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

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.

Synthesis of α‐MnO2, β‐C2S, and α‐MnO2/β‐C2S nanocomposite for effective removal of phosphate from water

“…The recycling of an adsorbent is an important factor in evaluating its potential application at commercial scale. The regeneration of the α‐MnO 2 /β‐C 2 S nanocomposite was evaluated for five consecutive cycles by washing with 25 mL of .1 M NaOH solution 45,46 . An amount of 100 mg of α‐MnO 2 /β‐C 2 S nanocomposite was added to 100 mL of 50 mg/L of phosphate solution and stirred at 300 ppm for 2 h on a magnetic plate.…”

“…The regeneration of the α-MnO 2 /β-C 2 S nanocomposite was evaluated for five consecutive cycles by washing with 25 mL of .1 M NaOH solution. 45,46 An amount of 100 mg of α-MnO 2 /β-C 2 S nanocomposite was added to 100 mL of 50 mg/L of phosphate solution and stirred at 300 ppm for 2 h on a magnetic plate. After that the adsorbent was collected and transferred into 25 mL of .1 M NaOH solution followed by stirring for 2 h, and the experiments were repeated to study the adsorption/desorption cycles.…”

Spectroscopic and Microestructural Evidence for T-2 Toxin Adsorption Mechanism by Natural Bentonite Modified with Organic Cations

“…The absence of K +1 in the interlaminar layer suggests that the divalent Ca +2 cation compensates the negative charges in the tetrahedral and octahedral layers, being displaced by the quaternary ammonium salts. The cation Ca +2 is usually present in the interlaminar zone when K +1 and Na +1 are found at low concentrations or are not present [ 41 ].…”

Preparation, Features, and Efficiency of Nanocomposite Fertilisers Based on Glauconite and Ammonium Dihydrogen Phosphate

“…Clay minerals (phyllosilicates) are common inorganic materials in the creation slow-release fertilisers [ 41 , 45 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ]. Clay minerals and clay-based complex materials are also used to purify water from phosphate and ammonium ions [ 63 , 64 ]. Phyllosilicates such as vermiculite, montmorillonite, kaolinite, halloysite, and sepiolite are considered relatively inexpensive and environmentally friendly adsorbents of different ions from polluted waters [ 65 ].…”