Adsorption And Desorption Properties Of IDA Resin R604 For Ni(Ⅱ)

With the development of modern industry, waste water containing heavy metals has led to severe environmental pollution. Nickel-containing wastewater, with extensive sources, is one of the main types of heavy metal wastewater. In addition, nickel is an important raw material of stainless steel, alloy steel and non ferrous alloy, and nickel products in China need to be imported in the long term because of the shortage of nickel resources. Therefore, an efficient and rational processing technology for nickel-containing wastewater treatment and nickel recycling will be of great significance.Ion exchange method, as one of the promising technologies applied in this field, was investigated systematically in the paper. The chelating exchange resin R604, which has iminodiacetic acid (IDA) functional ligand, was used to remove Ni2+ from synthetic aqueous solutions. The static and dynamic ion exchange property of R604 with Ni2+ and desorption performance of the resin were studied. In addition, fixed bed is the most widely used ion exchange equipment at present. According to the existing defects of fixed bed, the continuous countercurrent adsorption system and an original U-shaped continuous countercurrent desorption system were investigated for their property characteristics,so as to provide a reference for further research.Several influencing factors of the static ion-exchange adsorption properties such as the concentration, pH value, temperature and oscillation frequency of the resin-Ni2+ reaction system were studied to evaluate the impacts of these factors'variation on the adsorption capacity of R604 resin and the reaction rate of the adsorption process. Three derived models from fractal adsorption model were used to analyze the exchange adsorption process, from which some conclusions were found that the reaction process is a preferential adsorption and R604 resin has a complex surface of 2-3 Dimensional Space; The first order and Elovich kinetics equation could well describe the experimental results of the static ion-exchange adsorption process, which was demonstrated by the kinetic studies of the reaction;The Weber-Morris diffusion model revealed that the particle and film diffusion are the joint rate-limiting steps of the reaction process.Conventional straight column and continuous countercurrent straight column adsorption systems were investigated to discuss their respective performances when applied in the adsorption processing. In conventional straight column, the working capacity of resin is the breakthrough capacity,which was influenced by the initial concentration, flow rate of the inlet solution and the column height; The Bohart-Adams and BDST model could well describe the dynamic behavior of conventional straight column;In continuous countercurrent straight column adsorption system, the working capacity of resin is the equilibrium adsorption capacity, and the resin's utilization in the column was increased by 84.65% compared with the conventional straight column.In the static desorption of R604 resin, the impacts of two influencing factors on the desorption effects were discussed, including the concentration of desorption solution and temperature of the reaction system. The first order equation could well describe the dynamic behavior of the initial stage during the static desorption process, and the whole process meets the Elovich dynamic model. As to the dynamic desorption of R604 resin, the conventional straight column and an original U-shaped continuous countercurrent desorption system were investigated. If the same conditions were set, including the flow rate of desorption solution and the highest desorption efficiency of same amount of resin, the concentration of metal-bearing concentrated solution was increased by 2.87 times when the latter technology was used in split mode. Moreover, the consumption of desorption solution and the desorption time were saved by 46.15% with the U-shaped continuous countercurrent desorption system, which can also recycle the high-concentrated Ni2+-bearing solution.