Adsorption characteristics of divalent heavy metals onto a regenerated spent catalyst

• Main Authors: Chin-yung Wang, 王進永
• Other Authors: Chin-huang Weng
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/59938910875823473726

碩士 === 義守大學 === 材料科學與工程學系碩士班 === 94 === The objective of this paper is to characterize the adsorption of metals, namely, Cd, Co, Cu, Pb, Ni, and Zn onto a regenerated spent catalyst. The study includes two parts: (1) the adsorption kinetics, influence of the spent catalyst absorbent to the ionic strength, temperature and the stirred speed on the heavy metal adsorption, and discusses its applicability of adsorption kinetic. (2) the equilibrium adsorption, discusses the influence of the pH value, temperature on the heavy metal adsorption by the Langmuir equation. Resutls showed that spent catalyst pretreated with base washing process could increase its specific surface area. Doulbe exponential equaton can be used to describe the adsorption kinetics. Modeling fitting results indicated that the adsorption rate constant incrased with increasing temperature while decreased with increasing ionic strength. Values of activation energy implied that the adsorption mechanism involved in physical type of adsorption. Experiments also showed that the adsorbed amounts and KL increased with incrasing solution pH and temperature. In this study, Langmuir adsorption isotherm was applied to fit the equilibrium. The oder of maximum adsorption of each metal is as follows: Cu(0.861mg/g)＞Zn(0.418mg/g)＞Cd(0.416mg/g)＞Ni(0.262mg/g)＞Co(0.261mg/g). The obtained thermodynamic parameters are as follows: ΔG° is the negative value, ΔH° is the positive value, andΔS° is the positive value. The above values suggested that the adsorption is spontanesoud and endothermic.