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竹柳生物炭及负载MnO2的复合材料对土霉素的吸附和 催化降解性能研究
冯丽蓉
Subtype硕士
2020-05-23
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name工程硕士
Keyword生物炭,水产养殖水体,吸附,催化降解,土霉素
Abstract这项研究针对养殖水体中抗生素的大量添加导致水体严重污染这一问题,旨在通过筛选低成本的生物炭并改善其吸附和催化性能,开发可用于治理水体抗生素的具有成本效益的技术。具体采用限氧和曝氧法制备得到多种生物炭材料,通过理化性质表征和批吸附试验评估多种生物炭的吸附效果,对材料进行初步筛选。然后以该优选生物炭为载体和催化剂,探索了纳米二氧化锰(nano MnO2)-生物炭复合材料以及生物炭-过氧单硫酸盐(PMS)系统吸附、降解OTC的性能和机制。主要研究结论如下: (1)曝氧竹柳生物炭具有最大的比表面积(262.2 m2/g)和含碳量(60.30%),最低的H/C值,对两种抗生素的吸附性能最优。单一实验浓度(50 mg/L)下,其对土霉素(OTC)和磺胺甲恶唑(SMX)的吸附量分别达到11.98和10.12 mg/g。限氧芦苇生物炭和限氧棉杆生物炭也展现出了较强的抗生素吸附量。结合理化特性和吸附结果来看,对于芦苇、棉杆两种材料更适宜在限氧条件下制备,而竹柳更适宜在曝氧条件下制备。在中性及偏酸性pH下,π-π 电子给受体(electron donor-acceptor,EDA)相互作用是限氧、曝氧竹柳炭吸附OTC和SMX的主要机理。pH 8–10条件下,曝氧竹柳炭对OTC的吸附得益于生物炭与OTC之间的静电吸附,而孔隙填充可能对曝氧竹柳炭吸附SMX起到促进作用。 (2)随着nMnO2负载量的增加(纳米二氧化锰-BC的质量比为1:40,1:20,1:10),nMnO2-BC复合材料(MBC)的C、N含量下降,O、灰分含量增加。根据Langmuir模型的拟合结果,MBC对OTC的最大吸附量达到292.53(MBC40:1),360.50(MBC20:1)和383.39 mg/g(MBC10:1),分别比BC(14.56 mg/g)高出19、24和25倍。MBC20在pH=5时的OTC吸附量最大,且受水体NaCl(2,10 mM)和溶解性有机质(NOM,0–20 mg L-1)的影响较小,NaHCO3的加入增强了其对OTC的去除效果(络合了溶液中的Mn2+)。OTC的降解过程伴随着Mn2+的释放,在pH=5下反应24小时后,OTC降解率为58.5%,Mn2+释放量达到2.97 mg L-1。因而,OTC的去除是被MBC20吸附和被nMnO2降解的综合结果。生物炭与OTC之间的π-π EDA相互作用促进了MBC20对OTC的吸附,nMnO2则在去除过程中充当了氧化剂。 (3)BC具有优异的PMS催化活性。实验OTC剂量(300 mL,30 mg/L)下,BC-PMS系统去除OTC较佳的工艺条件为:pH=8.0–9.0,BC投加量为0.33 g/L,PMS投加量为10 µM。在此条件下,BC-PMS系统对OTC的去除率约为76.0%。该系统的OTC降解过程受Cl-和腐殖质的影响较小,而NaHCO3的加入提高了pH、加快了OTC的降解进程。BC-PMS系统降解OTC的过程是由自由基效应和非自由基过程共同促进的。其中,SO4·−是影响OTC降解的主要自由基。BC-PMS组合系统在模拟溶液和养殖水体中的OTC降解去除速率相近,受水的浊度、pH、电导率、有机质等基本特性差别的影响小。并且,系统中的BC可以重复使用,能对废水中的OTC进行多次有效修复。 综上所述,曝氧法制备的竹柳生物炭是一种低成本的高效修复材料,既可用作负载纳米MnO2的载体,也可以与PMS一起共同用于吸附去除和催化降解水中的OTC。这一生物炭材料有望用于治理养殖水体的抗生素污染。
Other AbstractThe intensive use of antibiotics in aquaculture have seriously polluted the water environment. This research aimed to develop cost-effective biochar techniques for use in reducing antibiotics in water by screening low-cost biochars and improve its performance. Here, a variety of biochars were produced via the oxygen-limited and aerobic carbonization methods developed, and their physical and chemical properties and antibiotic adsorption properties were determined and assessed to screen out the biochar. Then, the preferred biochar (BC) was used as a carrier and catalyst to systematically explore the performance and mechanism of OTC adsorption and degradation by nano-manganese dioxide (nano MnO2) - BC composite and BC-peroxymonosulfate (PMS) system. The main outputs are as follows: 1) The bamboo willow biochar prepared via aerobic carbonization had the largest specific surface area (262.2 m2/g) and carbon content (60.30%), the lowest H/C value, and the best antibiotic adsorption performance. It adsorbed 11.98 and 10.12 mg/g of OTC and SMX, respectively, from a solution with an initial concentration of 50 mg/L of the antibiotics. The reed biochar and cotton stalk biochar prepared by oxygen-limited method also showed good antibiotic adsorption capacity. Taken together, reeds and cotton stalks were suitable for preparation under oxygen-limited conditions, while bamboo willow was suitable for preparation under aerobic conditions. The π-π electron donor-acceptor (EDA) interaction was the primary mechanisms for the adsorption of neutral and acidic pH. Electrostatic attraction further promoted OTC adsorption on BC at pH 8–10, whereas pore filling could contribute to SMX adsorption. 2) As Mn-loading increased (MnO2/BC mass ratios of 1:40–10), C and N contents of MBC decreased, whereas ash and O content regularly rose. The maximum adsorption capacity of MBC for OTC, obtained from the Langmuir model, reached 292.53 (MBC40), 360.50 (MBC20), and 383.39 mg g−1 (MBC10), which were about 19, 24, and 25 times higher than that of BC (14.56 mg g−1), respectively. MBC20 achieved maximum OTC adsorption at pH=5, little affected by NaCl (2, 10 mM) or NOM (0–20 mg L−1) concentrations, but enhanced by NaHCO3 (2, 10 mM, complexed the Mn2+ in the solution). The OTC removal was accompanied by Mn2+ release. After 24 h reaction at pH 5.0, OTC degradation rate was 58.5% and Mn2+ release reached 2.97 mg L−1. OTC removal was the combined result of its adsorption onto MBC20 and its degradation by nMnO2. The π-π EDA interaction between BC and OTC promoted the adsorption of MBC20 to OTC, and nMnO2 acted as an oxidant during the removal process. 3) BC had excellent PMS catalytic activity. At the experimental OTC dose (300 mL, 30 mg/L), the optimal process conditions for the OTC removal by the BC-PMS system were: pH = 8.0-9.0, BC dosage was 0.33g/L, and PMS dosage was 10 µM. Under such conditions, the removal rate of OTC was about 76.0% within 2 h. The system was little influenced by NaCl (0-50 mM) and NOM (0-20 mg L−1), but accelerated by NaHCO3 due to an increase in pH. The process of BC-PMS degradation of OTC was jointly promoted by free radical and non-free radical process. Among them, SO4·− was the main free radical affecting degradation. The excellent ability of BC-PMS system to remove OTC from simulated solutions and aquaculture water was little affected by water turbidity, pH, electric conductivity, and DOM. In addition, the BC in the system can be reused, which can effectively repair the OTC in the wastewater for many times. In conclusion, biochar produced from local bamboo willow via aerobic carbonization was a cost-effective material for use either as a carrier of nano-MnO2 or along with PMS for the adsorptive removal and catalytic degradation of OTC. BC has the potential for commercial use in alleviating antibiotic contamination from aquaculture.
MOST Discipline Catalogue工学 ; 工学::环境科学与工程(可授工学、理学、农学学位)
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/25306
Collection中科院烟台海岸带研究所知识产出_学位论文
Recommended Citation
GB/T 7714
冯丽蓉. 竹柳生物炭及负载MnO2的复合材料对土霉素的吸附和 催化降解性能研究[D]. 北京. 中国科学院研究生院,2020.
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