Preparation Of Polythiocyanate-carbon Nanotubes And Removal Of Heavy Metal Ions

In recent years,with the rapid development of industry,China's"three wastes"problem has become very prominent,which leads to serious heavy metal pollution in water and seriously endangers our society.According to relevant data,more than 80%of rivers,lakes and oceans in China are polluted by heavy metals.The commonly used removal technologies of toxic metallic elements include adsorption,precipitation,solid phase extraction,ion exchange and membrane filtration.Common adsorbents include various inorganic materials,zeolite,exchange resin and activated carbon,etc.,but most of these adsorbents have problems such as long treatment time or low adsorption efficiency.Therefore,it is imperative to develop efficient and low-cost adsorbents for the removal of heavy metal ions in environmental water.Carbon nanotubes?CNTs?have attracted much attention due to their unique mechanical properties,high chemical stability and large specific surface area,making them of great application value in catalytic materials,adsorption materials and other aspects.In this paper,trimeric thiocyanate?TTCA?was covalently grafted onto the surface of multi-walled carbon nanotubes?MWCNTs?by schiff base reaction,and the trimeric thiocyanate-multi-walled carbon nanotubes?TTCA-MWCNTs?nanocomposite material was prepared.Multi-walled carbon nanotubes before and after the modification of trimeric thiocyanate were characterized by scanning electron microscopy,transmission electron microscopy,and infrared spectroscopy.Results showed that the synthetic TTCA-MWCNTs nanocomposite is uniform and has good dispersion.The structure of the TTCA-MWCNTs can not only enhance the mechanical strength of MWCNTs,but also increase the adsorption activity sites of MWCNTs,as well as improve the adsorption performance of the TTCA-MWCNTs.The wall of MWCNTS modified with trimeric thiocyanate contains a large number of sulfhydryl groups,which can greatly improve the adsorption capacity of heavy metal ions.Based on above study,we further investigated the adsorption performance of TTCA-MWCNTs through adsorption experiments.In addition,the adsorption time,adsorbent dosage,pH value,heavy metal ion concentration,etc.were also optimized.Moreover,the actual water samples including Ganjiang river water and tap water were tested,and the adsorption mechanism of TTCA-MWCNTs for heavy metal ions has also been studied.TTCA-MWCNTs solid phase extraction experiment and inductively coupled plasma mass spectrometry measurement results showed that TTCA-MWCNTs had excellent adsorption performance for heavy metal ions in water,especially Hg²⁺,and high removal efficiency for heavy metal ions in environmental water,which can be used to efficiently remove a variety of heavy metal ions in polluted water.