Evaluation of different forms of Egyptian diatomite for the removal of ammonium ions from Lake Qarun: A realistic study to avoid eutrophication

• Published in: Environmental pollution (1987) Vol. 266; no. Pt 2; p. 115277
• Main Authors: AbuKhadra, Moustafa R., Eid, Mohamd Hamdy, Allam, Ahmed Aly, Ajarem, Jamaan S., Almalki, Ahmed M., Salama, Yasser
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2020
• Subjects: adsorbents; Adsorption; ammonium; Ammonium Compounds; decontamination; Diatomaceous Earth; Diatomite; Egypt; Eutrophication; Ions; Kinetics; Lakes; Modification; pollution; Qarun lake; sorption isotherms; Water Pollutants, Chemical - analysis; Water Purification; Egypt; Qarun lake; Modification; Diatomite; Adsorption; Eutrophication
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2020.115277

Three types of diatomite-based adsorbents—diatomaceous earth (DE), purified diatomite (PD), and diatomite@MgO/CaO (D@MgO) were used for adsorption decontamination of ammonium from Lake Qarun water (28.7 mg/L). The adsorption properties of the three diatomite-based adsorbents were evaluated by both batch and fixed-bed column adsorption studies. The kinetic results demonstrated removal percentages of 97.2%, 69.5%, and 100% using DE, PD, and D@MgO, respectively, at a 1 g/L adsorbent dosage. The adsorption results using DE and D@MgO showed the best fitness with pseudo-first-order kinetic and Langmuir isotherm models, while the obtained results using PD demonstrate better fitness with the Freunlidich model. The recognised fitting results with the pseudo-first-order model and estimated adsorption energies demonstrated physical uptake of ammonium by DE (5.93 kJ/mol), PD (4.05 kJ/mol), and D@MgO (7.81 kJ/mol). The theoretical maximum ammonium uptake capacity of DE, PD, and D@MgO were 63.16 mg/g, 59.5 mg/g, and 78.3 mg/g, respectively. Using synthetic adsorbents in a fixed-bed column system for treating ammonium ions in Lake Qarun water resulted in removal percentages of 57.4%, 53.3%, and 62.6% using a DE bed, PD bed, and D@MgO bed, respectively, after treating approximately 7.2 L of Lake Qarun water using a bed thickness of 3 cm, a flow rate of 5 mL/min, pH 8, and the determined ammonium concentration in Lake Qarun water (28.7 mg/L). The curves demonstrated breakthrough times of 900 min, 900 min, and 960 min for the DE bed, PD bed, and D@MgO bed, respectively, with 1440 min as the saturation time. The columns’ performances also were studied based on the Thomas model, the Adams-Bohart model, and the Yoon-Nelson model. [Display omitted] •Three diatomite adsorbents were used in the removal of NH4 from Lake Qarun water.•The batch studies achieved removal percentages of 97.2%, 69.5%, and 100%.•The adsorption reactions are of homogenous, monolayer, and physisorption.•The column studies resulted in 57.4%, 53.3%, and 62.6% removal percentages.•The columns were described by Thomas model, Adams–Bohart, and Yoon–Nelson models.