A structural study of CN treated amorphous silicon

Recently, a remarkable technique to overcome the problem of light-induced degradation in amorphous silicon (a-Si) solar cells using a cyanide (CN) treatment has been developed. Structural and bonding characteristics of CN in a-Si has been studied using ab initio molecular dynamics simulations. It was found that CN incorporation results in more than just the termination of dangling bonds. The connectivity of the covalent random network increases because the CN changes from triply bonded, which is a common form in molecular CN, to the singly bonded form. This may be the mechanism by which CN incorporation produces significant reductions in light-induced degradation.     

Characterization of a 20 kHz sonoreactor. Part II: analysis of chemical effects by classical and electrochemical methods

A new electrochemical redox probe has been investigated in order to characterize the local production of radicals during the cavitation events. The results have been compared with those obtained with Fe(CN)6(3-)/Fe(CN)6(4-) (electrochemical probe for local mechanical effects) and classical chemical methods such as iodide and Fricke dosimeters (chemical probes for global effects).     

Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO₂ and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO₂ coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation.     

Combination of ultrasound-treated 2D g-C3N4 with Ag/black TiO2 nanostructure for improved photocatalysis

Herein, nanosheets of g-C₃N₄ (CN), prepared using a green ultrasonication process under various conditions, were combined with Ag/black TiO₂ nanocomposites (AgBT) to create two-dimensional (2D) CN/Ag/black TiO₂ tri-composites (CNAgBT). The thickness of the CN sheets varied with the ultrasonication conditions. The CNAgBT sample prepared using ultrasound-treated CN exhibited the highest average photocatalytic efficiencies for the degradation of two model pollutants, followed in decreasing order by AgBT, black TiO₂ (BT), sheet CN, bulk CN, and TiO₂. The order of pollutant degradation efficiencies by the photocatalysts was consistent with that of the charge carrier separation efficiencies. The degradation efficiency of the CNAgBT increased as the CN-to-AgBT ratio increased from 0.05 to 0.1, but decreased gradually for higher ratios between 0.15 and 0.20, indicating a lower optimal CN-to-AgBT ratio. A plausible photocatalytic degradation mechanism for the CNAgBT nanocomposites was proposed. Additionally, CNAgBT with a CN-to-AgBT ratio of 0.1 displayed a higher hydrogen generation rate with a maximum value of 21.5 mmol g⁻¹ over 5 h than those of the AgBT and BT. Overall, the CNAgBT prepared using ultrasonication-treated CNs showed enhanced photocatalytic performance for both pollutant degradation and hydrogen generation.     

电炉渣超微粉改性生物质废弃物制备生态活性炭的光谱学分析

利用木材、竹子、等其他生物资源制备具有发达多孔结构与丰富比表面积的活性炭,存在生产成本较高、不利于生态环境的可持续发展、使用寿命短和失效后容易造成室内环境二次污染的问题。冶金固体废弃物与生物质废弃物是工业生产与农业生产主要的副产品,因利用难度大、附加值低且成本高,导致大量堆放和填埋,不仅造成生态环境的污染,而且极大的浪费潜在资源。面对上述问题,利用冶金固体废弃物与生物质废弃物开发一种价格低廉且性能优越的生态活性炭,既是冶金固体废弃物与生物质废弃物的高附加值利用与资源可持续发展的重要途径之一,也是大幅降低改性活性炭生产成本与提高经济效益的重要途径之一。以核桃壳与电炉渣为研究对象,利用电炉渣中含有的金属氧化物对生物质废弃物进行改性处理制备用于甲醛降解的生态活性炭,依据《室内装饰装修材料人造板及其制品中甲醛释放限量》(GB18580-2017)对生态活性炭性能进行测试。利用X-射线光电子能谱(XPS)对元素含量进行测试与分析,X-射线荧光光谱仪(XRF)对化学成分进行测试与分析,傅里叶变换红外光谱仪(FTIR)对结构组成进行测试与分析,X-射线衍射仪(XRD)对矿物组成进行测试与分析,扫描电子显微镜(SEM)对微观结构进行测试与分析,激光粒度仪(LPSA)对粒度分布进行测试与分析和比表面积及孔径测定仪(BET)对孔结构进行测试与分析,以揭示核桃壳与电炉渣制备生态活性炭的机理,以及生态活性炭对甲醛的降解机理。结果表明:核桃壳超微粉与电炉渣超微粉进行复合制备具有良好降解甲醛性能的生态活性炭,不仅实现了冶金固体废弃物与生物质废弃物的高附加值的利用,而且提出了"以废治危"的新室内空气甲醛治理理念。电炉渣超微粉较好的被包裹于生态活性炭层状结构中,提高生态活性炭的粉化率,形成粒径较小的颗粒,有利于提高生态活性炭与甲醛的降解作用面积。电炉渣超微粉中含有Fe元素、Mn元素与Ti元素,Fe元素具有磁性促使大量甲醛在生物质活性炭孔结构表面形成富集,Mn元素与Ti元素对已经富集的甲醛进行催化降解,实现吸附降解与催化降解的协同作用。     

Treatment of cyanide containing wastewater using cavitation based approach

Industrial wastewater streams containing high concentrations of biorefractory materials like cyanides should ideally be treated at source. In the present work, degradation of potassium ferrocyanide (K₄F_e(CN)₆) as a model pollutant has been investigated using cavitational reactors with possible intensification studies using different approaches. Effect of different operating parameters such as initial concentration, temperature and pH on the extent of degradation using acoustic cavitation has been investigated. For the case of hydrodynamic cavitation, flow characteristics of cavitating device (venturi) have been established initially followed by the effect of inlet pressure and pH on the extent of degradation. Under the optimized set of operating parameters, the addition of hydrogen peroxide (ratio of K₄F_e(CN)₆:H₂O₂ varied from 1:1 to 1:30 mol basis) as process intensifying approach has been investigated. The present work has conclusively established that under the set of optimized operating parameters, cavitation can be effectively used for degradation of potassium ferrocyanide. The comparative study of hydrodynamic cavitation and acoustic cavitation suggested that hydrodynamic cavitation is more energy efficient and gives higher degradation as compared to acoustic cavitation for equivalent power/energy dissipation. The present work is the first one to report comparison of cavitation based treatment schemes for degradation of cyanide containing wastewaters.     

氮化碳薄膜的X射线光电子谱

用ＸＰＳ研究射频－直流等离子体增强化学气相沉积获得的氮化碳薄膜的化学结构。Ｃ１ｓ和Ｎ１ｓ芯能级电子谱分析表明：在ＣＮ膜中含有Ｎ－ｓｐ＾３和Ｎ－ｓｐ６２两类化学结构,在高含Ｎ膜中还含有少量的Ｎ－ｓｐ相,且代表Ｎ－ｓｐ＾３结构的原子 比为１．２８,接近４：３,证明此膜中存在类β－Ｃ３Ｎ４相。     

Dual-facing-target-sputtered amorphous CoMoN/CN compound soft-X-ray multilayers: structures and thermal stability

Amorphous CoMoN/CN compound soft-X-ray multilayers were fabricated by dual-facing-target sputtering. Their structural thermal stability has been investigated by monitoring the structural evolutions of CN and CoMoN sublayers at annealing temperatures up to 800 °C using complementary measurement techniques, and measuring the coefficient of interfacial diffusion at annealing temperatures below 300 °C. The period expansion at annealing temperatures below 600 °C, which is usually observed in annealed metal/carbon soft-X-ray multilayers, is only 5%. The enhanced sp² to sp³ bond ratio caused by the incorporation annealing effect of nitrogen [1] is thought to be responsible for the improved thermal stability of CN sublayers. Mo addition greatly suppresses the structural thermal evolution of CoMoN sublayers. XPS and TEM analyses indicate that the strong chemical bonding between N and Co atoms and Mo nitride aggregation in the grain boundary of cobalt are the main mechanisms for the high thermal stability of CoMoN sublayers. The layered structure of the CoMoN/CN multilayers still exists at the annealing temperature of 800 °C, while Co/C and CoN/CN multilayers have already been destroyed at this temperature. Compared with Co/C and CoN/CN multilayers, the smaller negative interdiffusivity measured by X-ray diffraction reveals the stable interfaces of CoMoN/CN multilayers. These results illustrate that refractory metal incorporation and strong chemical bond establishment are quite effective in obtaining thermally highly stable compound soft-X-ray optical multilayers . PACS 68.65+g; 68.55.Ln; 68.35.Fx; 68.60.Dv     

Effects of ultrasound energy on degradation of cellulose material

The rationale for selection of waste cellulose source and method for its degradation, such as ultrasound, aeration and coupled energy, is examined. Consideration is given to the availability of waste material for the conservation of global resources, pollution effects from energy forms and efficiency of energy transfer. Availability of the sources and possible ways of converting them to fuels, processes involved in its production and the possible effects on the environment are discussed. Manufactured cellulose and waste paper are used as the source for these experiments and the rationale behind their use in the environment is analysed. An ultrasound reactor that operates at 80 W and 38 kHz was used in breaking down the samples to produce glucose and other chemical species. One of the routes being explored is the further conversion of these molecules into fuel (alcohol).     

氮气对电晕放电等离子体降解甲基蓝的影响

电晕放电等离子体技术是近年发展起来的一种新型高级氧化工艺,因其处理效果好、操作简单、占地面积小的特点在印染废水处理领域得到了广泛应用。目前因大部分有机污染物的降解机理不详,该技术尚处于探索阶段。因此,为了尽早将电晕放电等离子体技术应用于工业印染废水的处理,不同污染物降解机理的研究对该技术的工业化和产业化应用具有重要意义。至今,电晕放电等离子体技术对研究较多的染料的降解效果均较好,然而,是否适合所有染料的降解有待进一步研究。采用电晕放电等离子体技术处理三苯甲烷类染料甲基蓝,研究了溶液的初始浓度对甲基蓝紫外-可见光谱中芳香环的降解率、发色基团吸光度变化的影响,测定了溶液的浓度、总有机碳（TOC）、总氮（TN）、pH值等指标随着放电时间的变化,并对其相关性进行了分析。结合紫外-可见光谱（UV-Vis）、三维荧光光谱（3D-fluorescence）和傅里叶变换红外光谱（FTIR）三种光谱学手段分析了电晕放电降解甲基蓝过程溶液的颜色、荧光物质和官能团变化,分析了电晕放电降解甲基蓝30 min后生成的中间产物。结果表明：电晕放电等离子体降解甲基蓝过程,溶液的浓度随着放电时间的延长逐渐减小,表明该技术对甲基蓝溶液有一定的降解能力;降解过程高压电极放电击穿含有大量氮气的空气产生N,NO·,N+₂等含氮高活性粒子,这些粒子通过扩散作用迁移至液相,使得溶液中TN含量在整个降解过程逐渐升高;另有部分含氮高活性粒子与钨钢针电极溶出的C元素键合生成发色的CN双键,使得溶液中的总有机碳在放电5 min时有所升高。延长反应时间产生的高活性粒子与溶液中的有机物（甲基蓝及中间产物）继续作用,部分有机物矿化生成CO₂,引起溶液中TOC含量的下降。电晕放电相同时间内产生的活性粒子数量相当,增大甲基蓝浓度,未被降解的甲基蓝分子越多,导致甲基蓝降解率的减小。电晕放电过程甲基蓝分子之间的聚合与发色CN双键的生成共同促使甲基蓝发色基团吸光度在放电5 min时达到最大;且甲基蓝溶液的初始浓度越高,吸光度（A₅-A₀）升高的越多。概括来说,甲基蓝结构中发色CN双键的存在是电晕放电等离子体降解甲基蓝过程溶液颜色加深再变浅的主要原因。反应过程羟基自由基的消耗导致放电5 min时溶液的pH值升高;随着反应的进行溶液中生成的硝酸及小分子酸增强了溶液的酸性,导致pH值降低。三维荧光光谱结果表明,甲基蓝降解过程出现了三类明显的荧光峰,位于E_X/E_M=310~320/430~450,E_X/E_M=240~250/320~340和E_X/E_M=280/340,分别代表腐殖酸类物质、芳香族蛋白质和溶解性微生物代谢副产物。甲基蓝溶液降解前的荧光物质主要为腐殖酸类,随着降解时间的延长,腐殖酸类物质首先降解生成了芳香族蛋白质,进一步降解产生可溶性微生物代谢副产物。比较电晕放电前后甲基蓝溶液的红外光谱图和红外分峰图发现,甲基蓝结构中N-H键3 432.8 cm-1处不对称伸缩振动峰红移了0.3 cm-1,烯烃和苯环上C-H键2 975.9 cm-1处的伸缩振动峰向高波数偏移了0.5 cm-1,1 638.7 cm-1处RCHCHR的双键伸缩振动位置蓝移了3.2 cm-1,芳仲胺的C-N伸缩振动峰1 341.6 cm-1向高波数偏移了1.3 cm-1,磺酸基SO的伸缩振动峰1 121.1和1 034.3 cm-1分别红移了3.8和13 cm-1,甲基蓝结构中的环外CC双键与CN双键吸收峰消失,在1 692.4和1 400.4 cm-1处分别出现了CO和NO的伸缩振动吸收峰,产生了2,5-环己二烯-1,4-二酮、对硝基苯磺酸钠和芳香酮类等中间产物。该结果对于利用电晕放电等离子体技术处理甲基蓝废水具有重要的理论意义和实用价值。     

钴超分子络合物中的氢键相互作用—59Co核磁共振研究及分子模拟

钴超分子络合物[12]aneN₄[Co(CN)₆], [18]aneN₆[Co(CN)_6^], [24] aneN₈[Co(CN)₆], [16] aneN₄[Co(CN)₆], [24] aneN₆[Co(CN)₆]以及[32] aneN₈[Co(CN)₆]中, 氢键相互作用的程度与它们在水溶液中的构象密切相关, 从而引起⁵⁹Co的化学位移向高场移动, 并且其四极矩耦合作用也随构象发生了变化. 实验证明, 络合物中的氢键越强, 化学位移越向高场移动, 四极矩耦合作用也越大. 另一方面, 尺寸大的超分子具有较长的分子转动相关时间,也导致⁵⁹Co具有较短的纵向弛豫时间. 简而言之,⁵⁹Co核磁共振不仅在小分子甚至在超分子络合物中都可以用作理想的探针研究分子的次层或弱相互作用.     

Nano-structured cellulose nanocrystals-xyloglucan multilayered films for the detection of cellulase activity

Multilayered cellulose nanocrystals-xyloglucan (CN-XG) films were assembled by spincoating at two CN concentrations inducing different structural colourations. Internal structure of both films was probed by neutron reflectometry (NR) revealing different thicknesses and architectures. The impact of film structure on degradation process by cellulases was revealed by a change in colours of the films, as CN and XG are both sensitive to cellulolytic enzymes.     

Experimental and kinetic modeling study of oxidation of acetonitrile

Oxidation of acetonitrile has been studied in a flow reactor in the absence and presence of nitric oxide. The experiments were conducted at atmospheric pressure in the temperature range 1150–1450 K, varying the excess air ratio from slightly fuel-lean to very lean. Oxidation of CH₃CN was slow below 1300 K. Nitric oxide, hydrogen cyanide and nitrous oxide were detected as important products. A detailed chemical kinetic model for oxidation of acetonitrile was developed, based on a critical evaluation of data from literature. The rate coefficients for the reactions of CH₃CN and CH₂CN with O₂ were calculated from ab initio theory. Modeling predictions were in satisfactory agreement with experiments. Calculations were sensitive to thermal dissociation of CH₃CN and to the branching fraction for CH₃CN + OH to CH₂CN + H₂O and HOCN + CH₃, respectively. More work is desirable for these steps, as well as for reactions of CH₂CN and HCCN.     

Decolourization of Rhodamine B: A swirling jet-induced cavitation combined with NaOCl

A hydrodynamic cavitation reactor (Ecowirl) based on swirling jet-induced cavitation has been used in order to allow the degradation of a waste dye aqueous solution (Rhodamine B, RhB). Cavitation generated by Ecowirl reactor was directly compared with cavitation generated by using multiple hole orifice plates. The effects of operating conditions and parameters such as pressure, pH of dye solution, initial concentration of RhB and geometry of the cavitating devices on the degradation rate of RhB were discussed. In similar operative conditions, higher extents of degradation (ED) were obtained using Ecowirl reactor rather than orifice plate. An increase in the ED from 8.6% to 14.7% was observed moving from hole orifice plates to Ecowirl reactor. Intensification in ED of RhB by using hydrodynamic cavitation in presence of NaOCl as additive has been studied. It was found that the decolourization was most efficient for the combination of hydrodynamic cavitation and chemical oxidation as compared to chemical oxidation and hydrodynamic cavitation alone. The value of ED of 83.4% was reached in 37 min using Ecowirl combined with NaOCl (4.0 mg L⁻¹) as compared to the 100 min needed by only mixing NaOCl at the same concentration. At last, the energetic consumptions of the cavitation devices have been evaluated. Increasing the ED and reducing the treatment time, Ecowirl reactor resulted to be more energy efficient as compared to hole orifice plates, Venturi and other swirling jet-induced cavitation devices, as reported in literature.     

锥形碳氮结构的发光性能

利用偏压增强化学气相沉积系统,以CH4、H2和NH3为反应气体,分别在沉积有钛膜和碳膜的Si衬底上制备锥形碳结构,并用扫描电子显微镜、X射线能谱仪和显微Raman光谱仪对其进行表征,结果表明所制备的样品为锥形碳氮结构.用显微Raman光谱仪对锥形碳氮结构在室温下的发光性能进行了研究,发光谱显示出中心在621,643,7...     

Phase studies and thermal stability of binary systems of cholesteric liquid crystals

The binary mixture of cholesteryl oleyl carbonate (COC) and cholesteryl nonanoate (CN) with different ratios has been characterized by differential scanning calorimetry (DSC) to determine the phase diagrams. Their normal shelf-life and accelerated stability studies were also examined. A novel microscopic Fourier-transform infrared (FT-IR) spectrometer equipped with DSC was also used to measure simultaneously the chemical structural variation and the thermal response of these liquid crystals. The results indicate that the binary mixture might transform from smectic to cholesteric and then to isotropic liquid (CN composition <50%); from solid to cholesteric and then to isotropic liquid (CN composition >50%). Therefore, the 50% CN composition might play a critical role in the phase transition of the binary COC-CN mixture. The microscopic FT-IR/DSCsystem could also confirm the phase transition, but could measure the phase trasition temperature of liquid crystals more easily and sharply than the DSC method. The long-term accelerated thermal stability of the COC-CN mixture seemed to be more constant when stored at 4 °C than in any other temperature conditions.     

Treatment of Low and Medium Active Waste by Hexacyanocobaltate(III)

The commercially available CO₃[Co(CN)₆]₂·12H₂O was used in this study as inorganic ion exchanger. The uptake of caesium and cobalt from simulated borate reactor waste on the exchanger was conducted as a function of pH and concentration of caesium or cobalt in solutions. The same study was also carried out on the sorption of caesium from simulated medium active waste. In addition some experiments were carried out on the sorption of radionuclides present in a real medium active waste concentrate.     

Chemical pumping of the far infrared HCN laser

This paper reports the observation of 337 μm and 311 μm stimulated emission from HCN in which the (11¹0)?(04⁰0) inversion has been established by photopumping of HCN and by chemical pumping with reactions between CN and H₂ or saturated hydrogen-rich organic compounds. Similarities in output pulse behavior between the discharge and chemical versions of the HCN laser are suggestive that the pumping mechanism in the discharge is the chemical reaction, CN + H₂ → HCN² + H. The well-known inefficiency of this laser is then due to the fact that the reaction is a slow one and its exothermicity does not match the energy of the upper lasing level, but depends for inversion on (randomizing) relaxation into (11¹0) among others. Substantial improvements in the power of the HCN laser cannot be made from this route.     

超声处理有机废水的现状与进展

从超声降解有机废水的机理入手,对当前单频和多频(二维正交和三维)超声以及超声技术与其他技术联用降解污水的原理、影响因素和效果和国内外研究现状进行了总结和回顾,同时对该技术在处理有机废水方面的研究趋势进行了展望。     

星际型CH_3CN－H_2含超精细能级的碰撞跃迁速率系数的理论计算

利用ＩＯＳ近似模型，计算了星际分子云条件下Ｅ型ＣＨ３ＣＮ－Ｈ２含超精细能级的的碰撞跃迁速率系数。其温度范围是２０Ｋ－１４０Ｋ。为研究分子云与恒星形成区的物理、化学性质提供了大量有用的基础分子数据。