Efficient Degradation of a Biorecalcitrant Pollutant from Wastewater Using a Fluidized Catalyst-Bed Reactor

This study investigated the treatment of an azo dye, as a biorecalcitrant model, from industrial wastewater by using Cu/Mg/Al-chitosan in a fluidized catalyst-bed reactor. A number of variables were used to study the impact they had on the oxidation process involving azo dye. The maximum degradation of the azo dye was achieved at 7 g Cu/Mg/Al-chitosan. The chloride and sulfate ions had a synergistic effect on azo dye removal. The oxidation of the azo dye under the selected conditions was of pseudo-first-order. Textile wastewater could effectively be treated using a low concentration of about 7 g of Cu/Mg/Al-chitosan in a short hydraulic retention time of 10 min. The use of Cu/Mg/Al-chitosan demonstrated a promising method to eliminate the azo dye from the wastewater.     

萘酚偶氮颜料

该文介绍了β-萘酚颜料的发展历史、化学性质及制作过程,β-萘酚颜料的性能及应用;并介绍了目前市场上的商用,该颜料系列色谱有橙、红、蓝相红直到紫红,其中颜料橙P.0.5以及颜料红P.R.3因为有较好的性价比,仍然保有一定的市场份额。     

Dyestuffs for synthetic polymer fibres: 4-N-morpholinoazobenzenes

A series of monoazo disperse dyes derived from the coupling to N-phenylmorpholine of diazotised anilines and aminothiazole derivatives is described. The colour, dyeing and fastness properties of the dyes is compared to those of the analogous dyes based on N-ethyl-N-β-hydroxy-ethylaniline. Dyes from the ring closed heterocyclic coupling components dye synthetic-polymer fibres in deep colours of good fastness properties and show significant hypsochromic colour shifts compared to the uncyclised derivatives.     

纤维素水凝胶包覆Fe_3O_4类Fenton纳米催化剂的制备及其催化降解性能

采用纤维素水凝胶包覆Fe_3O_4颗粒,制备得到核壳结构的羧甲基纤维素聚丙烯包覆Fe_3O_4类Fenton纳米催化剂(CMC-co-AA/Fe_3O_4),并应用于降解偶氮染料酸性大红GR。考察了体系pH值、催化剂用量、染料初始浓度等参数对降解效果的影响。SEM和FT-IR分析结果表明水凝胶成功地包覆在Fe_3O_4颗粒表面,且壳层厚度为20~30nm。XRD分析显示,包覆层不影响纳米Fe_3O_4的晶型结构,纳米催化剂在使用过程中仍保持Fe_3O_4磁响应性能,能够有效地分离回收。相比传统的Fe_3O_4纳米催化剂,包覆型CMC-co-AA/Fe_3O_4纳米催化剂水溶液显示出了较好的均一分散性。且当pH3直至中性条件下,此时传统未包覆的Fe_3O_4纳米催化剂对酸性大红GR的降解率为0,而CMC-co-AA/Fe_3O_4纳米催化剂的降解率仍能维持36%,说明了水凝胶壳层结构赋予CMC-co-AA/Fe_3O_4纳米催化剂较宽的pH适用范围。重复试验表明,该纳米催化剂在循环使用四次后,对染料的降解率仍能保持98%左右。     

Processable heat-resistant polymers: 14. Polyamides and polyamideimides containing azo linkages

Diamines containing azo groups were synthesized by reacting sulphanilamide or p,p′-di(aminophenyl) sulphone with aniline. These diamines were used for the synthesis of polyamides and polyamideimides by interfacial and solution polycondensation techniques. The polymers were characterized by elemental (N and S) analyses and by i.r. and u.v. spectroscopy. The physical, chemical, thermal and electrical properties of the polymers were studied. The polymers were found to be soluble in highly polar solvents. The thermal stability of polyamideimides is superior to that of polyamides. X-ray diffraction and electrical behaviour of the polymers were also reported.     

The use of ozone to decolorize residual direct paper dyes in kraft paper machine whitewater

Production of colored kraft papers results in strongly colored paper machine spent Whitewaters (ww). The residual dyes prevent efficient recycle of the ww and necessitate periodic system cleanings. Many of the dyes are not adsorbed or degraded by biological effluent treatment and therefore discolor receiving waters. Ozone was tested as a bleaching agent for 15 direct paper dyes added at typical residual levels to kraft mill ww. These dyes included azo, polyazo, stilbene, benzothiazole and phthalocyanine direct dyes commonly used in Canadian dyed paper production. Ozone charges of 15 ‐100 mg/L rapidly bleached most of the dyes, although a few of the yellow stilbene and azo dyes were quite resistant. The efficiency of ozone‐mediated residual dye bleaching was altered substantially by the pH, the ww concentration, and the target dye's chemical structure. Preozonation of residual dye‐containing ww greatly decreased the color conferred to bleached kraft pulp fibers added to the ww. Thus, ozonation should permit much more ww recycle (less effluent) when changing colors on the paper machine. Depending on the availability of oxygen or ozone in a mill, and local ozone economics, ozone may be the most efficient, cost‐effective way to improve ww quality, increase ww recycle and minimize effluent color problems and environmental impact.     

Mordant dyes as sensitisers in dye-sensitised solar cells

Many mordant dyes commonly used in the textile industry form coordination complexes at the surface of nanocrystalline TiO₂. Dyes having a salicylate chelating group are particularly effective. Forty-nine commercial mordant dyes were studied as sensitisers in a non-optimised dye-sensitised solar cell (DSSC) and their performance compared to the N3 ruthenium complex. Although N3 produced the highest output, six mordant dyes produced photocurrents >0.2 mA. UV–visible spectra of the dye-complexed photoanodes suggest that some mordant dyes are more strongly bound to the TiO₂ surface than N3. Photocatalytic oxidation of these dyes does not appear to occur in a DSSC environment.     

Surface-enhanced Raman study of electrochemical and photocatalytic degradation of the azo dye Janus Green B

The photocatalytic degradation of Janus Green B azo dye over silver modified titanium dioxide films was investigated by surface-enhanced Raman spectroscopy (SERS). An optimized SERS-active substrate was employed to study the photodegradation reaction of Janus Green B. Considering that photocatalytic degradation processes of organic molecules adsorbed on TiO₂ might involve either their oxidation or reduction reaction, the vibrational spectroelectrochemical study of the dye was also performed, in order to clarify the transformations involved in initial steps of its photochemical decomposition. In order to understand the changes in Raman spectra of Janus Green B after photodegradation and/or electrochemical processes, a vibrational assignment of the main Raman active modes of the dye was carried out, based on a detailed resonance Raman profile. Products formed by electrochemical and photochemical degradation processes were compared. The obtained results revealed that the first steps of the degradation process of Janus Green B involve a reductive mechanism.     

Nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica for the diazotization of aniline derivatives and subsequent synthesis of azo dyes

Imidazolium based nitrite ionic liquid containing trimethoxysilyl group was prepared from the reaction of N-methylimidazole and (3-chloropropyl) trimethoxysilane. This ionic liquid was immobilized on silica covalently to give nanoparticles with the imidazolium nitrite moiety remaining intact. The diazotization reaction was performed as a model reaction to examine the activity of these nanoparticles as a nitrosonium source. Excellent performance was exhibited in the diazotization reaction of various aniline derivatives in the presence of HCl under mild heterogeneous conditions (room temperature and short reaction time). In-situ coupling of diazonium salts to a range of tertiary anilines, phenols and naphthols afforded the requisite azo dyes in good yield, using standard experimental procedures.     

A new nitrite ionic liquid (IL-ONO) as a nitrosonium source for the efficient diazotization of aniline derivatives and in-situ synthesis of azo dyes

A new task-specific nitrite containing ionic liquid derived from the O-nitrosation of N-methyl-N-hydroxybutylimidazolinium chloride was synthesized and used as a source of nitrosonium ion to affect the efficient diazotization of arylamines. The diazonium salts thus obtained were coupled, using standard experimental procedures, to a range of tertiary anilines, phenols and naphthols to afford the requisite azo dyes in good yield. The diazotization and subsequent azo-coupling generated the related azo dyes at 0-5 °C in short reaction times with a simple experimental procedure.