| Waste residue containing vanadium(Ⅴ) and chromium(Ⅵ) from phosphorus chemical and metallurgical industries, which usually contain vanadium, chromium, phosphorus and other elements. If directly discharged into the environment will cause water pollution, waste of valuable metals and entrophication. This paper deals with an economical, effective ion exchange method to removal and recover vanadium(Ⅴ) and chromium(Ⅵ), provides process parameters for comprehensive ultilization of sodium phosphate residue.In this paper, D301R macroporous weak base anion exchange resin was selected as a suitable adsorptive material based on study of ion exchange capacities, adsorptive effects, and elution processes systematically, focusing on the influential factors of adsorption temperature, pH value, solid-liquid ratio and stirring rate. The kinetics and thermodynamics behaviors of ion exchange were studied by static method. The adsorptive process in ion exchange column was studied by dynamic method with the practical, and then the optimal parameters of ion exchange column were determined on the basis of experiments on factors such as initial concentration of solution, temperature, contact time and resin bed volume, including two-step elution process. Furthermore, the repeatability of resin was also verified through ten cycles of dynamic experiments.The statics experiment results showed that with D301R resin at pH=6.5, room temperature, and ratio of resin to solution of 1:10, stirring rate of 180 r/min, removal rates of vanadium(Ⅴ) and chromium(Ⅵ) were 90% and 80% respectively. The thermodynamics research suggested that adsorption isotherms of Vanadium(Ⅴ) approximately fitted the Langmiur or Freundlich equation with the experimental range of concentration, the correlative coefficients were 0.9803 and 0.9761. The thermodynamic study showed that the adsorption of vanadium(Ⅴ) and chromium(Ⅵ) were spontaneous, and the entropy were negative. The adsorption of vanadium(Ⅴ) and chromium(Ⅵ) were exothermic process.Dynamic data from the static experiment indicate that adsorption of vanadium( V) and chromium(Ⅵ) were instantaneous reaction under the room temperature conditions. A second-order adsorption-ion exchange kinetic equation was developed for the process. The apparent activation energy of vanadium(Ⅴ) and chromium(Ⅵ) were 59.84J/mol and 1183.33J/mol respectively, according to fitting the apparent sorption rate constant. The moving boundary model and stirring rate indicated that the adsorption of vanadium(Ⅴ) was controlled by particle diffusion and chemical reaction and chrommm(Ⅵ) was controlled by particle diffusion.The optimal conditions were obtained by dynamic process tests which showed that residue concentration of 120g/L, HRT=15min, room temperature(25℃), resin bed volume of 20 mL(L/D=13). 3 mol/L NaOH was chosen as desorption agent by means of two-steps elution process. Ten cycles of dynamic experiments showed that, removal rates of vanadium(Ⅴ) and chromium(Ⅵ) were 90% and 80% respectively, and the desorptive rates were 95% and 90%,which showed the performance of vanadium(Ⅴ) and chromium(Ⅵ) were stable.This process not only removed and recovered the valuable metallic elements effectively, meanwhile, purified sodium phosphate, but also improved the ratio of resource comprehensive utilization. If this process widely used, it will improve on the technical process in phosphorus industry, result in great economic efficiency, as well as social and environment benefit, which is good to realize circulate economy.
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