生物质碳材料的制备及在染料废水处理中的应用

发布时间：2018-04-03 05:05

本文选题：多孔碳　切入点：碳量子点　出处：《宁夏大学》2017年硕士论文

【摘要】：随着印染行业的高速发展,地球上有限的水资源污染越发严重,染料废水具有COD高、透光度低等特点,染料废水的处理已成为环保领域的一项重要工作。生物质碳材料的制备及应用于废水中有机染料的去除是实现高效水处理的一个重要途径。本课题以生物质为碳源制备了几种碳材料,用于对印染废水中亚甲基蓝(MB)的去除应用,具体研究结果如下:(1)以玉米秸秆为碳源,通过水热法和高温煅烧的方法制备了多孔碳材料。通过X射线衍射仪(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、物理吸附仪(BET)等对材料的形貌结构等进行表征。多孔碳形貌为多孔片层结构,比表面积为679.2378 m2/g。以多孔碳材料为吸附剂研究其对亚甲基蓝的吸附性能。考察了吸附剂加入量,pH,温度,吸附时间等对其吸附性能的影响。结果表明,吸附剂加入量为0.25 mg/L,MB初始浓度为50 mg/L,pH为6.7,温度为318 K,吸附时间为40 min时,多孔碳对MB的去除效果最好,去除率为99.2%。经过动力学拟合分析,多孔碳对MB的吸附符合准二级动力学模型。热力学数据表明,此吸附是自发进行、吸热的物理吸附过程。经过5次循环吸附后,去除率为93%,表明多孔碳具有较好的循环可再生性能。(2)以玉米秸秆为碳源,通过水热法制备了碳量子点(CQDs)。通过透射电镜(TEM)傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)等对材料的形貌结构等进行表征。碳量子点的平均尺寸为2.4nm,具有很好的水分散性,表面含有很多的含氧基团如OH,C=O,C-O-C等。以碳量子点为类Fenton催化剂,研究其对MB的降解效果。考察了催化剂加入量,MB初始浓度,H202加入量对MB降解率的影响。当H202加入量为6.68g/L,CQDs浓度为3.24g/L,MB初始浓度为10 mg/L,反应时间为180 min时对MB的降解效果最好,降解率为93.6%。经过动力学拟合分析,CQDs对MB的催化反应符合准一级动力学模型。(3)以尿素和三聚氰胺分别为原料经过煅烧制备了类石墨相氮化碳材料。SEM表征结果表明以尿素为原料制备出的类石墨相氮化碳(g-C_3N_4)具有更优异的片层形貌。将类石墨相氮化碳与碳量子点复合制备出类石墨相氮化碳/碳量子点(g-C_3N_4/CQDs)复合材料。制备的材料为类Fenton催化剂,采用超声-类Fenton技术相结合催化降解MB,g-C_3N_4/CQDs复合材料(降解率为91.2%)对MB的降解效果优于g-C_3N_4(降解率为15.5%)。考察了催化剂加入量,H202加入量和不同MB初始浓度条件下复合材料的催化性能,结果表明,催化剂加入量为0.66 g/L,氧化剂加入量为0.3388 g/L,MB初始浓度为10 mg/L,pH值为10.98时对MB的降解效果最好,降解率为97.1%。经过动力学拟合分析,g-C_3N_4/CQDs对MB的催化反应符合准一级动力学模型。催化剂经过4次循环后,降解率为90%,表明g-C_3N_4/CQDs复合材料具有较好的循环可再生性能。
[Abstract]:With the rapid development of printing and dyeing industry, the limited water pollution on the earth becomes more and more serious. Dye wastewater has the characteristics of high COD, low transmittance and so on. The treatment of dye wastewater has become an important work in the field of environmental protection.The preparation of biomass carbon material and its application in the removal of organic dyes in wastewater is an important way to achieve efficient water treatment.In this paper, several kinds of carbon materials were prepared from biomass as carbon source, which were used to remove methylene blue MBs from printing and dyeing wastewater. The specific results are as follows: 1) Corn stalk is used as carbon source.Porous carbon materials were prepared by hydrothermal method and high temperature calcination method.The morphology and structure of the materials were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and physical adsorption apparatus (BET).The morphology of porous carbon is porous lamellar structure with a specific surface area of 679.2378 m2 / g.The adsorption of methylene blue was studied with porous carbon as adsorbent.The effects of pH, temperature and adsorption time on the adsorption properties of adsorbent were investigated.The results show that when the initial concentration of the adsorbent is 0.25 mg / L, pH is 6.7, the temperature is 318K, and the adsorption time is 40 min, the removal rate of MB by porous carbon is the best and the removal rate is 99.2%.After kinetic fitting analysis, the adsorption of porous carbon to MB is in accordance with the quasi-second-order kinetic model.Thermodynamic data show that the adsorption is a spontaneous, endothermic physical adsorption process.After five cycles of adsorption, the removal rate is 93%, which indicates that porous carbon has better recycling and renewable performance.) the carbon quantum dots (CQDsN) were prepared by hydrothermal method using corn straw as carbon source.The morphology and structure of the materials were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).The average size of carbon quantum dots is 2.4 nm, which has good water dispersibility. There are many oxygen-containing groups on the surface of QDs, such as OHH CX, OOU C-O-C and so on.The degradation effect of carbon quantum dots (QDs) on MB was studied using carbon quantum dots (QDs) as Fenton-like catalysts.The effect of the initial concentration of MB and H _ (202) on the degradation rate of MB was investigated.When the concentration of H202 was 6.68 g / L, the initial concentration of CQDs was 3.24 g / L, the initial concentration was 10 mg / L, and the reaction time was 180 min. The degradation rate of MB was 93.6g / L when the initial concentration of H202 was 6.68 g / L and the initial concentration was 10 mg / L and the reaction time was 180 min.The catalytic reaction of CQDs to MB was in accordance with the quasi first-order kinetic model. (3) Graphite-like carbon nitride materials were prepared by calcination of urea and melamine respectively. SEM results showed that urea was used as raw material.The graphite-like phase nitrided carbon nitride (g-C _ 3N _ 4) has better lamellar morphology.The graphite-like carbon nitride / carbon quantum dots (QDs) composites were prepared by the combination of graphite-like carbon nitride and carbon quantum dots.The degradation rate of MB was better than that of g-C _ 3N _ 4 / C _ (4) / C _ (4) C _ (QDs) composite (degradation rate was 91.2%). The degradation rate was 15.5g / L (the degradation rate was 15.5g / kg), and the degradation rate of MB was better than that of g-C _ (3N) -C _ 3N _ (4) composite (degradation rate was 91.2%).The catalytic properties of the composites with different initial concentration of MB and catalyst amount of H202 were investigated.When the amount of catalyst was 0.66 g / L, the initial concentration of oxidant was 0.3388 g / L ~ (-1) and the initial concentration was 10 mg / L ~ (-1), pH value was 10.98, the degradation rate of MB was 97.1g / L.The kinetic fitting analysis shows that the catalytic reaction of MB by 4 / CQDs accords with the quasi-first-order kinetic model.After four cycles, the degradation rate of the catalyst was 90%, which indicated that the g-C_3N_4/CQDs composite had better cycling and renewable performance.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X791

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