Adsorption of Imidacloprid on Powdered Activated Carbon and Magnetic Activated Carbon

The adsorptive characteristics of imidacloprid on magnetic activated carbon (MAC12) in comparison to powdered activated carbon (PAC) were investigated. Adsorption of imidacloprid onto powdered activated carbon and magnetic activated carbon was studied as a function of time, initial imidacloprid concentration, temperature and pH. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models for both carbons were used to describe the kinetic data. The adsorption equilibrium data were analyzed using the Langmuir and Freundlich models. For powdered activated carbon the isotherm was 'H' type, and 'L' type for magnetic activated carbon. Equilibrium data fits well to the Langmuir model in the studied concentration range of imidacloprid. It was found that both the boundary layer and intraparticle diffusion for both adsorbents play an important role in the adsorption mechanisms of imidacloprid. The adsorption of imidacloprid on PAC and MAC12 followed a pseudo-second-order kinetic model rather than pseudo-first-order model. A decrease in the adsorption of imidacloprid on powdered activated carbon and magnetic activated carbon was observed with the increase in temperature. The pH of the solutions had no effect on the adsorption capacity of the adsorbents

Equilibrium, kinetic and mass transfer studies and column operations for the removal of arsenic(III) from aqueous solutions using acid treated spent bleaching earth

In the present study, a new adsorbent was produced from spent bleaching earth by H2SO4 impregnation method. The sorption of arsenic(III) by acid treated spent bleaching earth was studied to examine the possibility of utilizing this material in water treatment systems. The effect of time, pH, initial concentration, temperature on the adsorption of arsenic(III) was studied. Maximum adsorption was found to occur at pH 9.0. The adsorption process followed the first order Lagergren equation. Mass transfer coefficients and rate constants of intraparticle diffusion were calculated. The experimental data points were fitted to the Langmuir equation in order to calculate the adsorption capacity (Q) of the adsorbent and the value of Q(0) was found to be 0.46 mmol g(-1). In order to understand the adsorption mechanism, Dubinin-Radushkevich (DR) isotherm was used. The magnitude of E calculated from DR equation was found to be 5.12 kJ mol(-1). The heat of adsorption (DeltaH(o) = -30367 J mol(-1)) implied that the adsorption was physical exothermic adsorption. The column studies were also carried out to simulate water treatment processes. The capacity values obtained in column studies were found to be greater than the capacity values obtained in batch studies. This result was explained by the difference between batch system and column stem. The factors that affect the capacity values of column and batch systems were explained. The effect of other anions on e adsorption of arsenic(III) in the presence of NO3-, SO4-, Cl-, Br- was studied. The presence of these anions did not affect the adsorption of arsenic(III) significantly

2,4 D adsorption by the adsorbents produced from contaminated soil

The waste material from a gaswork site was converted into low cost adsorbents by physical and chemical methods and utilized for the adsorption of 2,4 - D (2,4-dichlorophenoxy acetic acid). Chemical activation method was found to be more effective than physical method, as confirmed by surface area and porosity data. In the batch experiments, some parameters such as contact time, adsorbent concentration, and temperature were studied. Kinetic studies were made using the first order equation. The equilibrium data fit well to the Langmuir and Freundlich models. Thermodynamic parameters were calculated and these values showed that adsorption process was exothermic and favoured at low temperatures

Adsorption of Imidacloprid on Powdered Activated Carbon and Magnetic Activated Carbon

The adsorptive characteristics of imidacloprid on magnetic activated carbon (MAC12) in comparison to powdered activated carbon (PAC) were investigated. Adsorption of imidacloprid onto powdered activated carbon and magnetic activated carbon was studied as a function of time, initial imidacloprid concentration, temperature and pH. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models for both carbons were used to describe the kinetic data. The adsorption equilibrium data were analyzed using the Langmuir and Freundlich models. For powdered activated carbon the isotherm was ‘H’ type, and ‘L’ type for magnetic activated carbon. Equilibrium data fits well to the Langmuir model in the studied concentration range of imidacloprid. It was found that both the boundary layer and intraparticle diffusion for both adsorbents play an important role in the adsorption mechanisms of imidacloprid. The adsorption of imidacloprid on PAC and MAC12 followed a pseudo-second-order kinetic model rather than pseudo-first-order model. A decrease in the adsorption of imidacloprid on powdered activated carbon and magnetic activated carbon was observed with the increase in temperature. The pH of the solutions had no effect on the adsorption capacity of the adsorbents

Removal of MCPA (4-chloro-2-methylphenoxy-acetic acid) from aqueous solutions using adsorbent produced from elutrilithe

Elutrilithe is a mixed alumina-silicate/carbon material and a solid waste of coal mines. In this study we tried to produce a new adsorbent from elutrilithe. The elutrilithe was treated with zinc chloride in an N-2 medium. The adsorption capacity of the new adsorbent was measured with MCPA (4-chloro-2-methylphenoxy-acetic acid), which is a pesticide

Adsorption of Cr(VI) from aqueous solutions by adsorbents produced from coal mining wastes

Large amounts of coal-mining wastes contaminate the environment and reprocessing of them as valuable products such as adsorbents will be a good approach from an environmental and economic point of view. Therefore, in this study some adsorbents were produced from these wastes and used for batch removing experiments of chromium(VI) ions from aqueous solutions taking into considerational parameters such as initial concentrations, pH, temperature and time. The adsorption kinetic results were interpreted by the Lagergren equation and the rate constant of intraparticle diffusion was calculated. The adsorption process was described with the Langmuir and Freundlich isotherms and also their constants were calculated. Additionally, the effect of different anions on the adsorption of Cr(VI) was studied. The presence of the anions reduced the adsorption capacity for Cr(VI). The experiments were also carried out at different temperatures. Endothermic effects of temperature played an important role in the adsorption process

Surface tension studies of lauryl sulfobetaine - beta-cyclodextrin and dodecyltrimethylammonium bromide - beta-cyclodextrin inclusion complexes in aqueous solution

beta-Cyclodextrin (beta-CD) is a cyclic oligosaccaride with an apolar cavity that shows a certain degree of selectivity in binding organic and inorganic compounds. Lauryl sulfobetaine (LSB) and dodecyltrimethylammonium bromide (DTAB), having the same hydrophobic and different polar groups are used in order to compare the influence of the polar group on complex formation with beta-CD. The surface tension increased as beta-CD is added to premicellar region of amphoteric (LSB) and cationic surfactant (DTAB) solutions. The relation between the surface tension and surfactant concentration can be expressed by the Szyszkowski equation, which combines the Langmuir adsorption model and the Gibbs equation. Binding constants were determined from the effect of added beta-CD on the surface tension vs, concentration curves for LSB and DTAB aqueous solutions

Removal of thiram from aqueous solutions with adsorbents produced from coal mining waste

Thiram (CAS Number: 137-26-8) is a widely used pesticide. In this study, its adsorption on adsorbents produced from coal mining waste was investigated. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The adsorption kinetic results were interpreted by the Lagergren equation and the rate constants of adsorption were calculated for different initial concentrations as well as those of intraparticle diffusion rate. According to the Giles isotherm, the adsorbent was found to be a H-type one. Dubinin-Radushkevich (DR) equation was used to describe the adsorption mechanism. The mean energy of sorption was found to be 0.55 kJ/mol, which is in the energy range for physical sorption (0-8 kJ/mol)

Adsorption of fluoride from aqueous solution by acid treated spent bleaching earth

Acid treated spent bleaching earth was studied to assess its capacity for the adsorption of fluoride from aqueous solutions. Adsorption isotherms have been modeled by Langmuir and Freundlich equations and isotherm constants for both isotherms were calculated. The effect of the adsorbent concentration on the adsorption was studied. The dependence of the adsorption of fluoride on the pH of the solution has been studied to achieve the optimum pH-value and a better understanding of the adsorption mechanism. It has been found that maximum adsorption of fluoride from aqueous solutions takes place at pH-value of 3.5. Second-order equation was used to describe the adsorption rate of fluoride and adsorption rate constant was calculated. Intraparticle and mass transfer coefficients were calculated. The influence of addition of the anions on the adsorption of fluoride was also studied to simulate industrial waste waters and the addition of anions decreased the adsorption of fluoride on the acid treated spent bleaching earth (SBE). (C) 2002 Elsevier Science B.V All rights reserved