H.I. Adegoke, F.A. Adekola, J.O. Balogun
University of Ilorin,
Keywords: manganese oxide, zeolite, composite, Pb (II), Cu (II), wastewater
Summary:Manganese oxide, zeolite and composite were prepared by hydrothermal method. The prepared nanoparticles were characterized using different physiochemical methods and spectroscopic methods such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), pH and point of zero charge (pHpzc). The prepared samples have been used as adsorbents for Pb (II) and Cu (II) ions removal from aqueous solution using batch adsorption studies. The data was fitted into different adsorption isotherms. The SEM micrographs showed that zeolite and manganese oxide composite displayed a uniform flower-like microsphere and a hierarchical architecture with micro spherical cores respectively, while the EDX shows a good elemental composition of the samples. The Langmuir monolayer adsorption capacity (Qmax) was found to be 43.66 mg/g and 39.06 mg/g for MOZ and 34.48 mg/g and 70.42 mg/g for ZE respectively. The monolayer adsorption was confirmed by high correlation coefficient (R2) for MOZ of 0.9565 and 0.9829 and heterogeneous layer for ZE of 0.9814 and 0.9719 for Cu (II) and Pb (II) ions respectively. The kinetic study was investigated and was observed to follow a pseudo-second order model with R2 value of 0.9999 and 1 for Pb(II) ion and 0.9999 and 0.9976 for Cu(II) ions for manganese oxide-zeolite composite and zeolite respectively. The thermodynamic parameters obtained from the plot showed that the negative values of ∆Go range from -5.40 kJmol-1 to -10.97 kJmol-1 for the adsorbents which indicate a spontaneous nature of adsorption and the positive value of ∆Ho (+19.65 kJmol-1and +8.29 kJmol-1 for MOZ and ZE) implies that the adsorption is endothermic. The positive value of ∆So suggests increasing randomness of the solid/liquid interface during adsorption. The percentage desorbed obtained for the adsorbents was in the range of 50-60% on zeolite and manganese oxide-zeolite composite. The desorption index (DI) results revealed a value in the range of 0.80 to 1.66 for the adsorbents which confirmed the irreversibility of the sorption reaction. The result obtained suggested that the adsorbents can be used and re-used for the treatment of Pb (II) and Cu (II) ions in wastewater.