| Summary: | 碩士 === 國立成功大學 === 資源工程學系碩博士班 === 100 === The current technology of the domestic recycle industry is unable to process the residue (blue sludge) which containing nickel and cobalt obtained from processing of wasted HDS catalyst. Currently the blue sludge was either disposed by land filling or transported to China as the raw materials for nickel refining. A technology of successfully recover nickel and cobalt in blue sludge is desperate.
The hot water leaching of acid-roasted blue sludge yields an solution rich in Co and Ni in addition to a large excess of Al. In this study we investigate the recovery of nickel and cobalt in blue sludge by ion exchange process.
Experimental measurements have been made on the batch ion exchange of Ni(II) and Co(II) from solution using cation exchanger of Amberlite IRC 748 and chelating resin of DOWEX M4195. The ion exchange behavior of two metals on the resin, depending on contact time, pH, temperature and resin dosage was studied. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. According to the Langmuir isotherm model, the ability for adsorption decreases in the order IRC748-Ni 〉 IRC748-Co 〉 M4195-Ni 〉 M4195-Co. The kinetic data were tested using Lagergren-first-order and pseudo-second-order kinetic models. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Various thermodynamic parameters of IRC748 and M4195 for Co and Ni such as Gibbs free energy ΔG°, enthalpy △H° and entropy △S° were also calculated. These parameters showed that the ion exchange of Ni(II) from solution was feasible, spontaneous and endothermic process in nature. The activation energy of ion-exchange (Ea) was determined as 17.8 kJ mol-1, 34.24 kJ mol-1 for Ni (II), Co (II) respectively using Amberlite IRC748 and was 11.02 kJ mol-1, for Ni (II) using DOWEX M4195 according to Arrhenius equation.
Finally, fixed-bed experiments were performed at inflow volumetric flow rate of 1-10 B.V./hr, and the elution volumetric flow rate was keep at 1 B.V./hr. The eluent H2SO4 concentrations were change from 0.025 N to 5 N. The results of fixed-bed experiments indicate a successful separation and purification of nickel and cobalt from a large excess of Al with DOWEX M4195 resin .
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