The adsorption of ammonium (NH+4) on zeolite was studied using initial NH+4 concentrations of 100, 200, 400, 600, 800 and 1000 mg/L 0.5, 1 and 2 g of zeolite samples. The suspensions were shaken for 1 h at the room temperature and then centrifuged and were analyzed for the remaining NH+4 cation in the solutions. The difference between the initial added amount of NH4+ in the solution and the amount remaining in solution was assumed to be adsorbed (mmol kg-1) by zeolite. Then, the sorbed NH+4 was analyzed by extraction from the same zeolite samples with 1M KCL (shaking time 1h). The obtained results of NH+4 adsorption experiment were interpreted using Langmiur and Freundlich adsorption isotherms as described by Equations. 1 and 2, respectively:
Ce/Cs = 1/(bQ) + Ce/Q (1) Log Cs = Log Kf + (1/n) Log Ce (2)
Where: Ce = The equilibrium solution phase concentration (mmol/L), Cs = The equilibrium solid phase concentration (mmol/kg), Q = Langmuir isotherm sorption capacity (mmol/kg), b = The enthalpy related sorption constant which refers to the adsorption energy coefficient (L/mmol), n= The sorption intensity constant, and Kf = The sorption capacity constant (L/kg).The essential characteristics of the Langmuir isotherm is the separation factor (RL = 1/1+bCo). The adsorbed ammonium percentage (%R) and the sorption capacity (Cs) (mg/g) were calculated:
%R = Co – Ce .100 / Co (4) Cs = (Co - Ce) . V / M (5)
V = the volume of the solution (L). M = the mass of zeolite (g).
Characteristics of ammonium adsorption and desorption by natural zeolite mineral
Ibrahim* M.S., A. Abd El-Galil*, M. A. El-Desoky**, O. E. Negim* and
Fatma N. Thabit*
Results& Discussion: The results showed that when the initial ammonium concentration increased from 100 to 1000 mg NH+4 /L, the NH+4 adsorption capacity (Cs) (mg/g) increased from 3.62 to 20.60 mg NH+4 /g with an adsorption percentage of 72.46 to 41.19% for Z1 dose (0.5 g zeolite), from 2.05 to 13.02 mg NH+4 /g with an adsorption percentage of 82.00 to 52.07% for Z2 dose (1.0 g zeolite) and from 1.25 to 9.04 mg NH+4 /g with an adsorption percentage of 100 to 72.33% for Z3 dose (2.0 g zeolite) respectively.
- The Langmiur model yielded a much better correlation coefficients (R2=0.9406 – 0.9987), fit than that of Freundlich model (R2=0.9015 - 0.9789 for NH+4 adsorption by zeolite mineral. The parameter RL lies between 0 and 1, which shows that the conditions for ammonium ions removal are favorable.
- The results showed high desorption (%) ranged from 77.81 to 92.66% of NH4+ sorbed to zeolite mineral, which differed according to the zeolite dosage and the sorbed amount of ammonium.