| With the development of nanotechnology, the use of nanoparticles has drawn increasing interesting. However, as new kind of pollutant, nanoparticles have bring environmental risks. The removal of such nanoparticles from wastewater is highly needed. The biosorption has been considered as a promising technology for the removal of various pollutants from contaminated waters due to their low cost and their environment friendly. In this thesis, the polyethyleneimine (PEI) modified grapefruit peel (GP) and eggshell membrane (ESM) were prepared and used as bipsorbents for the removal of CdTe quantum dots (CdTe QDs) and acid fuchsin (AF) from aqueous solution. The research was focused on the optimization of adsorption conditions. Also, the meshcniasm underlying the adsorption process was discussed.1.The polyethyleneimine (PEI)-decorated grapefruit peel (GP) composite adsorbent was facilely prepared, which was based on PEI grafting onto the GP through a simple one-step reaction. The as-prepared PEI-GP adsorbent was characterized by SEM, XRD, FT-IR and XPS, showing that PEI was successfully grafted onto GP. The as-prepared PEI-GP adsorbents were used for the removal of CdTe quantum dots (QDs). Batch adsorption experiments were performed to investigate the influences of pH, contact time, initial CdTe QDs concentration, ionic strength and humic acid concentration. Results show that the adsorption kinetics could be fit well by the pseudo-second-order model and the adsorption process could be described well by the Freundlich adsorption isotherm. The ionic strength caused significant effect on adsorption of CdTe QDs onto PEI-GP adsorbents due to aggregation of the CdTe QDs in the presence of salt. The presence of humic acid had minor effect on sequestration of CdTe QDs by the PEI-GP biosorbents. The results indicate that the PEI-GP can be used as a promising adsorbent for the removal of CdTe QDs from aqueous media.2. The PEI-ESM composite material was facilely prepared by PEI grafting onto the ESM through a simple one-step reaction and used as adsorbent for extracting CdTe QDs from the aqueous environment. Through the PEI content optimized, it is found that when the PEI content comes to 2.0 g/L, the highest adsorption capacity for CdTe QDs was obtained. Batch adsorption experiments were performed to investigate the influences of pH, contact time, initial CdTe QDs concentration, ionic strength and HA concentration. The adsorption kinetics could be fit well by the pseudo-second-order rate model. The equilibrium isotherm was fit well with the Langmuir adsorption isotherm, with a maximum equilibrium adsorption capacity of 400 mg/g, yet the raw ESM has no adsorption ability for CdTe QDs. This fully demonstrates that the superiority of the material. Finally, PEI-ESM-2.0 packed column was fabricated and used for real water samples purification. The result indicates that the PEI-ESM can be a low cost and environment friendliness material for the removal of CdTe QDs.3. Based on the positive charged surface of the PEI-ESM and the electrostatic attraction effect, the PEI-ESM was used as biosorbent for the removal of an anionic dye AF. When the PEI content reaches to 10 g/L, the highest adsorption capacity of PEI-ESM for AF was obtrained. Meanwhile, the PEI-ESM-10 showed a 3-fold higher adsorption capacity than the raw ESM. From the investigation, the adsorption of AF on PEI-ESM-10 was well described by the pseudo-second-order model. The equilibrium isotherm was fit well with the Langmuir adsorption isotherm, with a maximum equilibrium adsorption capacity of 333.33 mg/g. The adsorption of AF on PEI-ESM-10 was an exothermic and spontaneous process. The adsorption could be efficiently carried out at room temperature. The result demonstrated that PEI-ESM was an high efficient and green biosorbent for the removal of AF. |
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