"Chemical Studies on the Removal of Some Heavy Elements from Aqueous Solutions by Modified Pottery Materials"

Abstract

The primary goal of the present thesis was to assess the effectiveness of pottery materials for the removal of selected heavy metals from solution. This was accomplished through laboratory batch experiments involving known amounts of crushed pottery materials and predetermined concentrations of the following heavy metals: Cs, Ba, Co and Cu. Batch adsorption tests were modelled using both the Langmuir and Freundlich equations and adsorption kinetics was also analyzed. Based on the results, the following is concluded: • Batch studies on cesium, barium, cobalt and copper removal showed significant effects of the variables adsorbent dose, shaking time, initial metal concentration, pH etc. The results provide a good indication of the different operating conditions that would be required for efficient removal of each heavy metal from aqueous solution. • Raw pottery materials show high adsorption capacity towards cesium and barium but modified pottery materials show high capacity towards cobalt and copper. • pH is a significant factor in adsorption processes since it causes electrostatic changes in the solution. The maximum removal efficiency for Cs(I) is at pH 7.0, for Ba(II) at pH 7.0 for Co(II) at pH 6.0 and for Cu(II) at pH 5.0 • Langmuir and Freundlich isotherms were observed to fit the equilibrium data and the model parameters were calculated at various temperatures using linearized equations. Langmuir isotherm model (R2≈1) is in good agreement with the experimental data as compared to Freundlich model. • Kinetics data were best modeled by a pseudo second order kinetics equation. • The desorption study was also carried out and showed that the hydrochloric acid (HCl) 0.1N is the best extractant. • On the light of these data, the pottery materials effectively and quantitatively remove the studied elements from aqueous solutions. So, it would be useful to use these sorbents in the treatment of the waste solutions containing these elements. Also, it can be regarded as one of the promising materials in reprocessing and decontamination processes. Scope for Future Research • The technology, which uses locally available adsorbent materials like Pottery materials, is extremely low cost, effective and viable. Following are the scope for future research: • To explore the possibilities, other modifications or pretreatments of adsorbent to improve its adsorption capacity. • Studies with actual industrial or nuclear wastewater to evaluate parameters for field applications.