Effective Sequestration of Phosphate and Ammonium Ions by the Bentonite/Zeolite Na-P Composite as a Simple Technique to Control the Eutrophication Phenomenon: Realistic Studies

Mostafa R Abukhadra; Samar Mohamed Ali; Emad Abouel Nasr; Haitham Abbas Ahmed Mahmoud; Emad Mahrous Awwad

doi:10.1021/acsomega.0c01399

Effective Sequestration of Phosphate and Ammonium Ions by the Bentonite/Zeolite Na-P Composite as a Simple Technique to Control the Eutrophication Phenomenon: Realistic Studies

ACS Omega. 2020 Jun 11;5(24):14656-14668. doi: 10.1021/acsomega.0c01399. eCollection 2020 Jun 23.

Authors

Mostafa R Abukhadra^{1

2}, Samar Mohamed Ali^{2

3}, Emad Abouel Nasr^{4

5}, Haitham Abbas Ahmed Mahmoud^{4

5}, Emad Mahrous Awwad⁶

Affiliations

¹ Geology Department, Faculty of Science, Beni-Suef University, Beni Suef City 62511, Egypt.
² Materials Technologies and Their Applications Lab, Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef City 62511, Egypt.
³ Chemistry Department, Faculty of Science, Beni-Suef University, Beni Suef City 62511, Egypt.
⁴ Industrial Engineering Department, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia.
⁵ Faculty of Engineering, Mechanical Engineering Department, Helwan University, Cairo 11732, Egypt.
⁶ Electrical Engineering Department, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia.

Abstract

A bentonite/Zeolite-P (BE/ZP) composite was synthesized by controlled alkaline hydrothermal treatment of bentonite at 150 °C for 4 h for effective sequestration of phosphate and ammonium pollutants. The composite is of 512 m²/g surface area, 387 meq/100 g ion-exchange capacity, and 5.8 nm average pore diameter. The experimental investigation reflected the strong effect of the pH value in directing the uptake behavior and the best results were attained at pH 6. The kinetic properties showed an excellent agreement for phosphate and ammonium adsorption results with the pseudo-second-order model showing equilibrium intervals of 600 and 360 min, respectively, and maximum experimental capacities of 170 and 155 mg/g, respectively. Additionally, their equilibrium modeling confirmed excellent fitness with the Langmuir hypothesis, signifying homogeneous and monolayer uptake processes with a theoretical q _max of 179.4 and 166 mg/g for phosphate and ammonium, respectively. Moreover, the calculated Gaussian adsorption energies of phosphate (0.8 kJ/mol) and ammonium (0.72 kJ/mol) suggested physisorption for them with mechanisms close to the zeolitic ion-exchange process or the coulumbic attractive forces. This was supported by the assessed thermodynamic parameters which also suggested spontaneous uptake by endothermic reaction for phosphate and exothermic reaction for ammonium. The BE/ZP composite is of excellent reusability and used for eight recyclability runs achieving removal percentages of 61.5 and 74.5% for phosphate and ammonium, respectively, in run 8. Finally, the composite was applied in the purification of sewage water and groundwater, achieving complete removal for phosphate from sewage water and ammonium from groundwater and reduction of the ammonium ions in the sewage water to 2.3 mg/L.