HNO_(3)改性活性炭对不同价态离子的电吸附规律

Electric adsorption laws of HNO_(3)-modified activated carbon for different valence ions

以硝酸改性活性炭为原材料,制备电吸附电极,并研究其对8种常见金属盐离子的吸附特性;分别采用扫描电镜、比表面积及孔径分析仪、红外光谱仪和电化学工作站等对改性前后材料的性能进行表征和分析。结果表明:改性后的活性炭相比于改性前拥有更好的孔隙结构,含氧官能团增多,制备出的电极电化学性能更好;在除盐实验中,制备的电极对价态越高的离子去除速率越快但去除率越低;对于同价态离子,水合离子半径越小时去除速率越快且去除率越高;离子从溶液到电极表面再到活性材料孔道内部的过程,主要为物理吸附过程,也存在较微弱的化学吸附。

In this study,nitric acid-modified activated carbon was used as the raw material to prepare the electrodes for electrosorption,and its adsorption and removal characteristics of eight common metal salt ions were investigated.The properties of the materials before and after modification were characterized and analyzed by scanning electron microscopy,specific surface area and porosity analyzer,infrared spectrometer,electrochemical workstation and so on.The results showed that the modified activated carbon had a better pore structure and more oxygen-containing functional groups than before,resulting in better performance of the prepared electrode.According to the results of the desalination experiment,the higher the ion valence state was,the more quickly the electrode removed the ion,but the removal rate of ions was declining with increasing ion valence state.On the other hand,when the ion valence state was the same,the smaller the radius of hydrated ions was,the faster the electrode removed the ion,and the removal rate of ions was rising up with the declining of the radius of hydrated ions.The process of ions moving from the solution to the electrode surface and then to the inside of the pore of the active material was mainly a physical adsorption process,but there was also weak chemisorption.This study provided a reference for the practical application of electrode desalination.