【摘要】：隨著人口的不斷增加和國民經(jīng)濟快速發(fā)展,我國水資源污染日趨嚴(yán)重。六價鉻Cr(VI)作為第一類污染物,也是水污染五毒之一,普遍存在于工業(yè)污水中,工業(yè)上廣泛用于電鍍、制革、紡織印染等行業(yè)中。木質(zhì)素是一種三維網(wǎng)狀的可再生芳香基天然高聚物,在植物內(nèi)含量僅次于纖維素,占植物體的15%-36%。而堿木素作為制漿造紙工業(yè)的副產(chǎn)品,產(chǎn)量大,利用率低,且對水環(huán)境有嚴(yán)重的污染。由于堿木素分子結(jié)構(gòu)中含有多種活性基團,可對其化學(xué)改性制備功能材料,去除水中重金屬離子。本研究利用堿木素中羥基、羧基、羰基等官能團,分別合成了多孔磁性碳吸附劑及Bi_2O_3負載的不同系列的光催化劑,用于去除水中六價鉻Cr(VI)。具體工作主要分為以下三個方面:(1)利用球磨法引入聚乙烯亞胺中的氨基基團,并通過高溫煅燒負載Fe3O4制備了多孔磁性碳材料吸附劑,提高了對六價鉻Cr(VI)的吸附容量并實現(xiàn)了磁性分離。本實驗以酸析提純的堿木素為碳源,添加K_2CO_3、聚乙烯亞胺和Fe(NO_3)_3×5H_2O經(jīng)球磨充分反應(yīng)后高溫煅燒,得到多孔磁性碳吸附劑。通過透射電鏡、掃描電鏡、傅里葉變換紅外光譜、比表面測試和X射線光電子能譜等多種手段對多孔磁性碳吸附劑進行了表征。結(jié)果表明,木質(zhì)素表面孔隙增多、比表面積增大,氨基基團和Fe3O4成功接枝到木質(zhì)素表面。聚乙烯亞胺中的氨基基團能增強吸附劑對六價鉻Cr(VI)的吸附作用,并能將毒性較高的六價鉻Cr(VI)還原為毒性較低的三價鉻Cr(III)。因此,多孔磁性碳材料不僅吸附了溶液中的六價鉻Cr(VI),同時降低了溶液的毒性。溶液pH對吸附效果影響較大,在pH為2時最大吸附量可達到160 mg/g。(2)采用水熱合成法成功制備了系列Bi_2O_3負載的碳光催化劑。首先,Bi~(3+)與聚乙烯吡咯烷酮(PVP)上的羰基氧通過配位結(jié)合形成膠粒,然后膠粒緩慢釋放Bi~(3+)與木質(zhì)素表面羥基基團反應(yīng)形成Bi_2O_3負載的光催化材料。對所得產(chǎn)物通過透射電鏡、掃描電鏡、X射線粉末衍射、X射線光電子能譜和紫外-可見光譜進行了表征。結(jié)果表明,Bi_2O_3微球成功負載到木質(zhì)素表面。可見光激發(fā)下,對不同濃度、不同pH的六價鉻Cr(VI)溶液進行了光催化實驗,實驗證明光催化劑在pH=2時對六價鉻Cr(VI)光催化降解性能最佳。制備的C@Bi_2O_3負載的系列光催化劑為下一步研究提供了思路。(3)為了進一步提高負載Bi_2O_3系列光催化劑的催化效果,通過球磨法和水熱合成法制備了聚乙烯亞胺(PEI)修飾并負載α-Fe_2O_3-Bi_2O_3的復(fù)合木質(zhì)素光催化材料。采用透射電鏡、掃描電鏡、X射線粉末衍射、X射線光電子能譜等表征多種手段對光催化材料進行表征。結(jié)果表明,木質(zhì)素表面負載了α-Fe_2O_3-Bi_2O_3片層結(jié)構(gòu),對溶液中六價鉻Cr(VI)的催化速率及催化效果高于Bi_2O_3負載的系列木質(zhì)素光催化材料。這歸因于α-Fe_2O_3促使光電子能快速遷移躍遷,提高了光電子空穴對的分離效果,增強了Bi_2O_3的催化活性。制備的C@α-Fe_2O_3-Bi_2O_3復(fù)合光催化材料實現(xiàn)了資源的循環(huán)利用,具有廣闊的應(yīng)用前景。
[Abstract]:With the increase of population and the rapid development of national economy, the pollution of water resources in China is becoming more and more serious. As the first kind of pollutant, hexavalent chromium chromium (VI) is also one of the five poisons of water pollution. It is widely found in industrial wastewater. It is widely used in electroplating, leather making, textile printing and dyeing industries. The content of natural polymers in plants is only inferior to cellulose, accounting for 15%-36% of the plant. As a by-product of pulp and paper industry, alkali lignin has high yield, low utilization rate and serious pollution to water environment. In this study, porous magnetic carbon adsorbents and different series of Bi_2O_3-supported photocatalysts were synthesized by using hydroxyl, carboxyl and carbonyl groups in alkali lignin to remove hexavalent chromium (VI) from water. Porous magnetic carbon adsorbents were prepared by calcining Fe_3O_4 loaded on Fe_3O_4 at high temperature, which improved the adsorption capacity of Cr(VI) and achieved magnetic separation.The porous magnetic carbon adsorbents were prepared by adding K_2CO_3, polyethylenimine and Fe(NO_3)_3 The porous magnetic carbon adsorbents were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, specific surface testing and X-ray photoelectron spectroscopy. The adsorption of hexavalent chromium chromium (VI) on the adsorbent was enhanced and the toxic hexavalent chromium chromium (VI) was reduced to trivalent chromium (III) with lower toxicity. Therefore, the porous magnetic carbon materials not only adsorbed hexavalent chromium chromium (VI) in the solution, but also reduced the toxicity of the solution. A series of Bi_2O_3-loaded carbon photocatalysts were successfully prepared by hydrothermal synthesis. First, Bi~ (3+) and carbonyl oxygen on polyvinylpyrrolidone (PVP) were coordinated to form colloidal particles, and then the colloidal particles slowly released Bi~ (3+) and reacted with hydroxyl groups on the lignin surface to form Bi_2O_3-loaded photocatalytic materials. The materials were characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. The results showed that Bi_2O_3 microspheres were successfully loaded on the surface of lignin. Under visible light excitation, the photocatalytic activity of hexavalent chromium Cr (VI) solution with different concentration and pH was studied. The photocatalyst was proved to be at pH=2. The photocatalytic degradation of hexavalent chromium chromium (VI) was the best. A series of C@Bi_2O_3-supported photocatalysts were prepared to provide ideas for further study. (3) In order to further improve the catalytic effect of Bi_2O_3-supported photocatalysts, polyethylenimine (PEI) modified and loaded with alpha-Fe_2O_3-Bi_2O_3 were prepared by ball milling and hydrothermal synthesis methods. Composite lignin photocatalytic materials were characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The results showed that the catalytic rate and catalytic effect of hexavalent chromium Cr(VI) on lignin surface were higher than that on Bi_2O_3. This is attributed to the fact that alpha-Fe_2O_3 promotes the rapid migration and transition of photoelectron energy, improves the separation efficiency of photoelectron hole pairs, and enhances the catalytic activity of Bi_2O_3. The prepared C@alpha-Fe_2O_3-Bi_2O_3 composite photocatalyst realizes the recycling of resources and has broad application prospects.
【學(xué)位授予單位】：山東農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703;O643.36

【參考文獻】

相關(guān)期刊論文 前10條

1 竇俊;陳均;;剝離型聚吡咯/蒙脫土納米復(fù)合材料的制備及對Cr~(6+)的吸附研究[J];化工新型材料;2017年03期

2 丁秘;康文晶;馮程龍;余光輝;冉煒;沈其榮;;人工合成水鐵礦對水中六價鉻的吸附特征研究[J];工業(yè)水處理;2017年02期

3 朱富強;李月紅;賈會美;李夢醒;;離子色譜法測定工作場所空氣中六價鉻含量[J];理化檢驗(化學(xué)分冊);2017年02期

4 張婷婷;曹譯文;石慶柱;賀承瑞;李靖;堵錫華;;固相合成g-C_3N_4及其可見光催化還原水中六價鉻[J];現(xiàn)代鹽化工;2017年01期

5 滕洪輝;彭雪;高彬;;石墨烯基復(fù)合材料去除水中重金屬研究進展[J];化工進展;2017年02期

6 肖平平;鄧滿蘭;胡紅武;劉維政;;基于光波導(dǎo)技術(shù)的水中六價鉻離子痕量檢測[J];光子學(xué)報;2017年01期

7 董軍;任黎明;遲子芳;胡文華;;氧化石墨烯負載納米零價鐵(rGO-nZⅥ)去除地下水中Cr(Ⅵ)的XPS譜學(xué)表征[J];光譜學(xué)與光譜分析;2017年01期

8 朱琳;顧冬雨;李敏晶;陳濤;劉恒明;;龍須菜纖維素去除水中鉻(Ⅵ)離子的研究[J];廣州化工;2017年01期

9 蔡長明;;微污染源水中鉛、鉻重金屬含量檢測技術(shù)研究[J];世界有色金屬;2016年23期

10 趙國欣;趙明;李領(lǐng)川;;環(huán)境水中重金屬離子的現(xiàn)代檢測方法研究綜述[J];中州大學(xué)學(xué)報;2016年06期

，

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