China
Africa
Explore chapters and articles related to this topic
Carbon Dioxide Conversions
Published in Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda, 1 Chemistry, 2022
Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda
The synthesis of amino resins from formaldehyde and amino compound involves two successive steps (Scheme 6.9). The first step is the addition of formaldehyde to introduce the hydroxymethyl group, known as methylolation or hydroxymethylation. Then, a condensation reaction occurs which involves the linking of monomer units with the liberation of water to form a dimer, a polymer chain or a vast network. This is usually referred to as methylene bridge formation, polymerization, resinification or simply cure (Williams, 2002).
Wet oxidation of inhibitory compounds of distillery spent wash over ferrous sulfate catalyst
Published in Chemical Engineering Communications, 2021
Ganesh M. Bhoite, Prakash D. Vaidya
Wet oxidation can effectively treat distillery wastewater after biogas generation, also called biomethanated spent wash (Dhale and Mahajani 2000). This effluent has high COD (around 40 g/L) and low BOD/COD ratio (around 0.2), and thus, resists aerobic oxidation. Recently, we applied iron catalyst for controlled wet oxidation of spent wash to improve biogas recovery and facilitate aerobic treatment (Bhoite and Vaidya 2018a, 2018b). Also, we identified key contaminants originally present in the spent wash and new intermediary compounds formed during oxidation. In this work, four inhibitory organic pollutants among these were chosen as model compounds: 5-hydroxymethyl furfuraldehyde (HMF), p-coumaric acid (PCA), oleic acid (OA), and t-butyl alcohol (TBA). Using homogeneous FeSO4 catalyst, wet oxidation reactions of these typical substrates were studied in a batch reactor. The effects of reaction conditions on the rise in BOD/COD ratio and kinetics of conversion of total organic carbon (TOC) were studied.
Some of Physical and Mechanical Properties of Particleboard Panels bonded with Phenol- Lignin- Glyoxal Resin
Published in The Journal of Adhesion, 2020
Hamed Younesi-Kordkheili, Antonio Pizzi
the curing of the PLG resin with 30 wt% lignin compared to the PF control resin has been shown in Figure 2. As shown in Figure 2 the curing of both PLG and PF resins are exothermic and similar to each other, implying that the two resins undergo a similar curing process. The temperature peaks of the PF resin appeared at 140°C and 160°C, respectively. Previous research indicated that these peaks can be attributed to chain building condensation.[4] The first peak at 140°C is due to chain building condensation reactions involving both hydroxymethyl groups attached to various phenolic species and self-condensation reactions of 4-hydroxybenzyl alcohol.[33] The second peak at 160°C is attributed to self-condensation reactions of 2-hydroxybenzyl alcohol. Similar to PF resin, PLG resins exhibited two overlapping peaks at 145°C and 170°C. These peaks can also be related to self-condensation reactions between the groups of a PLG resin. Figure 1 indicates that the temperature peaks of an LPG resin appeared at a higher temperature than that of a PF resin. This DSC analysis confirms the gel time results as the LPG resins present slower gel times than the PF control resin. Conversely, Khan et al.[34] indicated that lignin-phenol-formaldehyde resins have a lower curing temperature than PF resins. Thus, the slower curing time and higher curing temperature of PLG resins indicate that lignin and glyoxal need a higher temperature and longer time for reaction with phenol than formaldehyde.
Reactions of gold(III) complexes with l -histidine-containing dipeptides: influence of chelated ligand and N-terminal amino acid on the rate of peptide coordination
Published in Journal of Coordination Chemistry, 2020
Darko P. Ašanin, Ivana M. Stanojević, Tina P. Andrejević, Biljana Đ. Glišić, Miloš I. Djuran
From Table 2 and Figure 4, it can also be seen that for both gold(III) complexes, [Au(en)Cl2]+ and [AuCl4]–, the following order of dipeptide reactivity was observed: Gly-L-His > L-Ser-L-His > L-Ala-L-His. The difference in the reactivity of these three dipeptides was more pronounced in the case of [AuCl4]– with respect to [Au(en)Cl2]+ (Table 2). Thus, Gly-L-His dipeptide is approximately two and four times more reactive than L-Ser-L-His and L-Ala-L-His, respectively, toward [AuCl4]–. On the other hand, Gly-L-His is two times more reactive than L-Ala-L-His toward [Au(en)Cl2]+, while the difference between Gly-L-His and L-Ser-L-His is not significant. The highest reactivity of Gly-L-His dipeptide in comparison to the remaining two dipeptides can be attributed to the steric hindrance of the methyl and hydroxymethyl groups of L-alanine and L-serine, respectively. However, the difference in the reactivity between L-Ala-L-His and L-Ser-L-His could be a consequence of electron-donating resonance effect (+R) of -OH group in L-serine, contributing to the enhancement of nucleophilic potential of the N-terminal amino group of the corresponding dipeptide and higher yield of [Au(L-Ser-L-His-NA,NP,N3)Cl].