Preparation Of Carbon Nanomaterials From Vascular Plants And Their Adsorptive Properties

This thesis focuses on the synthesis of carbon nanotubes(CNTs), graphene and carbon nanospheres(CNSs) using the vascular plants as carbon source. The formation mechanisms of the three kinds of carbon nanomaterials were discussed. Furthermore, the adsorptive properties of Rhodamine B(Rh-B) and heavy metal ion(Cu2+ and Zn2+) by obtained carbon nanomaterials were investigated. The results are summarized as follows:1. CNTs were synthesized from fallen leaves of poplar were mace-like, and the lengths were ranged from 400 nm to 1000 nm. The outward sides of CNTs were slender with open ends. CNTs were well crystallinity, but there were a few defects on the surface.2. Graphene was synthesized in the multiple pyrolysis processes with the assistant of oxygen from fallen leaves of lilac which had been acidized. There were a few defects on the surface of CNTs.3. CNSs were synthesized from in the multiple pyrolysis processes with the assistant of oxygen from fallen leaves of willow. The CNSs were solid sphere, and the diameter was about 100 nm. CNSs were well crystallinity.4. The adsorptive properties of obtained carbon nanomaterials for Rh-B and heavy metal ion(Cu2+ and Zn2+) were investigated. The results showed that the adsorption equilibration times of Rh-B, Cu2+, and Zn2+ by CNTs were 4, 1, and 2.5 h, respectively. The adsorption equilibration time of Rh-B、Cu2+、and Zn2+ by graphene was 9, 2, and 3.5 h, respectively. The adsorption equilibration time of Rh-B、Cu2+、and Zn2+ by CNSs were 5, 0.5, and 2 h, respectively. With the same initial concentrations and dosages, the order of adsorption capacity for Rh-B was graphene >CNSs >CNTs, the order of adsorption capacity for Cu2+ was CNSs>CNTs>graphene, the order of adsorption capacity for Zn2+ was graphene>CNTs>CNSs。5. The increasing initial concentrations caused an increasing of adsorption capacity, and the adsorbed capacities of Rh-B, Cu2+, and Zn2+ on the carbon nanomaterials were decreased with the increasing dosages of the carbon nanomaterials. The adsorbed capacities of Rh-B by the carbon nanomaterials were decreased with the increasing pH, but the adsorbed capacities of Cu2+ and Zn2+ on the carbon nanomaterials were increasing with the increasing pH.6. The mechanisms of all adsorptions were explained by pseudo-second-order reaction kinetic model. Freundlich model that described the adsorption process of carbon nanomaterials on Rh-B, Cu2+, and Zn2+ was better than Langmuir model.