| The rapid development of nuclear industry,more and more nuclear wastewater discharge into the environment,cesium and other radionuclides can form radioactive pollution in the wastewater,spread through the food chain enter human body and harm to health,so the treatment of wastewater containing cesium has drawn great attention of people.Cesium ions is the main component of radioactive wastewater,the pollution of excrement brought by cesium ions on environment has become more and more serious.Prussian blue nanomaterials have strong adsorption properties of radioactive cesium.In recent years,prussian blue nanoparticles(PB NPs)were used to treat the radioactive wastewater as the adsorbent in water environment.However,direct application of prussian blue nanoparticles for water treatment is not favorable since isolation of Cs-loaded PB from the water is a problems,easy to bring secondary pollution to the environment,so as to limit its the application.In addition,the biological toxicity of prussian nanoparticles have been less studied.It brings about a huge safety risk to the water environment and limits prussian blue nanoparticles in practical application.In order to solve this problem,we choose the biological degradable polylactic acid as the carrier of the prussian blue nanoparticles,design of adsorption and separation of adsorbent for removing cesium ions.Meanwhile,the effects on adsorption efficiency of prussian blue nanoparticles based adsorbents such as pH,time,temperature and initial concentration of cesium ions solution were studied.The adsorption isotherm models,kinetic models and adsorption thermodynamics were investigated to research the absorption mechanism.Synthesis of different forms of prussian blue nanoparticles,through the comparative biological toxicity of different size and chemical composition of prussian blue nanoparticles,to evaluate their biological safety.The main research contents as follows:Herein,prussian blue nanoparticles were immobilized on the surface of PLA MCs to give PB NPs-loaded MCs(PB-MCs)for Cs+ removal.The results revealed that PB-MCs had spherical structure,wih the average size was 2.31 ± 0.04 ?m and the zeta potential of-14.03 ± 1.68 mV.Meanwhile,PB NPs had been successfully immobilized on the PLA MCs by FT-IR and iron content was 5.11 % of PB-MCs.Adsorption experiments exhibited that the best range of pH was 5~9,the adsorption equilibrium time was 120 min,the optimal temperature was 293 K,the maximum adsorption was 4.85 mg/g.The study found that the removal rate of cesium ions can reach up 70.26% and the adsorption capacity reached 4.01 mg/g,the initial concentration of cesium ions reduce from 40 mg/L to 12 mg/L in 293 K.It was found that the goodness of mathematical fitting of the experimental datas on the adsorption isotherms was Langmuir,the kinetic models was pseudo-second-order.The adsorption process was endothermic reaction and controlled by diffusion steps in the granules.The improved adsorption efficiency of the PB-MCs can be attributed to the anchoring technology,which prevented the aggregation of prussian blue nanoparticles and thus increased the effective adsorption surface of the adsorbent.For improving the adsorption capacity and targeting capability of PB MCs,a novel magnetic prussian blue nanospheres(MPBNs)were developed from Poly(lactic acid)nanospheres as a carrier,loaded Fe3O4 nanoparticles inside and prussian blue nanoparticles outside to combine magnetic separation and removal of cesium.The results revealed that MPBNs had spherical shape,with the average size was 268.2 ± 1.4 nm.Meanwhile,the aturation magnetization of MPBNs was 41.71 emu/g and iron content was 40.01%.Adsorption experiments exhibited that the best range of pH was 5~9,the adsorption equilibrium time was 60 min,the optimal temperature was 293 K,the maximum adsorption was 17.03 mg/g.MPBNs was proved to have great capabilities of adsorption efficiency of cesium ions as well as rapid separation rate of cesium ions.For example,the datas found that the removal rate of cesium ions can reach up 82.46% and the adsorption capacity reached 16.49 mg/g,the initial concentration of cesium ions reduce from 40 mg/L to 4.8 mg/L in 293 K.Using three models for equilibrium and kinetic investigation,it was found that the goodness of mathematical fitting of the experimental data on the adsorption isotherms was Freundlich.the kinetic models were pseudo-second-order.The adsorption process was endothermic reaction and controlled by diffusion steps in the granules.In order to make prussian blue nanomaterials can be safely used in removing cesium in water,we researched the biological toxicity of prussian blue nanomaterials.So we prepared the different forms of prussian blue nanoparticles(PB-15 NPs,PB-25 NPs,PB-45 NPs,PB-85 NPs,Fe3O4@PB NPs and Au@PB NPs)with according to hydrothermal method of synthesis.The results showed that the synthesized prussian blue nanomaterials had uniform feature and good dispersity,with size distribution of 16.1±1.3 nm,28.3 ± 3.9 nm,44.7 ± 3.2 nm,87.2 ± 2.1 nm,15.3±2.4 nm and 13.7±1.7 nm.It was found that the cytotoxicity of cell significantly increased with the decreasing of the sizes of prussian blue nanoparticles,increasing of the concentration and processing time of prussian blue nanoparticles.The photos of TEM captured nanoparticles into cells by pinocytosis,and in the form of scattered clumps and separated distribution in cells,including Fe3O4@PB NPs can enter into the nucleus and intake is more.The cell toxicity assay of different forms of prussian blue nanoparticles showed that the cytotoxicity of small particle was more serious than larger one.In a certain dose and time,mice were intravenously injected in the tail vein with prussian blue nanomaterials,respectively.The results displayed that different forms of prussian blue nanomaterials did not occur significant toxicity in mice.The goal of this paper is governance wastewater containing cesium,using the adsorption properties of prussian blue,developed the suspension characteristics of PB-MCs to adsorbed cesium in water.Meantime,MPBNs adsorbent have great capabilities of adsorption efficiency of cesium ions as well as rapid separation rate of cesium ions,they showed great promise for the purification of radiative Cs+-contaminated wastewater.To study the biological toxicity of prussian blue nanomaterials,it was concluded that in less than 35 mg/kg dose,different forms of PB NPs did not change the biological characteristics on cellular level and organizational level;Prussian blue nanomaterials belong to a class of materials,promoting the development of nanomaterials in the field of environment.To the next research of containing cesium wastewater treatment,our work give the foundation of basic experiment technique and security. |
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