聚氨酯型固沙剂改性土室内试验研究

对自主研发的PUA、PUB和PUC 3种聚氨酯型固沙剂改性土的强度、抗冲刷性、抗风蚀性等性能进行了室内试验研究,并结合聚氨酯分子结构和功能对固沙剂改良原理进行了分析。试验结果表明:3种聚氨酯型固沙剂改性土的无侧限抗压强度、内聚力得到了提高,抗冲刷和抗风蚀性能得到了明显增强;3种固沙剂改性土的无侧限抗压强度和内聚力均随着固沙剂浓度的增加而增大;PUA、PUB和PUC浓度为3g/cm3的改性土试样的冲刷率分别只有4.4%、14.7%和0.6%,而参照样高达79.5%;PUA、PUB和PUC浓度达到1g/cm3以上的改性土风蚀后表面保持完整,没有风蚀破坏痕迹。因此,聚氨酯型固沙剂可以很好地增强土体粘聚力、促进表层固化、减少水土流失,可用于坡面防护、水土保持、防尘固沙、沙漠化治理等领域。     

3种刺激性化学战剂对鱼类的急性毒性

采用国际通用鱼种斑马鱼(Brachydaniorerio)及中国特有鱼种稀有鮈鲫(Gobiocyprisrarus)2种试验生物,对二苯氰胂、二苯氯胂、苯氯乙酮3种化学战剂进行了静态及半静态2种方式的急性毒性测试.结果表明,对于不稳定受试物,半静态试验方式更能满足对浓度的质量控制要求;对于鱼类,这3种化学战剂均属于极高毒性水平;这3种化学战剂对于鱼类的急性毒性程度不同,二苯氰胂、二苯氯胂的毒性在同一水平,其中二苯氯胂毒性略强些,苯氯乙酮较另2种物质的毒性弱一个量级,比较2种鱼类的试验结果得出,稀有鮈鲫与斑马鱼敏感性相似.      

基于成组生物毒性测试的PM2.5毒性

为了准确评估PM_(2.5)的综合生物毒性,采用发光细菌急性毒性、斑马鱼胚胎急性毒性和体外人肺腺癌细胞(A549)毒性试验对常州市冬季雾-霾天、冬季正常天和夏季这3个时间段的PM_(2.5)进行生物毒性评价,并结合大气理化指标进行分析.结果表明,3个时间段的PM_(2.5)均表现出急性毒性或发育毒性.冬季雾-霾天、冬季正常天和夏季PM_(2.5)对发光细菌的毒性单位(toxicity unit,TU)值分别为1. 74(有毒)、1. 19(有毒)和0. 92(微毒);对斑马鱼胚胎的TU值从大到小排列为:冬季正常天(TU=1. 14,有毒)、冬季雾-霾天(TU=0. 79,微毒)和夏季(TU=0,无毒);对A549的TU值为:冬季雾-霾天(TU=0. 61,微毒)夏季(TU=0. 38,微毒)冬季正常天(TU=0. 31,微毒).在发育毒性方面,除夏季PM_(2.5)样品,其余2个时间段的PM_(2.5)均对斑马鱼胚胎发育有影响,主要表现出心包囊肿、脊椎弯曲和尾部畸形.平均毒性(average toxicity,Av Tx)、毒性指数(toxic print,Tx Pr)和最敏感测试(most sensitive test,MST)综合毒性评价方法表明冬季雾-霾天和冬季正常天PM_(2.5)均表现出有毒,夏季则表现出微毒,以冬季雾-霾天PM_(2.5)样品的综合毒性最高.此外,3种测试生物对PM_(2.5)污染物的敏感度排序为发光细菌斑马鱼胚胎 A549.理化指标和生物毒性的相关性分析结果表明,PM_(2.5)中所含的污染物对生物毒性效应产生影响,可为PM_(2.5)生物毒性综合评价和人体健康风险评估提供依据.     

模拟酸雨对钝化剂修复镉污染土壤效果研究

采用土柱试验和盆栽试验方法,研究模拟酸雨淋溶和水淋溶1a期间,海泡石、生物炭和有机肥对四川(SC)和湖南(HN)镉(Cd)污染农田土壤稳定效果及小白菜富集Cd的影响.结果表明:与水淋溶相比,酸雨淋溶降低SC和HN土壤淋出液pH值,增加淋出液电导率(EC)、可溶性有机碳(DOC)和Cd含量,其中SC和HN土壤淋出液Cd含量增加幅度分别为48.85%~77.16%和50.92%~73.44%;而且酸雨淋溶降低两种土壤有机碳(SOC)含量,增加土壤Cd有效态含量(CaCl₂-Cd)和溶出量(TCLP-Cd),促进土壤Cd由残渣态向酸溶态转化,SC和HN土壤残渣态Cd含量平均降低3.61%和2.81%.无论是水淋溶还是酸雨淋溶,海泡石和生物炭均能显著降低两种土壤CaCl₂-Cd和TCLP-Cd含量(P<0.05),但有机肥仅对HN土壤Cd的固定效果显著.与水淋溶相比,酸雨淋溶后抑制小白菜的生长,促进小白菜对Cd的富集.添加海泡石和生物炭后两种土壤的小白菜产量显著增加(P<0.05),且小白菜可食部位Cd含量平均降低58.85%和43.08%.酸雨淋溶后SC土壤加海泡石和生物炭处理,小白菜可食部位Cd含量均满足国家安全食用标准(GB2762-2017) (Cd≤0.2mg/kg),HN土壤仅海泡石处理的小白菜可食部位Cd含量满足国家安全食用标准.本研究表明酸雨淋溶影响钝化剂对Cd的固定效果,进行污染土壤原位修复时要关注酸雨的影响,根据污染土壤性质选择合适的钝化剂.     

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths

Binary oxide systems (CuCr₂O₄, CuCo₂O₄), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al₂O₃), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O₂, NO_x, H₂O, CO₂) and O₃ as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO₂. Oxidants used can be arranged with reference to decreasing their activity in a following series: O₃ ? NO₂ > H₂O > NO > O₂ > CO₂. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O₃ occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the “cold start” problem.     

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths

Binary oxide systems(Cu Cr2O4, Cu Co2O4), deposited onto cordierite monoliths of honeycomb structure with a second support(finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine’s gas exhausts(O2, NOx, H2 O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3 NO2> H2 O > NO > O2> CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively(in the presence of copper chromite based catalyst) even at closing to ambient temperatures.Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem.     

Advances in research on haloalkane dehalogenases and its sulfur mustard degradation function北大核心CSCD

Sulfur Mustard (bis-(2-chloroethyl) sulphide, HD), also known as yperite, is one of the most important blister agents. It could react with a large number of biological molecules with a strong cytotoxicity effect, resulting in blistering, erosion and necrosis of the skin and various tissues. Recently, several classes of microbial enzymes have been found to be able to degrade HD with high catalytic activity but no disadvantages of the common chemical decontamination of HD. Haloalkane dehalogenases (HLDs, EC3.8.1.5) draws great research attention for environmentally friendly decontaminating HD with only nontoxic thiodiglycol produced. In order to provide theoretical reference basis for enzymatic decontamination of HD, this paper reviews the observation and evolutionary relationship, structures, substrate specificities, catalytic properties and potential applications of these HLDs with high catalytic hydrolysis of HD. The analysis shows that these HLDs belonging to the same subfamily have different substrate specificities but similar spatial structures of the catalytic triad contributing to the common SN2 nucleophilic substitution reaction mechanism for catalytic hydrolysis of HD. The paper also suggests that the problems on improving poor stability of HLDs and efficiency of catalytic hydrolysis of HD should be addressed by methods of molecular biology, genetic engineering and immobilized techniques.     

Al-Zn-In系铝合金牺牲阳极电化学性能研究

目的研究三种不同成分Al-Zn-In系铝合金牺牲阳极在常规海水环境中的电化学性能。方法使用牺牲阳极电流效率测试和表面形貌观察等方法。结果三种不同成分铝合金牺牲阳极的电流效率均超过了90%,其中成分3的阳极表面溶解最均匀,呈现均匀溶解形貌,并且未见明显的腐蚀坑和晶间腐蚀现象。结论Al-Zn-In系铝合金牺牲阳极中,加入一定量的In、Zn和适量的Si,可以提高牺牲阳极的电化学性能,三种不同成分Al-Zn-In系铝合金牺牲阳极中,成分3牺牲阳极具有最优异的电化学性能。     

不同接种量的微生物秸秆腐熟剂对蔬菜副产物堆肥效果的影响

为了明确不同接种量的微生物秸秆腐熟剂对蔬菜副产物堆肥效果的影响,以玉米秸秆为调理剂,在调节初始物料含水率为63％和C/N为28的条件下,设置了B1(堆肥混合物+1％秸秆腐熟剂)、B2(堆肥混合物+3％秸秆腐熟剂)、B3(堆肥混合物+5％秸秆腐熟剂)和CK(堆肥混合物+3％灭菌惰性载体)4个处理,测定不同堆肥处理对温度、含水率、碳氮比(C/N)、半纤维素、纤维素、木质素、总养分含量、发芽指数等指标的影响.结果表明,蔬菜副产物堆肥接种微生物秸秆腐熟剂均能够使堆肥周期缩短,有效降低堆肥含水率,提高有机质的降解幅度,并且使堆肥中半纤维素、纤维素、木质素降解率分别提高1.03％、1.16％和1.47％;氮磷钾养分含量也比不接种处理平均提高0.48％.4个处理的总体堆肥效果表现为:B2＞B1 ＞B3＞CK.     

铅蓄电池厂铅污染土壤清洗剂的筛选及清洗结果研究

为探索不同清洗剂对铅蓄电池厂区内铅污染土壤的去除效果及铅在不同粒径土壤清洗过程中的行为,本研究通过设定清洗剂的浓度梯度,对土样粒径分级、设定清洗时间等方法进行研究。结果显示EDTA和EDDS对铅具有最佳去除率(B点土107.19%和96.49%);盐酸对A点土最佳铅去除率为49.57%,B点、C点土在99.03%和89.93%;柠檬酸对3点位土的铅去除率最大为39.51%;鼠李糖脂对3份土铅去除率均低于10%。EDTA和EDDS在高浓度铅的去除中表现优势;柠檬酸适合去除中低浓度铅;盐酸的使用需考虑土壤本身情况。粗沙粒和细沙粒中的铅去除率高,粉粘粒的铅去除率低;最佳清洗时长为240min。此外,土壤本身理化性质对清洗剂效果的发挥有影响,清洗剂浓度过高可能降低清洗效率。该研究可为铅污染土壤清洗技术提供科学依据。