| With the development of industry and agriculture as well as the unreasonable landfill and stacking of civil solid wastes, sudden accident of heavy metal pollution for water happens occasionally. Among which the drinking water safety problem caused by heavy metal Ni has gradually aroused widely public attention. Except for natural geological process, some human factors such as the relevant industrial process (like mining, smelting,electroplating, currency casting) and fossil fuel burning has caused a large amount of Ni discharged into ambient air and water system. Research materials show that Ni2+can lead to contact allergic dermatitis and respiratory tract cancer. Besides it has accumulation function in human body. For occupational exposure crowd and urban residents who suffered long-term exposure of water source and air contaminated by Ni, it has increased the risk of Ni-poisoning virtually.Activated carbon is a kind of artificial material, also named as carbon molecular sieve. It is an excellent kind of absorbing material with rich internal pore structure and relatively high specific surface area. The physical and chemical properties of activated carbon are stable, and it’s insoluble in water and organic solvent. It is one renewable material which can withstand acid, alkali, wet, high pressure and high temperature. As a kind of cycle-economic material, the development and application technology of activated carbon conform to the sustainable development strategy of our country.Hygrophytes have abundant resources and high content of organic carbon, but they haven’t been adequately utilized for a long time, which caused a lot of biomass resources wasted for nothing. In order to reach the goal of turning waste into wealth, this research prepares and makes activated carbon with high added-value, wide range of application and large demand quantity by adopting hygrophytes as raw materials. At the same time, this research is of great importance for comprehensive utilization of hygrophytes resources of our country, new technology development of activatedcarbon production and environmental protection as well as sustainable development.Through comparing the surface feature and adsorptive property towards Ni(II) of activated carbon from different biomass, this research make clear the advantage of making activated carbon by using hygrophytes as raw materials. Based on experiment result, it increased the removal efficiency for Ni ion of lotus stem activated carbon by adopting Fe(II)-EDTA Compound Modification Method. Afterwards, in order of simplifying the modification technology, this thesis adopts acetic acid doping vario-property method as well as phosphate activation method so as to elevate the surface property, and eventually achieved the goal of improving the adsorptive property towards Ni(II) of activated carbon from hygrophytes biomass.The main conclusions of this thesis are as follows:1. Through characterization and analysis of activated carbon from different biomass, it has been founded that the physical and chemical property as well as the adsorptive property towards Ni ion of activated carbon of wetland plant biomass are all better than that of other biomass, among which lotus stem and carex zizaniifolia are the suitable materials for making high-performance activated carbon. The research result shows that the activated carbon sample of wetland plants have micropore-mesopore structure; after measurement it has been found that the activated carbon of wetland plant has relatively high specific surface area:the specific surface area of lotus stalk, and Zizania caduciflora are1318m2g·1and1297m2·g-1respectively, which are all higher than that of other biomass activated carbon; From the result of Boehm titration we can see that the functional group concentration of carboxyl, lactone and phenolic hydroxyl on the surface of activated carbon of wetland plant are all higher than those of other six kinds of activated carbon. Among them, Zizania caduciflora has the highest content of surface acidity functional groups, which is2.034mmol/g; while chicken feather has the minimum content of surface acidity functional groups, which is only0.918mmol/g.2. This research adopts wetland plant lotus stem as raw materials, and first conducts ferrous modification and then loading EDTA, which all aim at providing more adsorption points so as to improve adsorption efficiency. The result shows that the adsorption capacity of activated carbon which after Fe(II) as well as EDTA recombination and modifacation is higher than that of activated carbon which after raw carbon, Fe(II) and EDTA modification by themselves. After Fe(II)-EDTA compound modification, the maximum adsorption capacity of activated carbon towards Ni has reached57.1mg·g-1, which has enhanced10%,170%and20%compared with raw carbon, only Fe(II) modification activated carbon and only EDTA modification activated carbon respectively.3. In order to simplify the modification technology of activated carbon, this research merges the activation step and modification step together, ant1adopts the method of acetic acid doping and modification to make Zizania caduciflora activated carbon. The result shows that after acetic acid modification, the quantity of its acidity functional groups has increased from1.86mmol/g to2.64mmol/g. At pH8.0the maximum adsorption capacity of acetic acid-modified activated carbon towards Ni(II) has reached34.6mg·g-1, which increased about20%compared with28.9m·g-1of raw carbon.4. This research selects Zizania caduciflora as precursor, after steeping in phosphoric acid and five kinds of alkyl phosphotriester (APTEs), makescarex zizaniifolia activated carbon through direct pyrolyzation. Experiment result shows that the activated carbon after activation of five kinds of APTEs has more surface acidity functional groups compared with the activated carbon after activation of only phosphoric acid (1.718mmol/g). Among them, the activated carbon which uses TBP as activator has the highest content of surface acidity functional groups, which is2.695mmol/g; for the activated carbon which uses APTEs as activator, its Vmic/Vtot is30%～50%, among which the Vmic/Vtot of the activated carbon which uses TOP as activator has reached72.1%. This indicates that the activated carbon which uses APTEs as activator has multi-microcellular structure; the adsorption capacity towards heavy metal ion Ni(Ⅱ) of activated carbon made by alkyl phosphate activation is basically higher than that of activated carbon made by phosphoric acid activation. The maximum adsorption capacity for Ni(Ⅱ) of the activated carbon which uses TBP as activator has reached43.5mg·g-1, which increased about42%compared with the activated carbon which uses phosphoric acid as activator (Qm=30.6mg·g-1)... |
