Zeolite impeded geopolymer (Z/G) was synthesized from natural kaolinite and diatomite. The structure (Z/G) was characterized as an enhanced adsorbent for PO43- and NH4+ ions from aqueous solutions, groundwater, and sewage water. The synthetic Z/G structure exhibits sequestration capacities of 206 mg/g and 140 mg/g for PO43- and NH4+, respectively which are higher values than the recognized results for the geopolymer and other adsorbents in literature. The sequestration reactions of PO43- and NH4+ by Z/G are of Pseudo-Second order kinetic behavior considering both the Chi-squared (χ2) and correlation coefficient (R2) values. The sequestration reactions occur in homogenous and monolayer forms considering their agreement with Langmuir behavior. The Gaussian energies (12.4 kJ/mol (PO43-) and 10.47 kJ/mol (NH4+)) demonstrate the operation of a chemical sequestration mechanism that might be involved zeolitic ion exchange process and chemical complexation. Additionally, these reactions are exothermic processes of spontaneous and favorable properties based on thermodynamic studies. The Z/G structure is of significant affinity for both PO43- and NH4+ even in the existence of other anions as Cl-, HCO3-, SO42-, and NO3-. Finally, the structure used effectively in the purification of groundwater and sewage water from PO43- and NH4+ in addition to nitrate, sulfate, and some metal ions.
Keywords: Adsorption; Ammonium; Equilibrium; Geopolymer; Phosphate; Zeolite.
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