DETOXIFICATION OF HEAVY METALS FROM WASTEWATER USING AGRICULTURAL RESIDUES AS ABSORBENT MATERIAL AND NUCLEAR TECHNIQUE

Abstract

The present study deals with the application of rice straw, as low-cost agricultural residues, for the adsorptive removal of Pb (II), Cu (II) and Co (II) from its aqueous solutions. Effects of adsorbent dosage, initial metal ion concentration, pH and contact time on the adsorption of Pb (II), Cu (II) and Co (II) were investigated. Also the effect of radiation on rice straw as adsorbent was studied, where radiation gave negative effect on percent removal of studied metal ions. The Fourier transform infrared spectroscopy "FT-IR" spectra showed the functional groups of modified and unmodified rice straw such as cellulose and lignin. Scanning Electron Microscope "SEM" of the rice straw powder samples were recorded to explore the morphology of the studied adsorbent. It was clearly seen that the external surface of rice straw is full of cavities. Practical separation experiments for the above-mentioned cations on a rice straw column of the aqueous waste solution at (0.5, 3.5, 5ml.min-1) flow rate were carried out. Adsorption increases with increasing the pH of the solution for the studied metal ions until pH= 6.5. And also increases with increasing the amount of adsorbent and stay nearly constant for Pb (II) ,Cu (II) and Co (II) with no significant increase in percentage removal above 10 g l-1. Adsorption process favorable to Freundlich adsorption isotherm, also the results confirm occurrence multilayer adsorption on the surface. Thermodynamic parameters ΔGo decreased with rising of temperature, indicating that the adsorption is favorable at high temperatures also the values of ΔHo were positive, indicating that the adsorption process is endothermic, positive values of ΔSo show the