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Kinetic, isothermal and thermodynamic studies for the oil spills removal process have been conducted by Chitosan and novel amphiphilic Chitosan-g-Octanal Schiff base adsorbents developed by click chemistry and evaluated successfully in the removal of heavy crude oil spills. Chitosan was first prepared from wastes of marine shrimp shells, and then Chitosan and Chitosan-g-Octanal Schiff base adsorbents were synthesized and verified their structures, thermal stability and their morphological changes using FT-IR spectroscopy, TGA and SEM. The oil adsorption percentages (%) using heavy crude oil were 96.41% for the Chitosan-g-Octanal Schiff base adsorbent compared to 64.99% for native Chitosan counterpart. High rate of adsorption was observed where 40% of oil adsorbed within 15 min only using the Chitosan-g-Octanal Schiff base adsorbent compared to 90 min for native Chitosan adsorbent. The adsorption process followed the pseudo-second order model, and the equilibrium data were sufficiently fitted with the Langmuir model with a maximum adsorption capacity 30.30 g/g at 25 °C. Thermodynamic parameters computed from Van't Hoff plot confirmed the process to be endothermic, favorable and spontaneous. [ABSTRACT FROM AUTHOR]

A reusable adsorbent was developed based on semi-interpenetrated hydrogel made of poly(vinyl alcohol) (PVA) and poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) for the adsorptive removal of cationic methylene blue (MB) dye. The developed PVA/PAMPS adsorbent hydrogel was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA) and scanning electron microscope (SEM) analysis tools. Consequence of the variation of AMPS concentration on water uptake profile and polymer add-on (%) was explored. In addition, batch adsorption studies were performed to evaluate the aptitude of the developed adsorbent for MB dye removal under several adsorption conditions. The results showed an increase in the add-on (%) value up to 70% with increasing AMPS content up to 5%. Moreover, the MB dye removal was occurred quickly at the initial stage and recorded 60% after only 5 min from the initial contact time, while it recorded a maximum value of 86% at 25 ºC. The experimental adsorption data were well-fitted to the Langmuir isotherm model and followed the pseudo-second-order kinetic model. Moreover, the adsorption of MB dye by the adsorbent hydrogel was an endothermic process. Besides, the PVA/PAMPS adsorbent exhibited better reusability with a maximum removal (%) exceeded 70% after five consecutive cycles. The results obtained from this study infer that the PVA/PAMPS adsorbent hydrogel could be effectually used as an appropriate and reusable adsorbent for removing cationic MB dye molecules from wastewater bodies. [ABSTRACT FROM AUTHOR]

A novel chitosan grafted citronellal (Ch-Cit) schiff base amphiphilic polymer was developed for the adsorptive removal of oil spills. The chemical structure was verified by FT-IR spectroscopy and 1H NMR spectrometer, while the morphological changes and surface area were investigated by SEM and BET analysis tools. The amphiphilic character of Ch-Cit schiff base was controlled through variation of the grafting percentage (G%) of citronellal from 11 to 61%. Dramatic changes in the ion exchange capacity (IEC), solubility and water uptake profiles were established, while the oil adsorption capacity was founded in direct relation with the G (%) of citronellal. Operational conditions such as oil amount, adsorption time, adsorbent dose and agitation speed were investigated. The developed Ch-Cit schiff base exhibited a higher surface area (115.94 m2/g) compared to neat chitosan (57.78 m2/g). The oil adsorption capacity of the Ch-Cit schiff base was greatly improved by 166% and 120% for light crude and heavy crude oil, respectively. Finally, the adsorption process was optimized using response surface methodology (RSM).The results substantiate that the amphiphilic Ch-Cit schiff base could be efficiently applied as a low-cost oil-adsorbent for the removal of crude oil spills from sea-water surfaces. [ABSTRACT FROM AUTHOR]

In this study, the sorption of oil from seawater using chitosan grafted poly(butyl acrylate) copolymer was optimized using response surface methodology (RSM). The effect of various parameters such as time, initial oil concentration, temperature, sorbent dose, and agitation rate on the oil sorption capacity was investigated. Plackett-Burman design was utilized for screening the various sorption parameters. RSM was adopted to acquire the best sorption conditions of two chitosan derivatives namely; CS-g-poly(ButA10) and CS-g-poly(ButA20). In this respect, the Box-Behnken design was applied. A second-order-polynomial model indicated that the sorption was very useful and able to achieve highest sorption capacity ranged from 79.56 to 92.29 g/g using grafted chitosan derivatives compared to 35.2 g/g for native chitosan in 180 min, 41.23-50 g/L of oil concentration, 38°C-41°C at 155-160 rpm. These findings nominate the fabricated CS-g-poly(ButA10) sorbent as an effectual and promising oil sorbent for environmental control of crude heavy oil spills. [ABSTRACT FROM AUTHOR]

In this study, amylose, known as the food-grade biopolymers has been proved as a feasible solution for the controlled delivery of quercetin. The effect of reaction variables including reaction temperature, time, pH and quercetin addition amount on the content and conversion rate of quercetin was analyzed. Meanwhile, fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) provided evidence of quercetin complexation with amylose. Then, the molecular, cluster, and fractal structures of the complexes were investigated using 13C cross-polarization/magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR) and small-angle X-ray scattering (SAXS). Furthermore, laser scanning confocal microscopy (CLSM) identified the precise encapsulation structure from direct observation and scanning electron microscope (SEM) was conducted to show that complexes displayed a larger size granule with smooth and angular appearance. From the antioxidant study, amylose/quercetin complexes presented effective scavenging capacity toward DPPH•. Besides, complexes showed high retention of quercetin in simulated stomach conditions but gradual release in simulated small intestine conditions. It was therefore confirmed that the amylose/quercetin complexes could be served as suitable carriers for the controlled release of quercetin in the digestive tract. The present research expanded the application range of starch, meanwhile proved an alternative application prospect for the ameliorative bioactive quercetin products. [ABSTRACT FROM AUTHOR]

Since chitosan and its amino-, cinnamo- or cinnamo-amino- derivatives are acid-soluble, the effect of acetic acid on hyaluronan (HA) macromolecules degraded by Cu(II) ions and ascorbate was examined to produce reactive oxygen species (ROS). Further, the effects of glutathione (GSH), chitosan and its derivatives, added individually or in combination, on the quenching of ROS and ABTS•+ cation radical were examined using rotational viscometry and ABTS assay, respectively. The results of the rotational viscometry indicated a rapid degradation of HA by ROS after the addition of acetic acid. Chitosan and its derivatives moderately decreased the rate of HA degradation, while GSH decreased the rate of HA degradation more significantly. Moreover, GSH enhanced the protection of HA macromolecules against their degradation in the presence of chitosan or its derivatives. The results of the ABTS assay confirmed the results of the rotational viscometry. The GSH in the combination with chitosan and its derivatives reduced ABTS•+ more intensively than when added individually. [ABSTRACT FROM AUTHOR]

Since chitosan and its amino-, cinnamo- or cinnamo-amino- derivatives are acid-soluble, the effect of acetic acid on hyaluronan (HA) macromolecules degraded by Cu(II) ions and ascorbate was examined to produce reactive oxygen species (ROS). Further, the effects of glutathione (GSH), chitosan and its derivatives, added individually or in combination, on the quenching of ROS and ABTS.+ cation radical were examined using rotational viscometry and ABTS assay, respectively. The results of the rotational viscometry indicated a rapid degradation of HA by ROS after the addition of acetic acid. Chitosan and its derivatives moderately decreased the rate of HA degradation, while GSH decreased the rate of HA degradation more significantly. Moreover, GSH enhanced the protection of HA macromolecules against their degradation in the presence of chitosan or its derivatives. The results of the ABTS assay confirmed the results of the rotational viscometry. The GSH in the combination with chitosan and its derivatives reduced ABTS.+ more intensively than when added individually. [ABSTRACT FROM AUTHOR]