-
寻求和利用可再生绿色清洁能源替代化石燃料,是解决能源与环境危机的重要途径。微生物燃料电池(microbial fuel cell, MFC)作为一种集污水处理与生物产电于一体的新型技术,以产电细菌为主体,可将化学能转化为电能,同时去除水体中的污染物[1-2]。电极材料是影响MFC性能的关键因素之一,也是MFC产电微生物的附着载体和生长场所[3]。因此,找到一种可供微生物大量附着和生长的载体,同时具有良好导电性能的材料至关重要。
MFC电极多采用碳质材料,拥有良好的生物相容性、导电性和化学稳定性[4]。碳质材料一般包括石墨烯、碳毡、碳布、生物炭等。其中石墨烯电极机械强度较好,但其材料表面相对光滑,不利于微生物附着,因而导致胞外电子传递效率低[5-6];碳毡电极柔韧性良好,但其在MFC运行时,由于材质较厚,生物膜会妨碍底物由外向内的扩散,影响对污染物的降解效率;碳布电极表面粗糙但机械强度较差,不适于投入大规模的实际工程应用中[7]。相比于传统电极材料,生物炭材料具有来源广泛、成本低廉、电化学性能较好、比表面积高和孔隙结构多等优点。2018年CHEN等[8]大麻槿秸秆通过简单的碳化处理制成MFC阳极,其电流密度达到了32.5 A·m−2,是对照组石墨棒电极的3倍,由此可见生物炭作为MFC电极材料是具有一定优势的。
据2020年中国统计年鉴统计,我国核桃栽培面积为5.54×1010 m²,约1.3×109株[9]。每年有大量的废弃核桃壳产生,如何有效处理这些固体废物,实现减量化和资源化是环境领域的研究热点。采用高温裂解法制备生物炭,再通过化学活化,可使其表面结构相对于碳基材料的平面结构更为粗糙,更有效的提升活性表面积[10-13]。常见的生物炭化学活化剂包括ZnCl2、HPO4、KOH等,其中ZnCl2活化制备的活性炭具有产率高、过渡孔发达、价廉易得等优点[14],JIANG等通过ZnCl2活化甘蔗渣发现,锌离子浓度越高,比表面积越大[15]。
目前,以改性核桃壳作为电极材料的研究鲜有报道。因此,本研究主要以改性核桃壳作为生物炭基电极材料,通过不同温度的碳化、不同浓度的ZnCl2活化、不同比例的材料复合制成微生物燃料电池电极,通过表征分析,考察不同制备方法制备出的材料的性能差异,分析其在MFC中产电性能的差异,以及最佳条件MFC去除污染物的能力,为微生物燃料电池的发展方向提供参考。
核桃壳生物炭电极在微生物燃料电池中的产电性能及其对污染物的去除性能
Electricity production and pollutant removal performance of walnut shell biochar electrode in microbial fuel cell
-
摘要: 微生物燃料电池(MFC)的电极材料是决定MFC性能的关键。本研究利用核桃壳生物炭制成MFC电极材料,对核桃壳生物炭基电极的制备条件、MFC的产电性能进行了探讨,利用比表面积分析、扫描电镜、拉曼光谱及电极电化学等方法对生物炭电极进行表征。结果表明: 最佳电极制备条件为活化时生物炭:氯化锌质量比5:3,真空煅烧温度600 ℃,生物炭:聚苯胺:热熔胶质量比5:1:4,在进水COD平均值为685 mg·L−1、氨氮平均值为38 mg·L−1、外电阻为1 000 Ω条件下,MFC的稳定输出电压为0.136 V,最大功率密度达到51 mW·m−3,内阻为762 Ω,运行7 d后,COD和氨氮的去除率分别可达到85%和88%,以上研究结果为制备有前景的MFC的电极材料提供了参考。Abstract: The electrode material is the key to determine the performance of microbial fuel cell (MFC). In this study, walnut shell biochar was used to prepare the MFC electrode. Both the preparation conditions of walnut shell biochar based electrode and MFC electricity production performance were discussed. The biochar electrode was characterized by specific surface area analysis scanning electron microscopy, Raman spectroscopy and electrochemistry. The experimental results showed that the optimum fabrication conditions were as follows: the mass ratio of biochar to zinc chloride was 5:3, the vacuum calcination temperature was 600 ℃, the mass ratio of biochar, polyaniline and hot melt glue was 5:1:4. At the average influent COD concentration of 685 mg·L−1, the average ammonia nitrogen concentration of 38 mg·L−1 and the external resistance of 1000 Ω, the stable output voltage of MFC was 0.136 V, the maximum power density reached 51 mW·m−3 and the internal resistance was 762 Ω. After 7 days of operation, the removal rates of COD and ammonia nitrogen could reach 85% and 88%, respectively. These results provide a reference for the preparation of the promising MFC electrode materials.
-
Key words:
- microbial fuel cell /
- walnut shell electrode /
- electricity generation /
- electrode /
- activization
-
表 1 BET测量时获得的比表面积、孔径和孔容
Table 1. Specific surface area, pore size and pore volume determined by BET measurement
生物炭/氯化锌质量比 比表面积/(m2·g−1) 孔径/nm 孔容/(cm3·g−1) 5:1 590 3.818 0.009 5:3 657 3.424 0.015 5:5 883 3.421 0.017 -
[1] GOWTHAMI P, JUNG H Y, SADHASIVAM T, et al. A comprehensive review on microbial fuel cell technologies: Processes, utilization, and advanced developments in electrodes and membranes[J]. Journal of Cleaner Production, 2019, 221: 598-621. doi: 10.1016/j.jclepro.2019.02.172 [2] LI W Y, LIU Y X, REN R P, et al. Research progress on removal of nitrogen in water and wastewater by microbial fuel cell[J]. Chemical Industry and Engineering Progress, 2019, 38(2): 1097-1106. [3] ZHANG K X, MA Z K, SONG H H, et al. Macroporous carbon foam with high conductivity as an efficient anode for microbial fuel cells[J]. International Journal of Hydrogen Energy, 2020, 45(21): 12121-12129. doi: 10.1016/j.ijhydene.2020.02.123 [4] CHEN J F, HU Y Y, ZHANG L H, et al. Bacterial community shift and improved performance induced by in situ preparing dual graphene modified bioelectrode in microbial fuel cell[J]. Bioresource Technology, 2017, 238: 273-280. doi: 10.1016/j.biortech.2017.04.044 [5] LV W, LING Z J, DENG Y Q, et al. Graphene-based materials for electrochemical energy storage devices: Opportunities and challenges[J]. Energy Storage Materials, 2016, 2: 107-138. doi: 10.1016/j.ensm.2015.10.002 [6] CAI T, MENG L J, CHEN G, et al. Application of advanced anodes in microbial fuel cells for power generation: A review[J]. Chemosphere, 2020, 248(c): 125985. [7] LOGAN B, CHENG S, WATSON V, et al. Graphite fiber brush anodes for increased power production in air-cathode microbial fuel cells[J]. Environmental Science & Technology, 2007, 41(9): 3341-3346. [8] CHEN S L, HE G H, HU X W, et al. A three-dimensionally ordered macroporous carbon derived from a natural resource as anode for microbial bioelectrochemical systems[J]. Chemsuschem, 2012, 5(6): 1059-1063. doi: 10.1002/cssc.201100783 [9] 邓金龙. 我国核桃生产现状及发展策略[J]. 林产工业, 2016, 43(10): 56-58. doi: 10.3969/j.issn.1001-5299.2016.10.014 [10] JUAN J L, GUZMAN, MERYEM O, et al. Performance of electro-spun carbon nanofiber electrodes with conductive poly(3, 4-ethylenedioxythiophene) coatings in bioelectrochemical systems[J]. Journal of Power Sources, 2017, 356: 331-337. doi: 10.1016/j.jpowsour.2017.03.133 [11] LI Y Y, ZHU L H, SHEN F, et al. Highly conductive microfiber of graphene oxide templated carbonization of nanofibrillated cellulose[J]. Advanced Functional Materials, 2014, 24(46): 7366-7372. doi: 10.1002/adfm.201402129 [12] KARTHIKEYAN R, WANG B, XUAN J, et al. Interfacial electron transfer and bioelectrocatalysis of carbonized plant material as effective anode of microbial fuel cell[J]. Electrochimica Acta, 2015, 157: 314-323. doi: 10.1016/j.electacta.2015.01.029 [13] RAJAPAKSHA A U, GAO B, ZHANG M, et al. Engineered/designer biochar for contaminant removal/immobilization from soil and water: Potential and implication of biochar modification[J]. Chemosphere, 2016, 148: 276-291. doi: 10.1016/j.chemosphere.2016.01.043 [14] LI D, WANG Y, YANG J, et al. Activation characteristics comparison of activated carbons prepared from biomass and lignite[J]. Journal of Chemical Industry, 2013, 64(9): 3338-3347. [15] SI W J, WU X J, XING W, et al. Bagasse-based nanoporous carbon for supercapacitor application[J]. Journal of Inorganic Materials, 2010, 26(1): 107-112. [16] SONG S R, ZHANG M C, XU X Y, et al. Isolation of a heterotrophic nitrification-aerobic denitrification strain and identification of its potential electricity generation ability in microbial fuel cells.[J]. Environmental Technology, 2021, 1: 21-25. [17] SING K S W, EVERETT D H, HAUL R A W, et al. Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (recommendations 1984)[J]. Pure and Applied Chemistry, 1985, 57(4): 603-619. doi: 10.1351/pac198557040603 [18] 王乐, 周娴娴, 陈良, 等. 核桃壳衍生活性炭孔结构的调控及其对锂硫电池性能的影响[J]. 太原理工大学学报, 2021, 52(6): 863-872. doi: 10.16355/j.cnki.issn1007-9432tyut.2021.06.003 [19] SONG H H, LI H, WANG H, et al. Chicken bone-derived N-doped porous carbon materials as an oxygen reduction electrocatalyst[J]. Electrochimica Acta, 2014, 147: 520-526. doi: 10.1016/j.electacta.2014.09.146 [20] YANG G H, LI X, WANG Y Y, et al. Three-dimensional interconnected network few-layered MoS2/N, S co-doped graphene as anodes for enhanced reversible lithium and sodium storage[J]. Electrochimica Acta, 2019, 293: 47-59. doi: 10.1016/j.electacta.2018.10.026 [21] 缺少内容 [22] LU M, QIAN Y J, YANG C C, et al. Nitrogen-enriched pseudographitic anode derived from silk cocoon with tunable flexibility for microbial fuel cells[J]. Nano Energy, 2017, 32: 382-388. [22]CHENG Z, DENG Y D, HU W B, et al. A review of electrolyte materials and compositions for electrochemical supercapacitors[J]. Chemical Society Reviews, 2015, 44(21): 7484-539. [23] HUTCHINSON A J, TOKASH J C, LOGAN B E. Analysis of carbon fiber brush loading in anodes on startup and performance of microbial fuel cells[J]. Journal of Power Sources, 2011, 196(22): 9213-9219. doi: 10.1016/j.jpowsour.2011.07.040 [24] ZHOU G, ZHOU Y, SHI H. Assessment of a novel overflow-type electrochemical membrane bioreactor (EMBR) for wastewater treatment, energy recovery and membrane fouling mitigation[J]. Bioresource Technology, 2015, 196: 648-655. doi: 10.1016/j.biortech.2015.08.032 [25] LIANG P, FANMZ, CAO X X, et al. Composition and measurement of the apparent internal resistance in microbial fuel cell[J]. Environmental Science, 2007, 28(8): 1894-1898. [26] 廖绍华, 杨晓梅, 黄毕生, 等. 氯化锌活化柚子皮制备生物炭及其对亚甲基蓝的吸附[J]. 大理大学学报, 2020, 5(12): 15-20. doi: 10.3969/j.issn.2096-2266.2020.12.003 [27] YE X F, ZHOU H J, YU X N, et al. Physiochemical properties and yields of corn-stalk-biochar under different pyrolyzed temperatures[J]. Journal of Plant Nutrients and Fertilizer, 2017, 23(5): 1268-1275. [28] WANG R F, WANG H, ZHOU T B, et al. The enhanced electrocatalytic activity of okara-derived N-doped mesoporous carbon for oxygen reduction reaction[J]. Journal of Power Sources, 2015, 274: 741-747. doi: 10.1016/j.jpowsour.2014.10.049