超声-MnO2协同降解偶氮染料酸性红B

研究了MnO2、超声(US)单独作用和MnO2 US联合作用降解偶氯染料酸性红B(ARB)的情况。随着溶液pH的降低，ARB脱色率逐渐提高。SO4^2-、NO3^-与染料分子在MnO2表面发生竞争吸附。单独采用超声(50kHz)，对于染料无任何降解作用。当采用MnO2 US联合作用时，二者产生协同效应，ARB脱色率及TOC去除率明显上升。经过4h超声处理后，MnO2平均粒径由47．5μm变为3．19μm，并且产生大量纳米级MnO2颗粒，提高了MnO2的反应活性。     

Degradation of azo dyes by sequential Fenton's oxidation and aerobic biological treatment

A two stage sequential Fenton's oxidation followed by aerobic biological treatment train was used to achieve decolorization and to enhance mineralization of azo dyes, viz. Reactive Black 5 (RB5), Reactive Blue 13 (RB13), and Acid Orange 7 (AO7). In the first stage, Fenton's oxidation process was used while in the second stage aerobic sequential batch reactors (SBRs) were used as biological process. Study was done to evaluate effect of pH on Fenton's oxidation process. Results reveal that pH 3 was optimum pH for achieving decolorization and dearomatization of dyes by Fenton's process. Degradation of dye was assessed by COD reduction and reduction in aromatic amines (naphthalene chromophores) which was measured by reduction in absorbance at 200 nm. More than 95% of color was removed with Fenton's oxidation process in all dyes. In overall treatment train 81.95, 85.57, and 77.83% of COD reduction was achieved in RB5, RB13, and AO7 dyes, respectively. In the Fenton's oxidation process 56, 24.5, and 80% reduction in naphthalene group was observed in RB5, RB13, and AO7, respectively, which further increased to 81.34, 68.73, and 92% after aerobic treatment. Fenton's oxidation process followed by aerobic SBRs treatment sequence seems to be viable method for achieving significant degradation of azo dye.     

Treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process

In this work, the treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process has been studied. Decolorization was almost complete after 120min with an ozone concentration of 34.08mg/L, the biological oxygen demand for 5 days (BOD5)/chemical oxygen demand (COD) ratio increased from 0.102 to 0.406, which was more effective for the subsequent upflow biological aerated filter (UBAF) to reduce COD concentration. Under the conditions of gas/liquid=3, hydraulic load=4.8m3/m3.d, T=20-25 degrees C, the mass ratio of ozone to dye=4.5, pH 11, the COD and color of the effluent were less than 40mg/L and 20 Pt-Co units, respectively, and the average decolorization and COD removal efficiency were 97% and 90%, respectively. The experimental results showed that the combination of ozone oxidation and upflow biological aerated filter was a promising technique to treat wastewater containing azo dye.     

Nonlinear characteristic and optical limiting effect of oil red O azo dye in liquid and solid media

In view of a possible application in optical limiting devices for protection against laser radiation, the nonlinear optical absorption, refraction and optical limiting behavior of an organic dye, oil red O, under excitation with CW, Nd: YAG laser at 532 nm was studied. The nonlinear optical responses of the dye were studied both in solution (acetonitrile) and solid film, (methylmethacrylate [MMA]) respectively, using the single-beam Z-scan technique. The open aperture Z-scan of the solution and solid samples displayed reversible saturable absorption. The closed aperture Z-scan of the samples exhibited negative nonlinearity, which was larger in magnitude in the solid film compared to that in solution. The nonlinear refractive index was found to vary with concentration. Optical limiting characteristics of the dye at various concentrations were studied. The third-order nonlinearity of this dye is dominated by nonlinear absorption, which leads to strong optical limiting of the laser.     

Rapid decolourization and mineralization of the azo dye C.I. Acid Red 14 by heterogeneous Fenton reaction

The decolourization and mineralization of a solution of an azo dye using a catalyst based on Fe(II) supported on Y Zeolite (Fe(II)-Y Zeolite) and adding hydrogen peroxide (heterogeneous Fenton process) have been studied. The catalyst was prepared by ion exchange, starting from a commercial ultra-stable Y Zeolite. All experiments were performed on a laboratory scale set-up. The effects of different parameters such as initial concentration of the dye, initial pH of the solution of the dye, H(2)O(2) concentration, temperature and ratio of amount of catalyst by amount of solution on the decolourization efficiency of the process were investigated. A percentage of colour removal of 99.3±0.2% and a mineralization degree of 84±5% of the solution of the dye were achieved in only 6 min of contact time between the catalyst and the solution, under the following conditions: initial concentration of the dye of 50 ppm, pH 5.96, 8.7 mM of H(2)O(2), T of 80°C and catalyst concentration of 15 g/L. Moreover, the catalyst Fe(II)-Y Zeolite can be easily filtered from the solution, does not leach any iron into the solution (avoiding any secondary contamination due to the metal) and its effectivity can be reproduced after consecutive experiments.     

Efficient decolorization of azo dye Reactive Black B involving aromatic fragment degradation in buffered Co/PMS oxidative processes with a ppb level dosage of Co-catalyst

In order to generate powerful radicals as oxidizing species for the complete decolorization and degradation of azo dye Reactive Black B (RBB) at near neutral pH (pH 6), homogeneous activation of peroxymonosulfate (Oxone: PMS) by the trace Co²⁺-catalysts was explored. We not only took advantage of the high oxidation–reduction potential of produced hydroxyl and sulfite radicals but also an opportunity to oxidize RBB to less complex compounds with extremely low dosages, especially the ppb level of the Co²⁺-catalyst (stoichiometric ratio: [Co²⁺]₀/[RBB]₀ = 1.7 × 10⁻⁶–1.7 × 10⁻⁵; [PMS]₀/[RBB]₀ = 8–32). Anion effects and pH effects were also carried out and discussed to simulate an actual application such as that of a textile waste stream. Both the degradations of RBB and its derivative aromatic fragments were illustrated successfully at UV–visable absorptions of 591 and 310 nm, respectively, and the possible relationships between them were also proposed and discussed, based on the experimental results. The RBB degradation in this Co²⁺/PMS oxidative process successfully formulated a pseudo-first-order kinetic model at an isothermal condition of 25 °C with or without different anions present. The initial rate and rate constant were calculated under different comparative conditions, and the results indicate that the activity of both RBB decolorization and its degradation are not obviously dependent on the PMS concentration, but rather are related to the Co²⁺ dosage.     

Characterization and in vitro evaluation of an acid resistant nanosized dental eggshell-titanium dioxide material

This paper reports on novel nanosized acid resistant material base on the modification of eggshell powder and titanium dioxide (TiO₂-EB) for enamel remineralization. The TiO₂-EB was prepared by ball milling eggshell powder and titanium dioxide. Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), and ImageJ were used to characterise TiO₂-EB. A computation model using Material Studio Software was used to explain the mechanism of TiO₂-EB interaction. In addition, the acid resistant of TiO₂-EB was evaluated by comparison using three commercial toothpaste. The mean pressure value (kPa/s) was measured using a pressure sensor. The FTIR, XRD analysis confirmed the surface modification of TiO₂-EB. The SEM image revealed that pure TiO₂ particles are spread on the surface of eggshell powder. The TEM image revealed spherical particles in TiO₂-EB. The ImageJ showed the average particle size of TiO₂-EB to be 13 nm. In addition, the commercial toothpastes doped with TiO₂-EB showed an improved acid resistant. The salient features of this study indicate that TiO₂-EB will effectively remineralized enamel lesions while offering better protective covering to the enamel.     

阴离子还原剂对超级电容器材料MnO2的物性及电容特性的影响

本文通过化学液相还原法采用不同的阴离子还原剂制备了超级电容器电极材料二氧化锰.实验表明,还原剂酸碱度的不同对产物表观颜色也有着明显影响.TEM表明所制备的MnO2均为棒状体,以NaHSO3还原所制备的样1分布最均匀,通过电化学测试比较,样1表现出更好的电容特性,在电位窗口0～1.0V、电流密度为5 mA·cm-2时,其首次放电比容值为255.59 F·g-1,在循环700次后比容值为242.57 F·g-1,容量损失仅5.12%.     

MnO2的生长机理及其对罗丹明B的快速降解

采用水热法以高锰酸钾和四水合氯化锰为原料,在180℃下制备了α-MnO₂、β-MnO₂及γ-MnO₂;观察分析了不同晶型MnO₂的物相、形貌及微观结构,探究了水热时间对MnO₂晶型的影响及MnO₂的生长机理;研究了α-MnO₂+γ-MnO₂对罗丹明B(RhB)的降解性能。结果表明:在180℃水热条件下,最先产生α-MnO₂并伴有少量γ-MnO₂,适当延长水热反应的时间,MnO₂发生晶型转变,逐渐由α-MnO₂和γ-MnO₂向柱状β-MnO₂转变。此外,研究发现α-MnO₂+γ-MnO₂对RhB具有高效快速的催化降解能力,当RhB溶液为60 mL时,10 min后MnO₂对RhB的降解率可高达93%;当增加RhB溶液到100 mL时,30 min后降解率可达93%,可见,MnO₂在催化降解有机染料方面具有极好的应用前景。     

Heat treatment of nanometer anatase powder and its photocatalytic activity for degradation of acid red B dye under visible light irradiation

The phase transformation of nanometer TiO₂ powder from anatase to rutile was realized by heat treatment, and a new nanometer TiO₂ photocatalyst that could be excited by visible light was obtained. The heat-treated TiO₂ powder at different transition stage was characterized by powder x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The test of photocatalytic activity of the heat-treated TiO₂ powder was carried out by the photocatalytic degradation of acid red B dye in aqueous solution under visible light irradiation. The nanometer anatase TiO₂ heat-treated at 500°C for 30 min exhibited much higher activity than those of pure anatase and mechanically mixed (anatase and rutile) TiO₂. The remarkable improvement of photocatalytic activity was mainly illustrated by the special interphase between rutile and anatase, which not only restrains the recombination of photogenerated electron-hole pairs but also reduces the adsorbability of nanometer anatase TiO₂ powder to a certain extent. More significantly, the anticipatory interlaced energy level of heat-treated TiO₂ particles is convenient for capturing photons of low energy and thus achieves the intention of using visible light. The text was submitted by the authors in English.     

Kinetics of decolorization of an azo dye in UV alone and UV/H(2)O(2) processes

The decolorization of C.I. Acid Red 27 (AR27), a monoazo anionic dye, was studied in the ultraviolet radiation (UV) alone and UV plus hydrogen peroxide (UV/H(2)O(2)) processes. The experimental results indicated that the kinetics of both oxidation processes fit well by pseudo-first order kinetics. The reaction rate was sensitive to the operational parameters and increased with increasing H(2)O(2) concentration and light intensity. The reaction orders of H(2)O(2) concentration and light intensity in both processes were obtained with linear regression method. A regression model was developed for pseudo-first order rate constant (k(ap,UV/H(2)O(2))) as a function of the Cconcentration and UV light intensity. (k(ap,UV/H(2)O(2)))=(2 x 10(-4)I(0.75)(0) + k(3)I(1.38)(0)[H(2)O(2)](n)(0))phi(AR27). As a result of two opposing effects of H(2)O(2) concentration at low and high concentrations, n has a value of 0.49 and -0.39 and k(3) has a value of 3 x 10(-4) and 0.1 for the regions of 0 mg l(-1) < [H(2)O(2)](0) < 650 mg l(-1) and 650 mg l(-1) < [H(2)O(2)](0) < 1500 mg l(-1)1, respectively. PhiAR27 is the initial dye concentration correlation index for developing of model for different initial concentrations of AR27. This rate expression can be used for predicting k(ap,UV/H(2)O(2) at different conditions in UV alone and UV/H2O2 processes. The results show that UV alone cannot be an efficient method for decolorization of AR27 in comparison with UV/H(2)O(2) process, therefore the first term of the model can be neglected.     

含酸性桃红2R的TiO2杂化材料的制备与性能研究

用Sol-Gel法制备含偶氮类有机染料酸性桃红2R的TiO2杂化材料,探讨了材料的最佳制备工艺条件无机前驱体TBOT在溶剂DMF中的浓度为0.10～0.20mol·L-1,选用催化剂为冰乙酸,且冰乙酸与TBOT物质的的量之比为81至51.此外,还对最佳工艺条件下制得的材料进行了红外、紫外和热重、差热测试,发现与小分子染料酸性桃红2R相比,材料的热分解温度提高了30℃,而且透光性也比纯染料提高了很多,而且通过AFM检测发现薄膜表面平整,无相分离,为热释电材料及器件的制备及实用化提供了理论依据.     

Enhanced photocatalytic activity of Fe3O4-WO3-APTES for azo dye removal from aqueous solutions in the presence of visible irradiation

Development of highly active photocatalysts for treatment of dye-laden wastewaters is vital. The photocatalytic removal of azo dye Reactive Black 5 was investigated by Fe₃O₄-WO₃-3-aminopropyltriethoxysilane (APTES) nanoparticles in the presence of visible light. The Fe₃O₄-WO₃-APTES nanoparticles were synthesized via a facile coprecipitation method. The photocatalyst was characterized by XRD, FT-IR, SEM, EDX, VSM, UV–Vis, and pH_PZC techniques. The effects of some operational parameters such as solution pH, nanophotocatalyst dosage, initial RB5 concentration, H₂O₂ concentration, different purging gases, and type of organic compounds on the removal efficiency were studied by the Fe₃O₄-WO₃-APTES nanoparticles as a photocatalyst. Maximum phtocatalytic activity was obtained at pH 3. The photocatalytic removal of RB5 increased with increasing H₂O₂ concentration up to 5?mM. The removal efficiency declined in the presence of different purging gases and all types of organic compounds. First-order rate constant (k_obs) decreased from 0.027 to 0.0022?min^?1 and electrical energy per order (E_Eo) increased from 21.33 to 261.82 (kWh/m³) with increasing RB5 concentration from 10 to 100?mg/L, respectively. The efficiency of LED/Fe₃O₄-WO₃-APTES process for RB5 removal was approximately 89.9%, which was more effective than the LED/Fe₃O₄-WO₃ process (60.72%). Also, photocatalytic activity decreased after five successive cycles.     

Effect of a sulfonated azo dye and sulfanilic acid on nitrogen transformation processes in soil

Introduction of organic dyes into soil via wastewater and sludge applications has been of increasing concern especially in developing or under-developed countries where appropriate management strategies are scarce. Assessing the response of terrestrial ecosystems to organic dyes and estimating the inhibition concentrations will probably contribute to soil remediation studies in regions affected by the same problem. Hence, an incubation study was conducted in order to investigate the impact of a sulfonated azo dye, Reactive Black 5 (RB5) and sulfanilic acid (SA), a typical representative of aromatic sulfonated amines, on soil nitrogen transformation processes. The results apparently showed that nitrogen related processes in soil can be used as bioindicators of anthropogenic stress caused by organic dyes. It was found that urease activity, arginine ammonification rate, nitrification potential and ammonium oxidising bacteria numbers decreased by 10–20% and 7–28% in the presence of RB5 (>20 mg/kg dry soil) and SA (>8 mg/kg dry soil), respectively. Accordingly, it was concluded that organic dye pollution may restrict the nitrogen-use-efficiency of plants, thus further reducing the productivity of terrestrial ecosystems. Furthermore, the response of soil microbiota to SA suggested that inhibition effects of the organic dye may continue after the possible reduction of the parent dye to associated aromatic amines.     

Photocatalytic decolorization and degradation of dye solutions and wastewaters in the presence of titanium dioxide

In this study, the photocatalytic degradation of two commercial azo dyes in the presence of TiO(2) suspensions as photocatalyst has been investigated. The degradation of the dyes follows a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Under the certain experimental conditions, in the presence of TiO(2) P-25 decolorization is achieved within 100 min of illumination, while in the presence of TiO(2) Hombikat UV-100 complete color disappearance is accomplished in less than 50 min of light exposure. The influence of various parameters, such as the type and mass of the catalyst, the initial concentration of the dye, etc. on the degradation process was examined. The mineralization of organic carbon was also evaluated by measuring the dissolved organic carbon (DOC) of the dye solutions. Moreover, the toxic properties of the dye solutions treated by photocatalysis were examined by the use of a Microtox bioassay (Vibrio fischeri). Finally, experiments using real textile wastewater were also carried out, in order to examine the effectiveness of the method to a more complex substrate.     

Investigations of the properties of the manganese dioxide suspensions in the presence of guar gum and carboxymethylcellulose

Properties of manganese dioxide suspensions in the presence of two polysaccharides: non-ionic guar gum (GG) and anionic carboxymethylcellulose (CMC) were investigated using NaCl as a background electrolyte. The colloidal stability of MnO₂ suspensions in the presence and absence of these two polymers was measured. It was found that both polymers improve stability of measured suspensions. This fact results from steric stabilization (low polymer concentrations) and depletion stabilization (high polymer concentrations) for MnO₂ particles covered with macromolecules. Next the kinetics of the adsorption of these two polymers on MnO₂ as well as the heats of GG and CMC adsorption processes were measured. The obtained data proved that CMC is adsorbed more effectively on the manganese dioxide surface than guar gum. To obtain more information about the changes of adsorption of these polymers on MnO₂ some factors influencing this process (pH, ionic strength of the background electrolyte) were investigated. The data obtained from the surface charge density and the zeta potential measurements allowed the analysis of the structure of the electric double layer created by polymers on the solid surface.     

磷酸处理HZSM-5负载TiO2光催化降解活性艳红X-3B

以磷酸改性的HZSM-5分子筛为载体,采用溶胶-凝胶法制备TiO2/HZSM-5光催化剂,通过XRD,SEM,BET,FT-IR和XPS进行表征。结果表明:TiO2均匀地分散在HZSM-5表面,没有发生TiO2颗粒的聚集。负载后的TiO2保持了锐钛矿晶体结构,TiO2的晶粒尺寸在负载后有所减小。TiO2/0.5HZSM-5的比表面积和对活性艳红X-3B的吸附量都随HZSM-5含量的增加而增加。负载后的TiO2光催化活性均高于纯TiO2,50%(质量分数)TiO2/0.5HZSM-5具有最高的活性,经紫外光照射2h可使活性艳红X-3B降解93.4%,而染料在纯TiO2上的降解率只有61.0%。     

Jute stick powder as a potential biomass for the removal of congo red and rhodamine B from their aqueous solution

Jute stick powder (JSP) has been found to be a promising material for adsorptive removal of congo red (C.I. 22120) and rhodamine B (C.I. 45170) from aqueous solutions. Physico-chemical parameters like dye concentration, solution pH, temperature and contact time have been varied to study the adsorption phenomenon. Favorable adsorption occurs at around pH 7.0 whereas temperature has no significant effect on adsorption of both the dyes. The maximum adsorption capacity has been calculated to be 35.7 and 87.7mg/g of the biomass for congo red and rhodamine B, respectively. The adsorption process is in conformity with Freundlich and Langmuir isotherms for rhodamine B whereas congo red adsorption fits well to Langmuir isotherm only. In both the cases, adsorption occurs very fast initially and attains equilibrium within 60min. Kinetic results suggest the intra-particle diffusion of dyes as rate limiting step.     

HZSM-5分子筛负载SrTiO_3光催化降解活性艳红X-3B

采用溶胶-凝胶法制备HZSM-5分子筛负载SrTiO_3,对其进行XRD、FTIR和N2吸附-脱附表征,研究负载对活性艳红X-3B光催化降解过程的影响。通过分析降解液的FTIR谱图、紫外-可见光谱和总有机碳(TOC)数据,对活性艳红X-3B的光催化降解过程进行了探讨。结果表明:催化剂的主要成分为钙钛矿结构SrTiO_3,负载对SrTiO_3晶粒尺寸几乎没有影响。纯SrTiO_3没有明显的孔结构,负载后样品的比表面积和孔隙主要由HZSM-5提供。负载之后催化剂的降解活性显著提高,30%SrTiO_3/HZSM-5对活性艳红X-3B染料溶液的脱色和TOC去除速率最快。     

Realization of solid-state red fluorescence and concentration-induced multicolor emission from N,B co-doped carbon dots

As a new type of luminescent material, carbon dots (CDs) have attracted increased attention for their superior optical properties in recent years. However, solid-state fluorescent CDs, especially with red emission, are still a major challenge. Here, CDs with solid-state red emission were synthesized by co-doping of N and B using the one-step microwave method. The CD powder exhibits excitation-independent solid-state red fluorescence without any dispersion matrices, with optimum solid-state fluorescence wavelength of 623 nm. The hydrogen bonding interaction in CDs is helpful for solid-state fluorescence of CDs. The I_G/I_D value of CDs reaches up to 3.49, suggesting their very high graphitization degree, which is responsible for their red emission. In addition, CDs show the concentration-induced multicolor emission, which is attributed to the decreased energy gap in the high concentrated CD solution. To exploit their concentration-dependent emission, CDs with changing ratio in matrices are applied as a color-converting layer on ultraviolet chip to fabricate multicolor light-emitting diodes with light coordinates of (0.33, 0.38), (0.41, 0.48), (0.49, 0.44), and (0.67, 0.33), which belong to green, yellow, orange, and red light, respectively.