The specific characteristics and mechanism of adsorption of Cu(Ⅱ) were studied by using HAP/C composite (PBGC-HAP/C) as adsorbent, and using pH value of the solution system, initial concentration of Cu(Ⅱ) and particle size of the material as influential factors. The results showed that when the solution was weak acid (pH=5), the adsorption effect was the best; the increase of the initial concentration of the reaction system was not conducive to the enhancement of the adsorption effect; and the decrease of the particle size of the adsorbent facilitated the adsorption process. The pseudo-second-order kinetic model could accurately describe the adsorption process, and the calculated adsorption capacity(0.99, 1.93, 4.03 mg·g-1)was close to the experimental measured values(0.99, 1.93, 4.05mg·g-1); Langmuir model could fit the adsorption process very well, which indicated that adsorption was monolayer adsorption and the increase of temperature was conducive to adsorption. The thermodynamics test results of ΔGθ<0, ΔSθ>0 and ΔHθ>0 showed that the adsorption process was endothermic and spontaneous. Through comparative analysis of the SEM, EDS, XRD and FTIR of materials before and after adsorption, the results indicated that the chemical complexation reaction of Cu(Ⅱ) with the oxygen functional groups on the surface of PBGC-HAP/C was the main purification mechanism, which was accompanied with physical adsorption, electrostatic adsorption and ion exchange.
Keywords: Cu(Ⅱ); adsorption mechanism; dynamics; hydroxyapatite; relic structure; thermodynamics.