Adsorption of methylene blue by graphene oxide/polyvinyl alcoholaerogels with different oxidation degrees
-
摘要: 氧化石墨烯(GO)对水中染料有着优异的吸附性能,但其氧化程度对复合材料吸附性能和机制的影响还未被充分研究。采用Hummer法,制备3种不同氧化程度的氧化石墨烯,与聚乙烯醇(PVA)复合得到三种GO/PVA气凝胶。利用红外光谱(FTIR)、元素分析(EA)和热重分析(TG)分析了3种GO的氧化程度;以亚甲基蓝(MB)为模拟污染物,通过静态吸附实验考察了GO氧化程度对GO/PVA气凝胶在不同溶液pH、吸附时间、初始浓度下对MB吸附性能的影响。通过吸附动力学模型、吸附等温线模型和吸附热力学模型探究了GO氧化程度对GO/PVA气凝胶吸附机制的影响。研究结果表明:GO/PVA气凝胶对MB的吸附行为受pH影响较小;提高GO的氧化程度可以明显提升GO/PVA气凝胶的吸附容量和吸附速度,GO氧化程度的提高增加了气凝胶上的吸附位点,有利于吸附。此外,GO氧化程度对GO/PVA气凝胶的吸附机制无明显影响。Abstract: Graphene oxide (GO) has excellent adsorption performance for dyes in water, but the effect of its oxidation degree on the adsorption performance and mechanism of composite materials has not been fully studied. Three kinds of graphene oxide (GO) with different oxidation degrees were synthesized by the Hummers and then compounded with polyvinyl alcohol (PVA) to synthesize three kinds of GO/PVA aerogels. The oxidation degree of GO was characterized by infrared spectroscopy (FTIR), elemental analysis (EA) and thermogravimetric analysis (TG). Using methylene blue (MB) as a simulated pollutant, the effect of GO oxidation degree of GO/PVA aerogels on MB adsorption performance under different solution pH, adsorption time and initial concentration was investigated through static adsorption experiments. The absorption mechanism of GO/PVA aerogels had been explored by adsorption kinetics model, model of adsorption isotherm and adsorption thermodynamic model. The results show that the adsorption behavior of GO/PVA aerogels on MB is slightly affected by pH. Increasing the oxidation degree of GO can significantly improve the adsorption capacity and adsorption speed of GO/PVA aerogels. And the adsorption sites on aerogel can be increase by improving the oxidation degree of GO , which is conducive to adsorption. In addition, the degree of GO oxidation has no obvious effect on the adsorption mechanism of GO/PVA aerogels.
-
Key words:
- graphene oxide /
- polyvinyl alcohol /
- aerogel /
- adsorption /
- methylene blue
-
表 1 不同氧化程度GO的元素分析结果
Table 1. Elemental analysis of GO with different oxidation degrees
Label C/wt% H/wt% O/wt% GO-1 65.11 5.68 29.21 GO-2 59.24 6.67 34.09 GO-3 58.31 7.21 34.48 表 2 GO/PVA气凝胶吸附MB的准一级和准二级动力模型参数
Table 2. Pseudo-first-order and pseudo-second-order model parameters for MB adsorption by GO/PVA aerogels
Aerogel Pseudo-first-order Pseudo-second-order qe(cal)/(mg·g−1) K1/min−1 R2 qe(cal)/(mg·g−1) K2/(g(mg·min)-1) R2 GO/PVA-1 57.26 0.0044 0.9099 77.52 0.00043 0.9992 GO/PVA-2 64.48 0.0057 0.9840 90.91 0.00024 0.9999 GO/PVA-3 38.65 0.0078 0.9589 91.74 0.00065 0.9949 Notes: K1,K2—Pseudo-first-order kinetic constant and pseudo-second-order kinetic constant; qe(cal)—Calculation amount of MB removed per unit mass of adsorbent. 表 3 不同温度下GO/PVA气凝胶吸附MB的Langmuir和Freundlich等温吸附模型参数
Table 3. Langmuir and Freundlich isotherm adsorption model parameters for MB adsorption by GO/PVA aerogels at different temperatures
Aerogel T/K Langmuir isotherm Freundlich isotherm qmax/(mg·g−1) KL/(L·mg−1) R2 Kf/(L·mg−1) n R2 GO/PVA-1 293.15 80.97 0.21 0.9934 20.36 3.17 0.8682 303.15 76.51 0.24 0.9983 17.24 2.91 0.8159 313.15 73.86 0.15 0.9984 13.91 2.71 0.8091 GO/PVA-2 293.15 94.34 1.93 0.9999 40.23 4.02 0.6667 303.15 92.59 0.90 0.9998 31.90 3.45 0.8039 313.15 90.91 0.24 0.9985 20.42 2.79 0.8564 GO/PVA-3 293.15 100.00 2.88 0.9999 43.88 4.17 0.7662 303.15 94.34 1.43 0.9999 35.95 3.64 0.7737 313.15 92.68 0.34 0.9999 23.87 2.93 0.8826 Notes: qmax—Langmuir adsorption maximum; KL—Langmuir coefficient of distribution of the adsorption; KF—Freundlich coefficient of distribution of the adsorption; n—Freundlich isotherm constant. 表 4 GO/PVA气凝胶对MB吸附过程的热力学参数
Table 4. Thermodynamic dynamic parameters of the MB adsorption process onto GO/PVA aerogels
Aerogel T/K ∆G/(kJ·mol−1) ∆H/(kJ·mol−1) ∆S/(J·mol−1·K−1) R2 GO/PVA-1 293.13 −10.86 −30.91 −88.89 0.8894 303.15 −9.77 313.15 −6.72 GO/PVA-2 293.13 −6.51 −35.70 −99.59 0.9994 303.15 −5.48 313.15 −4.52 GO/PVA-3 293.13 −12.62 −82.89 −239.29 0.9867 303.15 −10.61 313.15 −7.82 Notes: ∆G—Gibbs free energy variation of the adsorption process; ∆H—Enthalpy change of the adsorption process; ∆S—Entropy change of the adsorption process. -
[1] 杨二帅, 蔡晓君, 周梅, 等. 重金属废水的处理技术研究[J]. 当代化工, 2018, 47(1):167-170. doi: 10.3969/j.issn.1671-0460.2018.01.043YANG E S, CAI X J, ZHOU M, et. al. Study on treatment technologies of heavy metal wastewater[J]. Contemporary Chemical Industry,2018,47(1):167-170(in Chinese). doi: 10.3969/j.issn.1671-0460.2018.01.043 [2] BAI H, ZAN X, JUAY J, et al. Hierarchical heteroar-chitectures functionalized membrane for high efficientwater purification[J]. Journal of Menbrane Science,2015,475:245-251. doi: 10.1016/j.memsci.2014.10.036 [3] WILLNER M R, VIKESLAND P J, et al. Nanomaterial enabled sensors for environmental contaminants[J]. Journal of Nanobiotechnology,2018,16(1):95. doi: 10.1186/s12951-018-0419-1 [4] 毕玉玺, 凌辉, 唐振平, 等. 磁性介孔TiO2/氧化石墨烯复合材料的制备及其对U(Ⅵ)的吸附[J]. 复合材料学报, 2019, 36(9):2176-2186.BI Y X, LING H, TANG Z P, et al. Preparation of magnetic mesoporous TiO2/graphene oxide composites and their adsorption for U(Ⅵ)[J]. Acta Materiae Compositae Sinica,2019,36(9):2176-2186(in Chinese). [5] CHENG Z, LIAO J, HE B, et al. One-step fabrication of graphene oxide enhanced magnetic composite gel for highly efficient dye adsorption and catalysis[J]. ACS Sustainable Chemistry & Engineering,2015,3(7):1677-1685. [6] LI Y H, DU Q J, LIU T H, et, al. Comparative study of methylene blue dye adsorption onto activated carbon, graphene oxide, and carbon nanotubes[J]. Chemical Engineering Research & Design,2013,92(2):361-368. [7] SHARMA P, DAS M R, et al. Removal of a cationic dye from aqueous solution using graphene oxide nanosheets: Investigation of Adsorption[J]. Journal of Chemical and Engineering Data,2013,58(1):151-158. doi: 10.1021/je301020n [8] RAMESHA G K, KUMARA A V, MURALIDHARA H B, et al. Graphene and graphene oxide as effective adsorbents toward anionic and cationic dyes[J]. Journal of Colloid and Interface Science,2011,361(1):270-277. doi: 10.1016/j.jcis.2011.05.050 [9] ERSAN G, KAYA Y, APUL O G, et al. Adsorption of organic contaminants by graphene nanosheets, carbon nanotubes and granular activated carbons under natural organic matter preloading conditions[J]. Science of the Total Environment,2016,565:811-817. doi: 10.1016/j.scitotenv.2016.03.224 [10] PERREAULT F, DEFARIA A F, ELIMELECH M, et al. Environmental applications of graphene-based nanomaterials[J]. Chemical Society Reviews,2015,44(16):5861-5896. doi: 10.1039/C5CS00021A [11] ERSAN G, APUL O G, PERREAULT F, et al. Adsorption of organic contaminants by graphene nanosheets: A review[J]. Water Research,2017,126:385-398. doi: 10.1016/j.watres.2017.08.010 [12] WANG J, CHEN B L, XING B S, et, al. Wrinkles and folds of activated graphene nanosheets as fast and efficient adsorptive sites for hydrophobic organic contaminants[J]. Environmental Science & Technology,2016,50(7):3798-3808. [13] CHEN X X, CHEN B L, et, al. Macroscopic and spectroscopic investigations of the adsorption of nitroaromatic compounds on graphene oxide, reduced graphene oxide, and graphene nanosheets[J]. Environmental Science & Technology,2015,49(10):6181-6189. [14] AMADEI C A, MONTESSORI A, KADOW J P, et, al. Role of oxygen functionalities in graphene oxide architectural laminate subnanometer spacing and water transport[J]. Environmental Science & Technology,2017,51(8):4280-4288. [15] COMPTON O C, NGUYEN S T, et, al. Graphene oxide, highly reduced graphene oxide, and graphene: Versatile building blocks for carbon-based materials[J]. Small,2010,6(6):711-723. doi: 10.1002/smll.200901934 [16] HAN Y, XUE T, ZHEN Y, et al. Effects of the oxidation degree of graphene oxide on the adsorption of methylene blue[J]. Journal of Hazardous Materials,2014,268(15):191-198. [17] 林本兰, 吴兰兰, 崔升, 等. 新型重金属离子吸附剂的研究进展[J]. 材料导报, 2015, 29(19):18-23.LIN B L, WU L L, CUI S, et al. Research progress of novel adsorbents of heavy metal ions[J]. Materials Reports,2015,29(19):18-23(in Chinese). [18] ALHWAIGE A A, HERBERT M M, ALHASSAN S M, et al. Laponite/multigraphene hybrid-reinforced poly(vinyl alcohol) aerogels[J]. Polymer,2016,91:180-186. [19] XIAO J, ZHANG J, LV W, et al. Multifunctional gr-aphene/poly(vinyl alcohol) aerogels: In situ hydrothermal preparation and applications in broad-spectrum adsorption for dyes and oils[J]. Carbon,2017,123:354-363. [20] HUMMERS W S, OFFEMAN R E. Preparation of graphitic oxide[J]. Journal of the American Chemical,1958,80(6):1339. doi: 10.1021/ja01539a017 [21] DEY R S, HAJRA S, SAHU R K, et al. A rapid room temperature chemical route for the synthesis of graphene: Metal-mediated reduction of graphene oxide[J]. Chemical Communications,2012,48(12):1787. doi: 10.1039/c2cc16031e [22] FENG Y, FENG N, DU G, et al. A green reduction of graphene oxide via starch-based materials[J]. RSC Advances,2013,3(44):21466. doi: 10.1039/c3ra43025a [23] PARK S, RUOFF R S, et al. Chemical methods for the production of graphenes[J]. Nature Nanotechnology,2009,4(4):217-224. doi: 10.1038/nnano.2009.58 [24] SHEN J, HU Y, SHI M, et al. Fast and facile preparation of graphene oxide and reduced graphene oxide nanoplatelets[J]. Chemistry of Materials,2009,21(15):3514-3520. doi: 10.1021/cm901247t [25] 唐振平, 毕玉玺, 刘迎九等. 氧化石墨烯/有机改性膨润土复合材料的制备及其对Cd (Ⅱ) 的吸附[J]. 复合材料学报, 2018, 35(11):3196-3204.TANG Z P, BI Y X, LIU Y J, et al. Preparation of graphene oxide/organo-modified bentonite composites and their adsorption on Cd (Ⅱ)[J]. Acta Materiae Compositae Sinica,2018,35(11):3196-3204(in Chinese). [26] LI Q, LI Y H, MA X M, et al. Filtration and adsorption properties of porous calcium alginate membranefor methylene blue removal from water[J]. Chemical Engineering Journal,2017,316:623-630. doi: 10.1016/j.cej.2017.01.098 [27] 王磊, 白成玲, 朱振亚. 氧化石墨烯/海藻酸钠复合膜对Pb(Ⅱ)的吸附性能和机制[J]. 复合材料学报, 2020, 37(3):195-203.WANG L, BAI C L, ZHU Z Y. Adsorption properties and mechanism of Pb(Ⅱ) adsorbed by graphene oxide/sodium alginate composite membrane[J]. Acta Materiae Compositae Sinica,2020,37(3):195-203(in Chinese). [28] 郭成, 郝军杰, 李明阳, 等. 海藻酸钠/聚乙烯亚胺凝胶球的合成及对Cr(Ⅵ)的吸附性能和机制[J]. 复合材料学报, 2021, 38(7):2140-2151.GUO C, HAO J J, LI M Y, et al. Adsorption of Cr(Ⅵ) on polyethyleneimine grafted porous sodium alginate beads and its mechanistic study[J]. Acta Materiae Compositae Sinica,2021,38(7):2140-2151(in Chinese).