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Organic Materials for Third-Order Nonlinear Optics
Published in Hari Singh Nalwa, Seizo Miyata, Nonlinear Optics of Organic Molecules and Polymers, 2020
Kaino et al.315 measured third-order NLO susceptibilities of a variety of chromophore-functionalized polymeric materials; dye-attached side chain polymers and dye-introduced main chain polymers. PMMA was copolymerized with methyacrylate esters of the dicyanovinyl- or nitro-terminated diazo dye derivatives and Dispersed Red 1. The chemical structures of these azo dyes, referred to as 3RDCVXY, 3RNO2, and 2RNO2, are shown below. These azo dyes were synthesized by a diazocoupling reaction. All these dyes had a diethylamino group as electron donor and dicyanovinyl and nitro groups as acceptors. Figure 34 shows the variation of ??3)values as a function of fundamental wavelengths, and the magnitude of ?(3)increases with the decrease of fundamental wavelength. The ?(3)value of 3RNO2 was "2.5 X 10" esu and of 2RNO2 was "0.8 X 10 1 esu for 7 mol% dye contents. The 3RDCVXY and 3RNO2 dyes have three benzene rings connected with azo groups, hence their ?3)values are more than five and three times higher than 2RNO2 dye due to the large conjugation length over the 1.5 to 2.0-??? range. The ?3)value of PMMA was 4 X 10~14 esu at 1.9 ?m, therefore the large optical nonlinearities of these dye-attached polymers originated from dye moiety only. The ?(3)values also increased linearly with increase of dye content up to 17 mol% for 3RNO2 and 33 mol% for 2RNO2. The ?(3)value of 3RNO2 was 4.8 X 10 11 esu at 1.5 ?m and reached 2 X 10 75 esu for 50 mol% azo dye contents.
Amines
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
The reaction of sodium nitrite and HCl generates HONO, which reacts with aniline to give benzenediazonium chloride. Diazonium salts react with activated aromatic rings to give an azo dye (see Section 16.4). In this case, reaction with anisole gives the azo dye, 1-(4-methoxyphenyl)-2-phenyldiazene.
Plant-Microbial Fuel Cells Serve the Environment and People
Published in Sonia M. Tiquia-Arashiro, Deepak Pant, Microbial Electrochemical Technologies, 2020
Lucia Zwart, Cees J.N. Buisman, David Strik
Next to COD and nutrient removal, the removal of azo dye with CW-MFCs has been documented by several researchers (Fang et al. 2013; Yadav et al. 2012). Azo dyes are a group of synthetic dyes intensively used in the paper and textile industry. Most azo dyes are biorefractory organics and are not removed by regular sewage treatment plants (Vandevivere et al. 1998). When present in the surface water, azo dyes will block the light, thereby inhibiting photosynthetic activity. This can decrease the dissolved oxygen concentration that can have negative consequences for aquatic life. Extensive research has been performed on the biotic (J.B.A. Arends et al. 2014) or abiotic reduction of azo dyes in natural sediments and waters (Weber and Lee Wolfe 1987; Wuhrmann et al. 1980). The process of degradation is comparable to that in constructed wetlands. The reductive environment of the anaerobic soil is beneficial to the chemical or biological reduction of the azo dye bond. The presence of an anode electrode in a CW-MFC promotes the growth of reducing EAB in the soil that can aid the biodegradation process (Cabezas et al. 2015; Lu et al. 2015). Azo dye wastewater can furthermore be treated by the wetland through phytoremediation. Plant enzymes and bacteria in the rhizosphere are able to break the complex chemical structure of the dyes (Khandare and Govindwar 2015).
Degradation of the dye methyl orange using cow and goat milk iron nanoparticles
Published in Green Chemistry Letters and Reviews, 2023
Isha Gautam, Tony Grady, Harshica Fernando
Environmental pollution is a global problem, with water pollution being one such issue. Water contamination by toxic chemicals, such as azo dyes, is a serious matter of concern. Azo dyes are used as colorants in the textile industry. Previous studies have shown that untreated dyes can accumulate in the environment, harm humans, and threaten the ecosystem (1). In the last few decades, many academic and industrial research studies have focused on developing new highly active and stable catalysts for selective oxidation and total degradation of organic substances (2). Hence, eco-friendly, cheap methods with shorter processing times are required to remove these dyes from wastewater. Metallic nanoparticles (NPs) have recently gained increased research attention owing to their applicability in many fields. Nanomaterials offer distinctive structural and physiochemical properties compared to their bulk counterparts owing to their high surface-to-volume ratio (3–8). Attempts are being made to produce new cost-effective NPs. In the past, many chemical and physical methods have been used for dye degradation studies; however, recently, biological routes have been investigated. This route of synthesizing NPs produces environmentally friendly and less toxic NPs of varying sizes (1, 3, 6). One of the drawbacks of this approach is the low yield, which is insufficient for commercialization (8).
Restricted substances for textiles
Published in Textile Progress, 2022
Arun Kumar Patra, Siva Rama Kumar Pariti
Azo dyes are obtained by coupling of a diazotised amine with a coupling component in aqueous solution or suspension. The chromophoric (colour producing) azo group is found in many classes of dyes, such as direct, acid, acid mordant, disperse, azoic, reactive and metal-complex dyes. Many studies have been carried out on azo dyes not least because a variety of substrates, including synthetic and natural fibres, plastics, leather, paper, mineral oils and waxes can be dyed by these dyes. As mentioned earlier, the chemistry of azo dyes ranges from simple monoazo compounds to complex polyazo structures with a molecular weight of 1800 or more, and their properties vary accordingly. A unique feature of azo dyes is that nature does not produce analogous coloured substances (Hunger, 2003; Shenai, 1997b). It is claimed that there is only one instance of an azo group being present in a natural substance (4,4′-dihydroxy azobenzene) and the industrially-produced azo dyes can all therefore be considered to be xenobiotic compounds (Stolz, 2001).
Preparation and characterization of Linde-type A zeolite (LTA) from coal fly ash by microwave-assisted synthesis method: its application as adsorbent for removal of anionic dyes
Published in International Journal of Coal Preparation and Utilization, 2022
Tahani Al-dahri, Adnan A. AbdulRazak, Sohrab Rohani
Azo dyes are used to dye different materials such as leather, textiles, food, and cosmetics. Nowadays azo dyes make 60–70% among the other commercial types of dyes. These dyes contain azo groups (−N = N−) in their chemical structure. Azo dyes are considered as a very serious health hazard to humans if they get into water supplies. They are harmful to ecosystems if discharged to the water system (AbdulRazak, Shakor, and Rohani 2018; Majid, AbdulRazak, and Noori 2019). Current methods used to remove dangerous azo dyes from wastewater include physical and chemical treatment processes such as adsorption, precipitation, flocculation, flotation, coagulation, and electrochemical destruction methods (Al-Dahri et al. 2018; Georgiou et al. 2002; Ledakowicz, Solecka, and Zylla 2001; Peralta-Zamora et al. 1999). Biodegradation by fungi and bacteria (Kapdan et al. 2000), and photocatalytic degradation (Kansal, Hassan Ali, and Kapoor 2010) have also been reported. Recent methods for removal of azo dyes include physical and chemical treatments due to high efficiency and low price compared with other methods. Various types of adsorbents are in use today to remove azo dyes from wastewater such as activated carbon (Rodríguez et al. 2009), chitosan beads (Chiou, Ho, and Li 2004), and modified bentonite (Ma et al. 2012).