The Adsorption Of Au Nanoparticles By Activated Carbon And Magnetic Carbon Nanomaterials

The preparation and application of new materials such as carbonaceous adsorbent materials and magnetic adsorbent materials have been a hot research issue in the removal of variety contaminates in aqueous water. With the increasing use of various nonomaerials in recent years, the negative impact caused by nanoparticles on biological health and the environment has also attracted tremendous attention. This thesis focused on the studies on the adsorpiton properties of activated carbon (AC) toward Au nanoparticles (AuNPs) from aqueous water, the adsorption of Au nanoparticles onto magnetic carbon nanomaterials (MCNMs) and the catalytic activity of the MCNMs/Au NPsin the reduction reaction of p-nitrophenol. The major contents are summarized as follows.1. We used low-cost, green carbonaceous adsorbent activated carbon (AC) as adsorbents for the adsorption study of Au nanoparticles. The effect of various factors such as solution pH and the concentration of humic acid were explored. The experimental results revealed that the activated carbon has a good affinity to Au nanoparticles when the solution pH was 6.0. In addition, the presence of humic acid inhibited the processe of adsorption. The adsorption was well described by the pseudo-second-order rate model. The equilibrium isotherm was better matched with the Langmuir model, with a maximum equilibrium adsorption capacity of 96.43 mg/g. The adsorption of activated carbon toward Au nanoparticles was an endothermic process. The activated carbon promises low cost and green, thus may be a potential adsorbent for water treatment.2. We report a one-pot method to synthesize magnetic carbon nanomaterials (MCNMs) using egg shell membrane as carbon source. We studied structures and properties using characterization methods such as TEM, FT-IR, XRD and XPS. The obtained nanomaterials possessed high performance and magnetic properties, which is promising for efficient and fast removing Au nanoparticles from water. The effect of solution pH, concentration of humic acid and the coatings of nanoparticles on adsorption behavior were investigated. The adsorption was well described by the pseudo-second-order rate model and the equilibrium isotherm was better matched with the Langmuir model. The maximum adsorption capacities (qmax) of MCNMs6.0, MCNMs-4.8, MCNMs-3.6, MCNMs-2.4, MCNMs-1.2 toward Au nanoparticles, obtained by the Langmuir model, were 1660.3,1492.3,1258.7,980.4,278.6 mg/g, respectively. The adsorption of Au nanoparticles onto MCNMs was an endothermic and spontaneous process. X-ray photoelectron spectroscopic analysis (XPS) was employed to study the adsorption mechanism. Taking into account their magnetic properties and excellent water dispersibility, the MCNMs may have quite practical applications for removing Au NPsfrom aqueous environment.3. We used magnetic carbon nanomaterials supported Au nanoparticles (MCNMs/AuNPs) as catalyst to catalytic reduction of p-nitrophenol (4-NP) by NaBH4. The experimental results revealed that MCNMs6.0/Au NPshas the best catalytic activity. Moreover ～85% of the catalytic activity could be well remained even after sixthrun.