• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.184-189
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• 2013

In the present study, batch experiments were carried out for the utilizatioin of activated carbon as a potential adsorbent to remove a hazardous malachite green from an aqueous solution. The effects of various parameters such as temperature, contact time, initial concentration on the adsorption system were investigated. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were also confirmed. The equilibrium process was described well by Langmuir isotherm model. From determined separation factor, the activated carbon could be employed as an effective treatment for removal of malachite green. From kinetic experiments, the adsorption process followed the pseudo second order model, and the adsorption rate constant ($k_2$) decreased with increasing both the initial concentration of malachite green and the adsoprtion temperature. Thermodynamic parameters like that activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the adsorption nature. The activation energy calculated from Arrhenius equation indicated that the adsortpion of malachite green on the zeolite was physical process. The negative Gibbs free energy change ($\Delta$G = -3.68~-7.76 kJ/mol) and the positive enthalpy change ($\Delta$H = +26.34 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption in the temperature range of 298~318 K.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.623-629
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• 2011

The adsorption characteristics of tricyclazole by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of tricyclazole were carried out at 298, 308 and 318 K, using aqueous solutions with 250, 500 and 1,000 mg/L initial concentration of tricyclazole. It was established that the adsorption equilibrium of tricyclazole on granular activated carbon was successfully fitted by Freundlich isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 250, 500 and 1,000 mg/L initial concentration of tricyclazole, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The positive value for enthalpy, -66.43 kJ/mol indicated that adsorption interaction of tricyclazole on activated carbon was an exothermic process. The estimated values for standard free energy were -5.08~-8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a exothermic process.

• Clean Technology
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• v.17 no.4
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• pp.346-352
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• 2011

The adsorption characteristics of propineb pesticide onto activated carbon has been investigated for the adsorption in aqueous solution with respect to initial concentration, contact time and temperature in batch experiment. The Langmuir and Freundlich adsorption models were applied to described the equilibrium isotherms and isotherm constants were also determined. The Freundlich model agrees with experimental data well. slope of isotherm line indicate that activated carbon could be employed as effective treatment for removal of propineb. The pseudo first order, pseudo second order kinetic models were use to describe the kinetic data and rate constants were evaluated. The adsorption process followed a pseudo second order model, and the adsorption rate constant($k_2$) decreased with increasing initial concentration of propineb. The activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The estimated values for change of free energy were -7.28, -8.27 and -11.66 kJ/mol over activated carbon at 298, 308 and 318 K, respectively. The results indicated toward a spontaneous process. The positive value for change of enthalpy, 54.46 kJ/mol, found that the adsorption of propineb on activated carbon is an endothermic process.

• Clean Technology
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• v.18 no.1
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• pp.76-82
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• 2012

The paper includes utlization of zeolite as potential adsorbent to remove a hazardous malachite green from waste water. The adsorption studies were carried out at 298, 308 and 318 K and effects of temperature, contact time, initial concentration on the adsorption were measured. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were also confirmed. The equilibrium process was described well by Freundlich isotherm model, showing a selective adsorption by irregular energy of zeolite surface. From determined isotherm constants, zeolite could be employed as effective treatment for removal of malachite green. From kinetic experiments, the adsorption process followed the pseudo second order model, and the adsorption rate constant ($k_2$) decreased with increasing initial concentration of malachite green. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The activation energy calculated from Arrhenius equation indicated that the adsorption of malachite green on the zeolite was physical process. The negative free energy change (${\Delta}G^{\circ}$ =-6.47~-9.07 kJ/mol) and the positive enthalpy change (${\Delta}H^{\circ}$ = +32.414 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption in the temperature range 298~318 K.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.96-102
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• 2014

Adsorption of metanil yellow onto granular activated carbon were studied in a batch system. Various operation parameters such as adsorbent dosage, pH, initial concentration, contact time and temperature were optimized. Experimental equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm. The equilibrium process was described well by Freundlich isotherm model. From determined separation factor (1/n), adsorption of metanil yellow by granular activated carbon could be employed as effective treatment method. By analysis of kinetic experimental data, the adsorption process were found to confirm to the pseudo second order model with good correlation and the adsorption rate constant ($k^2$) decreased with increasing initial concentration. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The activation energy was determined as 23.90 kJ/mol. It was found that the adsortpion of metanil yellow on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G=-2.16{\sim}-6.55kJ/mol$) and the positive enthalpy change (${\Delta}H=+23.29kJ/mol$) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.667-674
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• 2020

The adsorption of reactive orange 16 (RO 16) dye by activated carbon was investigated using the amount of adsorbent, pH, initial concentration, contact time and temperature as adsorption variables. The investigated process parameters were separation coefficient, rate constant, rate controlling step, activation energy, enthalpy, entropy, and free energy. The adsorption of RO 16 was the highest at pH 3 due to the electrostatic attraction between the cations (H⁺) on the surface of the activated carbon and the sulfonate ions and hydroxy ions possessed by RO 16. Isotherm data were fitted into Langmuir, Freundlich and Temkin isotherm models by applying the evaluated separation factor of Langmuir (RL=0.459~0.491) and Freundlich (1/n=0.398~0.441). Therefore, the adsorption operation of RO 16 by activated carbon was confirmed as an appropriate removal method. Temkin's adsorption energy indicated that this adsorption process was physical adsorption. The adsorption kinetics studies showed that the adsorption of RO 16 follows the pseudo-second-order kinetic model and that the rate controlling step in the adsorption process was the intraparticle diffusion step. The positive enthalpy change indicated an endothermic process. The negative Gibbs free energy change decreased in the order of -3.16 <-11.60 <-14.01 kJ/mol as the temperature increased. Therefore, it was shown that the spontaneity of the adsorption process of RO 16 increases with increasing temperature.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.161-166
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• 1979

To know the influence of temperature on the fermentation process, a strain of Lactobacillus bulgarius was experimentally cultured three different temperature conditions of $39^{\circ}C,\;42^{\circ}C\;and\;45^{\circ}C$, pH 5.8 and mechanical agitation of 500rpm. During 20 hour's fermentation, the microbial growth attained the maximum concentration under the conditions mentioned above. However, the culturing conditions resulted different outcomes in terms of maximum concentration of the microbes and the residual concentration of substrate. Among the three temperature conditions, the fermentation at $45^{\circ}C$ was most effective and the maximum specific growth temperature conditions, the fermentation at $45^{\circ}C$ was most effective and the maximum specific growth rate was 0.58/hr. Activation energy deduced from the Arrhenius equation was 9,220cal/mole and entropy was $-33.74\;cal/^{\circ}K$ mole. Activation enthalpy was 9,845 cal/mole and free energy was 19,800 cal/mole.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.512-519
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• 1991

The axial ligations of nitrogenous bases (pyridine, imidazole, 1-methylimidazole and 2,6-lutidine) to Zn(II)-, Cu(II)-, and Ni(II)-tetrakis(o-chlorophenyl)porphyrin(o-ClTPP), and -tetraphenylporphyrin (TPP) were investigated in organic solvents $(CH_2Cl_2,\;C_6H_6,\;CH_3NO_2,\;(CH_3)_2CO,\;CHCl_3,\;DMF\;and\;DMSO)$ and at 0.01M of ionic strength. The equilibrium constants for the ligation reactions of methalloporphyrins were determined using spectrophotometric method at 15∼35${\circ}C$. In case of M(II)-TPP the equilibrium constants K were considerably larger than those of M(II)-(o-Cl)TPP, depending on steric effect of the porphyrin. The linear relationships between logK of the axial ligation and $pK_a$ of nitrogenous base were shown in M(II)-TPP, but not in M(II)-(o-Cl)TPP. The stabilities of MTPP(L) were controlled by the reation enthalpy and entropy, while those of M(o-Cl)TPP almost by the reaction entropy. The coordinating power of solvent to the methalloporphyrin were also studied in $CHCl_3,\;(CH_3)_2CO$, DMF and DMSO. From those results the solvent effects on the equilibrium constants were discussed.

• Analytical Science and Technology
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• v.11 no.5
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• pp.366-373
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• 1998

Polydentate Schiff base ligands, BSDT(1,9-bis(2-hydroxyphenyl)-2,5,8-triaza-1,8-nonadiene) having $N_3O_2$ atoms, BSTT(1,12-bis(2-hydroxyphenyl)-2,5,8,11-tetraaza-1,11-dodecadiene) having $N_4O_2$ atoms, BSTP(1,15-bis(2-hydroxyphenyl)-2,5,8,11,14-pentaaza-1,14-pentadodecadiene) having $N_5O_2$ atoms were synthesized. Protonation constants of these polydentate ligands were measured by potentiometry. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1:1 complexes with Schiff base ligands. Stability constants for the complex formation were in the order of Cu(II)>Ni(II)>Zn(II), and for the ligands were in the order of BSTP>BSTT>BSDT. There are due to the increase in the number of donor atoms. Both enthalpy and entropy changes were obtained in negative values. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.