Adsorption of Pb(II) ions from aqueous solutions by carbon nanotubes oxidized different methods

This study investigated the heavy metal adsorption of the carbon nanotubes (CNTs) oxidized different methods. Besides the conventional ultrasonication method, the UV-light used as an oxidation agent. The two oxidation methods compared with each other by Pb(II) adsorption. The characterizations of oxidized CNTs were analyzed by FTIR, XRD, DTG, SEM and total acidity capacity analysis. The adsorption capacities of carbon nanotubes were compared with using Langmuir and Freundlich isotherms. Two different kinetic theories were applied to experimental data. These theories are pseudo-second order and intraparticle diffusion models. The adsorption results can be compared using non-linear Langmuir isotherm parameters. For single wall carbon nanotubes (SWCNTs), theoretical adsorption capacity value (Qin) of UV-light method is 511.99 mg/g and ultrasonication method is 342.36 mg/g. The UV-light increased the surface acidity of the carbon nanotubes more than ultrasonication. After the adsorption experiments, it is apparently seen that the UV-light oxidation method is a useful method for heavy metal adsorption. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved

Adsorption of Lactic Acid from Model Fermentation Broth onto Activated Carbon and Amber lite IRA-67

The aim of this study was to compare the adsorption efficiency of lactic acid onto activated carbon and Amberlite IRA-67, and to define the adsorption isotherms. Activated carbon is a well-known industrial adsorbent and was used in this study; Amberlite IRA-67 is a weakly basic polyacrylic resin with a tertiary amine functional group. Adsorption efficiencies of activated carbon and Amberlite IRA-67 were compared with respect to their percentage of removal acid. The result of this comparison is that Amberlite IRA-67 is more efficient than activated carbon. Each of these adsorbents is in compliance with both the Freundlich and Langmuir isotherms

Comparison of the Efficiencies of Amine Extractants on Lactic Acid with Different Organic Solvents

The aim of this study is to compare different types of solvents and amines for extraction of carboxylic acids from fermentation broth and to find the most effective amine solvent composition for the extraction. Studies have been made of the extraction of L-(+)-lactic acid and citric acids from fermentation broth by tridodecylamine (TDA), a long-chain tertiary amine, and Amber lite LA-2, a secondary amine mixture. These extractants dissolved in different solvents which have different chemical structures. The extraction of acids was carried out at 298 K. Comparison of the results was made using the distribution coefficients (K-d), loading factor (Z), and the percentage of extraction yield. 1-Octanol was found to be the most effective solvent with a maximum distribution value of 4.25 and 37.93 for TDA and Amberlite LA-2, respectively

Comparative Equilibrium Studies for Citric Acid by Amberlite LA-2 or Tridodecylamine (TDA)

Carboxylic acids like citric acid are produced by fermentation. They have been used in many industrial fields as intermediate and starting materials, and their importance is still growing. It is important to separate them from the fermentation broth. In this sense, comparison of different types of solvents and amines for extraction of carboxylic acids from the fermentation broth and the most effective amine-solvent composition is sought. Studies have been performed on the extraction of citric acid from fermentation broth by tridodecylamine (TDA) (a long chain tertiary amine), and Amberlite LA-2 (a secondary amine mixture). These extractants were dissolved in different solvents having different chemical structures. The extractions were carried out at 298 K. Comparison of the results were made using the distribution coefficient, loading factor, separation factor, and the percentage of extraction yield. The most effective solvent was determined as 1-octanol for both TDA and Amberlite LA-2 with a distribution value of 29.63 and 103.80, respectively. The maximum value of the extraction efficiency was found to be 99.05 % with Amberlite LA-2 in 1-octanol

Adsorption Equilibrium Data for Acetic Acid and Glycolic Acid onto Amberlite IRA-67

The removal of acetic acid and glycolic acid from aqueous Solution by the weakly basic adsorbent Amberlite IRA-67 has been Studied at three different temperatures. Amberlite IRA-67 removed both acids very well from aqueous Solution. The maximum adsorption efficiency has been found to be 86.29% and 61.36% for glycolic acid and acetic acid, respectively. Langmuir and Freundlich adsorption isotherms have been applied to the experimental data. The Langmuir isotherm fitted the experimental data better than the Freundlich isotherm for both acids. Thermodynamic parameters Delta G, Delta H, and Delta S were calculated

Investigation of Adsorption Equilibrium and Kinetics of Propionic Acid and Glyoxylic Acid from Aqueous Solution by Alumina

The adsorption equilibria of propionic acid and glyoxylic acid on alumina are investigated experimentally and theoretically in this study. Alumina was used as the adsorbent. The period of achieving the equilibrium state and the effects of the amount of adsorbent, temperature, and initial acid concentration were investigated experimentally. Langmuir, Freundlich, and Temkin adsorption isotherm equations are fitted well with the experimentally measured data. It was found that the equilibrium isotherms depended on the initial acid concentration significantly. The Langmuir isotherm was found to best represent the data for both of the acids. The pseudosecond-order model, intraparticle diffusion model, and Elovich model were applied to experimental data. The adsorption of both acids followed pseudosecond-order kinetics. Diffusion is not the only rate-controlling step

Adsorption of Glutaric Acid and Glyoxylic Acid onto Weakly Basic Ion-Exchange Resin: Equilibrium and Kinetics

Adsorption equilibria Of glutaric acid and glyoxylic acid on a weakly basic ion-exchanger which has a tertiary amine functional group were investigated experimentally and theoretically in this study. Amberlite IRA-67 was used as the ion-exchange resin. The time to reach an equilibrium state, effects of amount of adsorbent, temperature, and initial acid concentrations on adsorption efficiency and distribution coefficient of acid adsorption were investigated, experimentally. The Langmuir, Freundlich, and Temkin adsorption isotherms were calculated. The equilibrium isotherms were significantly dependent on initial acid concentration. The Langmuir isotherm was found to best represent the data for both acids. The adsorption of both acids followed pseudosecond-order kinetics. Diffusion is not the only rate-controlling step

Separation of Succinic Acid from Aqueous Solution by Alumina Adsorption

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.kg(-1). 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.kg(-1) for 0.45 mol.kg(-1) 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

Purification of Biotechnological Carboxylic Acids with an Adsorption Method Using Single-Walled Carbon Nanotubes

Adsorption is a very important and valuable method for separation of carboxylic acids from aqueous solutions. In this study, single-walled carbon nanotubes (SWCNT) were used as an adsorbent for this purpose. Important biotechnological acids, tartaric acid and citric acid, were used. The equilibrium time and the adsorption capacity at three different temperatures (25 degrees C, 35 degrees C, and 45 degrees C) were investigated. Reaction kinetics and the diffusion between the acid molecules and SWCNT pores were investigated. The aim of this study was to determine the adsorption capability of SWCNT for carboxylic acids of biological importance from their fermentation media