Preparation And Adsorption Properties Of Cs~+ Enriched Materials Based On CuFC

Radionuclide cesium is one of the main pollutants of marine nuclear pollution,it can cause serious threat to the marine ecosystems and human health after into ocean.The tracking monitoring of low-concentration radioactive cesium at sea has put forward new requirements for the detection limit of instruments and detection of timeliness,"On-site enrichment detection"has become a hot spot for monitoring low-level radioactive pollution in the ocean.To realize the rapid and efficient enrichment of cesium in seawater,the study prepared Cupric ferrocyanide?CuFC?powder,then adopted multiple crosslinking and burying of Calcium alginate?CA?and Polyvinyl alcohol?PVA?.Meanwhile,the multi-walled carbon nanotube?MWCNT?with a developed pore network was introduced to prepare composite microspheres.Based on CuFC powder and composite microspheres,static and dynamic adsorption experiments were conducted to investigate the adsorption behavior and mechanism of Cs⁺in both static and dynamic adsorption.The main results of the study were as follows:1.CuFC powder with good water dispersion were successfully prepared by co-precipitation method.When the initial concentration of Cs⁺was 10mg/L and solution pH was 7,the optimal dosage of CuFC was 2g/L,which could adsorb about 94.7%of Cs⁺after shaking for 50min at 298K temperature with strong anti-interference ability.The adsorption process conformed to the pseudo-second order kinetics and Langmuir isothermal adsorption model.The XRD,FT-IR,EDS characterizations of product before and after adsorption showed that product had-C?N,Fe???-C?N and C?N-Cu???characteristic absorption peaks,consistent with the standard spectrogram CuFC,and the product had good thermal stableility.The appearance and chemical composition of CuFC did not change significantly before and after adsorption,and the ion exchange between K⁺in CuFC and Cs⁺was the main mechanism for the adsorption of Cs⁺by CuFC.2.The adsorption performance of the microspheres was significantly improved after CuFC introduced.When the initial concentration of Cs⁺was 10 mg/L,and pH was7,the optimal dosage of the composite microsphere was 5.6g/L,which could adsorb about 97.21%of Cs⁺after shaking for 80min at 298K temperature,and the adsorption was hardly inhibited by K⁺,Na⁺,Ca²⁺and Mg²⁺.The adsorption kinetic behavior conformed to the pseudo-second-order kinetic model,also could be well fitted by Langmuir model.The chemical structure of the composite microspheres did not change significantly before and after adsorption,and the main mechanism of Cs⁺adsorption by composite microspheres was the ion exchange between K⁺and Cs⁺.After being embedded into a ball,some adsorption sites of CuFC powder were masked,and the adsorption rate of Cs⁺was slightly reduced,the adsorption equilibrium time was delayed for about 30min,but the applicable pH range was wider.3.The dynamic adsorption behavior of Cs⁺in two dynamic adsorption systems prepared by using composite microsphere filling and absorbent cotton fixation CuFC presented a consistent rule:when the height of adsorption column increased from 4cm to 10cm,the penetration curve moved to right and the penetration point and the depletion point both extend.When the initial concentration of Cs⁺increased from5mg/L to 15mg/L,the penetration curve gradually shift to left,and the penetration time and depletion time gradually shorten.Thomas model and Yoon-Nelson model could well fit the dynamic adsorption behavior linearly.The penetration time of the composite microsphere adsorption column was shorter than that of the absorbent column loaded with CuFC powder,the adsorption efficiency was lower,too.However,some CuFC powder were lost in the early stage of adsorption by the absorbent cotton column.