Preparation and adsorption-photocatalytic properties of Cu2O-PVA/nanocellulose composite
-
摘要: 为了改善氧化亚铜(Cu2O)的光催化性能,将Cu2O颗粒和聚乙烯醇(PVA)同时加入纳米纤维素(CNF)中,成功制备了具有三维(3D)多孔结构和丰富活性位点的功能化纤维素基气凝胶(Cu2O-PVA/CNF)。采用扫描电子显微镜、傅里叶变换红外光谱、X射线衍射仪、全自动比表面积、压缩测试对气凝胶样品进行了表征。以降解亚甲基蓝(MB)为模型污染物,评价了Cu2O-PVA/CNF复合催化剂的光催化性能,考察了6wt%Cu2O-PVA/CNF在不同初始浓度、不同催化剂用量及不同溶液pH条件下对MB光降解效率的影响。结果表明,三维多孔的纤维素气凝胶的使用提高了对MB的吸附能力,延长了对可见光的吸收。特别是在纤维素基体中掺杂的Cu2O在光照下激发出电子-空穴,增加了活性位点,从而提高了催化能力。6wt%Cu2O-PVA/CNF复合催化剂对MB的光降解率达到95.6%,远高于纯Cu2O的79.6%。Cu2O-PVA/CNF复合催化剂的光降解过程遵循表观准一级动力学模型。此外,与纯CNF气凝胶相比,PVA的加入使其压缩强度提高了4.4倍。该催化剂经5次光催化循环后再利用,对MB的可见光催化降解率仍能达到71.06%。这种Cu2O-PVA/CNF复合材料有利于用太阳辐射处理染料废水。Abstract: In order to improve the photocatalytic performance of cuprous oxide (Cu2O), Cu2O particles and polyvinyl alcohol (PVA) were added to nanocellulose (CNF) at the same time, and a functionalized cellulose-based aerogel (Cu2O-PVA/CNF) with three-dimensional (3D) porous structure and abundant active sites were successfully prepared by the exsitu method. The aerogel samples were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffractometer, automatic specific surface area, and compression test. Taking the degradation of methylene blue (MB) as a model pollutant, the photocatalytic performance of 6wt%Cu2O-PVA/CNF composite catalyst was evaluated, the effects of different initial concentrations, catalyst dosages and solution pH conditions on the photodegradation of MB were investigated. The results show that the use of the three-dimensional porous cellulose aerogel improves the adsorption capacity of MB and prolongs the absorption of visible light. In particular, Cu2O doped in the cellulose matrix excites electron-holes under light, which increases the active sites, thereby improving the catalytic ability. The photodegradation rate of 6wt%Cu2O-PVA/CNF composite catalyst to MB reaches 95.6%, which is much higher than 79.6% of pure Cu2O. The photodegradation process of Cu2O-PVA/CNF composite catalyst follows the apparent quasi-first order dynamics model. In addition, compared with pure CNF aerogel, the addition of PVA increases its compressive strength by 4.4 times. The catalyst is reused after 5 photocatalytic cycles, and the visible light catalytic degradation rate of MB can still reach 71.06%. The Cu2O-PVA/CNF composite material is beneficial to the treatment of dye wastewater by solar radiation.
-
Key words:
- nanocellulose /
- cuprous oxide /
- aerogel /
- dye adsorption /
- photocatalytic degradation
-
图 12 活性物质捕获剂对MB降解率的影响(a); 6wt%Cu2O-PVA/CNF (DMPO作为自由基捕获剂)的ESR光谱:在可见光照射下检测DMPO-•O2− (b)和DMPO-•OH (c)
Figure 12. Effect of active substance capture agent on MB degradation rate (a); ESR spectra of 6wt%Cu2O-PVA/CNF (DMPO as radical trapper): Detecting DMPO-•O2− (b) and DMPO-•OH (c) under visible light irradiation
BQ—Benzoquinone; IPA—Isopropyl alcohol; DMPO—Dimethyl pyridine-N-oxide
表 1 Cu2O-聚乙烯醇(PVA)/纳米纤维素(CNF)气凝胶的用量
Table 1. Amount of Cu2O-polyvinyl alcohol (PVA)/nanocellulose (CNF) aerogel
Sample CNF/g PVA/g Cu2O/g 2wt%Cu2O-PVA/CNF 5 5 0.1 4wt%Cu2O-PVA/CNF 5 5 0.2 6wt%Cu2O-PVA/CNF 5 5 0.3 8wt%Cu2O-PVA/CNF 5 5 0.4 表 2 CNF和Cu2O-PVA/CNF的比表面积和孔径结构参数
Table 2. Surface area and pore size structural parameters of CNF and Cu2O-PVA/CNF
Samples Specific
surface
area/(m2·g−1)Pore size/nm Total pore
volume/
(cm3·g−1)CNF 4.00 2.52 0.00250 2wt%Cu2O-PVA/CNF 14.00 6.23 0.02200 4wt%Cu2O-PVA/CNF 10.40 5.89 0.01500 6wt%Cu2O-PVA/CNF 6.91 5.44 0.00940 8wt%Cu2O-PVA/CNF 2.67 4.33 0.00380 表 3 Cu2O 和 Cu2O-PVA/CNF的去除率、速率常数和拟合系数r2
Table 3. Removal rate, rate constant and correlation coefficient afterfitting r2 of Cu2O and Cu2O-PVA/CNF
Samples Adsorption removal
rate/%Catalytic removal
rate/%Total removal
rate/%Κ/min−1 r2 Cu2O 10.1 69.5 79.6 0.0185 0.996 2wt%Cu2O-PVA/CNF 40.8 50.7 91.5 0.0243 0.983 4wt%Cu2O-PVA/CNF 45.0 47.0 92.0 0.0241 0.986 6wt%Cu2O-PVA/CNF 46.9 48.7 95.6 0.0311 0.991 8wt%Cu2O-PVA/CNF 40.7 42.4 83.2 0.0223 0.991 Notes: K—Catalytic efficiency; r2—Correlation coefficient after fitting. 表 4 不同溶液pH对亚甲基蓝(MB)脱色动力学模型的数据
Table 4. Data of the kinetic model of the decolonization of methylene blue (MB) in different solutions pH
pH R/(mg·L−1·min−1) r2 3 0.00347 0.993 5 0.02350 0.984 7 0.02860 0.988 9 0.02880 0.985 11 0.03760 0.962 Note: R—Rate constant. -
[1] ZULFIQAR M, SUFIAN S, BAHADAR A, et al. Surface-fluorination of TiO2 photocatalysts for remediation of water pollution: A review[J]. Journal of Cleaner Production,2021,317:128354. doi: 10.1016/j.jclepro.2021.128354 [2] ZHANG H, FANG Y. Temperature dependent photoluminescence of surfactant assisted electrochemically synthesized ZnSe nanostructures[J]. Journal of Alloys and Compounds,2019,781:201-208. doi: 10.1016/j.jallcom.2018.11.375 [3] 李佳欣, 高铭, 谭淋, 等. 静电纺丝纳米纤维膜材料吸附处理废水中污染物的研究进展[J]. 复合材料学报, 2022, 39(4): 1378-1394.LI Jiaxin, GAO Ming, TAN Lin, et al. Adsorption treatment of wastewater by electrospun nanofiber membranes: A review[J]. Acta Materiae Compositae Sinica, 2022, 39(4): 1378-1394(in Chinese). [4] YAGUB M T, SEN T K, AFROZE S, et al. Dye and its removal from aqueous solution by adsorption: A review[J]. Advances in Colloid and Interface Science,2014,209:172-184. doi: 10.1016/j.cis.2014.04.002 [5] SELINA H, MAJID E, KOLBRUN F H, et al. Direct membrane filtration for wastewater treatment and resource recovery: A review[J]. Science of the Total Environment,2020,710:136375. doi: 10.1016/j.scitotenv.2019.136375 [6] 申久英, 刘碧雯, 赵宇翔, 等. CuS-Bi2WO6/活性纳米碳纤维的制备及其光催化性能[J]. 复合材料学报, 2022, 39(3):1163-1172.SHEN Jiuying, LIU Biwen, ZHAO Yuxiang, et al. Preparation of CuS-Bi2WO6/activated carbon nanofiber and its photocatalytic performance[J]. Acta Materiae Compositae Sinica,2022,39(3):1163-1172(in Chinese). [7] THORBEN M, DENNIS H, MICHAEL S, et al. Electrochemical reactors for wastewater treatment[J]. ChemBioEng Reviews,2019,6(5):142-156. doi: 10.1002/cben.201900021 [8] CHEE Y T, PRETTY M B, KATRINA P, et al. Recent advancement of coagulation-flocculation and its application in wastewater treatment[J]. ACS Publications,2016,55(16):4363-4389. [9] 李婷婷, 李瑞雪, 马政, 等. 纤维素-海藻酸钠-海泡石多孔微球的制备及其对亚甲基蓝吸附性能[J]. 复合材料学报, 2021, 38(12):4273-4281.LI Tingting, LI Ruixue, MA Zheng, et al. Preparation of cellulose-sodium alginate-sepiolite porous bead and its application in adsorption of methylene blue[J]. Acta Materiae Compositae Sinica,2021,38(12):4273-4281(in Chinese). [10] PAOLA F, STEFANO C, ANTONIO T, et al. Porous aerogels and adsorption of pollutants from water and air: A review[J]. Molecules,2021,26(15):4440. doi: 10.3390/molecules26154440 [11] HAJAR M. Recent advances in aerogels for environmental remediation applications: A review[J]. Chemical Engineering Journal,2016,300:98-118. doi: 10.1016/j.cej.2016.04.098 [12] 林兆云, 戢德贤, 杨桂花, 等. 纤维素基金属纳米粒子复合催化剂的制备与应用[J]. 复合材料学报, 2022, 39(3):989-1000.LIN Zhaoyun, JI Dexian, YANG Guihua, et al. Preparation and application of cellulose-based metal nanoparticles composite catalysts[J]. Acta Materiae Compositae Sinica,2022,39(3):989-1000(in Chinese). [13] 邹静, 王正良, 佘跃惠. 生物纳米复合材料的合成及其在污水处理中的应用[J]. 复合材料学报, 2022, 39(4): 1534-1546.ZOU Jing, WANG Zhengliang, SHE Yuehui. Synthesis of bio-nano composite and its application in wastewater treatment[J]. Acta Materiae Compositae Sinica, 2022, 39(4): 1534-1546(in Chinese). [14] AZIMA A, KAM S L, SIEW X C, et al. Zinc oxide-filled polyvinyl alcohol-cellulose nanofibril aerogel nanocomposites for catalytic decomposition of an organic dye in aqueous solution[J]. Cellulose,2021,28:2241-2253. doi: 10.1007/s10570-021-03695-z [15] SHEN D Z, LIU J, GAN L H, et al. Green synthesis of Fe3O4/cellulose/polyvinyl alcohol hybride aerogel and its application for dye removal[J]. Journal of Polymers and the Environment,2018,26:2234-2242. doi: 10.1007/s10924-017-1116-0 [16] 吴树颖, 冯郁成, 张霄, 等. 氧化亚铜-纤维素复合材料的制备与应用进展[J]. 中国造纸, 2021, 40(9):81-92.WU Shuying, FENG Yucheng, ZHANG Xiao, et al. Progress in the preparation and application of cuprous oxide-cellulose composites[J]. China Pulp & Paper,2021,40(9):81-92(in Chinese). [17] 李卓豪, 陈秀婷, 李俊航, 等. Cu2O掺杂TiO2光催化降解亚甲基蓝的研究[J]. 应用化工, 2020, 49(12):3039-3042. doi: 10.3969/j.issn.1671-3206.2020.12.018LI Zhuohao, CHEN Xiuting, LI Junhang, et al. Study on photocatalytic degradation of methylene blue by Cu2O doped TiO2[J]. Applied Chemical Industry,2020,49(12):3039-3042(in Chinese). doi: 10.3969/j.issn.1671-3206.2020.12.018 [18] 龙丹, 周俊伶, 时洪民, 等. 氧化亚铜光催化剂性能提升及增强机制的研究进展[J]. 化工进展, 2019, 38(6):2756-2767.LONG Dan, ZHOU Junling, SHI Hongmin, et al. Advances in research on performance enhancement and enhancement mechanism of cuprous oxide photocatalyst[J]. Chemical Industry and Engineering Progress,2019,38(6):2756-2767(in Chinese). [19] SUBHEDAR A, BHADAURIA S, AHANKARI S, et al. Nanocellulose in biomedical and biosensing applications: A review[J]. International Journal of Biological Macromolecules,2021,166:587-600. doi: 10.1016/j.ijbiomac.2020.10.217 [20] NELE V, WOJCIECHOWSKI J P, ARMSTRONG J P K, et al. Tailoring gelation mechanisms for advanced hydrogel applications[J]. Advanced Functional Materials, 2020, 30(42): 2002759. [21] RASHMI S H, RAIZADA A, MADHU G M, et al. Influence of zinc oxide nanoparticles on structural and electrical properties of polyvinyl alcohol films[J]. Plastics, Rubber and Composites,2015,44(1):33-39. doi: 10.1179/1743289814Y.0000000115 [22] SELVI J, MAHALAKSHMI S, PARTHASARATHY V, et al. Optical, thermal, mechanical properties, and non-isothermal degradation kinetic studies on PVA/CuO nanocomposites[J]. Polymer Composites,2019,40(9):3737-3748. doi: 10.1002/pc.25235 [23] FAN J J, SHINDUKE I, WANG M Z, et al. Robust nanofibrillated cellulose hydro/aerogels from benign solution/solvent exchange treatment[J]. ACS Sustainable Chemistry & Engineering,2018,6(5):6624-6634. [24] TSUGUYUKI S, SATOSHI K, YOSHIHARU N, et al. Cellulose nanofibers prepared by TEMPO-mediated oxidation of native cellulose[J]. Biomacromolecules,2007,8(8):2485-2491. doi: 10.1021/bm0703970 [25] YANG H M, OUYANG J, TANG A D, et al. Electrochemical synthesis and photocatalytic property of cuprous oxide nanoparticles[J]. Materials Research Bulletin,2006,41(7):1310-1318. doi: 10.1016/j.materresbull.2006.01.004 [26] WU J, CARSON M J. Assembly of chitin nanofibers into porous biomimetic structures via freeze drying[J]. ACS Macro Letters,2014,3(2):185-190. doi: 10.1021/mz400543f [27] SATHISH M B, KELOTH B. Fabrication of multifunctional TANI/Cu2O/Ag nanocomposite for environmental abatement[J]. Scientific Reports,2020,10:1-16. doi: 10.1038/s41598-019-56847-4 [28] CHAN C H, CHIN H C, SARANI Z, et al. Cellulose nanofibrils: A rapid adsorbent for the removal of methylene blue[J]. RSC Advances,2015,5(24):18204-18212. doi: 10.1039/C4RA15754K