Adsorption Of Cs~+ In Aqueous Solution By Surface Modified Bagasse

The development and utilization of nuclear energy can promote the advancement of science and technology and solve the problem of energy shortage.However,with the rapid development of nuclear industry,a large amount of radioactive nuclear waste has been produced,which has caused more and more serious environmental pollution.As one of the main components of nuclear waste,radioactive Cs⁺,like K⁺,can easily enter organisms through food and water,causing harm to organisms through internal radiation and even posing a serious threat to life.Therefore,the removal of radioactive Cs⁺in nuclear waste water is an urgent problem for mankind to solve.At present,although some progress has been made in the removal of radioactive Cs⁺in wastewater by adsorption method,the cost of adsorbents is high and the adsorption effect is not good,and further research and improvement are still needed.As a cheap,easy-to-obtain and environmentally friendly biomass material,bagasse is an excellent raw material for preparing adsorbents.In order to overcome the low adsorption capacity of bagasse,this article uses succinic anhydride to modify bagasse to increase the carboxyl content of the adsorbent,provide more active sites for Cs⁺adsorption,and increase the Cs⁺adsorption capacity.On this basis,in order to increase the selective adsorption of Cs⁺by the adsorbent,Prussian blue was loaded on carboxyl bagasse,and the interaction between Cs⁺and cyano groups was used to increase the affinity of the adsorbent for Cs⁺,which helps to selectively adsorb Cs⁺.Finally,loading ammonium phosphomolybdate on bagasse further enhances the adsorption selectivity to low concentrations of Cs⁺.First,carboxyl bagasse was prepared by high temperature heating reaction using bagasse and succinic anhydride as raw materials.The structure and properties of carboxyl bagasse were analyzed by SEM,FT-IR,XRD,and TGA.The test results showed that the adsorbent presented an irregular lamellar fiber structure and had good thermal stability.The experimental study on the batch adsorption of Cs⁺found that alkaline conditions are more conducive to the adsorption of carboxyl bagasse to Cs⁺,and the adsorption process is more in line with the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model.It shows that the adsorption process of carboxyl bagasse to Cs⁺is affected by many factors and may be a uniform surface adsorption of a monomolecular layer.The maximum adsorption capacity simulated by the isotherm reaches 41.6 mg/g,which confirms that it has a large adsorption capacity.After five adsorption-desorption experiments,the removal rate of Cs⁺with an initial concentration of 10 mg/L by carboxyl bagasse still reached more than 80%,which has a high recycling value.Secondly,in order to improve the selectivity of carboxyl bagasse,carboxyl bagasse,K₄[Fe（CN）₆]solution and Fe Cl₃ solution were added step by step under ice-water bath conditions,and Prussian blue carboxyl bagasse was successfully prepared by precipitation method.The structure and properties of Prussian blue carboxyl bagasse were analyzed by different characterization methods.Batch adsorption experiments studied the effects of initial pH,adsorbent dosage,initial Cs⁺concentration,coexisting ions and temperature on the adsorption performance of Prussian blue carboxyl bagasse.The results show that the adsorption performance of Prussian blue carboxyl bagasse is significantly improved compared with carboxyl bagasse.The adsorption of Prussian blue carboxyl bagasse to Cs⁺is more in line with the pseudo-second-order kinetic model and Langmuir isothermal adsorption model,and the simulated maximum adsorption capacity reaches73.6 mg/g.In addition,Prussian blue loaded with carboxyl bagasse reduces the inhibitory effect of Na⁺and K⁺on the removal of Cs⁺from Prussian blue carboxyl bagasse,and has a certain Cs⁺selective adsorption capacity.The Cs⁺（10mg/L）removal rate by Prussian blue carboxyl bagasse remained above 80%after five cycles of recycling experiments.The above content proves that the modification of succinic anhydride and Prussian blue is beneficial to improve the adsorption performance and selectivity of bagasse,but the selectivity is still not high enough.In order to further improve the Cs⁺adsorption selectivity,ammonium molybdate,activated bagasse,phosphoric acid and nitric acid are used at room temperature to prepare ammonium phosphomolybdate bagasse by a step-by-step precipitation method.The adsorption performance test showed that the adsorption capacity and selectivity of ammonium phosphomolybdate bagasse for Cs⁺were further improved.Batch adsorption experiments show that low temperature is more conducive to the adsorption.The adsorption of Cs⁺by the ammonium phosphomolybdate bagasse material still conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model.The adsorption process is affected by many factors.The adsorption of Cs⁺by ammonium phosphomolybdate bagasse is a single-layer surface adsorption,and the simulated maximum adsorption amount reached 77.4 mg/g.Ammonium phosphomolybdate bagasse can selectively adsorb Cs⁺and has fast and efficient adsorption capacity.