湿地基质及阴极面积对人工湿地型微生物燃料电池去除偶氮染料同步产电的影响

本研究采用人工湿地型微生物燃料电池处理偶氮染料X-3B,实现降解偶氮染料同步产电的效果.为了构建性能最优的人工湿地型微生物燃料电池(CW-MFC)系统,本研究主要从湿地基质和阴极面积两个方面研究系统构型对去除X-3B同步产电的影响,提高系统性能.研究表明以粒径10 mm、孔隙率30%的小石子作为湿地基质构造的CW-MFC系统微生物生物量最大,去除X-3B效果最好,脱色率高达92.70%,但其产电性能最差.较小的粒径和孔隙率使底层微生物生物量增加,促进X-3B的去除,但随着湿地基质粒径和孔隙率的减小,导致阴阳极营养物质不足,系统传质阻力增加,抑制了系统产电性能.X-3B的去除效果随着阴极面积的增加而提高直到阴极面积为594 cm~2时取得最大脱色率99.41%.当阴极面积继续增加时,CW-MFC系统产电性能上升趋势趋于平缓,X-3B去除效果呈现下降趋势,这是因为阴极反应过快导致更多的阳极电子输送到阴极用于产生电流,与X-3B发生反应的电子减少,阳极成为提高CW-MFC系统性能的限制因素.     

微生物燃料电池改性阳极处理PTA废水

探讨了不同改性阳极对微生物燃料电池(microbial fuel cell,MFC)产电性能及其对MFC处理难降解废水能力的影响.以单室空气阴极为基础,利用0.1 g电气石、质量分数75%二氧化锰/埃洛石纳米管(manganese bioxide/halloysite nanotube,MnO_2/HNT)和多壁碳纳米管-羧基(multi-walled carbon nanotube-carboxyl,MWCNT-COOH)对MFC阳极进行修饰.结果表明,不同改性阳极的MFC对含精对苯二甲酸(purified terephthalic acid,PTA)废水的去除率均高于70%,且化学需氧量(chemical oxygen demand,COD)去除率在79%以上.相较于其他几种改性阳极,以MWCNT-COOH改性材料作阳极的MFC产生的最大输出电压最高,获得的最大功率密度最高,分别为529 mV和252.73 mW·m~(-2).     

The Kinetics of Interesterfication on Waste Cooking Oil (Sunflower Oil) for the Production of Fatty Acid Alkyl Esters using a Whole Cell Biocatalyst (Rhizopus oryzae) and Pure Lipase Enzyme

Recent research and technology have provided promising outcomes to rely on biodiesel as the alternative and conventional source of fuel. The use of renewable sources constitutes the main stream of research. Waste Cooking Oil (WCO) was used for biodiesel production in this study. Lipase enzyme producing fungi Rhizopus oryzae 262 and commercially available pure lipase enzyme were used for comparative study in the production of FAAE. The whole cell biocatalyst and pure enzyme were immobilized using calcium alginate beads. It was prepared by optimizing with different molar ratios of calcium chloride and different percent sodium alginate. Entrapment immobilization was done for whole cell biocatalyst. PE was also immobilized by entrapment for the transesterification reaction. Four different solvents methanol, ethanol, n-propanol, n-butanol were used as the acyl acceptors. The reaction parameters like temperature, molar ratio, reaction time, and amount of enzyme to be used were also optimized for methanol alone. The same parameters were adopted for the other acyl acceptors too. Among the different acyl acceptors, methanol whose reaction parameters were optimized showed maximum conversion of triglycerides to FAAE - 94% with PE and 84% with WCB. On the whole, PE showed better catalytic converting ability with all the acyl acceptor compared to WCB, further study, it was observed that three consecutive and reversible reactions occurred in the interesterification of triglycerides. So, a kinetic model based on Michaelis-Menten equation with competitive substrate inhibition was used to find the maximum reaction rate V_i for the four solvents using pure enzyme and WCB.     

双室微生物燃料电池处含银废水的产电性研究

以剩余污泥为阳极底,糖蜜废水为基质,Ag Cl废水为阴极电子受体,构建了双室微生物燃料电池(Two-chamber Microbial Fuel Cell,简称MFCs),并研究了电池的产电特性、库仑效率及金属去除率.结果表明:Ag+不仅可以作为阴极电子受体,而且还能稳定产电,外电阻为1000Ω时,获得的最大电压为514.5 m V,最大功率密度为65.82 m W·m-2.在阴极实现了对废水中Ag+的去除,最大去除率可达71.6%,而且Ag+浓度为2000 mg·L-1时,回收金属银单质质量为197.66 g.在阳极对废水的处理效果也很显著,库仑效率最高为2.66%,COD去除率最大为81.22%.     

一株产电菌嗜根考克氏菌(Kocuria rhizophila)的分离及其产电性能优化

本研究以天津泰达污水处理厂污泥浓缩间的污泥为接种物,启动并运行了微生物燃料电池(MFCs).从富集的阳极生物膜上分离得到了一株纯培养的微生物菌种,命名为P2-A-5.研究发现,菌株P2-A-5的16S rDNA序列与菌株Kocuria rhizophila DC2201具有100%的同源性,结合该菌的形态特征和生理生化实验,将其归属为嗜根考克氏菌(Kocuria rhizophila).通过化学剂处理、底物种类和浓度的优化,进一步提高其在微生物燃料电池中的产电性能.结果表明,菌株K.rhizophila P2-A-5经0.5 mg·L-1溶菌酶处理45 min后,接种到以2.0 g·L-1海藻糖为底物的阳极液中运行MFCs,其功率密度达到314.8 m W·m-2,比优化前(74.9 m W·m-2)提高了320.3%.这是首次对K.rhizophila种内微生物产电性能及其在微生物燃料电池中应用的报道,其成果对于丰富产电微生物的多样性,挖掘更多具有高电化学活性的微生物菌种,提高其产电性能具有重要的理论意义.     

Enhanced catalytic complete oxidation of 1,2-dichloroethane over mesoporous transition metal-doped γ-Al2O3

High-surface-area mesoprous powders of γ-Al₂O₃ doped with Cu^2 +, Cr^3 +, and V^3 + ions were prepared via a modified sol–gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al₂O₃ and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane (DCE) was studied in the temperature range of 250–400°C. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu^2 +- and Cr^3 +-containing catalysts showed 100% conversion at 300°C and 350°C, V^3 +-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride (C₂H₃Cl) and hydrogen chloride (HCl) at all temperatures, Cu- and Cr-doped catalysts showed significantly stronger capability for deep oxidation to CO₂.     

Investigation of physico-chemical properties and microbial community during poultry manure co-composting process

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1(V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy(FT-IR), thermogravimetry and differential thermal analysis(TG/DTA)and scanning electron microscopy(SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis(DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks.CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both Li P and Mn P activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16 S r DNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting.     

Influence of hypothyroidism on oxidative stress,c-Fos expression,cell cycle,and apoptosis in rats testes

The molecular basis of male reproduction for cross-regulation between androgen and thyroid hormone axes is still rudimentary. This study aims to define a possible mechanism of hypothyroidism-induced reproductive influence with respect to sex hormone, mineral, sperm motility, oxidative stress, c-Fos expression, cell cycle, and apoptosis in rat testes. The Wistar rats were randomly divided into control group (NS) and hypothyroidism group [1 ml/100g BW/day, 0.1% propylthiouracil (PTU)] by intragastric gavage for 60 days. Blood samples were collected to measure the serum levels. The epididymis was excised to measure sperm motility and testes were excised to measure mineral, oxidative stress, c-Fos expression, cell cycle, and apoptosis. After 60 days, body weight, relative testes weight, triiodothyronine, and total thyroxine were all significantly decreased, whereas thyroid stimulating hormone was increased in the hypothyroidism group. A significant increase in sex hormone level of estradiol (E2) and significant decreases in testosterone (T) and T/E2 ratio were observed following PTU treatment. And sperm quality was also significantly changed. There were significant decreases in the contents of calcium (Ca²⁺) and zinc (Zn²⁺). On the other hand, malondialdehyde and hydrogen peroxide contents significantly increased, whereas the activity of superoxide dismutase, catalase and nitric oxide synthase and nitric oxide content significantly decreased in hypothyroid rats. The mRNA and protein expressions of c-Fos decreased significantly. The cell percentage in G0/G1 phase increased significantly, whereas decreased significantly in S and G2/M phases. Also, a significant increase in testicular cell apoptosis was observed in hypothyroid-treated rats. These results suggested that hypothyroidism could affect reproductive function in the form of changed sex hormone levels, sperm motility and testicular Ca²⁺ and Zn²⁺, and enhanced oxidative stress leading to c-Fos abnormal expression and increased apoptosis.     

区域森林火灾危害程度评价指标构建

为弥补用发生次数和受害森林面积评价森林火灾危害程度的不足,在拟定了林火次数比率、森林燃烧率、森林受害面积比率、每起森林火灾平均受害面积、森林火灾发生次数变异系数、受害森林面积变异系数6个指标的基础上,利用权重法确定了综合指标。结果表明,单一指标可以从某个方面评价森林火灾危害程度,综合指标则能更好地评价某个区域森林火灾的危害程度,更便于区域间的比较和评价。     

毒性有机物BPA与普通小球藻的相互影响特性研究

考察了不同浓度双酚A(BPA)对普通小球藻(Chlorella vulgaris)生长特性的影响,以及普通小球藻生长过程对BPA的去除效能.研究表明,低浓度BPA(0~20 mg·L-1)对普通小球藻生长具有促进作用,而高浓度BPA(20~50 mg·L-1)对普通小球藻生长具有抑制作用,且抑制效应与BPA浓度呈正相关关系.低剂量BPA(<20 mg·L-1)对叶绿素含量并无明显的影响,高剂量BPA(>20 mg·L-1)造成叶绿素含量降低.在BPA初始浓度2~50 mg·L-1的范围内,普通小球藻对其都有一定的去除效能,单位普通小球藻对BPA去除速率与其初始浓度呈正相关关系.BPA投加量为50 mg·L-1时,BPA去除速率最大,且最大速率出现于延滞期与对数期之间.