碳质材料复合金属氧化物的制备及去除水中重金属的研究

发布时间：2018-03-13 06:38

  本文选题：碳质材料　切入点：金属氧化物　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：重金属污染给生态环境和人类生存带来了严重威胁。本文制备了碳质材料与金属氧化物的复合材料,如α-Fe_2O_3/碳球、Bi_2Fe_4O_9/生物质炭、TiO_2/石墨烯,采用吸附和光催化方法对其去除水中重金属离子的性能进行了考察,并详细讨论了其对水中重金属离子铬和铜的去除机制,具体研究内容如下:(1)以葡萄糖为碳源,(NH_4)_2Fe(SO_4)·6H_2O)为铁源,二次水为溶剂,水热法合成了α-Fe_2O_3/碳球复合吸附剂,用SEM、TEM和XRD对其结构进行表征,考察了其对水中Cr(Ⅵ)的吸附性能。结果发现,Cr(Ⅵ)在α-Fe_2O_3/碳球上的吸附在4h内达到平衡,去除率高达到88%,分别是α-Fe_2O_3和碳球的2.99倍和4.88倍。动力学拟合表明:该吸附过程符合准一级速率方程所描述的规律,主要为物理吸附;吸附等温线研究表明:Langmuir等温模型能够更好地表述该吸附行为,为典型的单分子层吸附,其最大吸附量为18.7 mg·g-1;吸附热力学研究表明该过程为一个自发进行的吸热反应;α-Fe_2O_3/碳球重复使用5次后吸附能力的下降仅为7.8%,表明此吸附剂可以重复使用。(2)以硝酸铋(Bi(NO_3)_3·5H_2O)和硝酸铁(Fe(NO_3)_3·9H_2O)为原料,采用水热法合成Bi_2Fe_4O_9纳米片。将原位生长的Bi_2Fe_4O_9与以松树叶粉末为原料的生物质炭复合,制备Bi_2Fe_4O_9/生物质炭复合吸附剂,并用于水中Cu(Ⅱ)的吸附去除。制备的Bi_2Fe_4O_9和Bi_2Fe_4O_9/生物质炭吸附剂比表面积分别为13.35 m2·g-1和17.51 m2·g-1;在pH=5时对Cu(Ⅱ)的吸附效果最佳;动力学拟合表明:该吸附过程适合于用准二级吸附动力学模型进行描述,为物理化学吸附过程;对热力学参数(Ea、ΔG、ΔH和ΔS)的分析表明:该吸附剂对Cu(Ⅱ)的吸附为自发的放热过程;Bi_2Fe_4O_9和Bi_2Fe_4O_9/生物质炭的最大吸附量分别为42.7 mg·g-1和61.61mg·g-1;溶液中共存的Cl~-,NO_3~-和SO_4~(2-)对Cu(Ⅱ)的吸附过程基本没有影响,而PO_4~(3-)则会起促进作用。Bi_2Fe_4O_9和Bi_2Fe_4O_9/生物质炭重复使用5次后吸附能力下降分别为7.3%和11.5%,表明这两种吸附剂可以重复使用。(3)以Hummers改性法制备的石墨烯和钛酸四丁酯为原料,采用一步水热法合成TiO_2/GO光催化剂,并用于吸附/光催化协同去除水中Cr(Ⅵ)的研究。通过SEM、XRD、BET、DRS和FTIR等手段对材料进行表征和分析。复合光催化剂中的TiO_2为锐钛矿型二氧化钛,呈规则方块状的二氧化钛颗粒均匀地分散在石墨烯表层,两者有效的结合在一起。制备的TiO_2和TiO_2/GO样品的比表面积分别为179.1和149.74 m2·g-1;最佳的降解实验条件为催化剂浓度为4.0g/L,溶液pH值为2.0;在最优条件下,TiO_2/GO吸附去除率为65.7%,光催化去除率成为33.1%,总去除率为98.8%;TiO_2/GO光催化还原降解Cr(Ⅵ)的过程主要是通过超氧自由基·O_2-和空穴h+来实现的。相较于TiO_2而言,TiO_2/GO光催化降解Cr(Ⅵ)的性能得到了有效改善。
[Abstract]:Heavy metal pollution poses a serious threat to the ecological environment and human survival. In this paper, composite materials of carbon materials and metal oxides, such as 伪 -Fe _ 2O _ 3 / C _ 2O _ 3 / C _ 2O _ 3 / Bi2Fe4O _ 9 / biomass carbon tio _ 2 / graphene, have been prepared. The removal of heavy metal ions in water was investigated by adsorption and photocatalysis. The removal mechanism of chromium and copper ions in water was discussed in detail. The specific contents of the study were as follows: 1) taking glucose as carbon source, NH _ 4S _ 4) 路6H _ 2O) as Tie Yuan. 伪 -Fe _ 2O _ 3 / carbon sphere composite adsorbent was synthesized by hydrothermal method with secondary water as solvent. The structure of 伪 -Fe _ 2O _ 3 / carbon sphere was characterized by XRD and TEM. The adsorption properties of 伪 -Fe _ 2O _ 3 / carbon sphere on 伪 -Fe _ 2O _ 2O _ 3 / carbon sphere were investigated. The results showed that the adsorption of 伪 -Fe _ 2O _ 3 / carbon sphere on 伪 -Fe _ 2O _ 2O _ 3 / carbon sphere reached equilibrium within 4 hours. The removal rate is up to 88, which is 2.99 times and 4.88 times of 伪 -Fe _ 2O _ 3 and carbon sphere respectively. The kinetic fitting shows that the adsorption process accords with the law described by the quasi-first-order rate equation, mainly physical adsorption. The adsorption isotherm study shows that the isotherm model of 1: Langmuir can better describe the adsorption behavior and is a typical monolayer adsorption. The maximum adsorption capacity was 18.7 mg 路g ~ (-1); the adsorption thermodynamics showed that the process was a spontaneous endothermic reaction; the adsorption capacity of 伪 -Fe _ 2O _ 3 / carbon sphere decreased only 7.8 after repeated use of 伪 -Fe _ 2O _ 3 / carbon sphere for 5 times, indicating that the adsorbent could be reused with bismuth nitrate. Bigno _ 3s _ _ _. Bi_2Fe_4O_9 nanoparticles were synthesized by hydrothermal method. The in situ growth of Bi_2Fe_4O_9 was combined with biomass carbon from pine leaf powder to prepare Bi_2Fe_4O_9/ composite adsorbent. The specific surface areas of Bi_2Fe_4O_9 and Bi_2Fe_4O_9/ were 13.35 m2 路g ~ (-1) and 17.51 m ~ (2) 路g ~ (-1), respectively, and the adsorption efficiency of Cu (鈪，

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