几种可作固相碳源的硝酸根吸附剂的制备及其性能
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摘要
研发具有既能吸附NO_3~-同时又能缓释碳源的材料对提高反硝化效率具有重要意义.本研究制备了3种不同的NO_3~-离子吸附剂:改性美人蕉(MCL)、改性稻秆(MRS)和改性花生壳(MPS),采用SEM、红外光谱和元素分析仪对其性能进行分析和表征,并考察了几种材料的NO_3~-吸附效果和释碳效果.研究结果表明,在20℃,pH值为6.72时,1 g·L~(-1) MCL、MRS和MPS对25 mg·L~(-1) NO_3~-的去除率分别可达56.5%、65.85%和65.72%;伪二级动力学方程能更好地描述吸附过程;Langmuir模型(R~2>0.99)能更好地拟合它们的等温吸附过程;MCL、MRS和MPS对NO_3~-的吸附量随温度升高而降低,在25℃下最大吸附量分别为27.17、29.85、29.59 mg·g~(-1);通过热力学计算,MCL、MRS和MPS对NO_3~-的吸附是放热、自发的过程;实验5 d后3种吸附剂的释碳量分别稳定在50、60、88 mg·(g·L·d)~(-1)左右.由此可见,3种吸附剂均具有作为反硝化固相碳源的潜力.
In order to improve the denitrification efficiency, it is important to develop new materials which can adsorb nitrate and release the carbon source slowly. Modified canna leaves(MCL), modified rice straw(MRS), and modified peanut shells(MPS) were prepared by chemical method as nitrate adsorbents. Physicochemical characteristics of those materials were analyzed by SEM, FTIR, and elementary analyzer. The performance of nitrate removal and carbon release of materials was investigated. The results showed that the removal rate of nitrate was respectively 56.5%, 65.85% and 65.72% by adding 1 g·L~(-1) MCL, MRS and MPS(initial concentration 25 mg·L~(-1); pH 6.72; temperature 20 ℃). The adsorption processes could be described by pseudo-second-order kinetic equation better. Isothermal adsorption processes of nitrate by MCL, MRS and MPS followed the Langmuir isotherm(R~2 > 0.99). Adsorption capacity of nitrate by MCL, MRS and MPS dropped with the increase of temperature. The maximum adsorption capacity of MCL, MRS and MPS was 27.17, 29.85 and 29.59 mg·g~(-1) at 25 ℃, respectively. Thermodynamic parameters calculation showed that adsorption of nitrate by MCL, MRS and MPS was all exothermic and spontaneous process. In addition, the carbon release rate reached 50, 60, and 88 mg·(g·L·d)~(-1) by MCL, MRS and MPS respectively after 5 days of experiment. Thus it can be seen that MCL, MRS and MPS could be used as solid carbon sources for intensifying heterotrophic denitrification.
In order to improve the denitrification efficiency, it is important to develop new materials which can adsorb nitrate and release the carbon source slowly. Modified canna leaves(MCL), modified rice straw(MRS), and modified peanut shells(MPS) were prepared by chemical method as nitrate adsorbents. Physicochemical characteristics of those materials were analyzed by SEM, FTIR, and elementary analyzer. The performance of nitrate removal and carbon release of materials was investigated. The results showed that the removal rate of nitrate was respectively 56.5%, 65.85% and 65.72% by adding 1 g·L~(-1) MCL, MRS and MPS(initial concentration 25 mg·L~(-1); pH 6.72; temperature 20 ℃). The adsorption processes could be described by pseudo-second-order kinetic equation better. Isothermal adsorption processes of nitrate by MCL, MRS and MPS followed the Langmuir isotherm(R~2 > 0.99). Adsorption capacity of nitrate by MCL, MRS and MPS dropped with the increase of temperature. The maximum adsorption capacity of MCL, MRS and MPS was 27.17, 29.85 and 29.59 mg·g~(-1) at 25 ℃, respectively. Thermodynamic parameters calculation showed that adsorption of nitrate by MCL, MRS and MPS was all exothermic and spontaneous process. In addition, the carbon release rate reached 50, 60, and 88 mg·(g·L·d)~(-1) by MCL, MRS and MPS respectively after 5 days of experiment. Thus it can be seen that MCL, MRS and MPS could be used as solid carbon sources for intensifying heterotrophic denitrification.
引文
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[23] 宋爱红,沈志强,周岳溪,等.以稻秆为固体碳源处理分散养猪冲洗水的试验研究[J].中国环境科学,2015,35(7):2052-2058.SONG A H, SHEN Z Q, ZHOU Y X, et al. Research on treating dispersed piggery rinse water using rice straw as solid carbon source [J]. China Environmental Science, 2015, 35(7):2052-2058(in Chinese).
[24] 武海涛.人工湿地反硝化脱氮外加碳源选择研究[D].杭州:浙江大学,2013,82.WU H T. Study on carbon source of denitrifying denitrification in constructed wetland [D]. Hangzhou: Zhejiang University, 2013,82(in Chinese).
[25] WANG B, HE S, WANG L, et al. Simultaneous nitrification and de-nitrification in MBR [J]. Water Science and Technology, 2005, 52 (10-11):435-442.
[26] 赵文莉,郝瑞霞,李斌,等.预处理方法对玉米芯作为反硝化固体碳源的影响[J].环境科学,2014,35(3):987-994.ZHAO W L, HAO R X, LI B, et al. Effect of pretreatment methods on corncob as carbon source for denitrification [J]. Environmental Science, 2014, 35(3):987-994(in Chinese).
[2] LAWRINENKO M, LAIRD D A. Anion exchange capacity of biochar [J]. Green Chemistry, 2015, 17(9):4628-4636.
[3] 安增莉,侯艳伟,蔡超,等.水稻秸秆生物炭对Pb(Ⅱ)的吸附特性[J].环境化学,2011,30(11):1851-1857.AN Z L, HOU Y W, CAI C, et al. Adsorption characteristics of Pb (II) on rice straw biochar [J]. Environmental Chemistry, 2011, 30(11): 1851-1857(in Chinese).
[4] MO W M, LI W, KANG C Y, et al. Studies on the dye adsorption studies on the dye adsorption by KCl and NaOH treated longan (Dimocarpus Longan Lour) fruit pericarp [J]. Fresenius Environmental Bulletin, 2012, 21(2):246-255.
[5] 莫蔚明,唐庆松,李旺,等.改性木薯秸秆对硝酸根的动态吸附及脱附[J].环境化学,2013,32(9):1668-1673.MO W M, TANG Q S, LI W, et al. Dynamic adsorption and desorption of nitrate by modified cassava straw [J]. Environmental Chemistry, 2013, 32(9): 1668-1673(in Chinese).
[6] 周品,谷麟,饶姗姗,等.秸秆-污泥复合基活性炭的制备及其对1,2,4-酸氧体的吸附特性[J].环境化学,2013,32(1):106-111.ZHOU P, GU L, RAO S S, et al. Preparation of sludge-straw based actived carbon and its adsorption for 1-diazo-2-naphtol-4-sulfonic acid [J]. Environmental Chemistry, 2013, 32(1): 106-111(in Chinese).
[7] 邵留,徐祖信,金伟,等.以稻草为碳源和生物膜载体去除水中的硝酸盐[J].环境科学,2009,30(5): 1414-1419.SHAO L, XU Z X, JIN W, et al. Nitrate removal from wastewater using rice straw as carbon source and biofilm carrier [J]. Environmental Science, 2009, 30(5): 1414-1419(in Chinese).
[8] 魏星,朱伟,赵联芳,等.植物秸秆作补充碳源对人工湿地脱氮效果的影响[J].湖泊科学,2010,22(6):916-922.WEI X, ZHU W, ZHAO L F, et al. Effect of the carbon of plant straw supplement in constructed artificial wetland on nitrogen removal [J]. Lake Science, 2010, 22(6): 916-922(in Chinese).
[9] 王宇.利用农业秸杆制备阴离子吸附剂及其性能的研究[D].济南:山东大学,2007.WANG Y. Preparation and properties of anionic adsorbents using agricultural straw [D]. Jinan:Shandong University, 2007(in Chinese).
[10] YANG X Y, Al-Duri B. Kinetic modeling of liquid-phase adsorption of reactive dyes on activated carbon [J]. Colloid and Interface Science, 2005, 287(1):25-34.
[11] LI X, LI B H, WU S, et al. Silica-based iminodiacetic acid functionalized adsorbent for Ni hydrometallurgical extraction of nickeliferous laterite [J]. Aiche Journal, 2012, 58(12):3818-3824.
[12] 谭优,刘云国,徐沛斌,等.水稻秸秆阴离子吸附剂的制备及其性能的研究[J].中国环境科学,2012,32(8):1456-1460.TAN Y, LIU Y G, XU P B, et al. Preparation and characterization of anion adsorbent derived from rice straw [J]. China Environmental Science, 2012, 32(8): 1456-1460(in Chinese).
[13] XU X, GAO Y, GAO B Y, YUE W W, et al. Adsorption studies of the removal of anions from aqueous solutions onto an adsorbent prepared from wheat straw [J]. Science China Chemistry, 2010, 53(6):1414-1419.
[14] WANG Y, GAO B Y, et al. Adsorption kinetics of nitrate from aqueous solutions onto modified wheat residue [J]. Colloids and Surfaces A: Physicochem. Eng. Aspects, 2007, 308(1-3):1-5.
[15] 丁洋,靖德兵,周连碧,等.板栗内皮对水溶液中镉的吸附研究[J].环境科学学报,2011,31(9):1933-1941.DING Y, JING D B, ZHOU L B, et al. The adsorption of aquatic cadmium(II) by chestnut inner shell [J]. Acta Scientiae Circumstantiae, 2011, 31(9): 1933-1941(in Chinese).
[16] 马锋锋,赵保卫.玉米芯生物炭吸附水中对硝基苯酚的特性[J].环境化学,2017,36(4):898-906.MA F F, ZHAO B W. Adsorption characteristics of p-nitrophenol in aqueous solution by corncob biochar [J]. Environmental Chemistry, 2017, 36(4): 898-906(in Chinese).
[17] EREN Z, ACAR FN. Adsorption of Reactive Black 5 from an aqueous solution: Equilibrium and kinetic studies [J]. Desalination, 2006, 194(123):1-10.
[18] YAO Y, GAO B, CHEN J, et al. Engineered carbon (biochar) prepared by direct pyrolysis of Mg-accumulated tomato tissues: characterization and phosphate removal potential [J]. Bioresource Technology, 2013, 138:8-13.
[19] 王博,曲乾,鲁子敬,等.改性水生植物对水体硝酸根、磷酸根的吸附效应[J].生态科学,2017,36(4):108-113.WANG B, QU Q, LU Z J, et al. Removal of nitrate (NO-3) and phosphate (PO) by modified straws prepared from reeds [J]. Ecological Science, 2017, 36(4):108-113(in Chinese).
[20] 武丽君,王朝旭,张峰,等.玉米秸秆和玉米芯生物炭对水溶液中无机氮的吸附性能[J].中国环境科学,2016,36(1):74-81.WU L J, WANG C X, ZHANG F, et al. The adsorption characters of inorganic nitrogen in aqueous solution by maize straw and corncob-derived biochars [J]. China Environmental Science, 2016, 36(1):74-81(in Chinese).
[21] 张建宇,钟金魁,赵保卫,等.棉花秸秆生物炭对水中硫酸根离子的吸附特性[J].环境化学,2017,36(11):2488-2497.ZHANG J Y, ZHONG J K, ZHAO B W, et al. Adsorption characteristics of sulfate ion onto cotton stalks biochar in aqueous solution [J]. Environmental Chemistry, 2017, 36(11): 2488-2497(in Chinese).
[22] 赵联芳,朱伟,高青.补充植物碳源提高人工湿地脱氮效率[J].解放军理工大学学报自然科学版,2009,10(6):644-648.ZHAO L F, ZHU W, GAO Q. Improving nitrogen removal of constructed wetlands by supplying plant carbon [J]. Journal of PLA University of Science and Technology (Natural Science Edition), 2009, 10(6):644-648(in Chinese).
[23] 宋爱红,沈志强,周岳溪,等.以稻秆为固体碳源处理分散养猪冲洗水的试验研究[J].中国环境科学,2015,35(7):2052-2058.SONG A H, SHEN Z Q, ZHOU Y X, et al. Research on treating dispersed piggery rinse water using rice straw as solid carbon source [J]. China Environmental Science, 2015, 35(7):2052-2058(in Chinese).
[24] 武海涛.人工湿地反硝化脱氮外加碳源选择研究[D].杭州:浙江大学,2013,82.WU H T. Study on carbon source of denitrifying denitrification in constructed wetland [D]. Hangzhou: Zhejiang University, 2013,82(in Chinese).
[25] WANG B, HE S, WANG L, et al. Simultaneous nitrification and de-nitrification in MBR [J]. Water Science and Technology, 2005, 52 (10-11):435-442.
[26] 赵文莉,郝瑞霞,李斌,等.预处理方法对玉米芯作为反硝化固体碳源的影响[J].环境科学,2014,35(3):987-994.ZHAO W L, HAO R X, LI B, et al. Effect of pretreatment methods on corncob as carbon source for denitrification [J]. Environmental Science, 2014, 35(3):987-994(in Chinese).