Nitrate and phosphate sorption efficiency of mordenite versus zeolite-A at the convergence of experimental and density functionalized evaluation

Abstract

In the modern era experimental and density functional theory are employed almost in every field of science to make a target investigation effective. In the current report a combined application of experimental-theoretical sorption evaluation of KH₂PO₄ and NH₄NO₃ on pure and surface modified forms of mordenite and zeolite has been carried out (using batch equilibrium method for practical measures). The sorption studies have been made by studying the influence of change in pH (pH 3, 5, 7, 9 and 11). The increase in pH values up to pH 7 has directly shown an enhancement in its sorption also increases. The equilibrium sorption time was observed to be about 12 hours. There was observed a change of zeta potential of particles from negative to positive and enhancement of sorption capacity on surface modification of the zeolites. Up to a temperature of 40 °C, the percentage of sorption was found to increase. All thermodynamic parameters, that is, standard free energy change (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) change by varying temperature. Theoretical study has also been invoked for mordenite in this work. LANL2DZ as basis set was specified for metallic atoms and 631g(d,p) for non-metallic entities under B3LYP functional. Nitate, phosphate and mordenite were first of all optimized followed by determination of reactive descriptors. Finally the theoretical evaluation was made to explain the respective relation with sorption efficiency of the target ions.

Keywords:

• Sorption
• mordenite
• zeolite
• phosphate
• nitrate
• DFT