formation of dispersed Mo—P heteropoly compounds (63). 

Addition of soluble inorganic phosphorus to soil increases the soil pore water phosphorus concentration. This results in rapid adsorption of phosphorus onto soil surfaces to maintain equilibrium. Soil s capacity to adsorb additional phosphorus dictates the concentration of phosphorus in soil pore water. These adsorption processes occur within a short time period. When soil particles become saturated with phosphorus, there is an increase in phosphorus concentration in soil pore water. Reaction kinetics are on the order of minutes to hours to reach sorption equilibrium. Figure 9.21 illustrates a two-step process in which rapid phosphate exchange takes place between soil pore water and soil particles or mineral surface (adsorption) followed by slow penetration (absorption) of phosphate into solid phase. Similarly, desorption of phosphorus can also... 

The precipitation of phosphorus as calcium phosphate has been studied extensively by soil scientists in evaluating applied fertilizer reactions. Initial adsorption of phosphorus onto calcite is followed by precipitation as calcium phosphate. Similar reactions can occur at the soil-flood-water interface of calcareous wetlands. For example, long-term phosphorus accumulation in the Everglades marsh is linearly correlated with calcium accumulation, suggesting the possibility of phosphorus and CaCOj interactions (Reddy et al., 1993). 

Phosphorus is the tenth most abundant element on Earth with an average crustal abundance of 0.1% and may be found in a wide variety of mineral phases. There are approximately 300 naturally occurring minerals in which PO4 is a required structural component. Phosphate may also be present as a trace component in many minerals either by the substitution of small quantities of POt into the crystal structure or by the adsorption of P04 onto the mineral surface (Nriagu and Moore, 1984 Slansky, 1986). 

Inorganic reactions in the soil interstitial waters also influence dissolved P concentrations. These reactions include the dissolution or precipitation of P-containing minerals or the adsorption and desorption of P onto and from mineral surfaces. As discussed above, the inorganic reactivity of phosphate is strongly dependent on pH. In alkaline systems, apatite solubility should limit groundwater phosphate whereas in acidic soils, aluminum phosphates should dominate. Adsorption of phosphate onto mineral surfaces, such as iron or aluminum oxyhydroxides and clays, is favored by low solution pH and may influence soil interstitial water concentrations. Phosphorus will be exchanged between organic materials, soil inter-... 

The reaction path DHQ THQl- OPA HC must be taken into account to explain the promotional effect of phosphorus in the absence of H2S. A strong promotional effect of phosphorus has been observed for the HDN of OPA over NiMo/AhOa catalysts, which could be explained by the larger adsorption constant of OPA on the P-containing catalyst. The HDN activity of OPA was even higher in the absence of H2S (16). 

Table 4 shows that the P-containing NiMoP/Al203 catalyst favours the adsorption of NHa and of DHQ. The adsorption of NHa is strongly enhanced in the absence of H2S for both catalysts. The effect of phosphorus, which is applied... 

The concentration of non-biodegradable compounds (measured as COD-Mn) was rather high, especially in the second half of the cooling season. These were supposed to origin from the wood chips (Ericsson, 2003). The content of phosphorus and some heavy metals in the snow were high, but in the outlet water most substances were considerably reduced. This was related to particle adsorption, as particles settled in the snow basin, which... 

The adsorption operation was conducted by feeding 1 mM phosphate solutions to the conditioned column at SV 10 or 20 h 1, and then 20 BV of water at SV 3 h 1. The elution operation consisted of feeding 0.1 M NaOH solution (80 BV) and then 20 BV of water at a flow rate of SV 3 h1. The regeneration of the column was conducted by feeding 0.5 M sulfuric acid (20 BV) and 20 BV of water at SV 10 h"1. All column effluents including washings in the adsorption and elution operations were collected on a fraction collector, and concentrations of phosphorus and zirconium in each fraction were determined by ICP-AES. Volume of each fraction was 5 BV for the adsorption operation and 4 BV for the elution operation. However, column effluents in regeneration operations were not analyzed. 

Jyo, A., Yamabe, K., Egawa, H., Behavior of macroreticular chelating resins having oxy acids of phosphorus in adsorption and elution of lead ion. in Chemistry for the Protection of Environment, 2, eds. L. Pawlowsky, W. J. Lacy, C. G. Uchrin, M. R. Dudzinska, Environmental Science Research, Vol. 55, Plenum Press, New York, 1996, pp. 121-129, ISBN 0-306-45373-8. 

Sato and Akamatu (139) report that alkali metals enhance the chemisorption of oxygen on carbon and weaken the carbon-carbon bonds at the surface so as to accelerate combustion. On the other hand, they report that phosphorus, while catalyzing the adsorption of oxygen on carbon, has a retarding effect on the release of the surface oxide. 

The hydrides of phosphorus, arsenic, and antimony thus form an interesting transition series. On similar sorts of surface antimony hydride is the least stable, decomposing with measurable speed at ordinary temperatures, and phosphine is the most stable, not decomposing at an appreciable rate below a red heat. Arsine occupies an intermediate position. At low temperatures the adsorption is considerable, and, as a result, the stibine decomposition requires the pn equation, while the more stable hydrides, which only decompose rapidly at higher temperatures where the adsorption is smaller, obey the unimolecular law. It is interesting, moreover, that with stibine itself the exponent n increases towards unity as the temperature at which the reaction takes place is raised. 

In 1948, red cobalt-containing crystals of vitamin B12 were obtained almost simultaneously by two pharmaceutical firms. Charcoal adsorption from liver extracts was followed by elution with alcohol and numerous other separation steps. Later fermentation broths provided a richer source. Chemical studies revealed that the new vitamin had an enormous molecular weight, that it contained one atom of phosphorus which could be released as P , a molecule of aminopropanol, and a ribofuranoside of dimethyl benzimidazole with the unusual a configuration. 

Mechanistic Multiphase Model for Reactions and Transport of Phosphorus Applied to Soils. Mansell et al. (1977a) presented a mechanistic model for describing transformations and transport of applied phosphorus during water flow through soils. Phosphorus transformations were governed by reaction kinetics, whereas the convective-dispersive theory for mass transport was used to describe P transport in soil. Six of the kinetic reactions—adsorption, desorption, mobilization, immobilization, precipitation, and dissolution—were considered to control phosphorus transformations between solution, adsorbed, immobilized (chemisorbed), and precipitated phases. This mechanistic multistep model is shown in Fig. 9.2. 

The correlation between the heat offormation AHf and the work function WF. Table 5.11 is showing the heat of formation of AHf of the oxides, sulfides, chlorides and phosphorus compounds and the average work function (WF) of the elements. The work function is a complicated physical property related to the crystal orientation, surface composition, and chemisorption (Shpenkov, 1995). Taking an aluminum surface as an example (Huber and Kirk, 1966), the adsorption of dry oxygen to one monolayer coverage will lower the work function by 0.05... 

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