埃洛石/g-C_3N_4-Cu_(2+1)O催化剂的制备及催化性能研究
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摘要
文章以埃洛石(HNTs)、g-C_3N_4和硝酸铜为原料,一步合成了埃洛石/g-C_3N_4-Cu_(2+1)O催化剂。采用X射线衍射仪(XRD)、扫描电镜(SEM)、比表面积测定仪(BET)、程序升温还原(TPR)对催化剂进行了表征。研究了埃洛石/g-C_3N_4-Cu_(2+1)O对结晶紫的吸附性能、光催化降解性能和催化氧化CO性能。结果表明,将Cu_(2+1)O负载到埃洛石和g-C_3N_4的表面能显著地改善Cu_(2+1)O的分散性,减小Cu_(2+1)O的粒径和增强Cu_(2+1)O的热稳定性。当埃洛石、g-C_3N_4和Cu_(2+1)O的质量之比为5∶10∶4时,催化剂具有最优的光催化和低温催化活性。在最优条件下,该催化剂对结晶紫的吸附率为58.64%;添加6‰的H2O2水后,对结晶紫的降解率为97.53%。在温度为200℃时,催化剂连续催化氧化CO 12 h时,CO的转化率仍为92.5%。催化剂具有较好催化活性的原因可能是催化剂中的g-C_3N_4和Cu_(2+1)O存在较强的协同作用。另外,催化剂具有较大的比表面积,Cu_(2+1)O在埃洛石/g-C_3N_4上较好的分散性和较小的Cu_(2+1)O粒径也能显著增强催化剂的催化活性。
A novel catalyst used for treatment of dyestuff wastewater was developed in a bench scale experiment. Preparation of the catalyst involved processes of one-step synthesis of a, halloysite/g-C_3N_4-Cu_(2+1)O, with halloysite, g-C_3N_4 and cupric nitrate as materials, and characterization of the catalyst by using XRD, SEM, BET(Brunauer-Emmett-Teller) and TPR(temperature-programmed reduction). And the adsorption of crystal violet onto the catalyst(halloysite/g-C_3N_4-Cu_(2+1)O) and the performances of the catalyst's photocatalytic degradation and catalytic oxidation of CO were investigated. The results of the experiment showed that the dispersibility of Cu_(2+1)O was improved and thermo-stability of Cu_(2+1)O was strengthened; when the mass ratio of halloysite to g-C_3N_4 and to Cu_(2+1)O was 5∶10∶4, the catalyst behaved in the best performances in terms of photo-catalytic activity and low-temperature catalytic activity; the degradation rate of crystal violet can reach up to 97.53% using this catalyst with the addition of 6‰ H2 O2 when the phtocatalytic reaction run for 50 min. Meanwhile, the catalyst maintained CO conversion rate up to 92.5% when the temperature was at 200 ℃ and the continuous catalytic oxidation of CO kept for 12 h.In conclusion, it was found that the strong adsorption and catalytic capacities of halloysite/g-C_3N_4-Cu_(2+1)O were likely attributed to the synergetic effects existed between the π-orbital of g-C_3N_4 and d-orbital of Cu_(2+1)O. Besides, catalytic activity was enhanced owing to the catalyst's larger specific surface area and improved dispersibility and tiny size of particles of Cu_(2+1)O.
A novel catalyst used for treatment of dyestuff wastewater was developed in a bench scale experiment. Preparation of the catalyst involved processes of one-step synthesis of a, halloysite/g-C_3N_4-Cu_(2+1)O, with halloysite, g-C_3N_4 and cupric nitrate as materials, and characterization of the catalyst by using XRD, SEM, BET(Brunauer-Emmett-Teller) and TPR(temperature-programmed reduction). And the adsorption of crystal violet onto the catalyst(halloysite/g-C_3N_4-Cu_(2+1)O) and the performances of the catalyst's photocatalytic degradation and catalytic oxidation of CO were investigated. The results of the experiment showed that the dispersibility of Cu_(2+1)O was improved and thermo-stability of Cu_(2+1)O was strengthened; when the mass ratio of halloysite to g-C_3N_4 and to Cu_(2+1)O was 5∶10∶4, the catalyst behaved in the best performances in terms of photo-catalytic activity and low-temperature catalytic activity; the degradation rate of crystal violet can reach up to 97.53% using this catalyst with the addition of 6‰ H2 O2 when the phtocatalytic reaction run for 50 min. Meanwhile, the catalyst maintained CO conversion rate up to 92.5% when the temperature was at 200 ℃ and the continuous catalytic oxidation of CO kept for 12 h.In conclusion, it was found that the strong adsorption and catalytic capacities of halloysite/g-C_3N_4-Cu_(2+1)O were likely attributed to the synergetic effects existed between the π-orbital of g-C_3N_4 and d-orbital of Cu_(2+1)O. Besides, catalytic activity was enhanced owing to the catalyst's larger specific surface area and improved dispersibility and tiny size of particles of Cu_(2+1)O.
引文
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[3]岳琳.VOCs催化反应过程与反应机理研究现状[J].江汉大学学报:自然科学版,2014,42(4):9-15.Yue Lin.Research of volatile organic compounds catalytic oxidation process and mechanism[J].Journal of Jianghan University:Nat Sci Ed,2014,42(4):9-15.
[4]Wu G,Guan N,Li L.Low temperature CO oxidation on Cu–Cu2O/Ti O2catalyst prepared by photodeposition[J].Catalysis Science&Technology,2011,1(4):601-608.
[5]赵福真,曾鹏辉,季生福.CuxCe(1-x)O(2-x)/SBA-15/堇青石整体式催化剂及其CO催化氧化性能[J].无机化学学报,2013,29(4):753-759.Zhao Fuzhen,Zeng Penghui,Ji Shengfu.Preparation,characterization and CO catalytic oxidation performance of CuxCe(1-x)O(2-x)/SBA-15/cordierite monolithic catalysts[J].Chinese Journal of Inorganic Chemistry,2013,29(4):753-759.
[6]Augugliaro V,Baiocchi C,Prevot A B,et al.Azo-dyes photocatalytic degradation in aqueous suspension of Ti O under solar irradiation[J].Chemosphere,2002,49(10):1223-1230.
[7]徐杰,张丽惠,鲁云,等.累托石/δ-Mn O2颗粒吸附剂的制备及其应用研究[J].环境科学与技术,2017,40(9):43-49.Xu Jie,Zhang Lihui,Lu Yun,et al.The preparation of rectories/δ-Mn O2 spherical particle adsorbents and its applied research[J].Environmental Science&Technology,2017,40(9):43-49.
[8]任南琪,周显娇,郭婉茜,等.染料废水处理技术研究进展[J].化工学报,2013,64(1):84-94.Ren Nanqi,Zhou Xianjiao,Guo Wanqian,et al.A review on treatment methods of dye wastewater[J].CIESC Journal,2013,64(1):84-94.
[9]徐杰,付林晨,郑建东,等.改性累托石负载Zn-Ti O2复合催化剂的制备及其光催化性能的研究[J].环境污染与防治,2017,39(1):88-92.Xu Jie,Fu Lincheng,Zheng Jiandong,et al.Preparation and photocatalysis performance study of modified rectories as support to load Zn-Ti O2composite catalysis[J].Environmental Pollution and Control,2017,39(1):88-92.
[10]李洁,姚超,张珊,等.δ型二氧化锰/埃洛石的制备及其对亚甲基蓝的吸附性能[J].硅酸盐学报,2014,42(2):241-247.Li Jie,Yao Chao,Zhang Shan,et al.Preparation ofδ-type manganese dioxide/halloysite composites and their adsorption properties for methylene bule[J].Journal of the Chinese Ceramic Society,2014,42(2):241-247.
[11]李长玉,刘守新,马跃.可见光响应Cu-Cu(2+1)O复合材料的水热法一步合成[J].物理化学学报,2009,25(8):1555-1560.Li Changyu,Liu Shouxin,Ma Yue.Preparation of visiblelight response Cu-Cu2O composites by a one-step hydrothermal method[J].Acta Phys-Chim Sin,2009,25(8):1555-1560.
[12]吴欢文.Cu2O(111)表面电子结构性质及CO2在此表面的吸附与活化的量子化学研究[D].南昌:南昌大学,2012.Wu Huanwen.Cu2O(111)Surface Electron Structure Properties and CO2Adsorption and Activation of Quantum Chemistry on Their Surface[D].Nanchang:Nanchang University,2012.
[13]陈金毅,李念,李晶,等.交联累托石/Cu O2纳米复合材料的制备及可见光催化性能[J].物理化学学报,2011,27(4):932-938.Chen Jingyi,Li Nian,Li Jing,et al.Synthesis and visible light photocatalytic activity of cross-linked sodium rectorite/Cu2O nanocomposites[J].Acta Phys-Chim Sin,2011,27(4):932-938.
[14]Shi H,Yu K,Wang Y,et al.Shape evolution,photoluminescence and degradation properties of novel Cu2O micro/nanostructures[J].Applied Physics A,2012,108(3):709-717.
[15]Li Z,Zhang Z.Tetrafunctional Cu2S thin layers on Cu2O nanowires for efficient photoelectrochemical water splitting[J].Nano Research,2017,58(4):1-11.
[16]Xu H,Miao B,Zhang M,et al.Mechanism of C-C and C-H bond cleavage in ethanol oxidation reaction on Cu2O(111):a DFT-D and DFT+U study[J].Physical Chemistry Chemical Physics Pccp,2017,19(38):2621-2622.
[17]Baber A E,Yang X,Kim H Y,et al.Stabilization of catalytically active Cu+surface sites on titanium-copper mixed-oxide films[J].Angewandte Chemie International Edition,2014,53(12):5336–5340.