Adsorption kinetics and isotherms for the removal of nickel ions from aqueous solutions by an ion-exchange resin: application of two and three parameter isotherm models
“…The equation defining of the Elovich (Yousef et al, 2016) model is based on a kinetic principle in which adsorption sites are assumed to increase exponentially with the amount of adsorption, implying a multilayer adsorption. It is resolved by the equation where K E represents the Elovich equilibrium constant (L mg −1 ), and q m represents the Elovich maximum adsorption capacity (mg g −1 ).…”
Section: Methodsmentioning
confidence: 99%
“…The Freundlich adsorption (Yousef et al, 2016) is used to express reversible adsorption in heterogeneous systems. The equation in linear form is as follows: where K F represents a constant indicative of the relative adsorption capacity of the adsorbent [mg 1 − (1/ n ) L 1/ n g −1 ] and n represents the strength of adsorption.…”
Section: Methodsmentioning
confidence: 99%
“…The adsorption heat of all molecules in the layer decreases linearly with the coverage rate, and the adsorption is characterized by the uniform distribution of binding energy to achieve a certain maximum binding energy. The Temkin isotherm model (Yousef et al, 2016) equation is given as where β T = RT / b , T represents the absolute temperature (K), R represents the universal gas constant (8.314 J mol −1 K −1 ), K T represents the equilibrium binding constant (L mg −1 ), β T is the heat of adsorption, b is the variation of adsorption energy (kJ mol −1 ), and θ is the fractional coverage.…”
Phosphate pollution remains a significant hazard to terrestrial and aquatic ecosystems. We developed an economical and efficient method for phosphate adsorption on waste construction concrete modified with seawater. Compared with raw concrete materials, the phosphate adsorption capacity of seawater‐modified waste concrete was highly efficient, especially at low phosphate concentrations. The inflection point for seawater‐modified concrete was 0.66 and 1.22 mg L−1 for the raw material. The relative phosphate adsorption was 4.64 and 2.39 mg g−1, respectively. Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials. Chemical and physical analysis of the modified concrete indicated that Ca and Mg particles were uniformly sequestrated on the surface, and Ca was the determinant controlling phosphate uptake. Phosphate adsorption isotherms fit well using the Freundlich, Temkin, Elovich, Fowler–Guggenheim, and Hill–de Boer models and indicated that intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater. This method can efficiently remove phosphate from polluted water and repurposes waste construction concrete.
Core Ideas
Phosphate adsorption capacity of modified waste concrete was highly efficient at low phosphate.
Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials.
Calcium was the determinant controlling phosphate uptake for seawater‐modified concrete.
Intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater.
“…The equation defining of the Elovich (Yousef et al, 2016) model is based on a kinetic principle in which adsorption sites are assumed to increase exponentially with the amount of adsorption, implying a multilayer adsorption. It is resolved by the equation where K E represents the Elovich equilibrium constant (L mg −1 ), and q m represents the Elovich maximum adsorption capacity (mg g −1 ).…”
Section: Methodsmentioning
confidence: 99%
“…The Freundlich adsorption (Yousef et al, 2016) is used to express reversible adsorption in heterogeneous systems. The equation in linear form is as follows: where K F represents a constant indicative of the relative adsorption capacity of the adsorbent [mg 1 − (1/ n ) L 1/ n g −1 ] and n represents the strength of adsorption.…”
Section: Methodsmentioning
confidence: 99%
“…The adsorption heat of all molecules in the layer decreases linearly with the coverage rate, and the adsorption is characterized by the uniform distribution of binding energy to achieve a certain maximum binding energy. The Temkin isotherm model (Yousef et al, 2016) equation is given as where β T = RT / b , T represents the absolute temperature (K), R represents the universal gas constant (8.314 J mol −1 K −1 ), K T represents the equilibrium binding constant (L mg −1 ), β T is the heat of adsorption, b is the variation of adsorption energy (kJ mol −1 ), and θ is the fractional coverage.…”
Phosphate pollution remains a significant hazard to terrestrial and aquatic ecosystems. We developed an economical and efficient method for phosphate adsorption on waste construction concrete modified with seawater. Compared with raw concrete materials, the phosphate adsorption capacity of seawater‐modified waste concrete was highly efficient, especially at low phosphate concentrations. The inflection point for seawater‐modified concrete was 0.66 and 1.22 mg L−1 for the raw material. The relative phosphate adsorption was 4.64 and 2.39 mg g−1, respectively. Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials. Chemical and physical analysis of the modified concrete indicated that Ca and Mg particles were uniformly sequestrated on the surface, and Ca was the determinant controlling phosphate uptake. Phosphate adsorption isotherms fit well using the Freundlich, Temkin, Elovich, Fowler–Guggenheim, and Hill–de Boer models and indicated that intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater. This method can efficiently remove phosphate from polluted water and repurposes waste construction concrete.
Core Ideas
Phosphate adsorption capacity of modified waste concrete was highly efficient at low phosphate.
Phosphate removal was >90% over a pH range of 3 to 11 for the raw and modified materials.
Calcium was the determinant controlling phosphate uptake for seawater‐modified concrete.
Intermolecular forces in the concrete particles were enhanced by calcium oxides from seawater.
“…As shown from Table 2, the value of the R 2 values was between 0.992-1.000, which are extremely high values fort he investigated range of concentrations. The values of K 1 is negative, indicating repulsive interaction among adsorbed molecules, and showing a decrease in the heat of adsorption with loading [35].…”
Section: Fig8 Elovich Adsorption Isotherm Plots For Adsorption Of Mmentioning
Langmuir, Freundlich, DKR, Temkin, BET, Harkins-Jura, Elovich, Fowler-Gugenheim, Hill de Boer, Frumkin, Halsey, Henderson, Smith, Jovanovic and Scatchard isotherm equations.
“…The overall consideration of nickel toxicology has lead to a recent number of reports about the removal of this metal from aqueous solutions using different technologies (El-Bahy and El-Bahy, 2016;Guan et al, 2016;Jain et al, 2016;Melo et al, 2016;Otrembska and Gega, 2016;Taha et al, 2017;Yousef et al, 2016;Zhang and Chen, 2016;Moghbeli et al, 2017). Next in the series of articles published by the author about the use of ion exchange technology in the removal of toxic metals (Alguacil, 2002;Alguacil et al, 2002;Alguacil, 2003;Alguacil, 2017), the present work reports about the use of the cationic exchange resin Dowex C400 on the removal of nickel(II) from aqueous solutions and under various experimental conditions, and different mathematical models were used to fit the various aspects in relation of the cationic exchange process.…”
ABSTRACT:The cationic exchange resin Dowex C400 was used to remove nickel(II) from aqueous solutions of different pH values and under various experimental conditions: stirring speed of the aqueous solution/resin system, temperature, resin dosage and aqueous ionic strength. The selectivity of the resin was investigated against the presence of various metals in the aqueous solution, and the removal of nickel(II) from aqueous solutions was also compared with results obtained using multiwalled carbon nanotubes or functionalized (carboxylic groups) multiwalled carbon nanotubes as adsorbents. According to batch experimental data, best fit of the results is obtained with the Freundlich model, whereas the ion exchange process is best explained by the pseudofirst order model. Experimental data fit well to the moving boundary controlled model. Elution of the nickel(II) loaded onto Dowex C400 resin is fully possible using acidic solutions.
RESUMEN: La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico.Parte V: níquel(II))/H+/Dowex C400. Se ha empleado la resina de intercambio catiónico Dowex C400 en la eliminación de níquel(II) de disoluciones acuosas de distintos valores de pH y en varias condiciones experimentales: velocidad de agitación del sistema acuoso/resina, temperatura, dosificación de la resina y disoluciones acuosas de distinta fuerza iónica, investigándose la eliminación del níquel de medios acuosos que contenían varios metales, así como las posibilidades de la resina frente a la utilización de otros potenciales adsorbentes como son los nanotubos de carbono de pared múltiple y los nanotubos de carbono de pared múltiple funcionalizados con grupos carboxílicos. Los resultados experimentales indican que la carga del níquel(II) en la resina responde al modelo de Freundlich, mientras que los modelos cinéticos y de control indican que el proceso de intercambio catiónico responde al modelo de pseudo-primer orden y núcleo recesivo. La elución del níquel(II) se realiza con disoluciones acidas.PALABRAS CLAVE: Dowex C400; Efluentes líquidos; Eliminación; Níquel(II); Nanotubos de carbono de pared múltiple ORCID ID: Francisco J. Alguacil (http://orcid.org/0000-0002-0247-3384)
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