| Solidago canadensis L.(SC) is originated in North America which could be introduced as ornamental plant in1935into China. It has spread more than10provinces in coastal areas of China since the1980s and comes to be a serious threat to agricultural production, afforestation and ecological environment in our country. As for the control of alien invasive plant, the safe and effective measure has not been formed yet. However, it contains about36%～45%cellulose and oxygen content is up to50%, which makes it a renewable material. As Solidago canadensis L. is difficult to control in large scale distribution, it can be transferred to environmental sorbent materials in order to make it recycling.Depending on the component analysis of SC stem, sorbent materials, including superabsorbent resin, oil sorbents and amphoteric adsorption materials could be producted by different methods. Characterizations of products were also studied. Then it can be applied to absorb simulated physiological saline and artificial urine, adsorb simulated wastewater containing toluene, Cr (VI), F-and dye wastewater. The main contents of this study include several parts:(1) Preparation of superabsorbent resin based on Solidago canadensis and performance test. Raw materials were pretreated by NaOH and HNO3, then grafted and copolymerized with acrylic acid (AA) and acrylamide (AM). The results showed that: When the mass ratio of monomer to Solidago canadensis fiber was12:1; the reaction temperature was75℃, the amount of initiator was2.8%, the amount of crosslinking agent was0.0694%, and neutralization degree of acrylic acid was75%, the water absorbency and normal saline absorbency was556.8g· g-1and73.7g·g-1respectively. At the room temperature, the water retention rate for48h was up to76%. SC-superabsorbent resins can be applied to hygienic products. The saturated adsorption capacity for artificial urine was65.5mL·g-1when this resin was used.(2) Preparation of oil sorbents and performance test. With Methyl Methacrylate (MMA) and Butyl methacrylate (BMA) as monomers, raw materials of solidago canadensis, Benzoyl Peroxide (BPO) as initiator, Gelatin as dispersant, Cetyl Trimethyl Ammonium Bromide (CTAB) as crosslinking agent, so oil sorbents were synthesized by suspension polymerization. The optimum conditions were as follows:the mass ratio of MMA to BMA was0.75:1, the amount of the initiator was0.7%, the amount of the crosslinking agent was1.2%, the synthesized oil sorbents had good performance and its oil absorbency was21.036g·g-1at45℃. Furthermore, oil retention rate and reusability of oil sorbents were also studied. The results showed that the oil retention rate was above90%, and reusability of oil sorbents in different synthesis condition were decreased by5%～30%. The oil sorbents were applied to treatment of toluene in wastewater. From the static and dynamic experiments, it showed that the removal rate of toluene can be reached up to98.3%at300min, and the resin can be used to dispose about299mL wastewater which contained toluene in150mg/L concentration.(3) Amphoteric adsorption materials synthesized by SC containing hydroxy easily underwent esterification with epoxy chloropropane and trimethylamine. and its can be used to adsorb the Cr (VI). F-in the wastewater. The experimental data showed that the best conditions were:the dosage of adsorbent was3.2g/L, the adsorption time was240min. the temperature was50℃and the pH was2, and the removal rate of Cr (VI) was maximal. The removal rate of F" at initial42min was up to32.5%. At the same time, the results showed that the data of adsorption Cr (VI) and F-fitted the pseudo second-order model better. Furthermore, the experimental data was analysed by Langmuir adsorption isotherm equation and Freundlich adsorption isotherm equation, and it fitted the Langmuir adsorption model better. NaOH solution had a good desorption capacity. The study of material reusing showed:campared with the first times, the adsorption capacity of Cr (VI) and F-decreased by3.4%and10.8%after three times using.(4) The coupling application of adsorbents was studied as follow:the different mass ratio of adsorbents made by ourselves was used to treat dye wastewater. The result showed that the removal rate of crystal violet and methylene blue was up to99.7%and99%, respectively, when the mass ratio of amphoteric adsorption materials to oil sorbents was1:2. The adsorbents which prepared from solidago canadensis have a good application prospects in dye wastewater treatment. |
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