Adsorbent carbon-containing mineral

Trinidad asphalt has a relatively uniform composition of 29% water and gas, 39% bitumen soluble in carbon disulfide, 27% mineral matter on ignition, and 5% bitumen that remains adsorbed on the mineral matter. Refining is essentially a process of dehydration by heating the cmde asphalt to ca 165°C. The refined product averages 36% mineral ash with a penetration at 25°C of about 2 (0.2 mm), a softening point (ring and ball method) of 99°C, a flash point (Cleveland open cup) of 254°C, a sulfur content of 3.3%, and a saponification value of 45 mg KOH/g. The mineral matter typically contains... 

Another phyllosilicate mineral, namely, biotite, has larger sorption capability as expected. It is likely related to the iron content of biotite. Similarly, the carbonates containing iron and magnesium (ankerite and dolomite Table 3.8) show more significant cesium sorption as calcite (calcium carbonate), which practically does not adsorb cesium. The low sorption ability of calcite can be explained by the Hahn adsorption rule (Chapter 1, Section 1.2.4) that is, the sorption is low when the sorbate (cesium carbonate) has great solubility. 

To be suitable for sugar operations, a suspension of the carbon in water should have a pH between 6.0 and 8.0, preferably as near 7.0 as is practical. Many data show that a neutral carbon will not cause inversion. Cases of inversion attributed to carbon have been traced to the use of acid carbons—those containing mineral acids. Activated carbon does not accelerate the inversion effect of acids present in the juice in fact, carbon can reduce such inversion by adsorbing a portion of the acids. Even though an acid condition aids the decolorization, carbons with a low pH should never be used because of inversion. 

Od-fumace blacks used by the mbber iadustry contain over 97% elemental carbon. Thermal and acetylene black consist of over 99% carbon. The ultimate analysis of mbber-grade blacks is shown ia Table 2. The elements other than carbon ia furnace black are hydrogen, oxygen, and sulfur, and there are mineral oxides and salts and traces of adsorbed hydrocarbons. The oxygen content is located on the surface of the aggregates as C O complexes. The... 

Cu and Zn enter sedimentary material in substantial proportions, both in the structure of minerals (carbonates, clays) and adsorbed on surfaces. Boyle (1981) showed that foraminiferal tests may contain Zn in excess of a few ppm. Partitioning of Cu and Zn between water and carbonates has been investigated by Rimstidt et al. (1998). The crystal chemistry of Cu and Zn in goethite has been investigated by EXAFS by Manceau et al. (2000). Typical Zn and Cu concentrations in FeMn nodules and encrustations are 500-1000 ppm and 800-6000 ppm, respectively (e.g., Albarede et al. 1997b). 

Biological. Under aerobic and anaerobic conditions, the rate of diquat mineralization in eutrophic water and sediments was very low. After 65 d, only 0.88 and 0.21% of the applied amount (5 mg/mL) evolved as carbon dioxide (Simsiman and Chesters, 1976). Diquat is readily mineralized to carbon dioxide in nutrient solutions containing microorganisms. The addition of montmorillonite clay in an amount equal to adsorb one-half of the diquat decreased the amount of carbon dioxide by 50%. Additions of kaolinite clay had no effect on the amount of diquat degraded by microorganisms (Weber and Coble, 1968). 

Surface complexation — is complexation of metal ions by ligands immobilized on the electrode surface (-> electrode surface area). The ligands may be incorporated in the structure of a -> carbon paste electrode, covalently bound to the surface of a chemically modified electrode (-> surface-modified electrodes), or adsorbed (-> adsorption) on the electrode surface etc. Surface complexation is not confined to electrodes. It can occur on many surfaces, e.g., minerals, when in contact with metal ion solutions or solutions containing complexing ions (in the first case, the surface provides the ligand and the solution the metal ion, whereas in the second case, the surface provides the metal ion and the solution the ligand). Surface complexation can be an important step in the dissolution of solid phases [ii]. 

The admixture of clay mineral (halloysite) to carbonaceous deposit (as for waste materials) remarkably enriches the texture of mineral-carbon adsorbents in mesopores and leads to the decrease of magnitude of micropores volume with dimension of 0.4 - 2 nm. In the case of hard coal and kaolinite mixture this char contains the maximum sub- and micropores at the lowest content of mesopores. 

With very few exceptions, surface and near surface waters contain an excess of Rn (Table I l-III) compared to Ra (Table 11-lV) and U (Table 11-VI). This Rn must come from Ra in solids such as rocks, soils and sediments. The solubility product of Ra salts is seldom reached in natural waters, because invariably it is adsorbed onto sulphates and carbonates at the surfaces of rocks and minerals. In the zone of oxidation it is also coprecipitated by hydrous oxides of Fe and Mn. Only in the vicinity of strong sources of very saline waters do Ra concentrations rise to 10 or even 10 g/L. 

The formation of carbon-mineral adsorbents containing carbon deposits in the form of dendrites, whiskers or carbon black is not advantageous because of the poor mechanical properties of these deposits. The morphology of the coke depends on the mechanism and conditions of its formation on the mineral surface. Two main mechanisms of formation of carbon deposits can be distinguished consecutive reactions and carbide-forming. The latter mode consists in the thermal decomposition of hydrocarbons. 

It is obvious that chemical composition of carbon deposit depends not only on the conditions in which pyrolysis is carried out but also on the chemical composition of carbonized organic substances on the surface of the solid carrier. As a result, carbon matter deposited on the surface of mineral carrier, besides C and H, can contain heteroatoms (S,N,0). The problem was discussed in the paper [2]. Similarly, the morphological composition depends on the conditions in which carbonization reaction is carried out. Gierak and Leboda showed [22], that it was possible to obtain graphitized carbon deposit of good mechanical properties under very mild conditions. The obtained adsorbents are applicable in chromatography in separation of polar substance mixtures [22,23]. 

The rate of the oxidation process is determined by the reactivity of the starting carbon and oxidizer. The greater the reactivity of the substrates the lower the temperature of the process in which uniform formation of the pores in the granules is observed. In the case of carbonaceous materials the cokes of brown coals show the greatest reactivity, and the cokes of hard coals the smallest activity. The cokes of pit coals show an intermediate reactivity. This is connected with the earlier mentioned ordering of the crystallographic structure of carbon, which is of significant importance in the case of modification of carbon deposits contained in the carbon-mineral adsorbents in which the carbonaceous compound may be characterized by a differentiated chemical and physical structure. Thus the surface properties of hydrothermally modified complex adsorbents are defined by the course of three processes ... 

The mineral adsorbs Cl and NO3 ions poorly and reversibly, whilst S04 is precipitated at the mineral surface. Phosphates are preferentially adsorbed on calcium carbonate. Soils which contain CaCOj show pH values ranging from about 7 to 8.4, due to the formation of calcium hydrogen carbonate. The formation of this compound is accelerated in biologically active soils, with a high production of carbon dioxide. Calcareous soils have a soil solution dominated by Ca + ions, and this limits swelling of soil days and prevents the dispersion of finer particles in the soil. If Ca predominates on the exchange complex of soils, the pH value is maintained above 5.5. 

Carbon adsorbents have a porous carbon structure, which contains small amounts of different heteroatoms such as oxygen and hydrogen. Some activated carbons also contain variable amounts of mineral matter (ash content) depending on the nature of the raw material used as precursor. The porous structure is perhaps the main physical proper that characterizes activated carbons. This is formed by pores of different sizes which according to lUPAC recommendations [15] can be classified into three major groups (see Fig. 2) ... 

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