Heterogeneous reaction of NO2 on the surface of montmorillonite particles

The studies on heterogeneous reactions over montmorillonite, which is a typical 2:1 layered aluminosilicate, will benefit to the understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the heterogeneous reaction mechanism of NO₂ on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO₂ on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.     

An unusual tricentric X chromosome detected prenatally

We describe a female fetus with a de novo X chromosome rearrangement detected prenatally in both chorion villi and a pleural effusion. Chromosome painting showed the chromosome to be composed entirely of X chromosome material, while G-banding indicated a duplication of X short arms, four copies of the proximal long arm, and deletion of the distal long arm of the X. C-banding showed the presence of one active and two inactive centromeres and X-inactivation studies demonstrated the tricentric chromosome to be late replicating in all cells examined. The origin of this complex de novo rearrangement appears to have involved two separate breakage events, the first leading to the production of a dicentric X chromosome and the second generating the tricentric X.     

论蒙脱石的脱水作用及其对地面沉降的影响

过去对开采地下水所引起的地面沉降，普遍采用有效应力原理进行解释。由于早期的有效应力观点是以假设土壤颗粒与孔隙水均不可压缩为前提，所以无法描述粘土矿物层间水脱水反应所造成的体积改变。因此对由地下水超采导致粘土发生脱水作用，从而产生地层次要压密并用于地面沉降的研究较少。蒙脱石作为第四纪土壤地层中粘土矿物的主要成分，虽然颗粒细小，但其具有特殊的形态和结构特征、特殊的物理化学性质，在其成岩转变的过程中，记录了地面沉降整个过程的演变信息。蒙脱石在地层压实过程中所发生的脱水作用，造成层间水释出，需纳入到地面沉降量的计算范围之内。本文讨论了用费脱石的脱水作用来计其次要地面沉降量的相关问题。     

An unusual archosaurian from the marine Triassic of China

A new Triassic archosaurian from China shows a number of aquatic specializations, of which the most striking is the extreme lateral compression of the long tail. Others that may also reflect aquatic adaptations include platelike scapula and coracoid, elongate neck with extremely long and slender ribs, and reduction of osteoderms. In contrast, its pelvic girdle and hind limb have no aquatic modifications. Anatomic features, taphonomy, and local geological data suggest that it may have lived in a coastal–island environment. This lifestyle, convergent with some Jurassic marine crocodyliforms that lived at least 40 million years later and the saltwater species of extant Crocodylus, contradicts with the prevailing view that Triassic archosaurians were restricted to nonmarine ecosystems. Its mosaic anatomy represents a previously unknown ecomorph within primitive archosaurians.Electronic Supplementary Material  Supplementary material is available for this article at     

羟基Fe、Al柱撑蒙脱石对庆大霉素的吸附行为

以蒙脱石(Mont)为原料,在不同OH/Fe物质的量比(x)和Fe/Al物质的量比(y)柱撑条件下制备出系列羟基铁(xOH/Fe-Mont)、羟基铝(OH/Al-Mont)和羟基铁铝(yFe/Al-Mont)柱撑蒙脱石,采用XRD和FT-IR对柱撑蒙脱石进行表征,并研究了柱撑改性对蒙脱石对庆大霉素(Gen)吸附行为的影响.结果表明:柱撑蒙脱石对Gen吸附量显著提高,且Mont(42.83mg/g) << OH/Al-Mont(63.50mg/g) < 1.5OH/Fe-Mont(70.50mg/g) << 0.025Fe/Al-Mont(87.20mg/g),吸附Gen最佳pH值为9.等温吸附适于采用Freundlich方程拟合,吸附动力学符合伪二级动力学方程,吸附3h可超过平衡吸附量的80%.XRD分析表明,羟基铁和羟基铝主导柱撑(y≤0.5)蒙脱石层间距扩增是吸附量增加的主要原因,而yFe/Al-Mont中y≥1.0时,层间距并不是吸附量变化的的主导机制;FT-IR分析表明阳离子交换是Gen和铝离子进入蒙脱石的主导机制.     

蒙脱石对溶液中镍和铜的吸附特性研究

本研究采用镍和铜作为溶液中的吸附质,探讨了蒙脱石对这2种重金属的吸附性能。通过实验研究了pH值、吸附剂用量、反应时间、浓度等因素对吸附Ni2+和Cu2+的影响。根据实验结果可知,蒙脱石对金属离子的吸附效率随溶液pH值、吸附剂用量、反应时间的增加而增加,但随着金属离子浓度的增加而降低。吸附动力学研究表明蒙脱石对Ni2+和Cu2+的吸附过程符合准2级动力学模型特征。     

有机改性蒙脱土去除球形棕囊藻赤潮研究

采用离子交换法制备出一种稳定的十六烷基三甲基溴化铵(CTAB)改性蒙脱土,考察了其对球形棕囊藻(Phaeocystis globosa Scherffel)赤潮的杀灭控制作用和絮凝沉降动力学。结果表明,当藻细胞起始密度为1.1×106/mL、改性粘土用量为14 mg/L时,作用48 h后对球形棕囊藻的除藻率为87%;用量为22 mg/L时的除藻率可达91%,而当藻细胞起始密度增大为6.3×106/mL时,同等用量和时间条件下,除藻率分别为62%、73%,呈现出明显的剂量-效应关系,除藻率受藻细胞起始密度影响较大。絮凝沉降实验发现,10 mg/L的改性粘土在60 m in时的沉降率即可达到80%,表明改性粘土对球形棕囊藻有较强的沉降作用及较快的沉降速率。     

An investigation of a Friedel-Crafts alkylation reaction in homogeneous supercritical CO2 and under subcritical and splitphase reaction conditions

This study investigates the Friedel-Crafts alkylation reaction of triphenylmethanol with methoxybenzene (anisole) in supercritical and subcritical carbon dioxide, and under two-phase (gas/liquid) reaction conditions at moderate pressures and temperatures. The reaction was initiated using trifluoroacetic acid to produce triphenylmethlycarbocation as the reaction intermediate. Isolated product yields of the Friedel-Crafts product, p-methoxytetraphenylmethane, are reported.     

改性蒙脱土固定化辣根过氧化物酶对2，4，6-三氯苯酚的催化去除及其影响因素研究

以黄腐酸改性的蒙脱土为模板固定辣根过氧化物酶(Horseradish peroxidase,HRP)研究其催化去除水中2,4,6-三氯苯酚(2,4,6-trichlorophenol,2,4,6-TCP)的效果及其影响因素,并与自由酶催化反应做对比研究了不同催化时间、pH值、温度和固定化HRP浓度对催化反应的影响,以及对固定化HRP催化降解2,4,6-TCP进行了动力学分析,考察了固定化HRP的重复使用性和储存稳定性.结果表明:黄腐酸活化的蒙脱土固定的HRP具有很高的生物活性,固定后的HRP活性高达112 U·g-1;固定化HRP催化降解100μmol·L-12,4,6-TCP,20 min后对2,4,6-TCP的去除率已达到96%,催化降解速率高于自由酶;HRP经过黄腐酸改性的蒙脱土固定化后,催化降解2,4,6-TCP的最优pH值为6;固定化后的HRP其催化反应的适宜温度范围(10~50℃)比自由酶(30~50℃)更宽泛.改性蒙脱土载体固定HRP对2,4,6-TCP的去除作用主要是由固定化HRP的催化作用引起的,吸附去除率贡献仅达到0.77%,氧化去除率仅为2.81%.固定化HRP催化2,4,6-TCP的Linerweaver-Burk反应动力学参数中最大反应速率Vmax=7.14×10-4mol·L-1·min-1,米氏常数Km=1.56×10-3mol·L-1.在储存稳定性方面,固定化HRP的储存稳定性极高,50 d后依然可以保留80%的活性.     

吸附苯酚的固定化改性蒙脱土的再生

在固定化改性蒙脱土对苯酚吸附的研究基础上,进一步对固定化改性蒙脱土进行了碱性条件和微生物条件下的再生,并检测再生的效果.碱性再生后固定化改性蒙脱土的吸附能力有一定程度下降.微生物再生效果好于碱性再生,在高效脱酚的瓶形酵母菌(Pityrosporum sp.)作用下,吸附在固定化改性蒙脱土上的苯酚降解率为98.6%,从而达到再生的目的.     

表面活性剂复配修饰添加不同含量蒙脱石的黄棕壤对苯酚的吸附作用

在两性修饰剂十二烷基二甲基甜菜碱(BS-12)和阳离子型表面修饰剂十六烷基三甲基溴化铵(CTMAB)复配修饰膨润土吸附苯酚最佳修饰比例的基础上,通过添加膨润土改变2种黄棕壤中的蒙脱石含量(分别为6%和43%),利用X射线衍射和有机碳含量表征了蒙脱石含量对BS+CTMAB复配修饰黄棕壤性质的影响.同时,采用批处理法研究了蒙脱石含量对BS-12+CTMAB复配修饰黄棕壤吸附苯酚能力的影响,对比了不同温度、p H和离子强度下吸附的差异,并探讨了影响机制.结果表明,CTMAB复配修饰增加了BS-12修饰土样的TOC含量并增强了土样对苯酚的吸附能力,且苯酚在复配修饰土中的解吸程度均高于CK、BS-12和CTMAB修饰土;随着黄棕壤中蒙脱石含量的增大,BS-12、CTMAB修饰和BS-12+CTMAB复配修饰土蒙脱石层间距、TOC含量和对苯酚吸附能力整体上均呈增加趋势;单因素对各修饰土样吸附苯酚的影响程度上,温度、p H逐渐减小,离子强度逐渐增大;蒙脱石含量决定的TOC是影响修饰土样对苯酚吸附能力大小的关键因素,修饰土样对苯酚的吸附依然以分配作用为主.     

蒙脱石粘土改性吸附剂处理印染废水实验研究

通过实验得到天然蒙脱石粘土改性和提高蒙脱石粘土吸附剂处理印染废水效果的方法,阐述了蒙脱石粘土改性和吸附有机污染物的机理。研究结果表明,天然蒙脱石经钠化和无机聚合物改性处理后,大幅度地提高了天然蒙脱石粘土对有机污染物的吸附能力。改性粘土吸附剂在投加量为0.1％时,处理红色印染废水,COD去除率85％,脱色率88％以上;处理兰色废水,COD去除率94％,脱色率达98％。处理后的水质达到回用要求。模拟实验表明,该吸附剂对含有各种类型染料的印染废水都有稳定的处理效果。本研究为印染废水处理提供了廉价高效的吸附剂。     

季磷盐改性蒙脱土去除球形棕囊藻的实验研究

用L9(34)正交实验对季磷盐改性蒙脱土制备的工艺进行了优化,在60℃、搅拌时间6h、pH7、季磷盐与蒙脱土的阳离子交换容量比为1.5:1.0的条件下,制备得到的季磷盐改性蒙脱土,并考察了其对球形棕囊藻去除效果和影响因素.结果表明,作用48 h后, 20.0mg/L的改性蒙脱土除藻率可以达到93.2%以上.通过FT-IR、XRD和SEM等方法表征发现,季磷盐插入蒙脱土的层间,能够有效降低黏土颗粒与藻细胞间的静电斥力,使其吸附藻细胞性能提高.对比除藻实验结果显示,季磷盐改性蒙脱土除藻效果明显优于未改性蒙脱土、季磷盐改性高岭土和季铵盐改性蒙脱土.     

海藻酸钠/蒙脱石联合负载型纳米Fe0对Cu(II)的去除研究

由于蒙脱石负载型纳米Fe~0(Mt-n ZVI)在使用中易随水迁移,造成出水水质混浊和Fe~0流失.因此,本研究制备了海藻酸钠(SA)和蒙脱石(Mt)联合负载型纳米零价铁(SA/Mt-n ZVI),探究其对水中Cu(Ⅱ)的去除效果,并考察了Cu(Ⅱ)初始浓度、pH值对去除率的影响.结果表明:以2%(质量分数)SA和6%(质量分数)Mt-n ZVI条件制备的SA/Mt-n ZVI小球对Cu(Ⅱ)处理效果好,反应24 h后,SA/Mt-n ZVI小球对初始浓度为40 mg·L-1Cu(Ⅱ)的去除率达到92.11%,与游离的Mt-n ZVI颗粒相比,其活性并未降低;Cu(Ⅱ)的去除率随其初始浓度升高而降低;在pH为2~6之间,Cu(Ⅱ)去除率随pH升高而升高.SA/Mt-n ZVI小球可有效净化污水中的Cu(Ⅱ),将其重复使用3次后,对Cu(Ⅱ)的去除率仍维持在59.52%.     

邻菲罗啉对蒙脱石吸附镍离子性能影响

利用镍离子能与邻菲罗啉反应生成螯合物的性质,研究了加与未加邻菲罗啉条件下,蒙脱石对金属镍离子的吸附行为,考察了镍离子浓度、吸附时间、温度和溶液pH值等因素对吸附性能的影响.结果表明:加入邻菲罗啉后,蒙脱石对镍的螯合离子的吸附量明显增大;吸附平衡时间约为120min;蒙脱石对[Ni(phen)n]2+的吸附性基本不受pH值的影响.动力学研究表明该吸附过程符合准二级反应动力学模型,吸附量随温度升高而增大.二级动力学参数证明加入邻菲罗啉可显著提高蒙脱石对Ni2+的吸附性.蒙脱石对简单Ni2+的吸附符合Langmuir的单层吸附等温式;而蒙脱石对镍的螯合离子的吸附则符合Freundlich等温式.蒙脱石对Ni2+和[Ni(phen)n]2+的吸附均为自发、吸热和更无序的;XRD及FTIR研究表明,蒙脱石对[Ni(phen)n]2+的吸附以层间的物理吸附为主.     

An unusual high ozone event over the North and Northeast China during the record-breaking summer in 2018

Under the background of global warming, the summer temperature of the North and Northeast China (NNEC) has significantly increased since 2017, which was accompanied by the aggravated ozone (O₃) pollution. In 2018, the NNEC experienced a record-breaking summer of the past 40 years. Influenced by the abnormal high temperatures, a regional ozone event occurred on 2-3 August, over 63% of 79 selected cities in the NNEC were exposed to O₃ pollution, and the maximum value of MDA8 O₃ reached 268 μg/m³. Observations indicated that ozone concentrations agree well with the maximum temperature at 2 meters (MT2M) over NNEC with a correlation coefficient of 0.69. During the pollution episode, strong downdraft in the local high (35°N-42.5°N, 112.5°E-132.5°E; LH) over the NNEC created the favourable meteorological conditions for O₃ formation. By analyzing the horizontal wind and wave activity fluxes (WAFs) at 200 hPa, we found that the LH formation was resulted from the Rossby wave propagation from upstream along the mid-latitude Asian jet. The split polar vortex intrusion further strengthened the amplitude of the Rossby wave and reinforced the LH. Moreover, a secondary circulation between Typhoon Jongdari and the LH contributed to the enhanced LH with strong subsidence. On the other hand, the stratospheric intrusions under the deep subsidence also contributed to the enhanced surface O₃. In this study, the deep-seated meteorological dynamical mechanisms contributing to the abnormal high temperatures were investigated, which can lead to a better understanding of the regional O₃ pollution over NNEC under the global-warming background.