【摘要】：隨著納米技術(shù)的發(fā)展,越來越多的貴金屬納米粒子被用于工業(yè)和家庭產(chǎn)品中,從而導(dǎo)致貴金屬納米粒子釋放到環(huán)境中,對生態(tài)環(huán)境和生物健康造成威脅。由貴金屬納米微粒帶來的環(huán)境污染問題逐漸受到了大家的重視。目前有少數(shù)的研究報道通過IER、CPE和離子交換樹脂等去除和富集提取環(huán)境中的銀納米微粒(Ag NPs),但是這些方法存在操作復(fù)雜、樣本量很小和富集效率較低等缺點。因此有必要開發(fā)簡便高效的方法和材料富集分離水體中的Ag NPs。另外,AgNPs不僅稀有珍貴而且是有效的催化劑材料�？梢妼で蠛啽阌行У姆椒ǜ患蛛x環(huán)境中的Ag NPs并將其回收加以利用意義重大。為此,本文研究了磁性聚多巴胺(Fe_3O_4@PDA)、MOF-235以及煅燒的GO/MIL-88(Fe)對水中Ag NPs的富集分離,并將富集Ag NPs后的材料回收,探究了其對染料和4-硝基酚(4-NP)的催化性能。主要內(nèi)容如下:1、我們采用簡便的方法合成了Fe_3O_4@PDA核殼微球。通過XRD、FT-IR、TEM等表征手段對材料進行了表征,表征結(jié)果證明了PDA成功修飾在了Fe_3O_4表面。制得的磁性材料作為吸附劑被用于富集分離水溶液中的阿拉伯膠銀納米(GA-Ag NPs),實驗研究了溶液p H、不同配體、吸附時間、GA-Ag NPs初始濃度以及離子濃度和腐殖酸(HA)對吸附的影響。結(jié)果表明,p H=10時吸附量最大,對GA配體的銀納米吸附效果最好,吸附等溫線符合Langmuir模型,最大吸附量為169.49mg/g。此外,我們將吸附銀納米后的材料(Ag NPs-Fe_3O_4@PDA)回收后用于催化去除亞甲藍(MB)。結(jié)果表明,20 m L、7.5 ppm的MB在30 min內(nèi)能被完全去除,Ag NPs-Fe_3O_4@PDA不僅酸穩(wěn)定性極好而且能重復(fù)使用至少8次。2、我們采用水熱法一步合成了金屬有機骨架材料MOF-235,并首次將其用于富集分離水溶液中的GA-Ag NPs。XRD、BET、TG、SEM、FT-IR等表征結(jié)果表明,我們成功合成出了高純度、晶型結(jié)構(gòu)完整的MOF-235,Ag NPs以團聚的形式成功的被富集到MOF-235表面。實驗中,我們系統(tǒng)的研究了溶液p H、離子強度、HA濃度、吸附時間等對吸附過程的影響。結(jié)果表明,p H=6時吸附效果最佳,外在離子對吸附起促進作用并且離子價態(tài)越高促進作用越好,HA抑制吸附的進行,12 h后吸附達到平衡。動力學(xué)符合準(zhǔn)二級動力學(xué)模型,等溫線符合Langmuir模型,最大吸附量為155.76 mg/g。此外,吸附銀納米后的材料(MOF-235/Ag NPs)對4-NP有較好的催化效果,Ks=2.7x10-3/sec。3、我們合成了GO/MIL-88(Fe)復(fù)合材料,將其煅燒后得到了新型磁性碳材料,然后用于富集分離水溶液中的Cit-Ag NPs。GO的加入不僅提高了MOF材料的產(chǎn)率,而且大大增加了煅燒后材料對Cit-Ag NPs的富集效果。通過XRD、TG、SEM、FT-IR等表征手段對吸附前后的材料進行了表征,結(jié)果表明通過煅燒我們成功得到了磁性材料,Cit-Ag NPs成功的被富集到了磁性碳材料表面。實驗探究了GO加入比例和煅燒溫度對材料吸附效果的影響以及溶液p H、離子強度、HA濃度、吸附時間等對吸附過程的影響。結(jié)果表明GO加入比例為2.5%時材料吸附效果最好,煅燒溫度設(shè)置為700℃時材料吸附效果最佳,溶液p H=6時吸附量最大,外在離子對吸附起促進作而HA對吸附起抑制作用。吸附動力學(xué)符合準(zhǔn)二級動力學(xué),吸附等溫線符合Langmuir模型,最大吸附量為483.59 mg/g。
[Abstract]:With the development of nanotechnology, more and more precious metal nanoparticles are used in industrial and household products, resulting in the release of precious metal nanoparticles into the environment, which poses a threat to the ecological environment and biological health. The removal and enrichment of silver nanoparticles (AgNPs) in the environment by IER, CPE and ion exchange resins are reported. However, these methods have some disadvantages, such as complicated operation, small sample size and low enrichment efficiency. Therefore, it is necessary to develop simple and efficient methods and materials for enrichment and separation of AgNPs in water. Therefore, this paper studies the enrichment and separation of Ag NPs in water by magnetic polydopamine (Fe_3O_4@PDA), MOF-235 and calcined GO/MIL-88 (Fe), and the recovery of Ag NPs after enrichment. The main contents are as follows: 1. Fe_3O_4@PDA core-shell microspheres were synthesized by a simple method. The materials were characterized by XRD, FT-IR and TEM. The results showed that PDA was successfully modified on the surface of Fe_3O_4. The effects of P H, ligands, adsorption time, initial concentration of GA-Ag NPs, ion concentration and humic acid (HA) on the adsorption of Ag nanoparticles in aqueous solution were studied experimentally. The results show that 20 m L, 7.5 ppm MB can be completely removed in 30 minutes. Ag NPs-Fe_3O_4@PDA has excellent acid stability and can be reused at least 8 times. MOF-235, a metal-organic framework material, was synthesized and used for the first time to enrich and separate GA-Ag NPs. XRD, BET, TG, SEM, FT-IR and other characterization results show that MOF-235 with high purity and complete crystal structure was successfully synthesized. Ag NPs were successfully enriched on the surface of MOF-235 in the form of agglomeration. The results showed that the adsorption effect was the best when the P H was 6, and the higher the valence of the ions, the better the adsorption effect. The adsorption was inhibited by HA, and reached equilibrium after 12 hours. IR model showed that the maximum adsorption capacity was 155.76 mg/g. In addition, the adsorbed silver nanoparticles (MOF-235/Ag NPs) had a good catalytic effect on 4-NP, Ks = 2.7x10-3/sec.3. We synthesized GO/MIL-88 (Fe) composite material, calcined it and obtained a new type of magnetic carbon material, which was used to enrich and separate Ce-Ag NPs.GO from aqueous solution. The yield of MOF material was increased and the enrichment effect of calcined material on it-Ag NPs was greatly enhanced. The materials before and after adsorption were characterized by XRD, TG, SEM and FT-IR. The results showed that magnetic materials were successfully obtained by calcination, and Cit-Ag NPs were successfully enriched on the surface of magnetic carbon materials. The results show that when the GO content is 2.5%, the adsorption effect is the best, when the calcination temperature is set at 700 C, the adsorption capacity is the greatest, and when the solution P H = 6, the external ions adsorb the most. The adsorption kinetics accorded with quasi-second order kinetics, the adsorption isotherm accorded with Langmuir model, and the maximum adsorption capacity was 483.59 mg/g.
【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O614.122;TB383.1

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