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Applications in the Dairy Industry
Published in V. Chelladurai, Digvir S. Jayas, Nanoscience and Nanotechnology in Foods and Beverages, 2018
V. Chelladurai, Digvir S. Jayas
Melamine is an organic chemical most commonly used in plastics, countertops, dishware, adhesives, and whiteboards. Milk producers and processors sometimes add water into raw milk to increase the volume, which decreases the protein content of milk. The protein content of milk and other food products is measured by standard analytical techniques using the nitrogen content of the product. Addition of melamine into the diluted milk increases the nitrogen content thus artificially inflating the protein content of the milk. Use of melamine in dairy or other food products is not approved by World Health Organization and also poses some health risks like kidney stone formation. Melamine presence in milk is being detected using regular analytical techniques, such as high-performance liquid chromatography (HPLC), gas chromatography/mass spectrometry (GC/MS), MS, surface-enhanced Raman spectroscopy (SERS), and HPLC coupled with MS (HPLC/MS). Most of these methods need a long time for detection, expensive equipment, and highly qualified personnel (Xin et al. 2015). Some of these methods also need pretreatments like extraction and derivatization. Nanotechnology-based sensors and sensing techniques can be used to easily detect melamine adulteration in milk by using colorimetric changes (Ai et al. 2009; Cai et al. 2014; Giovannozzi et al. 2014; Guo et al. 2014; Kumar et al. 2014; Ni et al. 2014; Song et al. 2015; Xin et al. 2015).
Polymers utilised in construction
Published in Ash Ahmed, John Sturges, Materials Science in Construction: An Introduction, 2014
Melamine is a thermosetting polymeric material with a wide range of applications. Melamine is a strong organic base with chemical formula C3H6N6, with the name 1,3,5-triazine-2,4,6-triamine. The melamine monomer is illustrated in Figure 15.4. Melamine is primarily used to produce melamine resin, which when combined with formaldehyde produces a very durable thermoset plastic. This plastic is often used as kitchen worktops (Figure 15.5), kitchen utensils or plates. Melamine is also used to make decorative wall panels and is often used as a laminate.
Development of a dual-channel LSPR biosensing system for detection of melamine using AuNPs-based aptamer
Published in Khaled Habib, Elfed Lewis, Frontier Research and Innovation in Optoelectronics Technology and Industry, 2018
Q.Q. Guo, S. Wang, H. Zhang, D.X. Li, J.J. Shang, H.F. Sun, Y.T. Yang, L.Z. Ma, J.D. Hu
Adulteration of food and drink has become one of the major problems in food industry (Chi et al. 2010; Bala et al. 2016). For instance, an adulterant, melamine (C3H6 N6) is a kind of white odorless crystalline powder with a high nitrogen content of 66.6% by mass due to containing three amino groups (Chang et al. 2017). Melamine is illegally added into milk to make it look protein rich (Filazi et al. 2012). Melamine in milk can result in kidney stones, renal failure, and even death in humans. The detection of melamine in food has become more and more important in the field of food safety (Vail et al. 2007; Li et al. 2014; Bala et al. 2015). Currently, the conventional detection methods of melamine involve high performance liquid chromatography (HPLC), enzyme linked immunosorbent assay (ELISA), and gas chromatography-mass spectrometry (GC-MS). Those methods have many advantages such as high selectivity and low limits of detection, however, they need expensive instruments, complicated sample pretreatment and trained operators (Wei et al. 2010; Bala et al. 2016). In this paper, an effective dual-channel LSPR biosensing system via optical fibers was put forward to the colorimetric detection of melamine using gold nanoparticles-based aptamer. The color of AuNPs solution shifts from red to blue due to the aggregation of AuNPs along with the increase of the concentration of melamine. The calibration curves of absorbance ratio (A640/A520) calculated from absorption spectra have been established, and square values of correlation coefficient of 0.98 and 0.96 are obtained from both channels. Based upon the experimental results, the melamine at a low concentration of below 1 μM can be rapidly and sensitively detected by the proposed LSPR biosensing system via optical fibers.
Thermogravimetric analysis of flax, jute, and UHMWPE fibers and their composites with melamine and phenol formaldehyde resins
Published in Cogent Engineering, 2023
Srinivas Shenoy Heckadka, Raghuvir Pai Ballambat, Poornima Bhagavath, Manjeshwar Vijaya Kini, Rajeev K Sinha, M.K Sonali, Diya Sen
Now coming to the resin, which is a polymeric material used to bond the fiber reinforcements in polymer composites. Resins such as epoxy, polyester and vinyl ester are extensively utilised with natural/synthetic fibers for manufacturing composites (Rajak et al., 2019). In addition to these resins, the use of formaldehyde resins such as phenol, melamine and urea-formaldehyde is gaining momentum for developing polymer composites. Phenolic resins produced due to the reaction between phenol and formaldehyde under alkaline conditions have excellent mechanical strength, water resistance and chemical and thermal stability. Phenolic resins are used to produce moulded products, including billiard balls, laboratory countertops, hot oil filter applications such as the lube oil filters of automobiles, coatings and adhesives (Kariuki et al., 2019). Melamine formaldehyde resin obtained by condensation of formaldehyde with melamine has improved heat, moisture, scratch, and chemical resistance (Merline et al., 2013). Melamine resins are used to manufacture many products, including kitchenware, laminate flooring, laminate countertops, overlay materials, particleboards, and floor tiles. Melamine and its salts are also used as fire-retardant additives in paints, plastics, and paper (Kumar & Katiyar, 1990; Park & Jeong, 2010; Raval et al., 2006).
Recovery of vanadium with melamine in acidic medium
Published in Environmental Technology, 2023
Hao Peng, Jing Guo, Qian Gong, Qiao Zhou, Xingxing Wang, Huaping Liu, Yao He, Bing Li, Wenbing Shi
Melamine (C3H6N6) is an organic compound widely used in adhesives, manufacturing plastics, lamination products, yellow dye, automotive surface coating, and cleaning agent [28–30]. Owing to its high nitrogen content (six nitrogen atoms) and low price, criminals add it to foods, especially milk [31], which resulting kidney failure and even death [32]. In China, melamine is well known for Sanlu milk scandal to common people [33]. Melamine has a great potential for adsorption with 8.71 m2/g of surface area and 0.0040 mL/g of pore volume [34]. Some research focused on the adsorption of heavy metal with melamine and related compounds have been conducted. The MOFs modified with melamine possess high adsorption capacity and display greater performance than the un-modified one [35–38]. The single melamine shows a high selective of Ag(I) with a capacity of 820 mg/g, which is much higher than Cu (II) (56.1 mg/g) and Pb (II) (71.7 mg/g) [38].
The hydrolytic stability and structure of the cured melamine-urea-formaldehyde resin
Published in The Journal of Adhesion, 2022
Zhongjian Ding, Zhongqiang Ding, Doudou Zhang, ChangMen Chao
On the DTG curve of MUF resins with different melamine levels added at the M1 stage, the mass-loss rate at peak 1 of three MUF resins increases with the increment of melamine levels. It indicates that the branched degree of MUF resin oligomers increases because of melamine. Interestingly, three MUF resins are of the same temperatures at peak 1 and peak 2, respectively. It means of three MUF oligomers are of very similar condensation reactivity despite different melamine levels. When melamine is added with the first batch of urea (M1 stage) during the resin synthesis process, the melamine preferentially reacts with formaldehyde to form methylomelamine because of the higher reactivity of melamine than urea. There is not free melamine in the MUF oligomers. All methylolmelamine groups integrate into the structure of the UF oligomer at the condensation stage of the synthesis process. The three-dimensional structure of melamine increases the branched structure of the MUF oligomer. In three MUF oligomers, the functional groups that will take part in the curing reaction should be methylolurea, regardless of melamine level. It should be due to the higher condensation reactivity of methylomelamine than methylourea. Furthermore, there is little difference in the amount of methylolurea in the three oligomers because of less than 5% melamine level. These results mean that the three MUF oligomers are of similar condensation reactivity. The different branched structures of cured MUF resins should mainly be derived from the different branched structures of the oligomers.