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题名: 粉煤灰-壳聚糖絮凝剂的制备及其絮凝效应研究
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.

 
 
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34461
Appears in Collections:环境纳米材料研究室_学位论文

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Recommended Citation:
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.
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