微晶纤维素辅助制备C-TiO2复合材料及其对Cd2+的吸附性能

采用溶胶-凝胶法,利用微晶纤维素（CMC）辅助制备了C-TiO₂复合材料,并对其进行了结构、组成和形貌的分析。XRD分析结果表明,所制备的C-TiO₂复合材料样品为具有较高的结晶度的锐钛矿相TiO₂和石墨碳的复合材料; SEM、TEM和XPS分析表明,CMC在C-TiO₂复合材料的制备中起到双重作用:既是复合材料中C的前驱体,同时会增大所制备的TiO₂的分散程度。同时,利用Cd2+考察了C-TiO₂复合材料样品对重金属离子的吸附能力。实验表明,与未添加CMC的TiO₂相比,所制备的C-TiO₂复合材料对重金属离子具有很好的吸附性能,吸附量达到37.15 mgg-1,是未添加CMC的平衡吸附量（17.32 mgg-1）的214.5%。C-TiO₂优异的吸附性能将使其在Cd2+的污水处理上具有很好的应用前景。      

Adsorption of Pb(II) and Cd(II) from aqueous solutions using titanate nanotubes prepared via hydrothermal method

Titanate nanotubes (TNs) with specific surface areas of 272.31 m(2)g(-1) and pore volumes of 1.264 cm(3)g(-1) were synthesized by alkaline hydrothermal method. The TNs were investigated as adsorbents for the removal of Pb(II) and Cd(II) from aqueous solutions. The FT-IR analysis indicated that Pb(II) and Cd(II) adsorption were mainly ascribed to the hydroxyl groups in the TNs. Batch experiments were conducted by varying contact time, pH and adsorbent dosage. It was shown that the initial uptake of each metal ion was very fast in the first 5 min, and adsorption equilibrium was reached after 180 min. The adsorption of Pb(II) and Cd(II) were found to be maximum at pH in the range of 5.0-6.0. The adsorption kinetics of both metal ions followed the pseudo-second-order model. Equilibrium data were best fitted with the Langmuir isotherm model, and the maximum adsorption capacities of Pb(II) and Cd(II) were determined to be 520.83 and 238.61 mg g(-1), respectively. Moreover, more than 80% of Pb(II) and 85% of Cd(II) adsorbed onto TNs can be desorbed with 0.1M HCl after 3h. Thus, TNs were considered to be effective and promising materials for the removal of both Pb(II) and Cd(II) from wastewater.     

金属Cd2+掺杂TiO2纳米颗粒的制备及能级结构的影响机理

采用溶胶-凝胶法制备了Cd2+掺杂改性TiO2纳米颗粒,利用XRD、TEM、XPS和UV-Vis光谱对掺杂前后颗粒的结构和性能进行了表征。结果表明,溶胶-凝胶法制备的Cd2+掺杂TiO2纳米颗粒主要为锐钛矿相,粒径尺寸在20nm左右,掺杂前后TiO2的尺寸和形貌没有明显变化;结构表征和光谱测试结果发现,Cd元素在TiO2纳米颗粒中部分取代TiO2晶格中的Ti元素,以Cd2+的形式存在,形成Cd—O键,使TiO2纳米颗粒的吸收带边红移,降低了TiO2的禁带宽度。并且采用基于密度泛函理论的第一性原理对Cd掺杂TiO2进行了能级结构的模拟计算,发现理论结果与实验结果有较好一致性。     

Zn2+固溶堇青石体系的结构与红外辐射特性

采用固相法制备了Zn2+固溶堇青石体系红外辐射材料,并对材料的结构及红外辐射性能进行了研究.在2(1-x)MgO@2xZnO@2Al2O3@5SiO2(x=0～0.6)体系中,x≤0.3时,可得到六方结构的堇青石固溶体;x＞0.3时,体系中镁铝尖晶石成为主要物相.x=0.2时,样品的红外辐射性能最佳,其法向全波段的辐射率达到0.89,8～14/μm波段的辐射率达到0.91以上.     

千层饼状Cd(OH)2微米结构的合成与表征

以羰基修饰的聚丙烯酰胺(缩写为PAM-COOH)作为形貌控制剂, 采用水相法合成了千层饼状Cd(OH)₂微米结构. 产物结构与形貌用X射线衍射仪(XRD), 扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射仪(SAED)进行了表征. 研究了不同实验条件(PAM-COOH的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-COOH作用下Cd(OH)₂千层饼可能的形成机理. 结果表明, Cd(OH)₂千层饼尺寸约1μm, 每个千层饼由尺寸约为35nm的Cd(OH)₂单晶薄片组成. 反应物浓度、反应温度对Cd(OH)₂尺寸与形貌都有一定的影响, 但起关键作用的是PAM-COOH. 在350℃煅烧Cd(OH)₂ 3h, 得到立方结构千层饼状CdO微米材料.     

Characterization of lead, barium and strontium leachability from foam glasses elaborated using waste cathode ray-tube glasses

Foam glass manufacture is a promising mode for re-using cathode ray tube (CRT) glasses. Nevertheless, because CRTs employ glasses containing heavy metals such as lead, barium and strontium, the leaching behaviour of foam glasses fabricated from CRTs must be understood. Using the AFNOR X 31-210 leaching assessment procedure, the degree of element inertization in foam glasses synthesized from waste CRT glasses (funnel and panel glasses, containing lead and barium/strontium respectively) were determined. The amount of leached lead from foam glasses prepared from funnel glass depends on the nature and concentration of the reducing agent. The effects of the reducing agents on the generation of cellular structure in the fabrication of foam glass were studied. The fraction of lead released from foam glass was less than those extracted from funnel glass and was lower than the statutory limit. Leached concentrations of barium and strontium were found to be approximately constant in various tests and were also below regulatory limits.     

Optimized preparation of nitrogen-doped carbon dots by response surface methodology and application in Cd2+ detection

The technical parameters of synthesizing N-doped carbon quantum dots (N-CQDs) from citric acid and tris(hydroxymethyl)aminomethane (Tris) were optimized using a Box-Behnken model of response surface methodology. Statistical analysis showed the quantum yield was significantly affected by reaction time and Tris weight. The optimal synthesis conditions were reaction temperature at 170?°C, reaction time of 4.50?h and Tris weight of 0.70?g, with the quantum yield up to 82.4%. The N-CQDs probe was further applied for Cd²⁺ detection. The fluorescence intensity and Cd²⁺ concentration were linearly related in the range of 20-300?µg·L^?1 with a relation coefficient of 0.9956 and a detection limit of 20.69?µg·L^?1.     

Accumulation of Cd, Pb and Zn by 19 wetland plant species in constructed wetland

Uptake and distribution of Cd, Pb and Zn by 19 wetland plant species were investigated with experiments in small-scale plot constructed wetlands, into which artificial wastewater dosed with Cd, Pb and Zn at concentrations of 0.5, 2.0 and 5.0mgl(-1) was irrigated. The results showed that the removal efficiency of Cd, Pb and Zn from the wastewater were more than 90%. Generally, there were tens differences among the 19 plant species in the concentrations and quantity accumulations of the heavy metals in aboveground part, underground part and whole plants. The distribution ratios into aboveground parts for the metals absorbed by plants varied also largely from about 30% to about 90%. All the plants accumulated, in one harvest, 19.85% of Cd, 22.55% of Pb and 23.75% of Zn that were added into the wastewater. Four plant species, e.g. Alternanthera philoxeroides, Zizania latifolia, Echinochloa crus-galli and Polygonum hydropiper, accumulated high amounts of Cd, Pb and Zn. Monochoria vaginalis was capable for accumulating Cd and Pb, Isachne globosa for Cd and Zn, and Digitaria sanguinalis and Fimbristylis miliacea for Zn. The results indicated that the plants, in constructed wetland for the treatment of wastewater polluted by heavy metals, can play important roles for removal of heavy metals through phytoextraction. Selection of plant species for use in constructed wetland will influence considerably removal efficiency and the function duration of the wetland.     

Mo6+掺杂TiO2纳米材料的表面性能及氧敏特性

以TiCl3为钛源, 采用溶胶-凝胶法制备Mo6+掺杂TiO2基纳米粉体,表明在400℃下低温烧结,即可得到金红石相为主晶相的TiO2基敏感材料.在低温工作条件(145℃)及1×10-4 O2下,Mo6+掺杂TiO2厚膜型气敏元件的氧敏特性比纯TiO2的好,并结合Zeta电位特性测量,其氧敏特性的增强在于表面电荷密度的提高.     

千层饼状Cd(OH)2微米结构的合成与表征

以羰基修饰的聚丙烯酰胺(缩写为PAM-COOH)作为形貌控制剂, 采用水相法合成了千层饼状Cd(OH)₂微米结构. 产物结构与形貌用X射线衍射仪(XRD), 扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射仪(SAED)进行了表征. 研究了不同实验条件(PAM-COOH的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-COOH作用下Cd(OH)₂千层饼可能的形成机理. 结果表明, Cd(OH)₂千层饼尺寸约1μm, 每个千层饼由尺寸约为35nm的Cd(OH)₂单晶薄片组成. 反应物浓度、反应温度对Cd(OH)₂尺寸与形貌都有一定的影响, 但起关键作用的是PAM-COOH. 在350℃煅烧Cd(OH)₂ 3h, 得到立方结构千层饼状CdO微米材料.     

镁离子掺杂对磷酸铁锂结构和性能的影响

为提高LiFePO4的充放电性能,用化学沉淀法制备了镁离子掺杂的磷酸铁锂,用电化学方法测量了Li1-xMgxFePO4(x=0.00、0.02、0.05、0.07、0.10和0.20,摩尔分数)的充放电性能,用X射线衍射(XRD)和里特沃尔特(Rietveld)方法表征了掺杂对LiFePO4的晶体结构的影响.结果表明少量镁离子掺杂能有效地提高LiFePO4的比容量和循环性能,其中Li0.95Mg0.05FePO4具有更好的电化学性能,放电比容量高出LiFePO4约20mAh/g,镁离子掺杂提高了LiFePO4中Fe3 /Fe2 共存态的浓度,使材料具有更好的导电能力.     

污泥制备活性炭对 Pb(Ⅱ)和Ni(Ⅱ)的吸附和回收利用

在静态条件下研究了用污泥制备的活性炭吸附剂去除水溶液中Pb(Ⅱ)、Ni(Ⅱ)的效果,考察了溶液pH值、吸附时间、吸附剂用量和Pb(Ⅱ)、Ni(Ⅱ)的初始浓度对去除率的影响.结果表明,污泥制备的活性炭吸附剂对Pb(Ⅱ)、Ni(Ⅱ)具有较强的吸附性能,pH值是影响吸附的主要因素;吸附过程符合Langmuir吸附等温式;在试验条件下,其对Pb(Ⅱ)具有更高的去除能力.还探讨了吸附Pb(Ⅱ)、Ni(Ⅱ)后回收铅和镍的可行性.     

聚丙烯中空纤维膜/二(2-乙基已基)膦酸体系萃取水溶液中铜离子的研究

研究了聚丙烯中空纤维膜接触萃取器中二(2-乙基已基)磷酸萃取金属铜离子的工艺条件以及溶剂夹带,分析了原料的pH值、两相流速、有机相初始铜离子浓度以及萃取膜面积对萃取效率的影响,结果表明,两相流速、萃取膜面积对萃取率基本无影响,而水溶液的pH值和有机相初始铜离子浓度的改变使萃取率在40%～99%之间变化.这主要是由于整个萃取过程的传质阻力主要来源于D2EHPA和Cu2 的界面配位络合反应阻力,当铜浓度比较高时,传质阻力或传质系数与铜浓度无关,其值基本不变;而当铜浓度降低时,传质阻力随着铜浓度的降低而增大,传质系数则随着铜浓度的降低而减小.     

双子表面活性剂为模板纳米二氧化钛的制备及光催化活性

以脱氢松香为原料,通过化学合成的方法制备出一种新颖的双子表面活性剂,采用FT-IR及1 HNMR对其结构进行确证;以酞酸四正丁酯（TNB）为起始原料,通过加入自制的双子表面活性剂,采用水热合成法制备了平均粒径为8.81nm的锐钛矿型纳米二氧化钛颗粒;利用FT-IR、TEM、XRD对纳米二氧化钛进行表征;以紫外光为光源,罗丹明B（RhB）为模型污染物考察了纳米二氧化钛的光催化活性,结果表明其催化活性优于未加表面活性剂制备的纳米二氧化钛,且在紫外光下反应3h,RhB的降解率为99.7%,基本完全降解。     

Batch desorption studies and multiple sorption-regeneration cycles in a fixed-bed column for Cd(II) elimination by protonated Sargassum muticum

The protonated alga Sargassum muticum was employed in batch desorption studies to find the most appropriate eluting agent for Cd(II)-laden biomass regeneration. Eleven types of eluting solutions at different concentrations were tested, finding elution efficiencies higher than 90% for most of the desorbents studied. Total organic carbon and biomass weight loss measurements were made. The reusability of the protonated alga was also studied using a fixed-bed column. Eleven consecutive sorption-regeneration cycles at a flow rate of 10 mL min(-1) were carried out for the removal of 50 mg L(-1) Cd(II) solution. A 0.1M HNO(3) solution was employed as desorbing agent. The column was operated during 605 h for sorption and 66 h for desorption, equivalent to a continuous use during 28 days, with no apparent loss of sorption performance. In these cycles, no diminution of the breakthrough time was found; although, a relative loss of sorption capacity, regarding the found in the first cycle, was observed. The slope of the breakthrough curves experiments a gradual increase reaching its maximum value for the last cycle tested (40% greater than for the first one). The maximum Cd(II) concentration elution peak was achieved in 5 min or less, and the metal effluent concentration was always lower than 0.9 mg L(-1) after 1 h of elution. The maximum concentration factor was determined to be between 55 and 109.     

Eu3+掺杂Nb2O5-La2O3-P2O5-Na2O-BaO玻璃的光谱性质

制备了χNb2O5-(10-χ)La2O3-60P2O5-10Na2O-19BaO-Eu2O3(以mol%记χ=9、7、5)的玻璃,测定了玻璃的吸收光谱、发射光谱、激发光谱、声子边带谱和差热分析曲线.从发射光谱出发获得了Eu3 光学跃迁的J-O参数Ω2、Ω4,并计算了Eu3 离子5DO→7FJ(J=1,2,4)的自发辐射跃迁几率A以及受激发射截面σp.结果显示,随着La2O3的增加和Nb2O5的减少,玻璃样品的热稳定性降低,强度参数Ω2减小,表明材料的对称性提高,共价性减弱,Eu-O键强减弱;随着La2O3的增加,电-声子偶合减弱,受激发射截面σp减小.     

戊二醛交联淀粉微孔发泡材料(SMCF)的制备及表征

以玉米淀粉为原料,将糊化后的淀粉溶液与戊二醛交联,采用溶剂置换制得高白度、表面带有微孔结构、并具有一定抗水性能的淀粉微孔发泡材料(starch microcellular foam,SMCF).研究了交联反应及溶剂置换各因素对SMCF白度、湿含量及微孔形成的影响,确定最优工艺:交联剂戊二醛的用量为10g戊二醛/100g...     

K~+和Na~+在C_3S-纳米SiO_2浆体上的存在形式

以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K~+和Na~+的影响以及浆体对K~+和Na~+的滞留能力;并采用29Si MAS NMR分析讨论了K~+和Na~+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随着液固比的增大,浆体释放的K~+和Na~+的百分数逐渐增大;经去离子水充分洗涤后仍有一部分K~+和Na~+存在于浆体中,且浆体对K~+和Na~+的滞留能力随着纳米SiO_2掺量的增加以及拌合液碱浓度的增大而增强。29Si MAS NMR分析证实了K~+和Na~+能够进入C-S-H凝胶层间形成不可逆的化学结合。K~+和Na~+通过取代C-S-H凝胶层间≡SiOCa+中的Ca2+,缩短了C-S-H凝胶中[SiO4]4-四面体链长,从而使凝胶中Q1和Q2峰向左移动。     

熔盐提拉法生长的Nd3+:KGd(WO4)2单晶的性能研究

采用熔盐提拉法生长出φ20mm×35mm的优质Nd3+KGd(WO4)2晶体,对晶体三个轴向的光谱进行了测试研究,结果表明a轴向的吸收和荧光谱峰最强,最适合于进行激光实验研究.采用脉冲氙灯泵浦φ3.5mm×26mm的激光器件,在1.067μm处得到125.5mJ的激光输出.在同等条件下对YAGNd激光晶体进行了激光实验研究,并对两种结果进行了比较,结果表明和YAGNd3+晶体相比,KGWNd3+晶体具有激光阈值低、效率高和输出光为偏振光等优点,因此在小型激光器的应用方面具有明显的优势.     

用标准加入光度法同时测定镀液中的Co2+与Ni2+

为寻找合金镀液中Ni2 ,Co2 快速、准确的测定方法,进行了用标准加入光度法同时测定镀液中的钴和镍的研究.用钴的等吸收点波长490 nm和530 nm作为测定波长,以镍为标准加入组分,用4-(2-吡啶偶氮)间苯二酚(PAR)作显色剂,溶液pH值为9～10.在镀液样品中进行加标回收试验,平均回收率钴为100.4%,镍为101.5%,最大相对标准偏差钴为6.1%,镍为4.6%;还探讨了测定条件对结果的影响.结果表明,该方法操作简单,可行性强,准确度较高.