Maximal adsorption capacity

Cathodic stripping voltammetry has been used [807] to determine lead, cadmium, copper, zinc, uranium, vanadium, molybdenum, nickel, and cobalt in water, with great sensitivity and specificity, allowing study of metal specia-tion directly in the unaltered sample. The technique used preconcentration of the metal at a higher oxidation state by adsorption of certain surface-active complexes, after which its concentration was determined by reduction. The reaction mechanisms, effect of variation of the adsorption potential, maximal adsorption capacity of the hanging mercury drop electrode, and possible interferences are discussed. 

Although the physical meaning of the Langmuir adsorption isotherm is limited, the experimental data can often be very accurately approximated. Q is the stationary phase concentration, C , is the mobile phase concentration, and a and h are empirical parameters reflecting the maximal adsorption capacity and the equilibrium binding constant. It has to be noted that the Langmuir adsorption... 

The Figure 17.6 shows spectra of L-BPA after immobilization on FeC microparticles at different weight ratios composite/L-BPA. Apparently immobilization occurs by physical adsorption into porous of composite. The highest absorption capacity of L-BPA for this composite 78.0 mg/g was detected at weight ratio composite/L-BPA equal 5. The maximal adsorption capacity of L-BPA 160.0 mg/g was reached for dextran-modified iron-particles. 

The major focus for maximizing performance of activated carbon is to provide an optimum balance between increasing adsorptive capacity for polyaromatic hydrocarbons and dioxins while decreasing oil retention in the filter cake. It has been found that steam-activated carbon derived from peat yields the best combination of properties for this application. 

The total adsorption capacity of the column filling for adsorption of organic matter from the combined primary treated oil refinery and municipal wastewaters was 27.885 g (iOD. The adsorption capacities of the column was calculated from its maximal value, (Table 1), and the mass of carbon in the column. 

In contrast to the case of gas adsorption, the adsorption capacities determined on organocomplexes suggest disaggregation, since the maximal value of the calculated specific surface area falls in the range of 90 to 120 m g for kaolinite and 170 to 190 m g for illite[22]. 

Although organic macromolecular systems, as mentioned previously, carbonize to micro-porous carbons, they do not maximize their porous potential. That is, their adsorption capacity, measured as a micropore volume or surface area, is too low for commercial applications. In addition, there may be a need to widen existing porosity to include wider micropores and some mesoporosity. Further, porosity within the carbon, which is closed to a specific adsorbate, can be opened to allow access to larger adsorbate molecules. 

Adsorption studies dealing with liquid systems clearly show the potential use of PILCs as adsorbents for environmental applications. One example is the uptake of toxicants such as chlorophenols on pillared and delaminated clay structures (67). Al-delaminated laponite is more effective in adsorbing pentachloro-phenol (PCP) than the Al-pillared montmorillonite. At an equilibrium time 24 h, an equilibrium pH = 4.7, and an initial PCP concentration of 38 p,mol L , the maximal adsorption of PCP was 27 pimol g on Al-delaminated laponite and 12 xmol g on Al-pillared montmorillonite. The binding of PCP onto the substrate is attributed to interactions between the PCP molecule and the immobilized AI2O3 species. The greater adsorption capacity for the delaminated structure arises from the greato- dispersion and availability of the Al oxide aggregates in the clay. 

If the adsorption process is not saturable within the concentration range of the experiment, it becomes a sink claiming a portion of the drug added to the medium—the magnitude of which is dependent on the maximal capacity of the sink ([ 2]) and the affinity of the ligand for the site... 

The cation-exchange capacity of the copper ferrocyanide gel used was found to be about 2.60 meq/g and its anion-exchange capacity about 0.21 meq/g. In all cases of various doses of gel used and types of anionic surfactants being removed, the tests indicated that a batch contact time of about 12 hours was sufficient for achieving maximum removals. Trials with various fractions of particle size demonstrated that both uptake and desorption (important in material regeneration) were most convenient and maximized on 170-200 BSS mesh size particles. Also, the adsorption of anionic surfactants was found to be maximum at pH 4 and decreased with an increase in pH. 

The performance of adsorptive (and indeed almost all multifunctional) reactors benefits from an expedient nonuniform distribution and integration of the functionalities at various levels. Simply combining given proportions of catalyst and adsorbent in a fixed-bed reactor seldom realizes the full potential available [52]. The objective may be to maximize utilization of adsorbent capacity or to optimize catalyst productivity. Although these aims need not be mutually exclusive, they often give rise to different strategies. 

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