| Both chromium?Cr?and arsenic?As?are common contaminants in the environment,which simultaneously present in many cases.As such,it is an urgency to develop a novel absorbent for efficient and simultaneous removal of Cr???-As???and Cr???-As???.This research is focused on the fabrication of core-shell CMNP@PDAP nanocomposites for simultaneous removal of Cr???-As???and Cr???-As???and their removal capacities and mechanisms.Novel magnetic carboxyl-functionalized Fe3O4 nanoparticles?CMNPs?coated with poly?2,3-diaminophenol?polymer?PDAP??CMNP@PDAPs?were prepared using a facile synthesis method.The well-defined core-shell nanostructures were characterized and the results confirmed that PDAP was successfully grafted on the surface of CMNPs.The as-prepared CMNP@PDAPs were applied for removal of Cr???,As???and As???in the single-solute and bi-solute systems.The maximum adsorption capacities of Cr???,As???and As???on CMNP@PDAPs in single-solute systems were calculated as 298.3,73.7 and 169.0 mg·g-1 at 30 oC,respectively.The influences of different conditions on the removal of Cr???,As???and As???were investigated,and the mutual effects between Cr???and As???/As???were discussed.It has been found the efficient reduction of Cr???to less toxic Cr???by amine were the driving force for Cr???adsorption.Inner-sphere surface complexation contributed to the adsorption of As???contrast to the electrostatic outer-sphere adsorption of As???on CMNP@PDAPs.Interestingly,the removal of As???/As???was promoted in the presence of Cr???while Cr???removal was hindered for the negative influence of As???/As???in binary systems.X-ray photoelectron spectroscopy?XPS?analysis indicated the reduction of Cr???and the interactions between the chelated Cr???and As???/As???for the enhanced As???/As???adsorption.Based on theoretical density functional theory?DFT?calculations,the possibility of the reduction of Cr???to Cr???was further confirmed.The CMNP@PDAPs have great potential in simultaneous removal of Cr???and As???/As???from seriously polluted water by muti-pollutants. |
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