CTAB-PdNPs聚集体对4-氯硝基苯的催化加氢研究
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摘要
利用表面活性剂的静电作用和自组装特性,在CTAB诱导下合成CTAB-PdNPs聚集体.研究显示,阳离子表面活性剂与阴离子Pd前驱体之间的静电作用力能有效抵消阳离子亲水头基团CTA+之间的静电斥力,从而从分子水平驱动形成表面活性剂组装体.研究选取水体中微污染物4-氯硝基苯为研究对象,以催化还原脱氯反应为探针反应,结果显示合成的CTAB-PdNPs聚集体具有高催化活性和强脱卤能力,可在90 min内将4-氯硝基苯完全脱氯形成苯胺.研究进一步考察了Pd投加量、CTAB浓度、起始pH值、硼氢化钠的投加量等因素对4-氯硝基苯的催化脱氯过程的影响,最佳条件为:Pd投加量为0.125 mmol/L,CTAB浓度为1.00 mmol/L,起始pH值为5,硼氢化钠的投加量为15 mmol/L.该CTAB-PdNPs聚集体还显示了较强的催化稳定性,8次循环实验后仍可达到81.9%的脱氯效率.本研究不仅报道了一种简易的合成特定规则形状PdNPs组装体的新方法,还为环境中微污染物的修复去除提供了一种可行技术.
This research mainly used the electrostatic interaction and self-assembly of surfactant to induce the formation of CTAB-PdNPs aggregation. The results showed that the electrostatic interaction between the cationic surfactant and anionic Pd precursor can shield the electrostatic repulsion between the hydrophilic groups of CTA+. It drives the formation of CTAB-PdNPs aggregation on the molecular level. This study chose p-CNB as target pollutant and its catalytic reduction as probe, showing that CTAB-PdNPs have high catalytic activity and dehalogenation ability which can convert p-CNB into aniline in 90 minutes. Besides, this study further investigated the effect of Pd dosages,CTAB concentration, initial pH and NaBH4 dosages on the catalytic reduction. The optimum conditions were Pd dosage value of 0.125 mmol/L,CTAB concentration value of 1.0 mmol/L,initial pH value of 5 and NaBH4 dosage value of 15 mmol/L. The dechlorination efficiency of p-CNB can reach up to 81.9% after eight times recycle tests,which proves the aggregation has an outstanding catalytic stability. Above all,this study not only reports a new method of synthesizing PdNPs assembly with special regular shapes,but also provides a feasible technology for the removal of micro-pollutants in the environment.
This research mainly used the electrostatic interaction and self-assembly of surfactant to induce the formation of CTAB-PdNPs aggregation. The results showed that the electrostatic interaction between the cationic surfactant and anionic Pd precursor can shield the electrostatic repulsion between the hydrophilic groups of CTA+. It drives the formation of CTAB-PdNPs aggregation on the molecular level. This study chose p-CNB as target pollutant and its catalytic reduction as probe, showing that CTAB-PdNPs have high catalytic activity and dehalogenation ability which can convert p-CNB into aniline in 90 minutes. Besides, this study further investigated the effect of Pd dosages,CTAB concentration, initial pH and NaBH4 dosages on the catalytic reduction. The optimum conditions were Pd dosage value of 0.125 mmol/L,CTAB concentration value of 1.0 mmol/L,initial pH value of 5 and NaBH4 dosage value of 15 mmol/L. The dechlorination efficiency of p-CNB can reach up to 81.9% after eight times recycle tests,which proves the aggregation has an outstanding catalytic stability. Above all,this study not only reports a new method of synthesizing PdNPs assembly with special regular shapes,but also provides a feasible technology for the removal of micro-pollutants in the environment.
引文
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[2]PANKAJ K A,CH S,CH V R.Degradation of chlorinated nitroaromatic compounds[J].Applied Microbiology and Biotechnology,2012,93(6):2265-2277.
[3]LI Q,MASAYASU M,TOMOYKI H,et al.Acute immunotoxicity of p-chloronitrobenzene in miceⅡ.effect of p-chloronitrobenzene on the immunophenotype of murine splenocytes determined by flow cytometry[J].Toxicology,1999,137:35-45.
[4]吴少伟.石墨烯负载铱、金催化对氯硝基苯选择性加氢的研究[D].大连:大连理工大学化工学院,2015:2-8.WU S W.Selective catalytic hydrogenation of p-CNB over grapghene supported iridium and Au catalyst[D].Dalian:College of Chemical Engineering,Dalian University of Technology,2015:2-8.(In Chinese)
[5]HUANG B B,WANG T,LEI C,et al.Highly efficient and selective catalytic hydrogenation of acetylene in N,N-dimethylformamide at room temperature[J].Journal of Catalysis,2016,339:14-20.
[6]HUANG B B,QI C Y,YANG Z,et al.Pd/Fe3O4nanocatalysts for highly effective and simultaneous removal of humic acids and Cr(VI)by electro-Fenton with H2O2in-situ electro-generated on the catalyst surface[J].Journal of Catalysis,2017,352:337-350.
[7]黎方正,周秋兰,欧恩才,等.溶胶凝胶法制备Pd/rGO纳米复合材料[J].湖南大学学报(自然科学版),2017,44(12):103-107.LI F Z,ZHOU Q L,OU E C,et al.Preparation of Pd/rGO nano composite by sol-gel method[J].Journal of Hunan University(Natural Sciences),2017,44(12):103-107.(In Chinese)
[8]HU J Y,YANG Q W,YANG L F,et al.Confining noble metal(Pd,Au,Pt)nanoparticles in surfactant ionic liquids:active nonmercury catalysts for hydrochlorination of acetylene[J].ACSCatalysis,2015,5(11):6724-6731.
[9]HU C Y,LIN K Q,WANG X L,et al.Electrostatic self-assembling formation of Pd superlattice nanowires from surfactant-free ultrathin Pd nanosheets[J].Journal of the American Chemical Society,2014,136(37):12856-12859.
[10]PEDRO S,AVELINO C.Transforming nano metal nonselective particulates into chemoselective catalysts for hydrogenation of substituted nitrobenzenes[J].ACS Catalysis,2015,5(12):7114-7121.
[11]ZHANG P,ZHAO Z B,BORIS D,et al.In situ synthesis of cottonderived Ni/C catalysts with controllable structures and enhanced catalytic performance[J].Green Chemistry,2016,18(12):3594-3599.
[12]ZHU B W,LIM T T.Catalytic reduction of chlorobenzenes with Pd-Fe nanoparticles reactive sites,catalyst stability,particle aging,and regeneration[J].Environmental Science Technology,2007,41:7523-7529.
[13]DU Y P,ZHANG Y W,SUN L D,et al.Atomically efficient synthesis of self-assembled monodisperse and ultrathin lanthanide oxychloride nanoplates[J].Journal of the American Chemical Society,2009,131(9):3162-3163.
[14]WU Z J,MAO X K,ZI Q,et al.Mechanism and kinetics of sodium borohydride hydrolysis over crystalline nickel and nickel boride and amorphous nickel-boron nanoparticles[J].Journal of Power Sources,2014,268:596-603.
[15]GUELLA G,ZANCHETTA C,PATTON B,et al.New insights on the mechanism of palladium-catalyzed hydrolysis of sodium borohydride from 11B NMR measurements[J].Journal of Physical Chemistry B,2006,110(34):17024-17033.