| Currently, based on the present status of uranium-containing wastewater treatmentat domestic and foreign, we introduce Zero-valent iron nanoparticles(INP) to treaturanium containing wastewater, including the laboratory simulation of uranium wastewater as well as the actual mine wastewater. The goal of the experiment is to find anew way to deal with uranium-containing wastewater that has the followingadvantages: low cost, low running expenses, excellent treatment effect, high treatmentefficiency, strong processing ability, environment friendly. These experiments canprovide theoretical data and process parameters for industrial processing.Throughexperiments, this paper obtained the following results:(1) Orthogonal test the results showed that, the value of pH, greatly effect on thetest results, is the main factor. Temperature, as a secondary factor, posted a minimaleffect on the results. The order of factors is: pH> Fe0dosage> U content> time>temperature. The optimal scheme is at room temperature, initial concentration ofuranium is100mg/L, INP dosage is1g/L, pH=6, reaction time is90min, thefrequency of oscillation is150r.min-1.Under this combination of conditions,theremoval rate of uranium reaches99.91%. Range analysis and variance analysis cometo a same conclusion.(2) When there are other ions in solution, they have different effect on uraniumremoval by nano-Fe0. Cr3+, Cu2+, Mn2+, Mg2+have an inhibitory effect and theinhibitory effect of Cr3+is maximum.Cu2+, Mn2+, Mg2+have slight effect on uraniumremoval compared to Cr3+and the trend was basically the same. The sequence wasCr3+> Cu2+> Mn2+> Mg2+.Cl-and SO42-have little or no effect on the uranium removalby nano-Fe0. while F-, CO32-, PO43-and SiO32-showed some inhibition on uraniumremoval, in which the maximum influencing factor is F-,while the the least is SiO32-.(3) Adsorption kinetics showed that the behavior of adsorption kinetics can bedescribed by the two-order kinetics model. The equilibrium adsorption amount gainedfrom practical experiment accords with theoretical equilibrium amount very well, andthe related coefficient approaches0.9998. The Langmuir adsorption isotherm modelcan better describe the INP adsorption for uranium, which illustrates the INPadsorption uranium belongs to the monolayer adsorption.Maximum monolayeradsorption capacity is238.095mg/g, the correlation coefficient is0.9985. (4) Uranium was removed by INP through active adsorption and reaction process.The mechanism of uranium removal from aqueous solution by INP is mainly based onthe redox reaction and co-precipitation. SEM and XRD analysis results indicated thata new substance was formed during the reaction process.(5) The actual uranium containing wastewater removed by INP by a static testwas conducted. The results show that, optimum operating parameters of the factorsshould be: temperature is at room temperature, pH is5~6, INP dosage is2g/L,reaction time is1h, the removal efficiency approached to99.9%.The remaininguranium concentration is less than0.05mg/L, reached the national surface waterdischarge standard for the practical treatment process, which can provide a referenceparameter and data. This process system has a great application prospects.(6) The study of simultaneous removal of uranium and other heavy metals inmine waste water using INP have shown that：The removal efficiency of pollutants inthe wastewater varies with the iron powder dosage. The more the amount of ironpowder dose, the better the removal effect. The reaction is very rapid. U, Cu, Cr wereremoved by forming Insoluble poly through redox reaction with INP.While Cd, Znand Ni abated as the pH value increased.Arsenic was removed by co-precipitatedwith Fe-hydroxide after reaction. |
PDF Full Text Request