纳米氧化锌的制备及其光催化活性研究

以硫酸锌和尿素为原料,采用均相沉淀法制备纳米ZnO颗粒,并用TEM,IR,TGA,XRD等测试手段对其进行了表征。以紫外灯为光源,以纳米ZnO为光催化剂,氧化水溶液中的甲基橙。研究了催化剂的用量、光照时间、空气流量、光源性质对甲基橙降解的影响及ZnO粉体掺杂Ag^ 对其活性的影响。实验结果表明,掺杂Ag^ 后的纳米ZnO光催化效能大大提高。     

掺杂La3+纳米ZnO的制备及其光催化性能

采用共沉淀法制备了不同La3＋含量的La3＋-ZnO催化剂,采用x射线衍射仪、透射电子显微镜等对催化剂的结构、相组成、形貌和粒径进行了表征,比较了不同La3＋含量的La3＋-ZnO催化剂对罗丹明B降解率的影响。实验结果表明,掺杂La3＋导致ZnO粒径减小,比表面积增大,延长了光生电子-空穴对的寿命,提高了ZnO的光量子产率,La3＋-ZnO催化剂的光催化活性比ZnO显著增强。La3＋质量分数为0．8％时,罗丹明B降解率最高,为92．5％。经La3＋质量分数0．8％的La3＋-ZnO催化剂降解后罗丹明B已被完全降解为无机小分子。     

ZnO/氧化石墨烯的制备及其对亚硝酸盐的光催化降解

利用沉淀法制备了ZnO光催化剂,并将其负载在氧化石墨烯上,制得ZnO/氧化石墨烯复合材料,研究了该复合材料对亚硝酸钠的光催化降解效果。采用XRD和SEM技术对光催化剂进行表征。考察了初始亚硝酸钠质量浓度、溶液pH、ZnO/氧化石墨烯加入量对亚硝酸钠降解效果的影响。表征结果显示：ZnO/氧化石墨烯晶体的晶型发育良好、结晶度高;新生成的混晶结构提高了催化剂的光催化活性。实验结果表明：在初始亚硝酸钠质量浓度246 mg/L、溶液pH 5、ZnO/氧化石墨烯加入量1.0 g/L的条件下,经过150 min的紫外光降解,亚硝酸钠的质量浓度降至70 mg/L,亚硝酸钠的降解率为71.38%;ZnO与氧化石墨烯的协同效应有效提高了光催化反应体系的效率,ZnO/氧化石墨烯对亚硝酸钠的降解能力远高于氧化石墨烯和ZnO。     

磁载光催化剂ZnO/SiO_2-Fe_3O_4的光催化活性

采用液相沉积法制备出了纳米SiO_2-Fe_3O_4复合粒子,并在其表面负载ZnO,得到了易于磁性固液分离的磁载光催化剂ZnO/SiO_2-Fe_3O_4,并通过傅立叶红外光谱仪、X射线衍射仪和透射电子显微镜等对光催化剂进行了表征.以亚甲基蓝为目标降解物,研究了光催化剂在紫外光下的光催化活性.实验结果表明,在Fe_3O_4和ZnO之间包覆一层无定形SiO_2可使亚甲基蓝降解率由20.34%提高到94.52%,所制备的ZnO/SiO_2-Fe_3O_4在3次重复使用后仍能保持较好的光催化性能.     

乙烯废碱液的ZnO沉淀法脱硫过程优化与动力学研究

采用ZnO沉淀法对乙烯废碱液进行脱硫,通过正交实验确定的最佳工艺条件为:反应温度80～85℃,n(ZnO)∶n(Na2S)=0.9,反应时间150min。在上述最佳工艺条件下,废碱液脱硫率和ZnS质量分数可分别达88%和95%以上。动力学研究结果表明,ZnO沉淀法的脱硫速率可用简化的Na2S浓度的幂函数模型描述,该模型的Na2S转化率计算值与实验值吻合良好。     

TiO2/凹凸棒土复合催化剂的制备及光催化降解活性大红

以凹凸棒土作为载体,以 TiOSO4为钛源,采用超声分散-再沉淀法制备了 TiO2粒径为 10 nm 左右的锐钛矿型 TiO2/凹凸棒土复合催化剂.并采用 X 射线衍射仪、透射电子显微镜、X 射线能谱仪对复合催化剂进行了表征.制备复合催化剂的最佳条件:凹凸棒土与 TiO2的质量比为 1:3.0,煅烧温度为 450 ℃....     

利用电石渣液相法制备纳米碳酸钙

以电石渣为原料、氯化铵溶液为浸取剂、碳酸铵溶液为碳酸化试剂、柠檬酸为晶形控制剂,采用液相法制备了高纯度的纳米级碳酸钙。考察了多种因素对反应的影响,通过X射线衍射仪和扫描电子显微镜对制得的碳酸钙进行表征。确定了最佳的工艺条件：碳酸化过程浸出液Ca^2＋浓度为0．6mol／L,柠檬酸与碳酸钙质量比为0．03,碳酸化反应温度为12℃。制得的碳酸钙粒径为40～60nm,为纯净的方解石型晶型。     

具有共轭结构的CDPVA/ZnO复合光催化剂的制备及其可见光催化性能

CDPVA是一种具有共轭多烯序列的聚乙烯醇(PVA)衍生物。通过低温热处理法制备了CDPVA/ZnO复合光催化剂。表征结果显示,PVA经低温热处理后形成了具有一定共轭结构的CDPVA并包覆于纳米ZnO颗粒表面,提高了光催化剂的可见光响应能力,有效促进了光生空穴和电子的分离。当PVA与纳米ZnO的质量比为1∶100时,CDPVA/ZnO的可见光催化活性最高;在催化剂投加量为0.5 g/L、初始罗丹明B质量浓度为4 mg/L、可见光照射50 min的条件下,罗丹明B降解率为97.51%,明显优于纯纳米ZnO;CDPVA/ZnO循环使用9次后仍保持较高的罗丹明B降解率,表明CDPVA的包覆有效抑制了纳米ZnO的光腐蚀,提高了光催化剂的稳定性。     

金属络合剂在烟气同时脱硫脱硝中的应用

液相络合法是烟气同时脱硫脱硝中广泛应用的方法之一。液相络合法常用的金属络合剂有亚铁络合剂和钴络合剂等。重点介绍了亚铁氨羧络合剂、含-SH的亚铁络合剂和六氨合钴络合剂、乙二胺合钴络合剂等同时脱硫脱硝的基本过程及常用吸收液的再生方法,指出了金属络合剂在烟气同时脱硫脱硝中应用时存在的问题及今后的发展方向。     

花瓣状ZnO光催化处理双酚A和Cr(Ⅵ)废水

以乙酸锌、柠檬酸三钠和氢氧化钠为原料,在室温下磁力搅拌制得ZnO。经XRD、SEM和TEM表征,ZnO具有良好的结晶度,为花瓣状形貌。在模拟太阳光的照射下,光催化反应80 min,ZnO对质量浓度为25 mg/L的双酚A溶液中双酚A的去除率仅为32.0%,对质量浓度为20 mg/L的Cr（Ⅵ）溶液中Cr（Ⅵ）的去除率为60.2%。将双酚A与Cr（Ⅵ）溶液混合后,ZnO对双酚A和Cr（Ⅵ）的去除率分别提高至77.6%和94.2%。     

Biomedical Textiles Through Multifunctioalization of Cotton Fabrics Using Innovative Methoxypolyethylene Glycol-N-Chitosan Graft Copolymer

Multifunctioalization of cotton fabrics was developed by a novel finishing formulation. The method is based on chitosan-N-polyethylene glycol graft copolymer along with citric acid and sodium hypophosphite (SHP) as catalysts. Treatment of the cotton fabric resulted in the chemical attachment of the copolymer to the cotton fabric via bridging-based esterification where the latter involves reaction of one molecule of the polycarboxylic acid (citric acid) with both the amino group of the copolymer and the hydroxyl groups of cotton. Inclusion of the copolymer in the crosslinked structure of cotton as well as by hydrogen bonding and van der Waals forces are additionally possible. Synthesis of the copolymer was raised out by the reaction of chitosan with methoxy polyethylene glycol (MPEG) aldehyde followed by the reduction with sodium borohydride. MPEG was prepared by oxidation of PEG with acetic anhydride in dimethyl sulphoxide at room temperature. Methoxypolyethylene glycol-N-chitosan graft copolymer (MPEG-N-CTS) structure was confirmed by IR, NMR, X-RD and TGA techniques. The copolymer is soluble in water. The pad dry-cure method was used for the cotton fabrics treatment with aqueous solution of prepared copolymer along with citric acid and SHP. The so treated fabrics were monitored for copolymer content (expressed as N%), crease recovery, tensile strength, elongation at break, air permeability, water permeability, roughness, bursting strength and antibacterial activity. Fabric performances based on the outputs of these measurements advocate these multifunctionalized fabrics for use as medical textile.     

Processing and Characterization of Glycerol-Plasticized Soy Protein Plastics Reinforced with Citric Acid-Modified Starch Nanoparticles

Citric acid-modified starch nanoparticles with an average size of 82 nm were prepared through precipitation from gelatinized starch solution by ethanol and further modification with citric acid. When being incorporated in glycerol-plasticized soy protein plastics, citric acid-modified starch nanoparticles displayed dramatic reinforcing effect. The resulted nanocomposite plastics exhibited improvement in mechanical performance. Also, the water uptake decreased, indicating an increase of water resistance. The modified starch nanoparticles had a good compatibility with soy protein matrix. Possessing a relative hydrophobic surface, the filler would prefer to interact with protein-rich domains in glycerol-plasticized soy protein. The work provided a green approach of biodegradable materials based on naturally occurring biopolymers.     

石墨烯量子点/Bi2WO6的制备及其对抗生素的降解性能

采用一步水热法与两步水热法制备了GQDs/Bi₂WO₆（GQDs为石墨烯量子点）复合材料,利用氙灯为光源,考察了暗反应与光反应条件下GQDs/Bi₂WO₆对目标污染物环丙沙星的吸附性能与光催化性能,并对所制备的部分材料进行了表征。实验结果表明,相比于纯Bi₂WO₆,一步法制备的0.20GQDs/Bi₂WO₆（柠檬酸CA与 Bi₂WO₆物质的量比为0.2）和两步法制备的2%GQDs/Bi₂WO₆（GQDs与Bi₂WO₆的质量比为2%）有着相对更好的吸附性能与光催化性能。其中,0.20GQDs/Bi₂WO₆光催化效果最好。暗反应30 min后,环丙沙星吸附去除率为50.4%。光反应60 min后,环丙沙星的光催化去除率为42.6个百分点,总去除率达93.0%。表征结果显示,0.20GQDs/Bi₂WO₆的比表面积最大,且光生空穴和电子复合概率也相对较低。     

超声辅助沉淀法制备γ-Bi_2MoO_6及其光催化性能

以Bi(NO3)3·5H2O和(NH4)6Mo7O24·4H2O为原料,采用超声辅助沉淀法制备了纳米可见光催化剂γ-Bi2Mo O6,用XRD,SEM,UV-Vis技术对其进行了表征,并以罗丹明B为目标降解物,考察了γ-Bi2Mo O6的可见光催化性能。表征结果显示,产物为高纯度正交结构的纳米γ-Bi2Mo O6,分散性良好。光催化实验结果表明:超声辅助沉淀法制备的γ-Bi2Mo O6的可见光催化活性优于普通沉淀法制备的产品;以超声辅助沉淀法制备的γ-Bi2Mo O6为光催化剂,在初始罗丹明B质量浓度为10 mg/L、初始溶液p H为7.2、γ-Bi2Mo O6加入量为10 g/L的最优条件下,反应180 min时的罗丹明B降解率达到97.48%。     

Polyvinyl Alcohol (PVA)/Starch Bioactive Packaging Film Enriched with Antioxidants from Spent Coffee Ground and Citric Acid

The bioactive packaging polyvinyl alcohol (PVA)/starch films were prepared by incorporating combined antioxidant agents i.e. extracted spent coffee ground (ex-SCG) and citric acid. Effect of citric acid content on chemical compatibility, releasing of antioxidant, antibacterial activities, and physical and mechanical properties of PVA/starch incorporated ex-SCG (PSt-E) films was studied. The results of ATR-FTIR spectra showed that antioxidant agents of ex-SCG can penetrate into the film and the ester bond of blended films by citric acid was also observed. The presence of ex-SCG increased efficiency of antioxidant release and antimicrobial activity. The PSt-E film incorporated 30 wt% citric acid showed minimum inhibitory concentration against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The incorporation of ex-SCG and citric acid into film showed a synergistic effect on antibacterial activity. The water resistance and kinetic moisture sorption improved with incorporation of citric acid. The tensile strength and biodegradability of samples were in range of 5.63–7.44 MPa and 65.28–86.64%, respectively. Based on this study, PSt-E film incorporated 30 wt% citric acid can be applied as novel food packaging materials.     

Determination of In Situ Esterification Parameters of Citric Acid-Glycerol Based Polymers for Wood Impregnation

The development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160?°C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (T_g) were studied using TGA/DSC and the effect of citric acid content and catalyst type determined. Dimensional stability of impregnated wood samples improved above 50% for each sample with HCl and p-TSA catalysts compared to control samples. FTIR spectra were studied to show the presence of the ester linkages of the polymer in situ at the wood cell walls. Bonding between the polymer and wood macromolecules were observed by scanning electron microscopy and interpreted as evidence of chemical bonds at the wood cells. When prepared using a catalyst, the polymer was intimately incorporated into wood structure significantly improving the substrate dimensional stability. Enhanced stability makes this approach of particular interest for exterior wood products especially as a green renewable option for the wood industry.     

光电催化氧化法脱色处理刚果红染料废水

采用阴极还原法制备了泡沫镍负载纳米ZnO（ZnO/Ni）电极,采用SEM和XRD技术对ZnO/Ni电极进行了表征。以高压汞灯为光源,ZnO/Ni电极为阳极,铂电极为阴极,对模拟刚果红染料废水进行了光电催化脱色处理。考察了催化工艺、电解质种类及浓度、初始废水pH和反应温度等因素对刚果红降解率的影响。表征结果显示, 制备的纳米ZnO呈六方晶系结构,平均粒径为23.6 nm。实验结果表明,当外加电流为1.0 mA时,在初始刚果红质量浓度为30 mg/L、电解质Na₂SO₄浓度为0.050 mol/L、初始废水pH为5、反应温度为50 ℃的条件下,光电催化反应60 min后,刚果红降解率为86.36%,COD和色度的去除率分别达到70.56%和92.86%。     

Biodegradation of Low Molecular Weight Organic Acids in a Limed Forest Soil

The effect of liming (3.45 and 8.75 t ha^-1 dolomite; 16 yr after application) on the biodegradation of three low molecular weight organic acids (citrate, oxalate and propionate) in forest soils was investigated. The concentration of organic acids in the soil solution followed the series propionate > citrate > oxalate with liming having no significant impact on soil solution concentrations (mean organic acid concentration = 8.7 ± 2.3 M). Organic acid mineralization by the soil microbial community was rapid in surface organic horizons (mean half-life for citrate = 2–6 h), with biodegradation rate gradually declining with soil depth. Concentration-dependent biodegradation studies (0 to 350 M) showed that the mineralization kinetics generally conformed well to a single Michaelis–Menten equation with V_max values following the series oxalate > citrate > propionate (mean = 9.8 ± 1.0 nmol g^-1 h^-1) and K_M values following the series oxalate = citrate > propionate (mean 168 ± 25 M). The V_max values declined with soil depth, which was consistent with a general reduction in microbial activity down the soil profile. Liming induced a significant increase in V_max for citrate with no change for propionate and reduction in V_max for oxalate. The latter was probably due to adsorption and precipitation of Ca-oxalate making it unavailable for microbial uptake. The higher adsorption/precipitation capacity for oxalate in the limed soils was confirmed by adsorption isotherms. Generally, liming increased soil microbial activity by approximately 10 to 35% with calculations based on soil solution concentrations indicating that organic acid mineralization constituted approximately 3 to 15% of the total soil respiration.