Removal Of Pentavalent Vanadium In Water By Stable Nano-zerovalent Iron Synthetic Materials

In recent years,the pollution of pentavalent vanadium（Ⅴ（Ⅴ））in water has gradually aroused widespread attention.Vanadium has been listed on the US Environmental Protection Agency’s（USEPA）drinking-water pollutant candidate list due to its carcinogenic effects,and is classified in the same category as mercury,lead,and arsenic.Among the various methods for remediation of Ⅴ（Ⅴ）polluted water,the adsorption method is considered to be a simple and effective Ⅴ（Ⅴ）removal technology due to its low cost,simple design and operation.However,most of Ⅴ（Ⅴ）removal adsorbent materials can only transfer Ⅴ（Ⅴ）from polluted water to the surface of adsorbent materials,and the high toxicity of Ⅴ（Ⅴ）still exists.Therefore,it is of great significance to develop an adsorbent material that can not only reduce Ⅴ（Ⅴ）toxicity but also effectively separate it from polluted water.Based on this,firstly,two stable materials of biochar（BC）and sodium alginate（SA）were used to stabilize nano-zero-valent iron（nZⅥ）,and two stable nZⅥ composite materials（nZⅥ/BC and nZⅥ/SA）were successfully prepared in this study.Secondly,the influence of different influencing factors on the performance of Ⅴ（Ⅴ）removal was explored.Finally,comprehensive adsorption kinetics,adsorption thermodynamics,adsorption isothermal model and different characterization analysis revealed the mechanism of Ⅴ（Ⅴ）removal by the two composite materials（nZⅥ/BC and nZⅥ/SA）.Experimental results showed that nZⅥ/BC and nZⅥ/SA composite materials can effectively remove Ⅴ（Ⅴ）from water when the pH was between 2.0¹0.0 and 4.0¹0.0,respectively.The process of removing Ⅴ（Ⅴ）by two composite materials（nZⅥ/BC and nZⅥ/SA）was the result of the combined action of physical and chemical adsorption,and chemisorption was the rate limiting step of the removal process of Ⅴ（Ⅴ）.The adsorption form of Ⅴ（Ⅴ）on the surface of the two composite materials was eventually homogeneous monolayer adsorption.The results of different characterization（SEM,EDS,XRD,etc.）showed that the nZⅥ was successfully loaded into biochar and sodium alginate,and the two stable materials of biochar and sodium alginate successfully blocked the agglomeration of nZⅥ.Synthesizing different analysis results inferred that the process of removing Ⅴ（Ⅴ）of the two composite materials（nZⅥ/BC and nZⅥ/SA）was mainly divided into three aspects:（1）Ⅴ（Ⅴ）ions were adsorbed on the two composite materials（nZⅥ/BC and nZⅥ/SA）surface through electrostatic attraction;（2）Ⅴ（Ⅴ）ions were coprecipitated with the generated Fe³⁺to form Fe-V precipitates（xFe₂O₃·yV₂O₅·zH₂O）on the two composite materials（nZⅥ/BC and nZⅥ/SA）surface;（3）Ⅴ（Ⅴ）adsorbed on the surface of the two composite materials（nZⅥ/BC and nZⅥ/SA）was reduced to V（IV）by Fe⁰ and Fe²⁺.The results of this study proved that the two composite materials（nZⅥ/BC and nZⅥ/SA）had wide application value for the remediation of Ⅴ（Ⅴ）in water.