Carbons organic species adsorption

In addition to the developed pore structure, small pore sizes, and large surface area, surface hydrophobicity is an extremely helpful property of active carbon [170-175], This property is particularly useful for the adsorption of organic species [176],... 

This study demonstrated that statistical models may be successfully applied to set up QSPRs available for prediction of adsorption enthalpy of an organic specie on one type of activated carbon. But for generalization, the specific influence of the properties of the GAC have also to be taken into account. 

Numerous challenges remain in the refinement of contemporary design and operation of carbon adsorption treatment systems. Those currently in the forefront include the transfer and regeneration of activated carbon, competitive effects on adsorption, the production of intermediate organic species in activated carbon systems, and bioactivity on activated carbon. 

It has to be said that carbon monoxide species can be formed from a dissociative adsorption of formic acid, formaldehyde, methanol, ethylene glycol, etc. and are species that are formed as those of the first type of distribution. This suggests that the surface structure is an open structure, since dissociative adsorption of the organic molecule requires adjacent free platinum sites and that at the electrochemical-environment interface, once carbon monoxide is formed, there is almost no mobility at all. 

Carbonate. Schulthess and McCarthy (72) determined carbonate and acetate adsorption by 5-AI2O3 and concluded that competitive adsorption of carbonate must be considered for prediction of organic ion adsorption under field conditions. Competitive adsorption of dissolved CO2 species has also been established for chromate on am-Fe hydroxide (7i) and goethite (7-7). These titration/adsorption studies demonstrate and quantify the importance of adsorption of dissolved CO2 species but do not provide information as to the specific species and mode of bonding with the oxide surface. 

Improved sensor respraise to several organic species can be achieved by exploiting the high adsorption capability of carbon surfaces, in adsorptive stripping voltammetry (AdSV). This procedure, based on very similar principles of solid phase microextraction (SPME), implies that analytes are pre-concentrated at carbon nanostructured surfaces prior to voltammetric detection. It has been successfully... 

Physicochemical methods, such as flocculation, membrane filtration or adsorption on activated carbon just transfer the pollutants from one phase to another without destroying them. Currently, the main progress in the decontamination of water is focussed on the use of advanced oxidation processes (AOP s) for the degradation of synthetic organic species resistant to conventional treatments, particularly those applying photochemical and photocatalytic reactions, which have the main advantage that they can be used for the treatment of relatively low levels of pollution in aqueous media [2, 3]. 

Applications of activated carbons (AC) in liquid-phase adsorptions are extensive, the number running into thousands. This Chapter makes no attempt to summarize such involvements, but concerns itself with explanations of mechanisms of adsorption of inorganic and organic species from the aqueous phase. In this way, an understanding of the factors which control extents of adsorption is made available and can be extended to other systems. This Chapter also highlights applications of major industrial importance. 

The strong adsorption of organic molecules occurring at carbon surfaces can be exploited to improve the sensitivity of the sensor response toward several organic species analytes can be pre-concentrated at carbon nanostructured surfaces in advance to the actual voltammetric detection, following an approach very similar to Solid Phase MicroExtraction (SPME). This analytical procedure, called Adsorptive Stripping Voltammetry (AdSV) has been applied for the detection of electroactive species of interest in the environmental field, such as herbicides or nitro-derivatives. Thanks to the occurrence of mechanisms similar to those... 

Direct measurements on metals such as iron, nickel and stainless steel have shown that adsorption occurs from acid solutions of inhibitors such as iodide ions, carbon monoxide and organic compounds such as amines , thioureas , sulphoxides , sulphidesand mer-captans. These studies have shown that the efficiency of inhibition (expressed as the relative reduction in corrosion rate) can be qualitatively related to the amount of adsorbed inhibitor on the metal surface. However, no detailed quantitative correlation has yet been achieved between these parameters. There is some evidence that adsorption of inhibitor species at low surface coverage d (for complete surface coverage 0=1) may be more effective in producing inhibition than adsorption at high surface coverage. In particular, the adsorption of polyvinyl pyridine on iron in hydrochloric acid at 0 < 0 -1 monolayer has been found to produce an 80% reduction in corrosion rate . 

Phenols, particularly the highly chloro-or nitro-substituted variety, are an important group of organic contaminants which, at typical ambient pH, can be present in groundwater predominantly as phenolate anions. Ulibarri et al. [154] studied the adsorption capacity of 2,4,6-trinitrophenol (TNP) on Mg/Al LDHs and their calcined products. The adsorption of TNP on LDHs by anionic exchange is dramatically affected by the identity of the interlayer anion and LDH chlorides have an adsorption capacity of more than 4 times that of LDH carbonates. However, calcined LDH carbonates are more effective adsorbents than those derived by calcination of LDH chloride samples. This possibly reflects the higher surface area of the former species. 

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