Influence Of Oxidation Degree Research Articles

Detailed investigation and influence of oxidation degree on synthesis, characterization and antibacterial activity of β- cyclodextrin

Oxidation of β-cyclodextrin (β-CD) using varying molar ratios of sodium periodate (NaIO4) was investigated in detail on synthesis, characterization and antibacterial property. Synthesis and characterization results showed that Oxidized β-cyclodextrins (OX-β-CDs) were obtained and aldehyde (CHO) groups were successfully introduced. Our results demonstrated that aldehyde content and yield increased with increasing NaIO4 molar amount. However, the structure of β-CD was degraded as a result of glycosidic ring opening with increasing stoichiometric ratio of NaIO4/β-CD to 5/1 and 7/1.Aldehyde functional groups in OX-β-CDs were characterized by employing FTIR, 1H NMR, XRD, SEM techniques and confirmed by the detection of CHO peak at 1730 cm-1 in the FTIR and detection of the aldehyde H peak between 9 to 10 ppm in the 1H NMR spectrum. In addition, SEM and XRD of OX-β-CDs showed alterations in the morphological and crystal structure (transforming from crystalline to amorphous) of β-CD as a result of increasing oxidation.Especially, antibacterial activity of OX-β-CDs was investigated against both Gram-negative and Gram-positive bacteria by using the minimal inhibitory concentration (MIC) and the Disk diffusion method. The results showed that OX-β-CDs possessed good antibacterial activity, which can destroy the bacterial cell wall, and may be used as an antibacterial agent.

Preparation of renewable collector from waste engine oil for clean flotation of fine coal with different oxidation degree

High precision flotation of fine oxidized coal is difficult to achieve because of very low floatability. In this study, the influence of oxidation degree on floatability and functional group composition of coal was studied. In addition, the feasibility of renewable collector prepared from waste engine oil for fine coal flotation was also analyzed. FTIR analysis results showed that the oxidation degree had no significant effect on the types of functional groups. However, XPS analysis results illustrated that with the deepening of oxidation degree, the content of CC/CH groups decreased significantly, which caused notable decrease in floatability. For the unoxidized coal, the clean coal yield and recovery rate were 62.51 % and 73.77 % respectively, which provided evidence support that renewable collector could be used for the flotation of fine coal. Moreover, with the deepening of oxidation, the yield and combustible recovery were finally reduced to 12.39 % and 14.09 % respectively due to oxidation of the particle surface. Thus, grinding pretreatment was proved to improve floatability of oxidized coal significantly. The yield of clean coal and combustible recovery reached 47.78 % and 52.93 %, which was mainly due to the fact that the oxide layer on the particle surface was stripped off by grinding. The research also proved that the flotation temperature should not be lower than 20 °C. The flotation of fine oxidized coal was realized by using waste engine oil, which brought an alternative collector for flotation on the premise of eliminating environmental threat of waste engine oil.

Tuning the properties of pineapple peel cellulose nanofibrils by TEMPO-mediated oxidation and ball milling

In this study, the oxidized cellulose nanofibrils from pineapple peel (PP-TOCNF) were prepared by TEMPO-mediated oxidation followed by ball milling. The influence of oxidation degree on the structure and properties of PP-TOCNF were investigated, including Fourier transform infrared spectroscopy , X-ray diffraction, atomic force microscope (AFM), X-ray photoelectron spectroscopy and thermogravimetry, as well as the potential application in aerogels. The results suggested that TEMPO oxidation facilitated the dispersion of PP-TOCNF due to the strong electrostatic repulsion between –COO− groups. Regulating oxidation degree by varying NaClO concentration could effectively adjust the –COO− content (0.167–0.550 mmol/g), zeta potential (− 18 to − 34 mV) and rheological properties. The obtained PP-TOCNF showed a long fibrillar structure, whose average diameter and CrI values gradually decreased with the increase of oxidation degree. The PP-TOCNF-based aerogels exhibited a light weight, good porosity, water absorption, and mechanical properties, which also can be easily adjusted by oxidation degree of PP-TOCNF. Furthermore, TEMPO oxidation improved the stability and shape recovery ability of aerogels in water.Graphical abstract

Influence of Oxidation Degree on Phenolic Composition, Antioxidant and Antimicrobial Activity of Turkish Oolong Teas Processed from the Same Tea Cultivar

Influence of Oxidation Degree on Phenolic Composition, Antioxidant and Antimicrobial Activity of Turkish Oolong Teas Processed from the Same Tea Cultivar

Influence of Oxidation Degree on Phenolic Composition, Antioxidant and Antimicrobial Activity of Turkish Oolong Teas Processed from the Same Tea Cultivar

Influence of Oxidation Degree on Phenolic Composition, Antioxidant and Antimicrobial Activity of Turkish Oolong Teas Processed from the Same Tea Cultivar

Influence of Oxidation Degree on the Physicochemical Properties of Oxidized Inulin.

This paper reports the oxidation of inulin using varying ratios of sodium periodate and the characterization of the inulin polyaldehyde. The physicochemical properties of the inulin polyaldehyde (oxidized inulin) were characterized using different techniques including 1D NMR spectroscopy, 13C Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), ultraviolet-visible spectroscopy (UV), and scanning electron microscopy (SEM). The aldehyde peak was not very visible in the FTIR, because the aldehyde functional group exists in a masked form (hemiacetal). The thermal stability of the oxidized inulin decreased with the increasing oxidation degree. The smooth spherical shape of raw inulin was destructed due to the oxidation, as confirmed by the SEM result. The 1HNMR results show some new peaks from 4.8 to 5.0 as well as around 5.63 ppm. However, no aldehyde peak was found around 9.7 ppm. This can be attributed to the hemiacetal. The reaction of oxidized inulin with tert-butyl carbazate produced a carbazone conjugate. There was clear evidence of decreased peak intensity for the proton belonging to the hemiacetal group. This clearly shows that not all of the hemiacetal group can be reverted by carbazate. In conclusion, this work provides vital information as regards changes in the physicochemical properties of the oxidized inulin, which has direct implications when considering the further utilization of this biomaterial.

The study on the influence of oxidation degree and temperature on the viscosity of biodiesel

AbstractJatropha curcas biodiesel was taken as the research object, studied the single and compound effects of oxidation degree and temperature on kinematic viscosity of biodiesel, and established a mathematical model. The results indicate that the kinematic viscosity of biodiesel decreases gradually with the increase of temperature, and the mathematical model affected by the single factor of temperature is η = e(A + Bt + Ct2) . The kinematic viscosity of biodiesel increases with the increase of oxidation time. The regression equation between kinematic viscosity and conductivity is established as follows: η = A + Bμ. It is found that the influence of temperature on the kinematic viscosity of biodiesel is much greater than that of oxidation, and the higher the temperature, the lower the influence of oxidation on the kinematic viscosity of biodiesel. Through the analysis of the influence weight of two factors and the change rate of kinematic viscosity, it is found that with the increase of temperature, the effect of conductivity on the change rate of kinematic viscosity of biodiesel is positive, but the influence decreases gradually. The relationship between kinematic viscosity, temperature and oxidation

Graphene enhanced flexible expanded graphite film with high electric, thermal conductivities and EMI shielding at low content

Expanded graphite (EG) films with low oxidation degree exhibit excellent thermal, electric properties and electromagnetic interference (EMI) shielding. However, the mechanical brittleness is the major limitation for their applications. To meet this challenge, in this work, a small amount of flexible graphene (GE) is introduced to endow EG films with good flexibility and mechanical properties by forming simulate shell structure. Moreover, the influence of oxidation degree and sheet thickness for carbon sheets as well as the lateral size of GE on the film performance is carefully discussed. As a result, a 431% enhancement of tensile strength from 7.7 Mpa to 40.9 Mpa and little sacrifice of electric, thermal conductivities up to 1467 S cm−1 and 348 W m−1 K−1 are observed with the loading of only 10% large GE (LGE) sheets in EG films. Besides, high EMI shielding of 48.3 dB is achieved as the film thickness reaches 43 μm. The excellent flexibility of prepared EG/LGE films can be retained even after more than 1000 times of direct folding. These excellent properties of light-weight EG/LGE films, together with their advantages of environmentally friendly and facile large-scale fabrication, endow the films with great potential applications in next-generation commercial portable flexible electronics.

The influence of oxidation degree on the redistribution rate of cations in Mg0.9Fe2.1O4 ferrite

The influence of oxidation degree on the redistribution rate of cations in Mg0.9Fe2.1O4 ferrite