KMnO4/H2SO4引发制备淀粉改性絮凝剂的研究

以高锰酸钾为引发剂,制备淀粉-丙烯酰胺接枝共聚物.研究酸浓度、引发剂浓度、单体浓度、温度和加料方式对接枝反应的影响.结果表明,少量KMnO4(0·45mmol·l-1)和H2SO4(0·8mmol·l-1)可有效引发淀粉-丙烯酰胺接枝共聚反应,接枝效率达到90%以上,分子量大大提高,对高岭土的絮凝效果较好.     

天然改性淀粉絮凝剂的合成与应用

以硝酸铈铵为引发剂,通过接枝共聚反应,在淀粉(Starch)骨架上引入丙烯酰胺(AM),制得St-AM接枝物.在引发剂用量为1.1 mmol·l-1,淀粉与单体质量配比为1∶ 3,25℃下反应3h,接枝物黏度可达587.83 ml·g-1,能使煤泥水中的细泥颗粒形成较大的絮团而快速沉降,固液分离效果好.用合成的絮凝剂进行了水处理试验,结果表明,当接枝物用量为50g·t-1干煤泥,辅以凝聚剂用量1.5kg·t-1干煤泥能有效解决选煤厂煤泥水中细粒含量多、压滤处理困难的问题,滤饼水分可控制在25%,滤液浓度在60g·l-1左右,与聚丙烯酰胺(PAM)对煤泥水和高岭土悬浮体絮凝作用相比,该接枝共聚物具有价廉、无毒、絮凝效果好等特点.     

木质素接枝改性影响因素的研究

对碱法麦草制浆黑液酸法回收的木质素与丙烯酰胺接枝共聚反应进行了试验研究.结果表明,接枝共聚反应的适宜条件为:丙烯酰胺单体用量1.0mol·1-1,过硫酸钾引发剂浓度1.0×10-2mol·1-1,反应温度70℃,固液比1:50(W/W),反应时间4h.木质素与木质素接枝聚合物以及聚丙烯酰胺的红外光谱表明,木质素与丙烯酰胺之间发生了接枝共聚反应.     

甲基丙烯酸甲酯与交联淀粉的接枝共聚物的制备及产物对水中微量金属离子的吸附

本文以硝酸铈铵为引发剂,制得了甲基丙烯酸甲酯与交联玉米淀粉的接枝共聚物,当〔Ce~(4+)〕为5×10~(-3)mol·L~(-1)、〔MMA〕为7.52×10~(-1)mol.L~(-1),于50℃反应4h,所得接枝共聚物的接枝率和接枝效率都较高。将接枝共聚物分别与NH_2OH及KH_2NH_2反应,所得的产物具有对Cu~(2+),Pb~(2+),Zn~(2+)等金属离子的吸附能力。     

高分子重金属絮凝剂CSAX除铜、除浊性能研究

研究高分子重金属絮凝剂交联淀粉-接枝丙烯酰胺-共聚黄原酸钠(CSAX)的除铜、除浊性能及其影响因素,并与不溶性淀粉丙烯酰胺接枝共聚物(ISA)、不溶性淀粉黄原酸钠(ISX)两种水处理剂进行了比较,结果表明:(1)CSAX兼具ISA和ISX的优点,具有很好的除铜、除浊性能;(2)该絮凝剂对铜的去除具有一定的化学计量关系;(3)pH值对Cu2 的去除有一定的影响,在pH2.0-5.O时,相同投药量下,pH值愈高,Cu2 的去除率愈高;(4)Na ,Mg2 和Ca2 对Cu2 的去除有一定的促进作用;Fe3 在pH值较低时会抑制Cu2 的去除,pH值高时会促进Cu2 的去除;(5)致浊物质的存在可以促进Cu2 的去除.     

杭州市空气中PM10的化学组成特征

于2001年2月至2002年4月在杭州5个空气质量自动监测子站采集了176组PM10样品,分析了22种化学元素、5种离子以及有机碳(OC)和元素碳(EC)的含量,并讨论了PM10的化学组成特征.杭州市空气中铅污染仍然存在,硫的存在形式主要为水溶性硫酸盐.5种水溶性离子的浓度由大到小排列的顺序是SO2-4> NO-3> NH+4>Cl->F-,大气中NH+4主要是以(NH4)2SO4,NH4HSO4和NH4NO3的形式存在.OC和EC浓度分别为20.4 μg·m-3和4.0 μg·m-3,其相关性不好表明碳的来源复杂.PM10的物质平衡计算表明,局地地质尘是最高的化学组分,达27.7%,其次为有机物23.9%,第三为硫酸盐16.2%,这3个组分占PM10的67.8%,其它为硝酸盐6.3%,铵盐6.1%,微量元素5.5%,元素碳3.4%以及未测组分11.0%.     

功能接枝微粒PSSS/SiO2的制备及其对水介质中含氮杂环农药的吸附特性

使用γ-氨丙基三甲氧基硅烷(AMPS)对微米级硅胶微粒进行表面改性,制得改性微粒AMPS-SiO2;使改性微粒AMPS-SiO2表面的氨基与溶液中的过硫酸盐构成氧化-还原引发体系,实施了对苯乙烯磺酸钠(SSS)在硅胶微粒表面的高效引发接枝聚合,将阴离子聚电解质聚对苯乙烯磺酸钠(PSSS)接枝于硅胶微粒表面,制得了接枝微粒PSSS/SiO2;采用红外光谱(FTIR)、扫描电子显微镜(SEM)、Zeta电位测定等多种手段对接枝微粒PSSS/SiO2进行了表征.在此基础上重点考察了接枝微粒PSSS/SiO2对抗蚜威和特丁津两种含氮杂环农药分子的吸附特性与吸附机理.研究结果表明,在静电相互作用下,接枝微粒PSSS/SiO2对含氮杂环农药分子具有很强的吸附能力,抗蚜威和的特丁津的吸附容量可分别达到104 mg.g-1及95 mg.g-1,且当水介质的pH=4时,吸附容量最高.吸附容量随温度的升高而降低.接枝微粒PSSS/SiO2既具有阴离子聚电解质PSSS的功能性,又具有硅胶微粒优良的机械性能与热稳定性,在环境治理与保护领域,是一种具有发展前景的功能复合微粒.     

溶胶制备工艺对TiO2光催化剂活性的影响

考察了不同酸、溶剂以及不同比例水制备的溶胶对TiO2光催化剂活性的影响进行了分析.结果表明,在盐酸、醋酸、草酸和甲基丙烯酸中,采用醋酸所得催化剂活性最好;在乙醇、正丙醇、异丙醇、正丁醇4种溶剂中,采用正丁醇作溶剂所得催化剂活性最好;最佳溶胶制备条件为钛酸丁酯∶水∶冰醋酸正丁醇＝1∶ 3∶ 8∶ 10(摩尔比);最优条件下制备的TiO2催化剂平均粒径为15.19nm,晶型为锐钛矿,对小于320nm的紫外光有良好的吸收;利用研制的TiO2光催化剂降解多菌灵废水,反应1h,COD去除率在35%左右;对9.606mg·l-1的苯酚溶液光降解半衰期为4.6min.     

胶束形态对十六烷基三甲基溴化铵(CTAB)增溶典型苯系物行为的影响

研究了30℃条件下,浓度为1.2×10-4mol·l-1—2.88×10-2mol·l-1的阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)溶液的吸光度及相应浓度条件时对典型苯系物(苯、甲苯和乙苯)的增溶作用.利用表面活性剂的紫外吸收随浓度变化这一特性,从其不同的拐点处求得CTAB的第一、第二临界胶束浓度分别为7.2×10-4mol·l-1和9.6×10-3mol·l-1.在实验浓度范围内,CTAB溶液对苯、甲苯和乙苯的表观溶解度增溶曲线上同样得到两个拐点,即苯7.2×10-4mol·l-1和9.6×10-3mol·l-1,甲苯7.2×10-4mol·l-1和7.2×10-3mol·l-1以及乙苯7.2×10-4mol·l-1和9.6×10-3mol·l-1,这与第一、第二临界胶束浓度相等或相近.由于溶液中CTAB胶束形态随浓度增加而变化,表明胶束形态对CTAB增溶苯系物的行为有显著影响。     

煤气化废水萃取脱酚工艺研究

采用溶剂萃取对煤气化废水进行酚回收处理.确定烷基酮类物质(M105)作为煤气化废水的脱酚萃取剂,并对脱酚工艺参数进行优化.工艺参数为:萃取温度40-60℃,pH＝9-10,相比=1∶ 6-1∶ 4.经四级逆流萃取,废水的总酚浓度从5410mg·l-1降至350mg·l-1,挥发酚降至50 mg·l-1以下.     

SO2-4/TiO2对SO2-C7H16-TiO2复相光化学反应的影响

研究了TiO2与SO2,C7H16复相光化学反应的光催化活性.在SO2-C7H16-O2-TiO2光催化反应过程中,TiO2表面可形成SO2-4/TiO2结构,它的存在可提高庚烷的光催化氧化速率,利用IR和XPS研究了反应过程中TiO2表面形成的SO2-4/TiO2结构.     

大气CO2、CH4、CO高精度观测混合标气配制方法

高精度、高准确度的大气CO2、CH4、CO浓度观测需使用以干洁大气为底气的标气.标气中水汽含量及CO2的δ13C对基于光学原理的观测系统有不可忽视的影响.本研究利用自组装的混合标气配制系统,以环境大气为底气,并通过添加高浓度气体或利用吸附剂吸附,调节目标物种浓度.CO2和CO吸附效率分别达99.7%和99.8%,标气水汽含量小于3.7×10-6(物质的量分数,下同),可配制不同浓度范围的CO2、CH4、CO混合标气.在青海瓦里关全球大气本底站配制环境大气浓度范围的标气,CO2、CH4、CO实际配制浓度同目标浓度的偏差小于10×10-6、30×10-9、30×10-9,CO2中δ13C同实际大气接近.本方法配制的标气已应用于我国本底站大气CO2、CH4、CO高精度观测,符合世界气象组织/全球大气观测(WMO/GAW)质量要求.     

A2型高粱细胞质雄性不育系与其保持系的胞质DNA和核DNA差异

以高粱细胞质雄性不育系A2V4（A）及其保持系V4（B）的总DNA为模板,对184个随机引物进行筛选,找到6个其RAPD扩增产物在A／B间存在稳定差异的引物,将该6个引物同时扩增A／B的总DNA、线粒线DNA（mtDNA）及叶绿体DNA（cpDNA）,以总DNA为模板时得到12个扩增片段,以mtDNA为模板时得到4个,以cpDNA为板时得到11个,结果分析表明,在这些扩增片段中,有7个仅仅出现在以胞质DNA为模板的扩增中,有5个在以总NDA和胞质DNA为模板时同时出现,即认为这12个片段来自胞质DNA,另有7个片段,在以胞质DNA为模板时未出现,而是仅仅出现在以总DNA为模板的扩增中,认为是来自核DNA,来自核DNA的7个扩增片段中,有5个来自保持系,有2个来自不育系,这表明,不育系与保持系在核DNA上存在差异,对A／B核DNA在CMS中的重要性及研究对策进行了讨论。     

3D flower-like mesoporous Bi4O5I2/MoS2 Z-scheme heterojunction with optimized photothermal-photocatalytic performance

3D flower-like hierarchical mesoporous Bi₄O₅I₂/MoS₂ Z-scheme layered heterojunction photocatalyst was fabricated by oil bath and hydrothermal methods. The heterojunction with narrow band gap of ～1.95 eV extended the photoresponse to near-infrared region, which showed obvious photothermal effect due to the introduction of MoS₂ with broad spectrum response. MoS₂ nanosheets were anchored onto the surface of flower-like hierarchical m...     

One-pot hydrothermal fabrication of BiVO4/Fe3O4/rGO composite photocatalyst for the simulated solar light-driven degradation of Rhodamine B

• BiVO₄/Fe₃O₄/rGO has excellent photocatalytic activity under solar light radiation. • It can be easily separated and collected from water in an external magnetic field. • BiVO₄/Fe₃O₄/0.5% rGO exhibited the highest RhB removal efficiency of over 99%. • Hole (h⁺) and superoxide radical (O₂^•−) dominate RhB photo-decomposition process. • The reusability of this composite was confirmed by five successive recycling runs. Fabrication of easily recyclable photocatalyst with excellent photocatalytic activity for degradation of organic pollutants in wastewater is highly desirable for practical application. In this study, a novel ternary magnetic photocatalyst BiVO₄/Fe₃O₄/reduced graphene oxide (BiVO₄/Fe₃O₄/rGO) was synthesized via a facile hydrothermal strategy. The BiVO₄/Fe₃O₄ with 0.5 wt% of rGO (BiVO₄/Fe₃O₄/0.5% rGO) exhibited superior activity, degrading greater than 99% Rhodamine B (RhB) after 120 min solar light radiation. The surface morphology and chemical composition of BiVO₄/Fe₃O₄/rGO were studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The free radicals scavenging experiments demonstrated that hole (h⁺) and superoxide radical (O₂^•−) were the dominant species for RhB degradation over BiVO₄/Fe₃O₄/rGO under solar light. The reusability of this composite catalyst was also investigated after five successive runs under an external magnetic field. The BiVO₄/Fe₃O₄/rGO composite was easily separated, and the recycled catalyst retained high photocatalytic activity. This study demonstrates that catalyst BiVO₄/Fe₃O₄/rGO possessed high dye removal efficiency in water treatment with excellent recyclability from water after use. The current study provides a possibility for more practical and sustainable photocatalytic process.     

Heterostructuring noble-metal-free 1T' phase MoS2 with g-C3N4 hollow nanocages to improve the photocatalytic H2 evolution activity

In this work,we report the preparation of 1T’-MoS₂/g-C₃N₄ nanocage(NC) heterostructure by loading 2D semi-metal noble-metal-free 1T’-MoS₂ on the g-C₃N₄ nanocages(NCs).DFT calculation and experimental data have shown that the 1T’-MoS₂/g-C₃N₄ NC heterostructure has a stronger light absorption capacity and larger specific surface area than pure g-C₃N₄ NCs and g-C₃N     

Self-assembly synthesis of phosphorus-doped tubular g-C3N4/Ti3C2 MXene Schottky junction for boosting photocatalytic hydrogen evolution

Establishing highly effective charge transfer channels in carbon nitride(g-C₃N₄) to enhance its photocatalytic activity is still a challenging issue. Herein, the delaminated 2D Ti₃C₂ MXene nanosheets were employed to decorate the P-doped tubular g-C₃N₄(PTCN)for engineering 1D/2D Schottky heterojunction(PTCN/TC) through electrostatic self-assembly. The optimized PTCN/TC exhibited the highest hydrogen evolution rate(565 μmol h^-...     

Catalytic oxidation of CO over Pt/Fe3O4 catalysts: Tuning O2 activation and CO adsorption

• Strong metal-support interaction exists on Pt/Fe₃O₄ catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe₃O₄. • Fe₃O₄ supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe₃O₄ powder to prepare heterogeneous-structured Pt/Fe₃O₄ catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe₃O₄ catalysts achieved a better catalytic performance of CO oxidation compared with the Fe₃O₄ powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe₃O₄, respectively. However, they are accomplished on Fe₃O₄ at temperatures higher than 310°C. XRD, XPS, and H₂-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe₃O₄ supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe₃O₄. The combined results of O₂-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe₃O₄ catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism.     

磷酸活化活性炭对Cu2+的吸附特征研究

寻求廉价而高效的吸附材料为目的,研究向日葵秸杆基活性炭对铜离子的吸附性能。以向日葵秸秆为原料,经H3PO4活化制备活性炭,通过静态实验研究了其对水溶液中Cu2+的吸附特性,考察了溶液pH值、吸附温度和离子强度对吸附的影响,探讨了吸附热力学、动力学和吸附机理。结果表明:溶液pH值为5～6时活性炭对Cu2+的去除效果最好;向50 mL 170 mg·L-1的溶液中加入0.5 g活性炭,温度为45℃、吸附时间为1 h时,对Cu2+的去除率可达98.3%;Langmuir方程能更好地描述Cu2+在活性炭上的等温吸附特征,静态吸附容量可达41.03 mg·g-1;吸附过程符合拟二级动力学过程,且为吸热的化学吸附过程,膜扩散为速率控制步骤,离子交换可能在吸附过程中起了重要作用。     

Highly effective visible-photocatalytic hydrogen evolution and simultaneous organic pollutant degradation over an urchin-like oxygen-doped MoS2/ZnIn2S4 composite

● An urchin-like OMS/ZIS composite was fabricated by a facile solvothermal method. ● The OMS/ZIS exhibits superior photocatalytic H₂ evolution for organics degradation. ● A probable mechanism of dual-functional photocatalysis was proposed in detail. ● This work provides an inspiration for rational design of dual-functional catalysts. Achieving hydrogen production and simultaneous decomposition of organic pollutants through dual-functional photocatalytic reactions has received increasing attention due to the environmentally friendly and cost-effective characteristics of this approach. In this work, an urchin-like oxygen-doped MoS₂/ZnIn₂S₄ (OMS/ZIS) composite was fabricated for the first time using a simple solvothermal method. The unique microstructure with abundant active sites and fast charge transfer channels further shortened the charge migration distance and compressed carrier recombination. The obtained composite exhibited an efficient H₂ evolution reaction rate of 12.8 mmol/g/h under visible light, which was nearly times higher than pristine ZnIn₂S₄, and the apparent quantum efficiency was 14.9% (420 nm). The results of the simultaneous photocatalytic H₂ evolution and organic pollutant decomposition test were satisfactory, resulting in decomposition efficiencies of resorcinol, tetracycline, and bisphenol A that reached 41.5%, 63.5%, and 53.0% after 4 h, respectively, and the highest H₂ evolution rate was 672.7 μmol/g/h for bisphenol A. Furthermore, natural organic matter (NOM) abundantly found in actual water was adopted as an electron donor for H production under simulated sunlight irradiation, indicating the promising practicability of simultaneous hydrogen evolution and NOM decomposition. Moreover, the mechanisms of the dual-purpose photocatalytic reactions, as well as the synergistic effect between the molecular structures of the organic pollutants and the corresponding adsorption behavior on the photocatalyst surface were illustrated in detail. These obtained results may serve as an inspiration for the rational design of highly efficient, dual-functional photocatalysts in the future.