Phenol adsorption characteristics

Economy and Lin [340] investigated the phenol adsorption characteristics of high-surface-area activated carbon fibers Fig. 17b shows that their correlation was not nearly as good, but the role of surface chemistry was not invoked. Additional evidence that the agreement shown in Fig. 17a is more often the exception [439] than the rule is contained in the study of Dondi et al. [342], who u.sed a chromatographic method to determine low-concentration phenol adsorption isotherms on four different carbons, as well as in many other investigations (see, for example. Refs. 356, 382, 384, and 436). 

Kawai, T Tsutsumi, K. Adsorption characteristic of surfactants and phenol on modified zeolites from their aqueous solutions. Colloid Polymeric Science, 1995 273, 787-792. 

The surface of a solid may differ in many ways from its bulk composition. Especially, such solids as commercial carbon black may contain minor amounts of impurities (such as aromatics, phenol, carboxylic acid). This would render surface adsorption characteristics different from that of pure carbon. It is therefore essential that, in industrial production, quality control of the surface from different production batch is maintained. Otherwise, the surface properties will affect the application. Another example arises from the behavior of glass powder and its adsorption character for proteins. It has been found that if glass powder is left exposed to the... 

Carbon black has been reported to possess different kinds of surface chemical groups. These are aromatics, phenol, carboxylic, etc. The different sites can be estimated by comparing the adsorption characteristics of different adsorbents (such as hexane and toluene). 

Phenol and dodecyl benzene sulfonate are two solutes that have markedly different adsorption characteristics. The surface diffusion coefficient of phenol is about fourteen times greater than that for dodecyl benzene sulfonate. The equilibrium adsorption constants indicate that dodecyl benzene sulfonate has a much higher energy of adsorption than phenol (20,22). The adsorption rates from a mixture of these solutes can be predicted accurately, if (1) an adequate representation is obtained for the mixture equilibria, and (2) the diffusion rates in the solid and fluid phases are not affected by solute-solute interactions. 

Table 5 shows the excellent adsorption characteristics of the home prepared carbons, in comparison with 3 of the 10 commercial carbons tested. The results obtained in the equilibrium adsorption study of phenol, pentachlorophenol, dodecylbenzenesulphonate, and p-toluenesulphonate were discussed in a previous paper [9 ]. Also this study showed a very good performance of the home produced carbons. Based on these results carbon J 23 and J 32 were selected for further research. 

Information about textural and substructural characteristics of the supports (surface area, micropore volume, crystallographic data) was derived from nitrogen and phenol adsorption data measurements, wide angle X-ray scattering (WAXS) spectra and high resolution electron microscopy (HREM). Concentrations of the surface oxides were determined using the data on the adsorption of NagCOs, NaOH, NaOEt and HCl in accordance with Boehm s method [3]. 

For all processes that involve the adsorption step, such as physical processes of separation or catalytic transformations, the usage of solid materials with optimised activity as adsorbents and catalysts is necessary. Various solids, such as porous materials (zeolites—molecular sieves with hierarchical porosities and natural clays), activated carbons, mesoporous silica-based materials, pillared clays and metal oxides, have shown the ability to act as adsorbents or as catalysts for the conversions of previously mentioned atmospheric pollutants. Solid materials are also used for the removal of pollutants that can be found in wastewaters. The possibilities to remove polyaromatic hydrocarbons (PAHs) and heavy metal particles using the adsorptive characteristics of activated carbon and porous materials from wastewaters have been proven [15-17]. The same classes of solids are used for the elimination of organic pollutants form wastewaters by heterogeneous catalytic oxidation processes one of the most important tasks is to eliminate phenolic compounds [13]. 

To elucidate some enzymatic characteristics of the isolated laccases I, II, and III, substrate specificities for several simple phenols, electrophoresis patterns, ultraviolet spectra, electron spin resonance spectra, copper content, and immunological similarities were investigated. Tyrosine, tannic acid, g c acid, hydroquinone, catechol, pyrogallol, p-cresol, homocatechol, a-naphthol, -naphthol, p-phenylenediamine, and p-benzoquinone as substrates. No differences in the specificities of these substrates was found. The UV spectra for the laccases under stucfy are shown in Figure 4. Laccase III displays three adsorption bands (280, 405, and 600nm), laccase II shows one band 280nm), and laccase I shows two bands (280 and 405 nm). These data appear to indicate differences in chemical structure. The results of the copper content analysis (10) and two-dimensional electrophoresis also indicate that these fractions are completely different proteins (10), Therefore, we may expect differences in substrate specificities between the three laccase fractions for more lignin-like substrates, yet no difference for some simple phenolic substrates. 

Development of solvent extraction processes in the petroleum industry and theoretical aspects of solvent extraction are reviewed. Six extraction processes which have received industrial acceptance are described and performance characteristics of furfural, phenol, and Duosol processes are compared. Data are presented to demonstrate the applicability of adsorption analyses for stock evaluation and prediction of commercial extraction yields. Correlations for predicting solvent requirements and layer compositions and process design and engineering considerations are included. The desirability of further fundamental work to facilitate design calculations from physical data is suggested. 

As seen from Table 2, phenol, j>-toluene sulfonate and 2 bromophenol have similar adsorption rate characteristics. The equilibrium data for these solutes indicate that phenol and p-toluene sulfonate have similar energies of adsorption (24), as indicated by the constant b in the component isotherm (qe Qbx,ce/ (1 + bLCe) -bromophenol and dodecyl benzene sulfonate are adsorbed more strongly than phenol (22). 

Example 8.8 A wastewater containing 25 mg/L of phenol and having the characteristic breakthrough of the previous example is to be treated by adsorption onto an activated carbon bed. The flow rate during the breakthrough experiment is 0.11 mVs this is equivalent to a surficial velocity of 0.0088 m/s. The XIM ratio of the bed for the desired effluent of 0.06 mg/L is 0.02 kg solute per kg carbon. If the flow rate for design is also 0.11 mVs, design the absorption column. Assume the influent is introduced at the top of the bed. The packed density of the carbon bed is 721.58 kg/ml... 

Mesoporous melamine-formaldehyde and phenolic-formaldehyde resins were synthesized in the process of polymerization in the presence of fumed silica as an inorganic template. The surface and structural characteristics of the obtained sorbents were investigated using XPS technique and sorption from gas phase. The parameters characterizing porous structure of the synthesized resins in a dry state were determined from nitrogen adsorption/desorption isotherms. The sorption processes of benzene and water vapor accompanied by simultaneous swelling of both polymers were also studied. 

The synthesis of phenolic-formaldehyde and melamine-formaldehyde resins in the presence of fumed silica allows obtaining porous organic materials with a differentiated porous structure and surface properties. The pore characteristics of the studied resins in dry state were determined from nitrogen adsorption isotherms. The differences in surface character of the synthesized polymers were estimated satisfactorily by XPS spectra showing the presence of various functional groups. The adsorption/desorption mechanism of water and benzene on the investigated porous polymers was different due to differentiated hydrophobicity of the bulk material. 

However, the usual tests for characterizing active carbon — such as the phenol number, the surface area (BET 2)> tl tannin index or the iodine index — are inadequate for evaluating the potential removal of the humic substances by the carbon. Moreover the resulting adsorption may differ according to the source and previous treatment of those substances and the characteristics of the feed water used. 

This work intends to show the complexity of the dynamic adsorption process and to evaluate capacity of some granular carbons of various firms to remove pollutants from water. Adsorbents have been tested by various methods, and static and dynamic adsorption have been compared. Characteristics of carbons has been evaluated by the determination of porous structure, specific surface, content of ashes (mineral substances) and crushing strength and abrasion resistance. Adsorption capacity of activated carbon has been determined by means of phenol, iodide, methylene blue, sodium lauryl sulphate and molasses indicators for static conditions, and surfactant has been used for dynamic conditions. Analysis of some factors influencing adsorption has been accomplished and directions of further studies have been shown. 

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