A comprehensive study (kinetic, thermodynamic and equilibrium) of arsenic (V) adsorption using KMnO4 modified clinoptilolite

Abstract

The sorption of As(V) on manganese oxide coated zeolite (MOCZ) was investigated through batch study to explore the feasibility of removing arsenic from groundwater. MOCZ was characterized by scanning electron microscopy, XRD, FTIR spectroscopy, and point of zero charge (pH PZC ) measurements. The effects of process parameters such as contact time, adsorbent size, temperature and pH were investigated. Arsenic detection was carried out by atomic fluorescence spectrometer. Arsenate adsorption onto MOCZ followed the pseudo-second-order kinetic model with a correlation coefficient more than 0.99. Optimum removal of arsenate occurred within pH range of 6-10. The equilibrium data were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The maximum adsorption capacity calculated from the Langmuir and D-R models was 151 and 152.8 μg g −1 , respectively, at 38 o C. The activation energy of adsorption (E a ) was found to be 3.68 kj mol −1 , suggesting that the adsorption process may be physical sorption. Thermodynamic parameters: ΔH o , was 1.181 kj mol −1 ; ΔS o , was −0.29 kj mol −1 , while the values of ΔG o were −83.9, −86.7 and 89.8 kj mol −1 at 18, 28 and 38, respectively, suggesting endothermic and spontaneous process and a rise in temperature favoring the adsorption.

Silica-coated magnetite nanoparticles core-shell spheres (Fe3O4@SiO2) for natural organic matter removal

“…This can also be explained by either the split in the flux or the concentration gradient between solute concentration in the HA concentration in the solution and the HA concentration in the adsorbent surface, resulting in that then amount of HA adsorbed onto unit weight of adsorbent gets reduced with increasing adsorbent dosage [15, 40]. In this regard, it can be speculated that the reason for this behavior has to do with the decrease of the ratio of adsorbate per mass unit of the adsorbent [41]. …”

“…The negative values also indicate that the reaction rate is decreasing and has an indirect relationship with the temperature. The negative values of ΔS° revealed a decrease in randomness at the solid-liquid interface in the adsorption system within the adsorption of HA onto the adsorbents [20, 41]. …”

Simultaneous adsorption of lead and aniline onto magnetically recoverable carbon: optimization, modeling and mechanism

“…Equilibrium isotherms are used as important parameters in designing adsorption systems. They, in fact, describe the relationship between the adsorbate concentration and adsorption capacity of the adsorbent . In this regard, two common models the Freundlich and Langmuir models were employed in this study.…”

“…They, in fact, describe the relationship between the adsorbate concentration and adsorption capacity of the adsorbent. 14,15 In this regard, two common models the Freundlich and Langmuir models were employed in this study. Further details of these models (i.e.…”

Removal of Basic Blue-41 dye from Water by Stabilized Magnetic Iron Nanoparticles on Clinoptilolite Zeolite

“…On the other hand, Freundlich isotherm is assumed that a layer of adsorption process takes place on an unsteady surface [50]. The linear equations related to isotherm and kinetics are listed in (table 4) [51,52]. In equation qe is the amount of absorbed substance in mass unit of adsorbent (mg/g), Ce is equilibrium concentration of absorbing substance in solution after adsorption process (mg/L), n is adsorption intensity, qm is illustrator of adsorption capacity and kl, kf are respectively presenter of Langmuir and Freundlich constants.…”