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Functionalization of Carbon-Based Additives
Published in Andreas Sapalidis, Membrane Desalination, 2020
Myrsini Kyriaki Antoniou, Andreas Sapalidis, Zili Sideratou
Zambare et al. (2017) developed mixed matrix membranes by blending amine functionalized graphene oxide (fGO) in polysulfone. Three polyamines, ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA), with different chain lengths were used in order to functionalize GO, and it was shown that by increasing the interlayer space of GO nanosheets with polyamines, the dispersion in polysulfone–NMP solution is improved. The presence of polyamines in the membranes resulted in the increase of hydrophilicity and the formation of finely porous structures, which enhanced the membrane’s permeability. The antifouling properties of the membranes were tested by using BSA as a foulant. BSA rejection was greater than 90% for all fGO based polysulfone mixed matrix membranes, while a remarkably high pure water flux of 170.5 LMH/bar was displayed (Figure 3.14).
Plastics
Published in Ronald M. Scott, in the WORKPLACE, 2020
Toxicologically, this is a very troublesome group of compounds. Epichlorohydrin is an irritant to the skin, causing burning, itching, and redness, with pain and blistering appearing after contact. It can be absorbed through the skin. It is irritating to the eyes, causing damage at higher concentrations. It is severely irritating to the lungs, producing pneumonitis (fluid in the lungs) hours after exposure. Liver and kidney damage result, and sterility is caused. Finally, it is a sensitizer, leading to later allergic response upon contact with even small quantities of epichlorohydrin. The PEL is 5 ppm. Compounds used with epichlorohydrin to produce epoxy resins include bisphenol A, glycidyl ethers, and aliphatic polyamines such as p-phenylenediamine, diethylenetriamine, and triethylenetetramine. All these are irritants and sensitizers. The polyamines are particularly hazardous, causing severe irritation, chemical burns, reddened and itching skin, blistering, facial swelling, and asthma. They can cause bronchospasms and coughing for days after exposure. Sawing or machining finished plastic products can release amines and unreacted epichlorohydrin.
Polymers
Published in Ronald Scott, of Industrial Hygiene, 2018
Toxicologically, this is a very troublesome group of compounds. Epichlorohydrin is an irritant to the skin, causing burning, itching, and redness, with pain and blistering appearing after contact. It can be absorbed through the skin and is irritating to the eyes, causing damage at higher concentrations. Epichlorohydrin is severely irritating to the lungs, producing pneumonitis (fluid in the lungs) hours after exposure. In the body, liver and kidney damage result, and sterility is caused. Finally, it is a sensitizer, leading to later allergic response upon contact with even small quantities of epichlorohydrin. The PEL is 5 ppm. Compounds used with epichlorohydrin to produce epoxy resins include bisphenol A, glycidyl ethers, and aliphatic polyamines such as p-phenylenediamine, diethylenetriamine, and triethylenetetramine. All these are irritants and sensitizers. The polyamines are particularly hazardous, causing severe irritation, chemical burns, reddened and itching skin, blistering, facial swelling, and asthma. They can cause bronchospasms and coughing for days after exposure. Sawing or machining finished plastic products can release amines and unreacted epichlorohydrin.
Extraction of Erbium(III) from Nitrate Solutions Using Mixtures of Neodecanoic Acid and Diacylated Ethylene Amines
Published in Solvent Extraction and Ion Exchange, 2020
S. O. Bondareva, Yu. I. Murinov
Many types of mixed extractant systems have been reported for the extraction and separation of rare earths,[1–4] for example, combinations of acidic extractants,[5,6] mixtures of neutral extractants,[7,8] combinations of acidic and neutral extractants,[9–11] and mixtures of acidic and amine extractants.[12–15] The mixtures of diacylated ethylene amines[16] with α,α´-branched synthetic carboxylic acids can be attributed to the latter ones. Thus, diacylated diethylenetriamine (Figure 1, DAD) and diacylated triethylenetetramine (Figure 1, DAT), along with amide groups, contain secondary amine functional groups and may be classified as amido-functionalized amine reagents. The basicity of the secondary N atoms of the amino groups decreases due to the redistribution of the electron density in the chain stipulated by the (-J)-effect of the С=О groups – their pKa values are about 8.0–8.5.[17] On the other hand, the N,N’-substituted alkyl amides are well known to extract lanthanides from acidic nitrate media alone[18] or in mixtures with acidic extractants.[19,20] DAD and DAT contain two amide functional groups and can be attributed to amine-containing C,C-alkyl-disubstituted amides, as well.
The influence of curing conditions on the strength of adhesive joints
Published in The Journal of Adhesion, 2020
Cold-curing adhesives are obtained from a liquid diane resin of the average molecular weight. Aliphatic polyamides (diethylenetriamine, triethylenetetramine, dimethylaminopropylamine), adducts of amines or polyaminoamides are most commonly used as curing agents.[13,16] The pot-life of resin and amine mixtures is short, e.g. in case of diethylenetriamine, it is 30–60 min. The amount of amine should be carefully calculated according to the content of epoxy groups in the resin as the excess of unreacted amine reduces the bond strength. Curing at room temperature lasts for 1–3 days in most cases; nevertheless adhesive joint acquires optimal strength no sooner than approx. in 7 days.[3] Gladkikh et al.[29] investigated the properties of fast-curing adhesive materials based on modified cold-curing epoxy resins. Prolongo et al.[13] carried out the research related to the adhesive behaviour of different epoxy resins and found out that the epoxy cured with aromatic amines present high adhesive strength.
Coordination polymers and a dinuclear complex constructed from zinc(II) ions and fluorescein: iodine adsorption and optical properties
Published in Journal of Coordination Chemistry, 2019
Mihai Răducă, Cristian D. Ene, Sorana Ionescu, Mihaela Florea, Augustin M. Mădălan
Crystallographic investigation of the first type of crystals from the synthesis employing the mixture of isomers of triethylenetetramine reveals the formation of centrosymmetric dinuclear complexes containing four monoanions of fluorescein (fl) and one N,N′-bis(2-aminoethyl)piperazine ligand (dienpip), [{Zn(fl)2}2(dienpip)]·4H2O·4EtOH (1). The presence of N,N′-bis(2-aminoethyl)piperazine was initially unexpected since this is not an isomer of triethylenetetramine, but we found other reports concerning the occurrence of this impurity in the triethylenetetramine commercialized as mixture of isomers [19]. The zinc ions in 1 are five-coordinated with a distorted trigonal bipyramidal environment, N2O3. The equatorial plane is formed by two oxygens from the carboxylato groups of two different fluorescein anions and one nitrogen from the dienpip ligand (a primary amine group). The bond lengths in the equatorial plane are: Zn1-O4 = 2.0218(19), Zn1-O9 = 1.942(2), and Zn1-N1 = 2.009(3) Å. The axial bond lengths are longer than the equatorial ones: Zn1-N2 = 2.168(2) and Zn1-O5 = 2.316(2) Å. N2 originates from a tertiary amino group of dienpip, whereas O5 belongs to a chelating carboxylato group (Figure 1).