Dispersion of zero valent iron nanoparticles onto bentonites and the decolourization of orange II

Nano Zero valent iron (Fe0) were reported as an effective material for azo dye removal, however, similar to other nano-materials, ultra-fine powder has a strong tendency to agglomerate into larger particles, resulting in an adverse effect on both effective surface area and catalyst performance. Here we report nano sized Fe0 particles dispersed onto the surface of natural bentonites. X-ray diffraction was used to study the sample phases. Scanning electron microscopy and transmission electron microscopy were applied to study the morphology and morphological changes. Spherical individual Fe0 particles were observed after dispersion onto bentonites, and these samples were used for orange II (OII) decolourization with wide working pH range. Higher reactivity is attributed to good dispersion of Fe0 particles on clay minerals’ surface. This study is significant for providing novel modified clay based catalyst materials for the decolourization of azo dye contaminants from wastewater.

Decolourization of anthraquinone reactive dye by electrochemical reduction on reticulated glassy carbon electrode

The electrochemistry reduction for the removal of Reactive Blue 4 (RB4) dye from aqueous solution using reticulated glassy carbon electrode is investigated. At pH < 8.0 the anthraquinone group of the RB4 dye are reduced in one cathodic step to hidroquinone after a reversible two-electron process involving a precedent two protons reaction. A stable semiquinone is detected by spectrophotometric technique. At pH > 8.0 the reduction process involves two reversible 2-electron steps, whose species are generated by a protonation equilibrium of anthraquinone group. The results shows that 60% of color removal was obtained after 3 hours of RB4 dye electrolysis at acidic and neutral conditions and only 37% at alkaline conditions. Simultaneously 64% of total organic carbon was removed after electrolysis at pH 2.0.

Synthesis, characterization of palygorskite supported zero-valent iron and its application for methylene blue adsorption

In this work, natural palygorskite impregnated with zero-valent iron (ZVI) was prepared and characterised. The combination of ZVI particles on surface of fibrous palygorskite can help to overcome the disadvantage of ultra-fine powders which may have strong tendency to agglomerate into larger particles, resulting in an adverse effect on both effective surface area and catalyst performance. There is a significant increase of methylene blue (MB) decolourized efficiency on acid treated palygorskite with ZVI grafted, within 5 mins, the concentration of MB in the solution was decreased from 94 mg/L to around 20 mg/L and the equilibration was reached at about 30 to 60 mins with only around 10 mg/L MB remained in solution. Changes in the surface and structure of prepared materials were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy, surface analysing and scanning electron microscopy (SEM) with element analysis and mapping. Comparing with zero-valent iron and palygorskite, the presence of zero-valent iron reactive species on the palygorskite surface strongly increases the decolourization capacity for methylene blue, and it is significant for providing novel modified clay catalyst materials for the removal of organic contaminants from waste water.

温梯法蓝宝石（Al2O3）晶体的脱碳去色退火研究

温度梯度法（TGT）生长的Al2O3晶体因石墨发热体在高温时的挥发和原料中过渡性金属离子的存在，晶体在不同部位呈现不同颜色，一般上部为浅红色，尾部为浅黄绿色，将TGT法生长的Al2O3晶体（Ф110×80mm^3）依次经过高温氧化气氛、高温还原气氛脱碳、去色退火实验，即“两步法”退火实验，晶体变成无色、透明，经测试，Al2O3晶体的完整性、光学透过率和光学均匀性均有显著提高。

Degradação de corante por partículas de ferro zero suportadas em sílica

A água é um bem essencial a todos os seres vivos. Porém, o homem não tem dado o valor e atenção necessários para a preservação dessa riqueza. Por mais que o ser humano não faça a água desaparecer do planeta, ele tem contribuído e muito para o decréscimo de sua qualidade. Dentre as várias atividades antropogênicas, que tem contribuído para a poluição das águas, destaca-se a atividade industrial. A indústria têxtil, por exemplo, libera enormes volumes de dejetos, destacando-se os corantes, além deles prejudicarem a ocorrência de fotossíntese, apresentam elevada toxicidade ao meio marinho. Com isso, este trabalho visa estudar a degradação do corante Alaranjado de Metila via catálise heterogênea. Neste estudo, foram realizadas a preparação e a caracterização de partículas metálicas estabilizadas em sílica, sendo essas partículas com diferentes teores de ferro (50 %wt, 25 %wt e 5 %wt) aderido ao suporte. Após o preparo dos catalisadores realizou-se o estudo de sua eficiência frente a diferentes parâmetros como: quantidade de catalisador, temperatura e pH. Por meio dos testes realizados foi possível observar que a quantidade do catalisador influência a reação de redução do corante Alaranjado de Metila. Porém, quando se atinge o ponto de saturação, mesmo que se adicione mais catalisador não é possível aumentar a degradação. Através da variação da temperatura, observou-se que quanto maior a temperatura maior a degradação do corante. Isso pode ser explicado devido o aumento do número de colisões entre os sítios ativos do catalisador e as moléculas do corante. E por meio da variação de pH, concluiu-se que pHs ácidos permitem que a reação de redução do corante ocorra mais rápido e pHs elevados tornam a reação de degradação do corante mais lenta, porém ainda assim ocorrem de forma satisfatória. O catalisador pôde ser reutilizado por até 3 vezes, sem nenhum tratamento prévio. Os catalisadores a 50 %wt, assim como, a 25 %wt foram capazes de degradar o corante de forma eficiente, porém o catalisador a 5 %wt não se mostrou ser eficaz. Foram realizados testes sob radiação microondas e a reação de redução ocorreu de forma muito eficaz, apresentando 100% de degradação em apenas 2 minutos. Além disso, realizou-se o estudo cinético, onde segundo dados experimentais, as reações foram classificadas como sendo de primeira ordem

染料脱色菌株筛选及染料脱色作用研究

染料废水成分复杂，色度高，是主要的环境污染源之一。应用微生物对染料废水脱色具有处理费用低和操作管理方便等优势，具有较好的发展前景。 本文采用筛选到一株短刺小克银汉霉(Cuuninghamella echinulata) KM3及一株红酵母(Rhodotorula sp.)YR-1分别对偶氮染料刚果红废水和酸性红废水进行了脱色研究，同时利用KM3及YR-1组成的复合菌种脱色体系对酸性红废水进行了脱色实验，为染料脱色真菌的应用奠定了基础。 KM3形成的菌丝球对多种染料具有较好脱色效果。KM3最适菌丝球形成条件：pH6-7、装液量90ml、孢子悬液浓度105个/ml (接种5ml)、摇床转速120rpm、培养温度30℃、培养时间72h；成球机理为凝聚型发育。KM3菌丝球对刚果红最佳脱色条件为：染料溶液初始pH值7.0，温度为33℃，摇床转速为120rpm。在刚果红50~200mg/l 浓度范围内， KM3菌丝球对刚果红吸附脱色动力学可用拟二级动力学方程描述。菌丝球对刚果红的吸附行为符合Langmuir和Freundlich 等温方程模型，Langmuir方程能更好的描述菌丝球对刚果红的吸附行为。丙酮对刚果红的解吸率最高，其解吸动力学过程符合二级动力学方程。将KM3应用在真菌生物滤床反应器中，在非灭菌和灭菌情况下接种孢子悬液后处理刚果红废水的过程中，均需长时间挂膜，处理效果一般。反应器中投加菌丝球后处理刚果红废水在3小时内达到92%以上的脱色效果。 YR-1对酸性红脱色机制属于降解脱色。YR-1对酸性红的最佳脱色培养条件为：初始pH 5.0、接种量5%、温度30℃；最佳碳源是葡萄糖，其次是蔗糖；最佳氮源是酵母膏或蛋白胨。在替换分批脱色实验和连续补料脱色实验中，脱色率一直保持在75%以上，显示YR-1在上述脱色体系中均具有良好适应性。 在三种复合菌种对酸性红的脱色体系中，体系Ⅲ（菌丝球与海藻酸钠固定化的酵母细胞混合培养）的脱色效果可达98%以上。对该体系而言，3种粒径固定化酵母小球（Ø1.1mm、1.8mm、3.1mm）中Ø1.8mm、3.1mm小球脱色率较为理想，而酵母细胞初始密度对脱色效果的影响不大。 KM3、YR-1分别具有处理刚果红废水和酸性红废水的应用前景，而KM3与YR-1联合应用对酸性红的脱色效果更好。

Biodegradação enzimática de aminas aromáticas tóxicas

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

Photoelectrocatalytic oxidation of remazol turquoise blue and toxicological assessment of its oxidation products

The ability of photoelectrocatalytic oxidation to degrade the commercially important copper-plitalocyanine dye, remazol turquoise blue 15 (RTB) was investigated. The best experimental condition was optimized, evaluating the performance of Ti/TiO2 thin-film electrodes prepared by sol-gel method in the decolourization of 32 mg L-1 RTB dye in 0.5 mol L-1 Na2SO4 pH 8 and applied potential of +1.5 V versus SCE under UV irradiation. Spectrophotometric measurements, high performance liquid chromatography, dissolved organic carbon (TOC) evaluation and stripping analysis of yielding solution obtained after 3 h of photoelectrolysis leads to 100% of absorbance removal from wavelength of 250-800 nm, 79.6% of TOC reduction and the releasing of up to 54.6% dye-bound copper (0.85 mg L-1) into the solution. Both, original and oxidized dye solution did not presented mutagenic activity with the strains TA98 and WOO of Salmonella in the presence and absence of S9 mix at the tested doses. Nevertheless, the yielding photoelectrocatalytic oxidized solution showed an increase in the acute toxicity for Vibrio fischeri bacteria, explained by copper liberation during treatment. (c) 2006 Elsevier B.V. All rights reserved.