Studies On Establishment Of Alginate Core-shell Microspheres Adsorbent And Its Performance

The discharging of wastewater with overproof concentration of uranium,strontium and fluoride discharges from the uranium ore processing will cause damage to aquatic organisms and human,hence,the removal method and material research of uranium,strontium and fluoride are of great importance.Compared with other methods,adsorption has been paid more attention owing to its easy operation and low cost.However,the reported adsorbent has a lot of shortcomings,such as poor adsorption capacity of adsorbent,difficult to recycle and so on.As a result,the development of an adsorbent with the advantage of environment friendly,high efficiency is still a problem to be solved.This work was supported by Nuclear Power Development Special item,alginate core-shell particle adsorbents were fabricated via electro-coextrusion in this study to remove uranium,strontium and fluoride from wastewater,and the adsorption performance and adsorption mechanism were studied,main contents are as follows:1.With two kinds of environmental friendly materials?attapulgite clay and alginate?as the raw materials,anhydrous calcium chloride as cross linking agent,alginate-Ca/attapulgite clay core/shell particle adsorbent was synthesized via electro-coextrusion,and the adsorption performance for uranium were studied in a systematic way.The results showed that the maximum adsorption capacity of the adsorbent for uranium was 199.345 mg/g at pH of 3,temperature of 328.15 K and initial uranium concentration of 340 mg/L.The experimental data were well followed linear Langmuir isotherm model and pseudo-second-order model,and the uranium adsorption process was endothermic,feasible and spontaneous.The adsorption capacity of the adsorbent for uranium is 16.682 mg/g after four recycling,the adsorbent shows excellent reusability.The adsorption of uranium on the adsorbent was realized through the combination of ion-exchange and electrostatic interaction.2.Sodium alginate and zeolite as the raw materials,alginate-Ca/attapulgite clay core/shell particles were synthesized via electro-coextrusion and the adsorption performance for strontium were studied in a systematic way.Results showed that the maximum adsorption capacity of the adsorbent for Sr???ionswas 83.3100 mg/g at pH 4,328.15 K and initial strontium concentration of 140mg/L.The adsorption data were well described by the linear Freundlich isotherm model and pseudo-second-order model.The strontium adsorption process was endothermic,spontaneous and entropically favorable from thermodynamic parameter.The effect of initial strontium concentration,bed height and flow rate on dynamic adsorption properties of the adsorbent were investigated.Results showed that breakthrough time and depletion time were increased with the bed height increased,while decreased with increasing the initial strontium concentration and flow rate.The removal rate of the adsorbent for strontium is 62.671% after three recycling,and the adsorption of Sr???ions on the adsorbent was realized via ion exchange.3.The magnetic core-shell Fe₃O₄@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion,and the adsorption performance for fluoride were studied in a systematic way.The result showed that the maximum fluoride adsorption capacity was 66.284 mg/g at pH 4,298.15 K,contact time of 900 min,initial fluoride concentration of 150 mg/L.The presence of other anions like Sr²⁺,UO₂²⁺,SO₄^2-,Cl^-,HCO₃^-,PO₄^3-,in the concentration range of 0-20 mg/L,had almost no effect on the fluoride adsorption.The adsorption data was well described by the linear Freundlich isotherm model and pseudo-second-order model.The fluoride adsorption process was exothermic,entropically favorable and spontaneous from thermodynamic parameter.The dynamic adsorption properties of the adsorbent for fluoride were investigated,results showed that breakthrough time and depletion time were increased with the bed height increased,while decreased with increasing the initial fluoride concentration and flow rate.The adsorption capacity of the adsorbent for fluoride can be reached to 17.592 mg/g after three recycling.The adsorption mechanism of the adsorption process of fluoride may be related to electrostatic attraction and Lewis acid-base interaction.