粉煤灰-壳聚糖絮凝剂的制备及其絮凝效应研究
文献类型：学位论文
| 作者 | 袁玉婷 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 潘纲 |
| 关键词 | 有害藻华、浊度、絮凝、粉煤灰、壳聚糖，cyanobacterial harmful algae blooms, turbidity, flocculation, coal fly ash, chitosan |
| 其他题名 | Development of A Bi-component Flocculant Using Coal Fly Ash Modified Chitosan and Its Flocculation Effects |
| 学位专业 | 环境工程 |
| 中文摘要 | 本文利用粉煤灰提取液改性天然高分子絮凝剂壳聚糖，制备粉煤灰改性壳聚糖复合絮凝剂（ CFAL-Chitosan），通过室内实验，研究该絮凝剂对铜绿微囊藻（Microcystis aeruginosa）和浊度的去除效率，为水质净化和粉煤灰的回收利用提供一种新方法。本文主要研究成果如下： （1）采用盐酸提取粉煤灰中 Al/Fe，制备粉煤灰提取液（CFAL），用于壳聚糖改性。通过单因素实验，依次研究了盐酸浓度、粉煤灰与盐酸固液比及提取时间对 Al/Fe 提取量的影响。实验结果显示，随着盐酸浓度增加，Al/Fe 提取量显著增加；与此同时，提高盐酸浓度也导致粉煤灰中有害重金属浸出量增大；当粉煤灰与盐酸固液比增大时，Al/Fe提取量先增加后趋于平缓；Al/Fe提取量虽然随提取时间缓慢增加，但受提取时间影响较小。结合实验数据，CFAL制备条件为：盐酸浓度 2.0 %，粉煤灰与盐酸固液比 1 g : 5 mL，提取时间 24 h，此时 Al和Fe提取量分别为 3.53和 2.37 mg/g。 （2）絮凝剂成分分析结果显示，壳聚糖经过 CFAL改性后，Al/Fe与壳聚糖分子相互作用，在 CFAL-Chitosan 中形成与壳聚糖结合的 Al/Fe。红外光谱分析进一步发现壳聚糖分子链上的 NH2和 OH是与 Al/Fe结合的主要基团。 （3）在室内铜绿微囊藻（M.A.）培养体系中，研究了 CFAL-Chitosan 的絮凝效应。结果显示，少量 CFAL 改性壳聚糖（CFAL/Chitosan 比例为 12:1），提高了壳聚糖的电中和能力；在 3 mg/L时，M.A.去除率达到 98.2 %，该去除率比未使用 CFAL改性的壳聚糖高出 16.8 %。随着投量继续增加，去除率稳定保持在90 %以上；形成絮体较大，比较稳定，沉降速度快。然而当 CFAL/Chitosan比例提高时，过量 CFAL导致壳聚糖分子水解，分子量下降，影响架桥网捕作用，藻细胞去除率显著降低。在 CFAL-Chitosan最佳投量下，絮凝后对藻液 pH和重金属离子残留影响较小。 （4）在高岭土模拟浊度体系内，研究了单独使用 CFAL 的絮凝效应。对原浊度为 100 NTU的高岭土悬浊液，单独使用 CFAL剂量为 0.44 mg/L时，浊度去除率达到 90 %以上，剩余浊度<10 NTU；去除率高于聚合氯化铝（PACl，78.7 %）和氯化铝（AlCl3，79.2 %）。CFAL形成的絮体大小约为 400 μm，相对 PACl和AlCl3分别提高了 35.0 % 和 17.5 %；沉降速度快，20 min后去除率稳定在 90 %以上。在最优剂量时，使用 CFAL絮凝后，对高岭土悬浊液 pH无明显影响，余铝满足《生活饮用水卫生标准》（GB5749-2006）。 （5）在高岭土模拟浊度体系内，研究了 CFAL-Chitosan的絮凝效应。结果表明，当 CFAL/Chitosan比例为 12:1时，对原浊度为 100 NTU的高岭土悬浊液，在 CFAL-Chitosan投量为8 mg/L时，浊度去除率81.6 %，剩余浊度为 22NTU，比未改性壳聚糖提高了 61.7 %。使用粉煤灰-壳聚糖絮凝除浊的最佳效率低于单独使用粉煤灰提取液的效率，表明在无藻浊度体系中，无需添加壳聚糖，单独使用粉煤灰提取液就能达到较好的除浊效果。当 CFAL/Chitosan 比例增加到20:1时，过量 CFAL 造成壳聚糖水解和分子量降低，限制了壳聚糖的架桥网捕作用，因此浊度去除率明显降低。 |
| 英文摘要 | In this study, a compound flocculant was prepared using coal fly ash modified chitosan (CFAL-Chitosan). Coal fly ash (CFA) is an industrial by-product and chitosan is a natural bio-polymer. The flocculation effects of Microcystis aeruginosa (M.A.) and turbidity removal of kaolin suspension were investigated. The study may provide new ways for water purification and CFA recycling. Five results are summarized in this paper. (1) Leachate of coal fly ash （CFAL） containing Al/Fe was obtained to modify chitosan using hydrochloric acid. The leaching protocol was optimized by single factor experiments and three factors were investigated i.e. the hydrochloride acid concentration, solid to liquid ratio and leaching time. The results showed that the leaching of Al/Fe and sensitive metals in CFA increased as the hydrochloride acid concentration elevated. The Al/Fe leaching firstly increased with the solid to liquid ratio and flatted off when solid to liquid ratio was 1 g: 5 mL. The Al/Fe leaching increased gently as leaching time increased. Based on the data, the leaching protocol was set as hydrochloride acid concentration of 2.0 wt%, solid to liquid ratio of 1 g: 5 mL and leaching time of 24 h. The leaching of Al and Fe was 3.53 and 2.37 mg/g, respectively. (2) The component analysis implied that the Al and Fe interacted with chitosan molecules and the chitosan bonded with Al/Fe were found in CFAL-Chitosan. The Fourier transfered infrared spectrum (FT-IR) further validated that the NH2 and OH on the chitosan polymer chain mianly participated in chelation with Al/Fe during the preparation of CFAL-Chitosan. (3) CFAL facilitated chitosan for M.A. removal by enhancing the charge neutralization. When CFAL-Chitosan was used at 3 mg/L, the M.A. removal reached to the maximum of 98.2 %, which was 16.8 % higher than chitosan without CFAL. When CFAL-Chitosan dosage was beyond 3 mg/L, the removal efficiency stayed over 90 %. The flocs formed by CFAL-Chitosan were larger and denser and sedimented faster than chitosan without CFAL. However, excessive CFAL inhibited M.A. removal due to the hydrolysis of chitosan and declining of chitosan molecular weight which influencd the bridging and netting effects. The pH and sensitive metal residuals in the algal solution after flocculation were not significantly influenced at the optimized dosage of CFAL-Chitosan. (4) The flocculation effects of using CFAL alone was studied in kaolin suspension.When CFAL alone was 0.44 mg/L, the removal rate reached over 90 % and residual turbidity was below 10 NTU for kaolinite suspension with initial turbidity of 100 NTU. The removal efficiency was superior to poly aluminium chloride (PACl, 8.7 %) and aluminium chloride (AlCl3, 79.2 %). Flocs formed by CFAL were 400 μm, which were 35.0 % and 17.5 % larger than PACl and AlCl3. The flocs settled down faster and over 90 % removal rate was achieved within 20 min. The pH was not significantly influenced and the residual Al was within the Chinese drinking water standards (GB5749-2006). (5) The flocculation effects of using CFAL modified chitosan were studied in kaolin suspension. When CFAL/Chitosan ratio was 12:1, the turbidity removal reached 81.6 % at 8 mg/L, 61.7 % higher than chitosan without CFAL. The optimal flocculation efficiency of CFAL-Chitosan was lower than that of using CFAL alone. It indicated that CFAL alone was effective enough to obtain promising removal rate in turbid systems without algae cells such kaolin suspension. When CFAL/Chitosan was 20:1, excessive CFAL led to the hydrolysis of chitosan and the decrease of molecular weight impairing bridging and netting ability and the removal rate declined evidently. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34461]  |
| 专题 | 生态环境研究中心_环境纳米材料实验室 |
| 推荐引用方式 GB/T 7714 | 袁玉婷. 粉煤灰-壳聚糖絮凝剂的制备及其絮凝效应研究[D]. 北京. 中国科学院研究生院. 2015. |
入库方式： OAI收割
来源：生态环境研究中心
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