Adsorption on organic matter

Now we are ready to consider the practical application of metal-ligand stability constants to metal adsorption on organic matter. First we will take the case of a metal-humus system that is undersaturated with respect to the metal hydroxide. 

PROBABLE FATE photolysis-, direct photolysis is probably not important, if released to atmosphere, will degrade by reaction with photochemically produced hydroxyl radicals (estimated half-life 1.15 days) oxidation photooxidation in atmosphere can occur, photooxidation half-life in air 4.61-46.1 hrs hydrolysis slow hydrolysis of carbon-chlorine bond, may be important fate mechanism volatilization if released to water, volatilization is expected to be the principle removal process, but may be slow, volatilization half-lives for a model river (1 m deep) and a model environmental pond 13.9 hr, and 6.6 days respectively sorption adsorption on organic matter is possible biological processes no data on bioaccumulation or biodegradation... 

Tables 12.2 and 12.3. The effect of vertical variability is shown in Table 12.2, while the lateral spatial variability is shown in Table 12.3. The vertical and lateral spatial variabilities were defined on the basis of either the measured adsorption coefficient K), as generated from adsorption isotherms on soil profiles, or on adsorption coefficients on soil organic matter calculated as adsorption on organic carbon per unit weight of soil. We see that both vertical (Table 12.2) and lateral (Table 12.3) variability of soil affect the adsorption coefficients. A comparison between the bromide (conservative) and the two nonconservative herbicides distributions with depth after about 900mm of leaching is shown in Fig. 12.3. We see that, in the case of bromide, there is a continuous displacement of the center of mass with cumulative infiltration. In contrast, the bulk of the herbicide contaminant mass remains in the upper soil layer, with very little displacement.

Yoon, T. H., Johnson, S. B., and Brown, G. E., Jr. (2005). Adsorption of organic matter at mineral/water interfaces 4. Adsorption of humic substances at boehmite-water interfaces and impact on boehmite dissolution. Langmuir 21,5002-5012. 

Hayes, M. H. B. (1970). Adsorption of triazine herbicides on soil organic matter, including a short review on organic matter chemistry. Res. Rev. 32,131-174. 

The use of centrifugation to separate the liquid from solid phases in traditional batch or tube techniques has several disadvantages. Centrifugation could create electrokinetic effects close to soil constituent surfaces that would alter the ion distribution (van Olphen, 1977). Additionally, unless filtration is used, centrifugation may require up to 5 min to separate the solid from the liquid phases. Many reactions on soil constituents are complete by this time or less (Harter and Lehmann, 1983 Jardine and Sparks, 1984 Sparks, 1985). For example, many ion exchange reactions on organic matter and clay minerals are complete after a few minutes, or even seconds (Sparks, 1986). Moreover, some reactions involving metal adsorption on oxides are too rapid to be observed with any batch or, for that matter, flow technique. For these reactions, one must employ one of the rapid kinetic techniques discussed in Chapter 4. 

It may be best to consider this bacterial-mechanical hypothesis for the formation of laminated aragonitic odids as a precursor to more recent models, where adsorption of organic matter on odid surfaces influences the precipitation of CaC03. 

Adsorption, 167-169 See Double layer effect Metals on organic matter, 137 Metals on clays, 167,171 Organic compounds, 181, 355 Oxyanions, 190 Inner-sphere coordination, 169 Outer-sphere coordination, 168 Models, 178,186 Constant capacitance, 186... 

The ability to control NOM adsorption through modification of surface chemistry was demonstrated previously [20] the uptake of several model humic substances and natural organic matter isolated from surface waters decreased significantly with increasing surface acidity (as measured by NaOH neutralization). The uptake was partially restored by subsequent heat treatment of the oxidized surfaces (i.e. OX 9/70 HT650). For the wood-based carbons, the impact of surface treatment on adsorption of organic matter was surprisingly small or absent. Overall, the reactivity of carbon surfaces to DOM uptake depended on the raw material type, activation conditions and surface treatment. 

In this paper the adsorption of organic matter on activated caii>on from primary microbiologically treated mixtures of oil refinery and municipal wastewaters, as well as its simultaneous desorption by microbiological oxidation is considered. It has been established that the denitrification bacteria use the adsorbed organic matter as a carbon source in the denitrification process. In this way a bioregeneration of the activated carbon has been achieved, as well as the control of organic and nitrate load in the effluent. 

The objective of the present work is to investigate the process of continuous adsorption of organic matter from the biologically treated mixtures of wastewaters from an soil refinery and a municipal source on activated carbon, which is accompanied by its desorption via biodegradation. 

Our results show that the adsorption on suspended matter is increased in the presence of suspended humic acid (Figure 10). This is supported by the finding of other authors (53,54) showing that organic flocculant coatings greatly affect the cation exchange capacities of sediment and suspended matter. 

Johnson, S.B. et al.. Adsorption of organic matter at mineraPwater interfaces. 6. Effect of inner-sphere versus outer-sphere adsorption on colloidal stability, Langmuir, 21, 6356, 2005. 

Crozes G., Anselme C, Mallevialle J. (1993a), Effect of adsorption of organic matter on fouling of ultrafiltration membranes. Journal of Membrane Science, 84, 61-77. 

The amount of Mo adsorbed has been found to be closely related to the soil s organic-matter content (Karimian and Cox, 1978). Because Mo acts as an anion in the soil, it is difficult to explain its adsorption by organic matter. However, certain soils high in organic matter have been found to be deficient in Mo (Mulder, 1954 Davies, 1956). Mulder (1954) found pronounced responses to added Mo in several crops grown on soils with high amounts of organic matter. 

Ward and Upchurch (340) found an inverse relationship between the solubilities of 18 substituted anilines and their adsorption by nylon (R2 = 0.77) and cellulose triacetate (R = 0.80). It was suggested that steric and electronic effects of the molecules were also responsible for the adsorption differences of the compounds. Because of the low solubilities of the substituted anilines, adsorption by organic matter probably occurs at lipophilic sites through dipole-dipole interactions—e.g., hydrogen bonding or charge-transfer complexes. Low adsorption at clay surfaces probably occurs because the hydrophobic molecules do not readily associate with hydrated surfaces. Adsorption of the substituted anilines by dry clays might occur on the soil surface for instance, but in the... 

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