The Adsorption Properties Of Lodate By Low-value Plant Material And Its Derivatives

With the rapid development of nuclear plant,it will product a large amount of radioactive waste and will bring great influence to the environment.129I(T1/2=1.57×107a),which are emitted from nuclear power plants,has the long half-life and is hazardous radionuclides because of its high toxicity and mobility in environment With the large number of active groups,large specific surface area,not require chemical synthesis,extensive sources,eco-friendly and the advantage of low cost,low-value plant material and its derivatives can remove radionuclides.It has broad application prospects.It is studied the adsorption properties of IO3-by low-value plant material(Landoltia punctata,corn stalk,Leucoides and salix babylonica)anA its derivatives(biochar)in this paper.The pH,contact time,intital concentration,temperature and coexisting anions were investigated by static adsorption experiments.The adsorption mechanism of low-value plant material and its derivatives was primary analyzed by adsorption kinetics,adsorption isotherm and adsorption thermodynamics.The results prove that the Kd of IO3-by Landoltia punctata,Leucoides,salix babylonica and corn stalk are 150,110.3,236.1 and 49.73 ml/g under general condiation.It is helpful for the adsorption of IO3-in acidic condition.The adsorption kinetics of IO3"adsorption by Landoltia punctata,corn stalk,Leucoides and salix babylonica follow the pseudo-second-order equation.The adsorption isotherm of IO3-adsorption by Landoltia punctata,Leucoides and salix babylonica is well described by the Freundlich model and the adsorption isotherm of IO3-adsorption by corn stalk fits Langmuir model.The adsorption process of IO3-adsorption by Landoltia punctata,corn stalk,The thermodynamic study indicates that Leucoides and salix babylonica are non-spontaneous,endothermic and randomness.Cl-and SO42-would compete for the adsorption sites with IO3-on the surface of corm stalk and reduced the adsorption of IO3-.The adsorption capacity of IO3-on biochar of corn stalk increased with the increasing of carbonization temperature.The adsorption mechanism of low-value plant material(Landoltia punctata,corn stalk,Leucoides and salix babylonica)and its derivatives(biochar)was further analyzed with the method of BET、SEM-EDS、Elemental mapping、FTIR 和 XPS.The results that the specific surface area of Landoltia punctata,corn stalk,Leucoides and salix babylonica was up to 0.8911,27.9,7.6 and 26.1 m2/g,respectively.When the carbonization temperature is 400,500 and 600℃,the specific surface area of biochar of corn stalk was 57,61 and 159 m2/g,respectively.The result of SEM-EDS and Elemental mapping showed that iodine present different valence states after the adsorption by Landoltia punctata,corn stalk,Leucoides and salix babylonica.And,the spatial distribution of iodine are consisitent with that of carbon and oxygen,and not relevant of that of nitrogen,suggesting that IO3-might be bonded with oxygen-containing groups.With the carbonozation temperature increasing,the surface of of biochar of corn stalk becomes more and more rough,which maybe help to the adsorption of IO3-.The result of FTIR showed that hydroxyl and carbonyl groups of Landoltia punctata,corn stalk,Leucoides and salix babylonica might participate in the sorption of IO3-and the methylene and amide groups have minimal contributions to the sorption of IO3-.Hydroxyl,methylene and amide groups of corn stalk are reduced in the carbonization,indicating that carbonization is a simple process of water loss.The result of XPS showed that the sorption of IO3-and the reduction of IO3-to I2 and I-by Landoltia punctata,corn stalk,Leucoides and salix babylonica.Through the above analysis,there are three possible mechanisms for IO3-adsorption by low-value plant material:ion-exchange,electrostatic attraction and oxidation-reduction mechanisms.Based on all the experimental datas and analyses,low-value plant material(Landoltia punctata,corn stalk,Leucoides and salix babylonica)and its derivatives(biochar)exhibited good adsorption ability.It is shown that low-value plant materials could be potentially attractive candiate not only for commercial application in the field of radioactive wastewater treatment and environmental remediation,but also for new method to enhance the value of low-value plant materials.