Preparation And Adsorption Properties Of Cu(Ⅱ) Imprinted CTS/PVP And CTS/PVP/C

The selective enrichment and separation of metal ions is an important researchfield in chemistry. Compared with adsorption material obtained by traditionaltechniques, metal ion imprinted beads prepared by imprinting technique, which have theselective adsorption and recognition on the target metal ions, ha ve a wide prospect ofdevelopment.In this work, copper (Ⅱ) ion imprinted chitosan(CTS)/polyvinylpyrrolidone (PVP)(Cu(Ⅱ)-IICP) and Cu (Ⅱ) ion imprinted CTS/PVP/activated carbon(C)(Cu(Ⅱ)-IICPC) were prepared by mixing CTS, PVP,Cu(Ⅱ) and C to form compositematerial, in which Cu(Ⅱ) was used as a template. The optimal conditions for preparingthe composite materials with best absorption capacity of Cu(Ⅱ) were listed:6:4for themass ratio of CTS and PVP，0.6%for C,1.0%for cross-linking agent,50℃for thecross-linking temperature,2.0%for coagulating bath,50℃for heat treatmenttemperature,0.5mol·L-1for concentration of eluant and elution time for30min and0.05%for Cu(Ⅱ).SEM imagines shows the increased specific surface areas of the materials aftereluting Cu(Ⅱ). BJH analysis also indicates that the ion imprinted material becomelarger than the no-ion imprinted material in specific surface area. FTIR spectra implythat the template Cu(Ⅱ) is mainly coordinated with the amino group and hydroxyl inCTS and PVP. XRD patterns show that the original crystal structure and crystallinity ofCTS have changed due to the interaction among CTS, PVP, C, and Cu(Ⅱ).Static equilibrium test show that the adsorption capacity increased with growingthe equilibrium concentration of Mo (VI) until it reached saturation. The Langmuir andFreundlich models are used to fit experimental data in this work. Langmuir model didnot exhibit good fit to the sorption data, but Freundlich model is suitable for explain the sorption process. The Qmof Cu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC were found to be29.9mg·g-1and28.2mg·g-1, respectively.Pseudo-first-order and Pseudo-second-order sorption kinetic model were tested tointerpret data obtained from batch experiments. The results suggest that thepseudo-second order adsorption mechanism was predominant for this adsorbent systemof Cu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC. Obviously, the granular internal diffusion is thecontrol step for Cu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC.Adsorption/desorption were carried out for14runs. The results indicate thatCu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC have good durability. The selective study of adsorptionshows that Cu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC have good selectivity for Cu(Ⅱ) ions.The breakthrough curves of Cu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC at various flow ratesand bed height of the adsorbents were investigated using column adsorption．The resultsshowed that breakthrough time of Cu(Ⅱ)-IICP became later than that of Cu(Ⅱ)-IICPC.This conforms further that adsorption capacity of Cu(Ⅱ)-IICP was larger than that ofCu(Ⅱ)-IICPC in the static equilibrium test. The breakthrough time of both Cu(Ⅱ)-IICPand Cu(Ⅱ)-IICPC became earlier with decreasing bed height. The critical bed height ofCu(Ⅱ)-IICP and Cu(Ⅱ)-IICPC were calculated by BDST model (bed depth servicetime model) to be3.20cm and3.03cm, respectively.