Adsorption Isotherms Of Phenol Research Articles

Solute adsorption from dilute solutions on structurally heterogeneous solids

A new adsorption isotherm equation for describing solute adsorption from dilute solutions on structurally heterogeneous solids is applied. This equation is associated with a gamma-type distribution function, which characterizes the structural heterogeneity of a microporous solid. Parameters of this equation permit calculating the mean adsorption potential and the dispersion associated with the adsorption potential distribution. These two quantities characterize the energetic heterogeneity of a nonuniform microporous solid. The measured adsorption isotherms of phenol, p-nitrophenol, and p-chlorophenol from dilute aqueous solutions on two samples of activated carbon are used to examine the above-mentioned equation and to evaluate the adsorption parameters that characterize the structural heterogeneities of these samples.

Comparative Adsorption of Phenol, P-Nitrophenol and P-Hydroxybenzoic Acid on Activated Carbon

Adsorption isotherms of phenol, p-nitrophenol and p-hydroxybenzoic acid at three temperatures in the range 1–40° C on activated carbon have been obtained experimentally. Curve fitting to several theoretical equations shows that the Prausnitz equation gives the lowest deviations (1–3%). An inversion of the adsorption capacity of phenol with temperature has been observed, probably as a consequence of the high microporosity of the carbon and the restricted accessibility of phenol to the smaller pores. Adsorption at 40°C is also accompanied by the degradation of phenol by aerobic micro-organisms (ficomicetus-type fungi). Approximate values of the isosteric heats of adsorption of p-nitrophenol have been calculated, being in the range 5.8–6.5 kcal/mol. Differences in the behaviour of the three adsorbates are commented upon in terms of their physicochemical properties.

Water Treatment by Means of Activated Carbon, Prepared from Locally Available Waste Materials (II)

Man's natural water supplies are threatened by a large number of nonbiodegradable and toxic organic compounds. Proper environmental standards often can only be attained using tertiary treatment processes, such as adsorption on activated carbon. The latter is an expensive process, owing to the initial cost of activated carbon and the losses occurring during regeneration. Methods are being investigated at the Free University of Brussels for producing and activating carbon, using various types of waste as a raw material. Following materials have already been used : cacao hulls, sawdust, fruit stones, bark, and waste tyres. Both carbonization and activation have been conducted under the carefully controlled conditions of a fluidized bed reactor. The influence of the following process parameters has been investigated : pyrolysis temperature and time, activation temperature and time, and composition of the furnace atmosphere. The resulting activated carbons should exhibit the following qualities : high adsorption capacity and rate, good resistance to attrition, and possibility of regenerating the carbon. The properties of the carbon obtained have been evaluated by means of a number of standard tests (Iodine-index, BET-surface, Tannin-index, Methylene blue-index, and Phenol-index), and adsorption isotherms of phenol, pentachlorophenol, p. toluene sulphonate and dodecyl benzenesulphonate. In general the properties of the carbons obtained were comparable to those of commercial qualities. Some of the activated carbons tested will soon be evaluated using synthetic and real phenolic industrial wastewaters (1.5 % of phenol).

Adsorption equilibria of aqueous phenol and indol solutions on activated carbons

Adsorption isotherms of aqueous phenol and indol solutions have been measured in a concentration range of 10 −3–2 mmol/l on four different activated carbons at 20°C and for phenol on one carbon at 55°C. Pretreatment of the carbons with hydrochloric acid had little effect on the equilibrium data. The experimental results have been fitted with six different isotherms. For the calculation of kinetic processes or of breakthrough curves an isotherm is proposed, combining the Redlich-Peterson equation with elements of the Dubinin-Radushkevich analysis. For equal weight concentrations in the aqueous phase indol is adsorbed more strongly than phenol, but for equal adsorption potentials phenol is adsorbed more strongly, i.e. the affinity of the carbons for phenol is greater. At the higher temperature more phenol is adsorbed than at the lower, indicating a greater packing density of phenol in the adsorbed phase at the higher temperature.

ADSORPTION OF SUBSTITUTED PHENOLS BY SOIL

ABSTRACTI evaluated the effect of introducing other functional groups to phenol on adsorption by soil and developed equilibrium adsorption isotherms for phenol, catechol, resorcinol, and the ortho, meta, and para isomers of cresol, methoxyphenol, nitrophenol, and chlorophenol. Introducing —CH3, —OCH

Removal and Recovery of Organic Pollutants from the Aquatic Environment. VII. Adsorption of Phenol and Carboxylic Acids on Crosslinked Poly(4-vinylpyridine)

Abstract Molecular adsorptions of phenols and carboxylic acids on crosslinked poly(4-vinylpyridine) were studied in comparison with those on various polymeric adsorbents. Enthalpies for the adsorption of phenol on various polymeric adsorbents were evaluated based upon the temperature dependence of the phenol adsorption isotherms. The enthalpy on crosslinked poly(4-vinylpyridine) was close to that on porous poly(styrene-divinylbenzene) resin with no ion exchange functional group, and was much smaller than that on commercial weak base anion exchange resin. The relative adsorption capacities of various polymeric adsorbents for carboxylic acids and substituted phenols indicated that the acid-base interaction as well as hydrophobic interaction between these organic acids and crosslinked poly(4-vinylpyridine) was an important factor in the adsorption.

Adsorption of benzoic acid and phenol from aqueous solution by activated carbons—effect of surface acidity

Effect of surface acidic groups of activated carbons on their adsorption characteristics for substrates from aqueous solutions were studied. Six kinds of carbons obtained commercially and their heat-treated products were used. Pore-size distribution, BET surface area and surface acidity were measured. Adsorption isotherms for benzoic acid and phenol from aqueous solutions (single or double components) were obtained. Substitution adsorption, i.e. substrate adsorbed preliminarily is substituted by another substrate, was also carried out. It was found that adsorption of benzoic acid is scarcely affected by surface acidity of carbons and the amount adsorbed is almost entirely controlled by the specific surface area of carbons. On the contrary, adsorption of phenol is retarded considerably by the acidity of carbons. In the case of solution of double components, benzoic acid is adsorbed predominatedly. The phenol adsorbed preliminarily is easily substituted by benzoic acid, but the substitution of benzoic acid by phenol scarcely proceeds.

STUDIES ON THE DYEING OF WOOL

In order to investigate the various behaviors of solvent assisted wool dyeing by adding several sparingly soluble solvents in water to Suminol Red PG (C. I. Acid Red 85), (a) the time of half dyeing, (b) diffusion coefficient, (c) affinity, (d) the effects of pH and temperature on the rate of dyeing, (e) the solvent absorption from aqueous solution by wool, and (f) partition ratio between water and solvent has been examined.Of the organic solvents used, phenol, n-amyl alcohol and benzyl alcohol are effective and the last solvent was found to be the most suitable in its practicality.The effects of aliphatic alcohol as solvent are seen to depend on the average carbon chain length and hydrophobic property of compounds. The solvents, giving their effect, are not sufficient at 20_??_50°C, but the most effective at 65_??_80°C. The effects are remarkable according to increase Hconcentration. The dye's affinity is only a little decreased as a result of adding the previous solvent. The adsorption isotherms of phenol and benzyl alcohol agree with Henry's equation. The molar free energy of desorption ΔG°(=RT lnP) of phenol and benzyl alcohol from water to wool are 925 and 530 cal/mol respectively. The time of half dyeing of both solvents, on the other hand, are 30 and 44min. respectively, so that their effects are closely connected with the time of half dyeing and the absorption of the solvent by the wool. The dye's solvility of each solvent is greater than that of water, and the greater is the partition ratio, the higher the rate of dyeing, The effect of solvent, therefore, is influenced to the absorption of the solvent by wool, and partition ratio between water and solvent.