Synthesis of mesoporous polymeric carbon nitride exhibiting enhanced and durable visible light photocatalytic performance

A thiourea precursor was employed to synthesize mesoporous carbon nitride(C3 N4) by a thermal polycondensation process with high surface area SiO2 and nanosphere SiO2 as two types of hard templates. The resultant mesoporous C3 N4 samples have high surface areas(105–112 m2/g) and mesopores with narrow sizes distribution(9.3 nm). Photocatalytic performance was evaluated by removal of NO in air under visible light irradiation. The results showed that mesoporous C3 N4 samples exhibited significantly improved photocatalytic activity in comparison with bulk C3 N4, which also exceeded that of N-doped TiO2 and C-doped TiO2. The activity enhancement can be ascribed to the synergistic effects of large surface area and pore volume, enhanced light-harvesting ability, increased redox potential, and reduced recombination of charge carriers. In addition to the high activity, the mesoporous C3 N4 samples also showed high photochemical stability. The mesoporous C3 N4 photocatalysts with enhanced and durable activity could provide a new efficient material for environmental pollution control.     

高比表面积石墨相氮化碳的制备及其光催化应用研究进展

石墨相氮化碳（g-C3N4）具有较好的物理化学稳定性,合适的能带结构,良好的可见光吸收性能,因而在光催化领域得到了广泛关注。作为异相催化剂,高比表面积可以提供较多的反应位点,增加反应物的接触,改善传质,从而促进催化性能的提升。本文综述了高比表面积g-C3N4的合成方法,介绍了两种增加g-C3N4比表面积的途径：（1）模板法制备多孔g-C3N4;（2）剥离法制备薄层g-C3N4纳米片。本文对高比面积g-C3N4的光催化应用也做了相应的介绍,并对g-C3N4的发展前景做了展望。     

Preparation of graphitic carbon nitride by electrodeposition

A new C-N compound b-C3N4 with the mechanicalproperties similar to those of diamond was predictedthrough the ab initio calculations of Liu and Cohen[1] in1989. The high hardness, high wear resistance, low coef-ficient of friction and wide energy gap make it attractive for industrial applications. With further theoretical work,five C3N4 structures, a-C3N4, b-C3N4, cubic (c-C3N4), pseudocubic (p-C3N4 ) and graphitic (g-C3N4), were pro-posed[2]. Many efforts have been made in attempts to s…     

Ferrites boosting photocatalytic hydrogen evolution over graphitic carbon nitride: a case study of (Co,Ni)Fe2O4 modification

The charge carrier separation and surface catalytic redox reactions are of primary importance as elementary steps in photocatalytic hydrogen evolution. In this study, both of these two processes in photocatalytic hydrogen evolution over graphitic carbon nitride（g-C₃N₄） were greatly promoted with the earth-abundant ferrites（Co,Ni）Fe₂O₄modification. Co Fe₂O₄ was further demonstrated to be a better modifier for g-C₃N₄ as compared to Ni Fe₂O₄,due to the more efficient charge carrier transfer as well as superior surface oxidative catalytic activity. When together loading Co Fe₂O₄ and reductive hydrogen production electrocatalyst Pt onto g-C₃N₄, the obtained Pt/g-C₃N₄/Co Fe₂O₄ photocatalyst achieved visible-light（λ>420 nm） hydrogen production rate 3.5 times as high as Pt/g-C₃N₄, with the apparent quantum yield reaching 3.35 % at 420 nm.     

Catalytic self-assembly preparation and characterization of carbon nitride nano-tubes by a solvothermal method

A solvothermal reaction of anhydrous CaNaCl3 and sodium using cyclohexane as solvent and NiCI2 as catalyst precursor has been carried out to prepare carbon nitride nanotubes successfully at 230℃ and 1.8 MPa. The carbon nitride nanotubes were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), electron energy loss spectrum (EELS) and Raman spectrum.SEM and TEM results indicated that the tubes have a length of 20-30 μm, a uniform outer diameter of about 50-60 nm,an inner diameter of 30-40 nm and are highly ordered assembled as bundles. The EELS measurement indicated that the ratio of N/C was about 1.00. The ED and XRD analyses revealed that the tube may have a new CN crystalline structure. The growth mechanism of nanotubes was discussed.     

微波热处理再生颗粒状活性炭的研究

本文利用微波热处理法,分别在大气和氮气气氛两种情况下快速再生了已经充分吸附SO2的颗粒状活性炭.微波热处理过程中,应用红外热成像技术,采集了样品的一系列热图像,直观显示了温度分布,表明热处理的最高温度仅为300℃.将再生产物用于模拟烟气脱硫实验,结果表明大气气氛下,微波再生活性炭的脱硫性能还不及原炭的一半;换以氮气气氛隔绝空气后,其脱硫性能提升到原炭的97%.隔绝空气条件下的微波热处理再生法比传统热再生方法,降低了处理温度、极大缩短了再生时间,体现了高效、低能耗两大优势.     

石墨相氮化碳光催化产氢性能提升策略研究进展

石墨相氮化碳(g-C3N4)因带隙窄、稳定性高、成本低、污染小等优势在光催化产氢领域受到了研究者们的广泛关注.然而,纯g-C3N4直接作为光催化剂在应用时常存在比表面积小、可见光利用效率低以及光生载流子复合过快等缺陷,导致其光催化产氢性能较不理想.因此,如何改善g-C3N4的光催化产氢性能是目前光催化领域的研究热点.该文针对g-C3N4光催化产氢性能的优化研究,系统综述了g-C3N4在形貌调节、杂原子掺杂和异质结构建三个方面的改性研究进展,归纳总结了目前存在的问题,并对今后g-C3N4产氢光催化剂的研究重点和方向做出了展望.     

利用FT-IR和XPS研究纳米和微米氮化硅粉体在不同气氛下的表面结构变化(英文)

采用红外光谱技术和光电子表面能谱技术比较纳米和微米氮化硅粉体表面结构在空气中和在氮气中的变化规律.研究结果显示,纳米氮化硅在空气中逐渐吸附氧气和有机物质,其表面形成了Si—OH、C—C、C—N等化学基团,而在惰性的氮气气氛中,纳米氮化硅的表面氧化被有效抑制.上述研究工作为纳米氮化硅的表面改性研究提供了一定的理论支持.     

Magnetically separable and visible light-active Ag/NiCo_2O_4 nanorods prepared by a simple route for superior photodegradation of atrazine in water

Atrazine(ATZ) is a known herbicide used in agriculture and caused many concerns according to its toxicity.Herein,we have prepared NiCo_2 O_4 nanorods that can work as a photocatalyst under visible light exposure by Ag loading through a simple route.The characterizations revealed the role of Ag for improving the structural,optical and optoelectronic properties of the produced photocatalyst.The Ag loading with 5 wt% confirms the minimization of the bandgap from 3.6 down to 2.57 eV with enhanced visible light absorption and sustaining the magnetic properties.The Ag/NiCo_2 O_4 nanorods showed a superior photodegradation of ATZ within 20 min at2.0 g L~(-1) with excellent recyclability.The enhancement of the photocatalytic activity is referred to the local surface plasmon resonance of Ag-loaded photocatalyst.This reduces the electron-hole recombination and outperforms the unloaded sample.This work is highlighting the application of magnetically separable spinel photocatalysts for the removal of herbicides and water remediation.     

计及碳交易的某天然气处理厂含光伏光热的综合能源系统优化运行

随着“双碳”目标的提出,以光伏光热等为主的综合能源系统快速发展,为提高用能单位的经济效益和系统低碳性,考虑碳排放约束条件下多种能源发电的厂区供用能系统优化运行问题亟待研究。首先,在经济调度模型中,引入碳交易机制,构建阶梯型碳交易成本模型,对厂区的碳排放进行约束。然后,建立以系统运行成本和碳交易成本之和最小为目标的规划模型,利用马尔科夫决策过程对基于成本最小的经济调度进行建模,并采用近端策略优化算法进行求解,利用经济节约指数和二氧化碳减排指数,对拟题方案进行经济性和碳减排分析。结果表明：(1)训练后的模型在无需重新计算的情况下能够处理四个随机变量变动所代表的各种运营场景;(2)光伏光热子系统与热电联产系统具有削峰填谷效应,能提高系统稳定运行能力;(3)所设计计及碳交易下联产系统有利于优化厂区能源结构,促进清洁能源消纳。     

美拉德反应对花生分离蛋白体外消化特性的影响

为了探讨花生蛋白饮料在热杀菌过程中的美拉德反应发生情况以及对后续模拟消化特性的的影响,本文在80℃、100℃、121℃条件下分别对外加葡萄糖的花生分离蛋白湿热处理30min,然后进行体外模拟消化,并与同样处理条件但未加葡萄糖的样品进行比较.分别检测了热处理后样品在294nm和420nm处的吸光值,模拟消化产物的水解度、蛋白消化率、肽分子量分布和游离氨基酸组成.试验结果表明:未加葡萄糖的样品热处理后也发生了褐变,加入葡萄糖后褐变程度显著加深;热处理及美拉德反应致使后续的模拟消化产物中分子量较大的肽段含量增加;三个热处理条件中只有121℃超高温热处理有利于消化产物水解度的提高,而美拉德反应的发生总体上不利于花生分离蛋白的消化利用.     

负载型纳米二氧化钛光催化技术 处理含乙硫醇废气工艺探讨

基于负载型纳米二氧化钛光催化氧化技术处理难降解乙硫醇为目标污染物,为乙硫醇等恶臭气体的无害化处理探讨可行且高效的技术工艺。在450℃下焙烧得到活性较高的锐钛矿型二氧化钛催化剂,考察不同气体流量、光能密度、湿度、O₂体积分数等参数下反应器的降解效率,得到体系最佳运行条件。结果表明：乙硫醇的降解效果与废气流量呈负相关趋势,在废气流量为0.3 L/min、湿度为45%、O₂体积分数为30%时,乙硫醇降解效率最佳;乙硫醇降解效率随光能密度的增大而逐渐上升,考虑能耗问题,将光能密度控制在7 W/cm²时乙硫醇的综合降解效果可达最优。通过显著相关性分析发现,乙硫醇进气质量浓度、光能密度和乙硫醇降解效率之间呈显著正相关关系,废气流量与乙硫醇降解效率之间呈显著负相关关系。     

原位观察TiN粒子对低合金高强度钢模拟焊接热影响区粗晶区晶粒细化作用

采用高温激光共聚焦显微镜原位观察和电子背散射衍射技术研究TiN粒子在低合金高强度钢模拟大线能量焊接热循环过程中晶粒细化效果。研究发现合理的Ti和N含量能形成大量细小弥散分布的纳米级TiN粒子,在焊接热循环过程中有效钉扎热影响区粗晶区奥氏体晶界,抑制晶粒粗化。同时,TiN附着在Al2 O3表面析出,在冷却过程中有效促进针状铁素体形核,得到有效晶粒尺寸非常细小的由少量针状铁素体和大量贝氏体构成的复合组织。     

烟囱工程密集桩检测与处理

通过洛河电厂三期工程2×600MW机组烟囱桩基础的152根Ⅱ、Ⅲ类工程桩复打、高低应变检测及静载试验等一系列工作,验证工程桩设计竖向、水平承载要求;但因其接桩处虽闭合但无抗剪能力,难以承受地震产生的水平力,为降低费用和减小处理工作量,采取取出桩内孔土芯及插筋浇灌混凝土的方法加强桩接头,并在工作中总结出一套避免由于土体挤压而抬升桩体被拉断的成功经验。     

有害元素对高炉炉缸侧壁碳砖的侵蚀

对湘钢2号高炉炉缸七个有代表部位的样品进行扫描电镜、能量色散谱、X射线衍射和原子吸收光谱分析,研究有害元素对高炉炉缸侧壁碳砖的侵蚀以及粉化断裂机理.结果表明,高炉炉缸不同部位的碳砖侵蚀机理不同.第一层以有害元素在碳素熔损反应中的催化作用及生成白榴石为主;上部碳砖侵蚀以K渗透到砖缝中,改变砖质为主;风口以Zn侵蚀为主;铁口K含量较多,另有Pb富集.同种有害元素在不同部位侵蚀碳砖的机理有所不同.K元素在最上部以催化作用为主,在下部以渗透到碳砖内部使碳砖改性为主;Zn在风口碳砖有明显的结晶,在炉缸炉底上部含有大量的Zn并没有结晶,而是附着在砖表面上部.     

特种光量子技术降解水体中微量4-氯酚

文章研究了特种光量子技术对水体中微量4-CP的降解情况,考察了溶液浓度、光解时间、溶液pH值以及加入氧化剂等对降解4-CP的影响,确定了适宜的反应条件,对光解产物进行了GC/MS分析及其降解机理探讨;研究结果表明,该种技术能有效降解微量4-CP,处理3 min时加入K2S2O8的4-CP溶液的CODCr去除率和脱氯率均达到100%。     

Measurement of the Average Molecular Weight of Cotton Cellulose Crosslinked by a Polycarboxylic Acid at Different pH Using Multiple Angle Light Scattering Photometer in a DMAc/LiCl Solvent System

Durable press finishing of cotton fabrics with polycarboxylic acid increases fabric wrinkle-resistance at the expense of its mechanical strength. Severe tensile strength loss is the major disadvantage for wrinkle resistant cotton fabrics. Tensile strength loss of cotton fabric crosslinked by a polycarboxylic acid can be attributed to depolymerization and crosslink of cellulose molecules. Measurement of the molecular weight of cotton fabric before and after crosslinked by polycarboxylic acids can offer a possibility of direct understanding of the depolymerization. In this research, a multiple angle laser light scattering photometer was used to determine the absolute molecular weight of cotton fabric treated with BTCA at different pH and then hydrolyzed with 0.5 M NaOH solution at 50℃ for 144 h. The results indicate that average molecular weights of cotton fabric treated with polycarboxylic acids at different pH are almost the same.     

流动管道内噪声源辐射声场数值预估

流动管道内噪声源辐射声场问题难度很大。该文给出了经实验考核的流动管道内声源辐射声场数值预估方法,并给出了圆管外声压级指向性系数图。利用这些图和简单公式,通过测量管外一点的声压级就可确定管内声源声功率。该文数值方法采用线化Euler方程,四阶MacCormack差分格式和Tam与Webb的无反射边界条件数值预估有流动的圆管出口辐射声场,并用声强扫描仪和声级计在半消声室中测量了管内声功率及管外声压分布,数值计算和实验所得声压指向性系数符合良好,最大误差小于1dB。     

Variation law of gas holdup in an autoclave during the pressure leaching process by using a mixed-flow agitator

The multiphase reaction process of pressure leaching is mainly carried out in the liquid phase. Therefore, gas holdup is essential for the gas-liquid-solid phase reaction and the extraction rate of valuable metals. In this paper, a transparent quartz autoclave, a six blades disc turbine-type agitator, and a high-speed camera were used to investigate the gas holdup of the pressure leaching process. Furthermore, experiments determining the effects of agitation rate, temperature, and oxygen partial pressure on gas holdup were carried out. The results showed that when the agitation rate increased from 350 to 600 r/min, the gas holdup increased from 0.10% to 0.64%. When the temperature increased from 363 to 423 K, the gas holdup increased from 0.14% to 0.20%. When the oxygen partial pressure increased from 0.1 to 0.8 MPa, the gas holdup increased from 0.13% to 0.19%. A similar criteria relationship was established by Homogeneous Principle and Buckingham's theorem. Comprehensively, empirical equation of gas holdup was deduced on the basis of experimental data and the similarity theory, where the criterion equation was determined as ε=4.54×10-11n3.65P_g0.18. It can be seen from the formula that agitation rate made the most important impact on gas holdup in the pressure leaching process using the mixed-flow agitator.