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Attempts were made to recover succinic acid (IUPAC systematic name as ethane 1,2-dicarboxylic acid) from aqueous solutions by alumina adsorption. Experimental adsorption works were conducted with aqueous solutions containing succinic acid in four different concentrations: (0.13, 0.22, 0.32, and 0.45) mol 3 kg À1 . Alumina were used in 10 different amounts: (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2) g. Also adsorption experiments were carried out at three different temperatures: (298, 308, and 318) K. The equilibrium distributions of succinic acid were determined. The minimum equilibrium concentration of succinic acid was 0.28 mol 3 kg À1 for 0.45 mol 3 kg À1 initial succinic acid concentration with 2 g of alumina. The adsorption data fit well within the Langmuir, Freundlich, and Temkin isotherms. Isotherm parameters have been obtained. Also the kinetics of the adsorption for succinic acid were determined as the pseudosecond-order model. ' EXPERIMENTAL SECTIONAlumina and succinic acid were purchased from Merck Company (acid purities > 99.0 %). We prepared four different concentrations for succinic acid: 0.13 mol 3 kg À1 , 0.22 mol 3 kg À1 , 0.32 mol 3 kg À1 , and 0.45 mol 3 kg À1 . Mixtures of a known amount of adsorbent and 5 mL of 0.45 mol 3 kg À1 succinic acid solution

Extraction of citric acid (0.595 mol•kg −1 ) from aqueous solutions has been investigated by using binary extractant system comprising of trioctylamine (TOA) + tridodecylamine (TDA) at six different concentrations (0.19 mol•kg −1 to 1.16 mol•kg −1 ). The extractant system is diluted using five different solvents such as dimethyl phthalate (DMP), methyl isobutyl ketone (MIBK), 2-octanone, 1-decanol, and cyclohexylacetate (CHA). The batch extraction results of citric acid for the design of a separator have been obtained. The data are interpreted in terms of distribution coefficient (D), loading factors (Z), and extraction efficiency ( %E). The values of D for the citric acid extraction are found to vary from 0.40 to 118 for DMP, MIBK, and 2-octanone. For 1-decanol and CHA diluent, the values are observed in the range of 0.38 to 98.16 and 0.39 to 86.76, respectively. Considerable amount of citric acid is recovered (almost 99 %) by all the amine−diluent systems at 1.16 mol•kg −1 initial concentration of (TOA + TDA) mixture.

The adsorption capabilities of multiwall carbon nanotubes (MWCNTs) for acetic acid have been investigated experimentally and theoretically. Carbon nanotubes (CNTs) are an important new material in the carbon family. Adsorption time required to attain the steady state and influences of quantities of alumina, effects of temperature, and effects of initial values of acetic acid concentrations have been determined experimentally. The most common used adsorption isotherms have been drawn by using experimental results. These are selected as Langmuir, Freundlich, and Temkin. In experimental works, the equilibrium is considerably affected by initial concentration values of acetic acid at various temperatures (278 K, 298 K, 318 K). Langmuir isotherm has been found the best suitable for acetic acid. Also kinetic models for adsorption such as Elovich and pseudo-first and -second orders have been used. The equilibrium results fit well within the Elovich model and while the pseudo-second order model is a good representation of the adsorption, the pseudo-first order approach does not fit with experimental data. The model parameters have been calculated.