Baybars Ali Fil

Adsorption of Methyl Violet Dye, A Textile Industry Effluent onto Montmorillonite—Batch Study

In this study, methyl violet (MV) dye adsorption from synthetically prepared solutions onto montmorillonite was investigated. Experimental parameters were selected as stirring speed, adsorbent dosage, initial dyestuff concentration, initial solution pH, ionic strength, and temperature. It was determined that adsorption rate increased with increasing stirring speed, initial dye concentration, solution pH, ionic strength, and temperature, but decreased with increased adsorbent dosage. The experimental data were analyzed by Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms, and it was found that the isotherm data were reasonably correlated by Langmuir isotherm. Maximum adsorption capacity of montmorillonite for MV dye was calculated as 230.04 mg g−1. Pseudo-first-order, pseudo-second-order, Elovich, and intraparticle particle diffusion models were used to fit the experimental data. Pseudo-second-order rate equation provided realistic description of adsorption kinetics. Thermodynamic parameters were calculated as 62.14 kJ mol−1, 59.55 kJ mol−1, 51.98 kJ mol−1, and 0.0242 kJ mol−1 K−1 for Ea, ΔH*, ΔG*, and ΔS* at 293 K, respectively. The value of the calculated parameters indicated that the physical adsorption of MV on the clay was dominant and the adsorption process was also endothermic. The positive values of ΔS° suggest the increased randomness. The positive ΔG° value indicated the un-spontaneous nature of the adsorption model.

Isotherm, kinetic, and thermodynamic studies on the adsorption behavior of malachite green dye onto montmorillonite clay

ABSTRACT Systematic batch mode studies of adsorption of malachite green (MG) on montmorillonite clay were carried out as a function of process parameters which include pH, adsorbent dosage, agitation speed, ionic strength, initial MG concentration, and temperature. Montmorillonite was found to have excellent adsorption capacity. Equilibrium adsorption isotherms were measured for the single-component system, and the experimental data were analyzed by using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. It was found that the Langmuir equation appears to fit the equilibrium data. The monolayer (maximum) adsorption capacity (qm) was found to be 262.494 mg g−1 for montmorillonite. The experimental kinetic data were analyzed using the first-order, second-order, Elovich, and intraparticle kinetic models and the second-order kinetic model described the adsorption kinetics accurately for MG. Thermodynamic activation parameters such as ΔG*, ΔS*, and ΔH* of the adsorption of MG on montmorillonite were also calculated.

Application of Nonlinear Regression Analysis for Methyl Violet (MV) Dye Adsorption from Solutions onto Illite Clay

Dyes are toxic chemicals and the main source of color pollution in the textile wastewaters. Therefore, the use of illite clay as an adsorbent to remove methyl violet dye from solutions was investigated in this study. Equilibrium experiments were carried out in batch mode as a function of temperature, ionic strength, and pH. The equilibrium was attained within 24 hours. The capacity of illite clay increased when pH, temperature, and ionic strength were raised. Four adsorption isotherm models, viz, the Langmuir, Freundlich, Khan, and Sips, were used to analyze the equilibrium data. The nonlinear optimization technique was used to fit the data to the isotherm models, and for this purpose five error functions were used. The equilibrium data could be explained by the Sips isotherm model, and among the entire error equations generally the HYBRID error function provided the lowest sum of the normalized error values. Thermodynamic parameters indicated that dye adsorption had endothermic and unspontaneous nature. Also, the positive enthalpy change indicated that dye uptake occurred by physical binding. The maximum dye capacity of illite was found as 159.95 mg g−1 at 60°C. High dye capacity exposed that illite would be used effectively in cationic dye removal. GRAPHICAL ABSTRACT

Pre-Treatment of Pistachio Processing Industry Wastewaters (PPIW) by Electrocoagulation using Al Plate Electrode

The objective of the present study is to assess the efficiency of electro-coagulation treatment of pistachio processing industry wastewaters (PPIW) using an aluminum plate electrode. The effect of some of the parameters was examined on the removal of chemical oxygen demand (COD), total organic carbon (TOC), and total phenols (TP) removal efficiency. The treatment was carried out in a batch system. The influences of current density (from 1 to 6 mA cm−2), initial pH of wastewater (from 2 to 8), constant pH of wastewater (from 3 to 7), stirring speed (from 100 to 500 rpm), and supporting electrolyte concentration (from 10 to 50 mg L−1 NaCl) on removal efficiency were investigated to determine the best experimental conditions. The evaluation of the physico-chemical parameters during the treatment by electrocoagulation showed that the best removal efficiency was obtained under the conditions of 180 min electrolysis time, wastewater with constant pH of 6, and 6 – mA cm−2 current density. Under such experimental conditions, COD, TOC, and TP removal efficiency were found to be 60.1%, 50.2%, and 77.3%, respectively, while energy consumption was 39.6 kW-h m−3. The results of the study show that the electrocoagulation can be applied to PPIW pre-treatment.

Adsorptive removal of cationic (BY2) dye from aqueous solutions onto Turkish clay: Isotherm, kinetic, and thermodynamic analysis

ABSTRACT The removal of Basic Yellow 2 (BY2), a cationic dye, from aqueous solution by using montmorillonite as adsorbent was studied in batch experiments. The effect of pH, agitation speed, adsorbent dosage, initial dye concentration ionic strength, and temperature on the removal of BY2 was also investigated. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms were applied to fit the adsorption data of BY2 dye. Equilibrium data were well described by the typical Langmuir adsorption isotherm. The maximum monolayer adsorption capacity was calculated as 434.196 mg g−1 from the Langmuir isotherm model. The adsorption data was fitted to both the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle kinetic models, and the calculated values of the amount adsorbed at equilibrium (qe) by pseudo-second-order equations were found to be in good agreement with the experimental values. The thermodynamic factors were also evaluated. The entropy change (ΔS*) was negative, suggesting that the adsorption process decreases in entropy and enthalpy change (ΔH*) was positive which indicates endothermic nature. The positive ΔG* value confirms the un-spontaneity of the process. In addition, a semiempirical model was calculated from kinetic data.

AN EMPIRICAL MODEL FOR ADSORPTION THERMODYNAMICS OF COPPER (II) FROM SOLUTIONS ONTO ILLITE CLAY-BATCH PROCESS DESIGN

The copper causes important health problems risk when it exists at high concentrations in drinking waters and daily feeds. Therefore, in this study, copper adsorption from solutions onto illite clay was investigated in batch mode as a function of the initial solution pH (3-6), temperature (30-60 oC) and ionic strength (0-0.1 mol/L-1 NaCl). The equilibrium was attained within 24 hours. Optimum conditions were determined as pH 6, temperature 60 oC and 0 mol/L-1 NaCl concentration. The isotherm data followed the S-class isotherm. The reason of this S-class isotherm was either solute–solute attractive forces at the surface causing cooperative adsorption or a competing reaction such as complexation with a ligand. Mathematically, the isotherm data were explained with the sum of several single Freundlich models. Also, the thermodynamic parameters of the process were calculated. Positive values of Gibbs free energy change (ΔGo) indicated that the adsorption process was unspontaneous. As the enthalpy change (ΔHo) had positive value for all the parameter intervals, copper adsorption was concluded to be physical and endothermic process. The positive entropy values indicated that the randomness at solid-liquid interface increased with concentration decrease. Maximum copper adsorption capacity of illite clay was calculated at 60 oC as 1.823×10-5 mol/g. Furthermore, an empirical model was developed to determine the thermodynamic parameters of the process and operation conditions of the batch reactor as follows.

A semiempirical kinetic model for removal of iron (Fe3+) from saturated boric acid solution by ion exchange using amberlite IR–120 resin

ABSTRACT The removal of iron (Fe3+), originating in raw colemanite, from saturated boric acid solution is important in the production of pure boric acid. In this study, the kinetics of iron ion removal from saturated boric acid solution was studied by ion exchange technology using Amberlite IR–120, a strong acidic resin. The experiments were carried out as a function of solution pH, reaction temperature, resin-to-solution ratio, and resin contact time. Optimum conditions were determined as solution pH = 1.3, reaction temperature 313 K, resin-to-solution ratio 4.9625 g/250 mL, and 20 min contact time. Under these conditions, maximum iron removal was about 99%. Also, data calculated from a mass balance equation were employed for pseudo-first-order and pseudo-second-order kinetic equations. The pseudo-second-order kinetic equation was the equation which best fit the data. Furthermore the sorption mechanism was also investigated using diffusion models such as film diffusion, pore diffusion, and moving boundary process. It was found that rate limiting steps in the ion exchange reaction were both film and pore diffusion. Activation energy of the ion exchange reaction was calculated as 23.64 kJ/mol and this indicated a diffusion controlled process. Based on adsorption capacity approach, an empirical kinetic model was developed to predict operational conditions of the batch process as follows: