Controllable Preparation, Characterization And Performance Study Of Nickel-based Catalysts And Multi-walled Carbon Nanotube

Nowadays,dye pollution to water body is increasing day by day,its main source is textile,papermaking,rubber,plastic,paint,printing and leather and other industries.Therefore,it is necessary to find an appropriate treatment method to remove these dyes from contaminated water.There are many ways to remove dyes from wastewater,including filtration,oxidation,adsorption,and biological/photodegradation.Among these methods,adsorption is the most commonly used to remove dyes from wastewater because of its advantages of simple operation,renewable and low cost.Carbon nanotube（CNT）is considered as an ideal material for absorbing various dye pollutants due to its high specific surface area and good stability.As is known to all,the preparation of carbon nanotubes with uniform and controllable diameter by Chemical vapor deposition（CVD）is a hot research topic in the scientific field This thesis use nickel load in different metal oxide nanoparticles as a catalyst,through different reduction time to control the size of catalyst particles,the preparation of the diameter of the controllable multi-walled CNTs（MWCNTs）,its adsorption capacity in different dyes was studied.In this thesis,five kinds of catalysts with different particle sizes（Ni-1#～5#）were prepared by changing the composition and ratio of catalyst by co-precipitation technique,and two kinds of catalysts with different particle sizes（Ni-6#and Ni-7#）were prepared by changing the calcination temperature.Ten kinds of MWCNTs（CNT-1～10）with controllable diameters were prepared by changing the reduction time of the catalysts with seven kinds of different particle sizes,and the effect of the particle sizes of the catalysts on the diameters of MWCNTs was discussed.The experimental results show that in the Ni or Ni-Mn catalyst supported by Al₂O₃,the higher the Ni content,the larger the diameter of the prepared catalyst,and then the larger the diameter of MWCNTs.In addition,because Mg O has a smaller radius and a larger surface area than Al₂O₃ and La₂O₃,more active catalysts can be retained on the surface of Mg O,thus obtaining high-quality MWCNTs.Finally,we systematically studied the correlation between the diameter of MWCNTs and the amount of dye adsorption,and explored the effects of different temperatures and initial dye concentration on the adsorption performance of MWCNTs.The experimental results show that CNT-1 with small diameter（10～20 nm）has the largest adsorption capacity for Rhodamine B（Rh B）;When the temperature increased from room temperature to 50 o C,the adsorption capacity of MWCNTs increased.At the same time,we carried out kinetic and thermodynamic studies on CNT-1 using adsorption isotherms,quasi-first-order kinetic model and quasi-second-order kinetic model.The results showed that CNT-1 adsorbed Rh B rapidly and efficiently in the first 100 minutes.The adsorption of CNT-1 in Rh B is spontaneous,endothermic and random.In addition,the cyclic adsorption/desorption properties of CNT-1 were further studied.The results showed that under the same conditions,CNT-1 had no obvious decrease in adsorption capacity after 5 cycles of regeneration,indicating that CNT-1 had reversible adsorption and desorption capacity.