Kinetic study of metal ion adsorption from wastewater onto coal industry by-products

Se llevó a cabo un estudio comparativo sobre el uso de cenizas volantes y clinker natural como adsorbentes de metales pesados de agua contaminada a partir de experimentos de adsorción a temperatura ambiente. Las concentraciones de metales pesados en los filtrados se determinaron por espectrometría de emisión atómica por plasma inductivamente acoplado. En los estudios de adsorción en batch, la retención aumento con el aumento del tiempo de contacto, la cantidad de adsorbente y el pH de la solución. La adsorción de los metales a partir de la solución contaminada artificialmente fue Cr>Cu>Pb>Ni>Zn, mientras que a partir de drenaje ácido de mina fue Pb>Zn>As>Fe>Cr>Cu>Ni. Las constantes de primer orden de Lagergren se calcularon para concentraciones iniciales de iones metálicos específicas, dando un excelente ajuste como lo indica el coeficiente de correlación (R2), con valores próximos o iguales a 1 para el tratamiento de la solución contaminada artificialmente y de 0.25 a 0.99 para el tratamiento del drenaje ácido de mina. Los datos de este estudio revelan que los cationes metálicos en solución acuosa pueden ser adsorbidos exitosamente en cantidades significativas por los adsorbentes usados

Use of Calixarenes Bearing Benzoyl Groups for the Adsorption of Heavy Metals Cations: Equilibrium and Kinetics Studies

This study aims to examine the potential of p-tert-butylkalix[4]arene derivatives, namely 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrahydroxy-calix[4]arene (TBCA), and 5,11,17,23-tetra-tert-butyl-25-monohydroxy-26,27,28-tribenzoyloxycalix[4]arene (TBMTCA) as adsorbent for metal cations, such as Pb(II) and Fe(III). The synthesized compounds were characterized using FT-IR and 1H-NMR spectroscopy. The adsorption studies were then carried out with contact time as a parameter, while the kinetics were evaluated using the Lagergren and Ho-McKay equations. The isotherms were analyzed using the Langmuir and Freundlich equations. For the kinetics of TBCA adsorbents, Pb(II) cations followed the Ho-McKay model, while Fe(III) was based on Lagergren. Furthermore, for the TBMTCA adsorbent, Pb(II) followed the Lagergren kinetic model, while Fe(III) was based on the Ho-McKay. The cation adsorption isotherms of Pb(II)-TBCA, Pb(II)-TBMTCA, Fe(III)-TBCA, and Fe(III)-TBMTCA are more in line with the Langmuir model. These results indicate that they can be used as heavy metal adsorbents, and recycled to increase their economic value

Functional Characterization of Green Sorption Media and Scaling of Pilot Studies for Copper Removal in Stormwater Runoff

Green adsorption media with the inclusion of renewable and recycled materials can be applied as a stormwater best management practice for copper removal. A green adsorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was physicochemically evaluated for its potential use in an upflow media filter. The results found that the use of the green adsorption media mixture in isolation or the coconut coir with an expanded clay filtration chamber could be an effective and reliable stormwater best management practice for copper removal. A suite of tests were conducted on the media mixture and the individual media components including studies of isotherm, reaction kinetics, column adsorption and reaction kinetics. Batch adsorption tests revealed that the media and media mixture follow both the Freundlich and Langmuir isotherm models and that the coconut coir had the highest affinity for copper. A screening of desorbing agents revealed that hydrochloric acid has good potential for copper desorption, while batch tests for desorption with hydrochloric acid as the desorbing agent showed the data fit the Freundlich isotherm model. Reaction kinetics revealed that the adsorption reaction took less than 1 hour to reach equilibrium and that it followed pseudo-second order kinetics for the mixture and coconut. Desorption kinetic data had high correlation with the pseudo-second order model and revealed a rapid desorption reaction. Batch equilibrium data over 3 adsorption/desorption cycles found that the coconut coir and media mixture were the most resilient and demonstrated that they could be used through 3 or more adsorption/desorption cycles. The coconut coir also performed the best under dynamic conditions, having an equilibrium uptake of 1.63 mg?g-1, compared to 0.021 mg?g-1 at an influent concentration of 1.0 mg?L-1 and a hydraulic retention time of 30 minutes. A physical evaluation of the media found the macro-scale properties, such as particle size distribution and mass-volume relationships, and observed the micro-scale properties such as surface and pore microstructures, crystalline structures, and elemental composition. FE-SEM imaging found a strong correlation between the porosity of the micro pore structure and the adsorptive capacity. The equilibrium and dynamic adsorption testing results were confirmed by elemental analysis, which showed measureable quantities of copper in the coconut coir and media mixture after adsorption followed by partial desorption. A new scaling-up theory was developed through a joint consideration of the Damköhler and Péclet numbers for a constant media particle size such that a balance between transport-controlled and reaction-controlled kinetics can be harmonized. A series of column breakthrough tests at varying hydraulic residence times revealed a clear peak adsorptive capacity for the media mixture at a Damköhler number of 2.7. The Péclet numbers for the column breakthrough tests indicated that mechanical dispersion is an important effect that requires further consideration in the scaling-up process. However, perfect similitude of the Damköhler number cannot be maintained for a constant media particle size, and relaxation of hydrodynamic similitude through variation of the Péclet number must occur

Benzene Uptake onto Modified Tea Waste: Perspective Applicability of Empirical Sorption Kinetic Models

The uptake of Benzene onto modified solid materials have been reported most commonly with abrupt peripheral application of the defining models based chiefly on regression parameter validation. This paper considered a perspective application of mainly the empirical kinetic models of predetermined applicability as well as their parent nature to contemporary kinetic models. Verification of the applicable kinetic mechanisms defined by the models were based mainly on interpretations of the model parameters other than the statistical regression parameters. The Tea waste used was modified by impregnation using iron salt and carbonized at 500oC. The modified Tea waste (TW) of average particle diameter of 0.09mm was used in the batch sorption of benzene dissolved in methanol. The Z(t) plot predetermined the applicability of the Diffusion, Elovichian and Quasi first order models. The linearity change in the Elovich plot illustrated the energetic heterogeneity typical of heterogeneous sorbents. Though the PFO showed lower error and lesser deviation of the estimated and observed uptake, the authentication coefficient ( 1.06 ) indicates that the PFO may not really be applicable at the process time (60min). However, the PSO gave higher correlation (0.999), significantly low error and deviation, and a higher rate constant. Hence, based on time effect of rate constant and the equilibrium coefficient ( 1 2 f ), the Langmuirian uptake is better in the PSO domain. The transfer of benzene sorptive for uptake was complementarily controlled first by internal diffusion then by film diffusion

Kinetic and Isotherm Studies of Nitrate Adsorption in Salt Water Using Modified Zeolite

Nitrate is the main form of nitrogen species in natural waters. Excessive nitrate concentration in water is highly undesirable, so that removal of the excessive nitrates in waters is very important. However, the challenge is purposed to remove the excessive nitrates in sea waters by considering anions-rich sea water. Adsorption is a favorable method for the nitrate removal process. Therefore, this research was aimed to study the kinetics and isotherm of nitrates adsorption in salt water. The adsorbent preparation was done by modifying natural zeolite with iron oxide. The adsorbent characterization was carried out by FT-IR spectroscopy and Gas Sorption Analyis methods. The results showed that the modified zeolite have Fe−O group vibrations as indicated by a peak at a wave number of 1404.18 cm−1 and an increased specific surface area. The modified zeolite is capable of adsorbing nitrate ions. The adsorption isotherms studies indicated that the modified zeolite is appropriate to the Dubinin-Radushkevich model. The average adsorption energy value (ED), obtained based on the Dubinin-Radushkevich isotherm <2 kJ/mole, showed that the nitrate adsorption on zeolite surface occurred physically. The most suitable adsorption kinetics model is the pseudo second order with the rate constant of 1.80´10−2 g/mg.min. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The Effectiveness of Magnetite Modified Gallic Acid Synthesized by Sonochemical Method As AuCl4- Adsorbent-Reductor

In recent years gallic acid has been developed as an AuCl4- adsorbent-reducing agent. In this research, gallic acid was modified with magnetite by sonochemical method (GA-Fe3O4), and its effectiveness as an AuCl4- adsorbent was studied. GA-Fe3O4 was synthesized through one-stage (GA-Fe3O4-SK1) and two-stage (GA-Fe3O4-SK2) methods. The effectiveness of GA-Fe3O4 was studied through optimization studies on pH, time, kinetics, and isotherm adsorption of AuCl4-. The adsorption method used was the batch method in the pH range 2-7. While the kinetics model used was the Lagergren and Ho kinetics model. The adsorption isotherm model used was the Freundlich and Langmuir isotherm model. The results showed that the optimum pH conditions for adsorption of AuCl4- on GA-Fe3O4 occurred at pH 3. Adsorption of AuCl4- on GA-Fe3O4-SK1 and GA-Fe3O4-SK2 both followed the Ho kinetic model, while the adsorption isotherm followed the Freundlich isotherm model with values KF were 0.041 and 0.034 mol/g respectively

Kinetic Study of Cr(VI) Adsorption on Hydrotalcite Mg/Al with Molar Ratio 2:1

Chromium(VI) is one of the metals that is harmful to biota and humans if large amount present in environments. One method for reducing metal contamination of Cr(VI) inaqueous is by adsorption using Mg/Al hydrotalcite with molar ratio 2:1. This study is determined the effect of contact time and adsorption models of Cr(VI) adsorption on Mg/Al hydrotalcite with molar ratio 2:1. Capacity of Cr(VI) adsorption on Mg/Al hydrotalciteoccursat the optimum contact time of 180 minutes with 93.81% percent adsorption. Adsorption kinetics model equations are analyzed with first order, second order, pseudo first order, pseudo second order, Elovich equation, the equation Dumwald-Wagner and Weber-Morris equation. Analysis model of adsorption kinetics of Cr(VI) followed pseudo second order models are characterized by the highest coefficient of determination, which is 0.998

Equilibrium, Thermodynamics, and Kinetic Sorption Studies for the Removal of Coomassie Brilliant Blue on Wheat Bran as a Low-Cost Adsorbent

The sorption studies of coomassie brilliant blue (CBB) from aqueous solution have been carried out on wheat bran (WB). Coomassie brilliant blue on wheat bran was used to study the adsorption behavior under various parameters such as pH, dosage amount, and contact time. It was observed that under optimized conditions up to 95.70% dye could be removed from solution onto WB. Langmuir and Freundlich adsorption isotherms were used to elaborate the results. Freundlich model was found to be fitted well and favored multilayer adsorption. The Freundlich constants n and KF were determined as 0.53 and 2.5 × 10−4. Thermodynamic parameters such as ΔG, ΔH, and ΔS studied were taking into account, showed spontaneous and favorable reaction for coomassie brilliant blue on wheat bran. The maximum adsorption capacity qm was found to be 6.410 mg/g. The investigations show that non treated WB is a low-cost adsorbent for the removal of dyes from textile industry effluents

Cryogel composites for cadmium removal : evaluating combinations and adsorption by molecularly imprinted polymers

Tese de mestrado integrado. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 201