Oxidation Of Amine Group Research Articles

Synergistic effect and interaction of nano zero-valent iron and Al13 in carbamazepine removal

In this study, a multi-functional coagulant with both coagulation and oxidation function was obtained by pre-doped nano zero-valent iron (nZVI) with Al13 for the removal of the typical emerging contaminants Carbamazepine (CBZ). At the optimal doped dosage of nZVI, the pre-doped agent (Al13@nZVI) showed 23% improvement of the maximum removal rate of Carbamazepine compared with Al13 under pH 7. It was found that Al13@nZVI could produce H2O2 in situ at pH 2 to pH 8, especially under acid conditions. By the analysis of FT-IR, it could be found that the groups of C-N, benzene, and CO were disappeared after treatment. Instead, -NO2 was found in treated water which indicated the breakage and oxidation of amine group. Thus, the effects of pH on Al13 and Al13@nZVI were different. Al13 will undergo depolymerization and decompose into small polymers with low positive charge density with the increasing of pH, while, because of Al13@nZVI having oxidation ability, effect of pH on Al13@nZVI was not that significant. The influence of Humic acid (HA) with different concentration on CBZ removal were analyzed. The system with 2 mg/L HA showed better removal performance of both CBZ and total dissolved organic carbon (DOC) compared to the system with 1 mg/L HA, which may because of the increase of the necessary nuclei for the flocs formation, as well as the bridging function by the long chain structure of HA. Moreover, Al13@nZVI was found improved the removal efficiency of organic matters with molecular weight about 1500–2000 Da compared to Al13.

Polyethylenimine facilitated ethyl cellulose for hexavalent chromium removal with a wide pH range.

Ethyl cellulose (EC) composites modified with 20.0 wt % polyethylenimine (PEI) (PEI/ECs) demonstrated effective hexavalent chromium, [Cr(VI)], removal from solutions with a wide pH range. For example, 4.0 mg/L Cr(VI) solution with a pH below 3.0 was completely purified by 3.0 g/L PEI/ECs within 5 min, much faster than the as-received EC (2 h) and activated carbon (several hours). These PEI/ECs adsorbents has overcome the low pH limitation of Cr(VI) removal; for example, 4.0 mg/L Cr(VI) solution with a pH of 11.0 was completely purified within 15 min. These adsorbents followed chemical adsorption as revealed from the pseudo-second-order kinetic study. These PEI/ECs following the isotherm Langmuir model have a maximum adsorption capacity of 36.8 mg/g, much higher than pure EC (12 mg/g), tetrabutylammonium-modified celluloses (16.67 mg/g), and magnetic carbon (16 mg/g). The reduction of Cr(VI) to Cr(III) by the oxidation of amine groups and hydroxyl groups of PEI/ECs was verified as the main mechanism for the Cr(VI) removal.

Degradation kinetics and mechanism of β-lactam antibiotics by the activation of H2O2 and Na2S2O8 under UV-254 nm irradiation

The extensive production and usage of antibiotics have led to an increasing occurrence of antibiotic residuals in various aquatic compartments, presenting a significant threat to both ecosystem and human health. This study investigated the degradation of selected β-lactam antibiotics (penicillins: ampicillin, penicillin V, and piperacillin; cephalosporin: cephalothin) by UV-254nm activated H2O2 and S2O82− photochemical processes. The UV irradiation alone resulted in various degrees of direct photolysis of the antibiotics; while the addition of the oxidants improved significantly the removal efficiency. The steady-state radical concentrations were estimated, revealing a non-negligible contribution of hydroxyl radicals in the UV/S2O82− system. Mineralization of the β-lactams could be achieved at high UV fluence, with a slow formation of SO42− and a much lower elimination of total organic carbon (TOC). The transformation mechanisms were also investigated showing the main reaction pathways of hydroxylation (+16Da) at the aromatic ring and/or the sulfur atom, hydrolysis (+18Da) at the β-lactam ring and decarboxylation (–44Da) for the three penicillins. Oxidation of amine group was also observed for ampicillin. This study suggests that UV/H2O2 and UV/S2O82− advanced oxidation processes (AOPs) are capable of degrading β-lactam antibiotics decreasing consequently the antibiotic activity of treated waters.

Unprecedented Blue Intrinsic Photoluminescence from Hyperbranched and Linear Polyethylenimines: Polymer Architectures and pH‐Effects

AbstractThe intrinsic photoluminescence properties of hyperbranched polyethylenimines (PEIs) and their linear counterpart (LPEIs) have been studied in absence of any classical fluorescent probes. The comparison of the inherent fluorescence emission between hyperbranched polyethylenimines and their linear analogues demonstrates that linear polyamines are capable of producing strong intrinsic photoluminescence species having long excited lifetimes without need of having a tridimensional‐branched structure. The creation of inherently fluorescent polymeric centers from hyperbranched and linear polyethyleimines can be modulated by specific chemical modification and oxidation of amine groups as well as by adjusting the acidity of the polymer.magnified image

Identification of metabolites during biodegradation of pendimethalin in bioslurry reactor

Bioslurry phase reactor was used for the degradation of pendimethalin, a pre-emergence herbicide in the contaminated soil under aerobic environment. More than 91% degradation of pendimethalin was observed for 5 days of reactor operation augmented with sewage from effluent treatment plant (ETP). The performance of the reactor was monitored regularly by measuring pH and colony forming units (CFU). The metabolites of pendimethalin formed during degradation were identified using various analytical techniques, viz., thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and liquid chromatography–mass spectroscopy (LC–MS/MS). Four metabolites were formed and identified as N-(1-ethylpropyl)-3,4-dicarboxy 2,6-dinitrobenzenamine- N-oxide, N-(1-ethylpropyl)-3,4-dimethoxy-2,6-dinitrobenzenamine and benezimadazole-7-carboxyaldehyde. The reactions involved were monohydrolysis of 2-methyl groups followed by dihydrolysis. Further oxidation of amine groups and hydroxylation of propyl groups produced the above said metabolites. Degradation pathway of pendimethalin has been proposed in the bioslurry phase reactor.

A Comparative Study on Chemical and Electrochemical Degradation of Reactive Blue 4 Dye

The degradation of a reactive blue 4 dye in acidic solution has been compared using electrochemical reduction and oxidation at reticulated vitreous carbon electrode (RVC) and Ti/SnO2/SbOx (3%mol)/RuO2 (30%mol) electrodes and photo–Fenton method under UV irradiation. The reduction of RB4 dye at –0.6 V on RVC electrode results in 50% of color removal and up to 64% of TOC removal. The direct oxidation of RB4 dye at +1 V on RVC promotes only the oxidation of amine group and there is no color removal. On SnO2 electrode, 58% TOC was removed and the decolorization is around 100 % after 1 hour of electrolysis at 2.4 V indicating good efficiency. Best performance was obtained by photo-Fenton method that indicates 80% elimination of TOC and 100% of color removal but the method requires oxidant addition and time of rest to remove the generated residues.

Chlorination of Pyridinium Compounds: POSSIBLE ROLE OF HYPOCHLORITE, N-CHLORAMINES, AND CHLORINE IN THE OXIDATION OF PYRIDINOLINE CROSS-LINKS OF ARTICULAR CARTILAGE COLLAGEN TYPE II DURING ACUTE INFLAMMATION

Reactive oxygen species produced by activated neutrophils and monocytes are thought to be involved in mediating the loss of collagen and other matrix proteins at sites of inflammation. To evaluate their potential to oxidize the pyridinoline (Pyd) cross-links found in collagen types I and II, we reacted hydrogen peroxide (H(2)O(2)), hypochlorous acid/hypochlorite (HOCl/OCl(-)), and singlet oxygen (O(2)((1)delta g)) with the Pyd substitutes, pyridoxamine dihydrochloride and vitamin B(6), which share the same chemical structure and spectral properties of Pyd cross-links. Neither H(2)O(2) (125-500 microm) nor O(2)((1)delta g) (10-25 microm) significantly changed the spectral properties of pyridoxamine or vitamin B(6). Reaction of HOCl/OCl(-) (12.5-50 microm) with pyridoxamine at pH 7.2 resulted in a concentration-dependent appearance of two new absorbance peaks and a decrease in fluorescence at 400 nm (excitation 325 nm). The new absorbance peaks correlated with the formation of an N-chloramine and the product of its subsequent reaction with pyridoxamine. In contrast, the extent to which HOCl reacted with vitamin B(6), which lacks a primary amine group, was variable at this pH. At lysosomal pH 5.5, Cl(2)/HOCl/OCl(-) reacted with both pyridoxamine and vitamin B(6). Four of the chlorinated products of this reaction were identified by gas chromatography-mass spectrometry and included 3-chloropyridinium, an aldehyde, and several chlorinated products with disrupted rings. To evaluate the effects of Cl(2)/HOCl/OCl(-) on Pyd cross-links in collagen, we exposed bone collagen type I and articular cartilage type II to HOCl. Treatment of either collagen type with HOCl at pH 5. 0 or 7.2 resulted in the oxidation of amine groups and, for collagen type II, the specific decrease in Pyd cross-link fluorescence, suggesting that during inflammation both oxidations may be used by neutrophils and monocytes to promote the loss of matrix integrity.