Liquid-phase adsorption equilibria of eight phenolic compounds onto activated carbon fibers were measured in the concentration range 40−500 g·m-3 at 303 K. High adsorption capacities were observed for the chlorinated phenols compared to the methyl-substituted phenols. Several two- and three-parameter isotherm equations were tested. Among the equations tried, the three-parameter equation of Jossens et al. based on a heterogeneous surface adsorption theory was found to be the most satisfactory over the entire range of concentration. The widely used two-parameter equations of Langmuir and Freundlich were not applicable to the present adsorption systems.

Equilibrium constants for the binding of poly(ethylenimine) (PEI) with metal ions and metal chelates of ethylenediaminetetraacetic acid and nitrilotriacetic acid in the aqueous sulfate solutions were determined by batch ultrafiltration (UF) in the pH range of 3.0−3.8. The average coordination number of PEI groups interacting with one metal ion and metal chelate was also obtained by varying the initial concentration ratio of PEI to metal ion. A simple chemical equilibrium model proposed in this work enabled us to satisfactorily predict the rejection coefficient of UF of metal ions and metal chelates in the presence of PEI. Also, the effect of the formation of soluble hydroxy complexes of metal chelates on their retention was emphasized.

A comparative study was made on the extraction equilibria of succinic and tartaric acids from aqueous solutions with tri-n-octylamine in xylene. It was shown that the extractability of tartaric acid was higher than succinic acid under comparable conditions. The compositions of the multiple-extracted complexes in the organic phase and the equilibrium constants for the formation of the complexes were numerically determined. Furthermore, the mole fractions of the species present in the organic phase were quantitatively obtained as a function of initial concentrations of the acids and amine. The effect of temperature on the extraction of acids was also examined and a change of complex composition with temperature was seen for succinic acid in the temperature range 293−323 K. Finally, the related thermodynamic data were calculated.

Based on iodine number, adsorption capacity of methylene blue, the BET specific surface area, and the yield, the conditions for preparation of activated carbon as adsorbents from bamboo were optimized. The activation temperature and activation time tested were in the ranges 700~880 °C and 1~3 h, respectively. Equilibrium isotherms and rates for the adsorption of two dyes and phenol from aqueous solutions onto such activated carbons were measured at 30 °C. The equilibrium isotherms could be fit by the Langmuir equation and the adsorption rates could be analyzed by a plot of amounts of adsorption versus the square root of time. The present results showed that the activated carbons prepared in this work appeared to be economically promising for the removal of dyes and phenol, compared to other commercial adsorbents.

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