FABRICATION AND CHARACTERIZATION OF ZEOLITES AND ITS APPLICATION IN HEAVY METAL CAPTURE

FABRICATION AND CHARACTERIZATION OF ZEOLITES AND ITS APPLICATION IN HEAVY METAL CAPTURE

ABSTRACT

Zeolite crystals were synthesized by mixing sodium silicate and sodium aluminate to obtain aluminosilicate gel which was further treated hydrothermally to obtain the final product. The zeolite crystals were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD result identified the synthesized crystals as zeolite z; additional evidence was provided by the SEM images which showed that the zeolite crystals were disc-shaped and the particle sizes ranged between 13.4 – 53.6 µm. batch adsorption studies using the synthetic zeolite showed efficient removal of chromium (III) ion from aqueous solution. The atomic absorption spectroscopy (AAS) result which gave the final metal ion concentration indicated that the rate of adsorption increased with increase in the mass of adsorbent (zeolite) and decrease in particle size of the zeolite crystals. In the course of treatment, different quantities of zeolite ranging from 0.5 – 2.5 g were used; also different concentrations of Cr (III) ion .(10, 15, 20, 25, 30 ppm) were used to determine the extent of adsorption. The percentage adsorption increased from 55.75 – 96.6 % and decreased from 98 -88.3 % respectively in each case. As the pH values were adjusted between 1 – 11, percentage adsorption increased from 55 – 97 % with a sharp increase at pH 7. While in the case of the zeolite samples with different particle sizes, the percentage adsorption reduced from 98.9 -70 % as particle sizes increased from 13.4 – 53.6 µm. The high percentage adsorption of the zeolite samples suggests that zeolites are good adsorbents for the removal of Cr from aqueous solutions. Also the batch experiment conducted showed that the adsorption pattern followed the Langmuir and Freundlich isotherm models with correlation factors (R2) values of 0.997 and 0.963 respectively.