Adsorption of nitrate and phosphate in an aqueous solution on composites of PVA and chitosan prepared from a Somanniathelphusa sinensis shell

Chitosan Solution ◽

Solution Concentration ◽

Ph Titration ◽

Box Behnken Design ◽

Removal Time ◽

Phosphate Ions ◽

Level 3 ◽

Pseudo Second Order

Abstract In this study, chitosan was prepared from the shell of Somanniathelphusa sinensis, which is a crab ubiquitous in Vietnam. The 3-level, 3-factor Box–Behnken design was applied to the preparation of chitosan to investigate effects of factors, such as the HCl solution concentration, protein removal time and deacetylation time, on the degree of deacetylation (%DD). Scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and gel permeation chromatography were employed to examine the chitosan structure, as well as pH titration and antibacterial testing of the chitosan solution. Results revealed that as-p chitosan comprises specific functional groups, with almost no impurities. Its average molecular weight was ∼225,000 g/mol, and %DD was ∼89.7%. The chitosan/PVA composite was prepared and investigated for the adsorption of nitrate and phosphate ions in water. Experimental results revealed that the adsorption capacity of a chitosan/PVA (1:2) composite is better than that of chitosan. Accordingly, the theoretical maximum adsorption capacities of nitrate and phosphate ions on chitosan were 122.0 mg/g and 344.8 mg/g, respectively. The corresponding values on the chitosan/PVA (1:2) composite were 135.1 mg/g and 384.6 mg/g. Adsorption kinetics data at 25 °C were well fitted to the pseudo-second-order model (R2 > 0.998). These results revealed that crab shell chitosan and the chitosan/PVA (1:2) composite can be used for the adsorption of nitrates and phosphates in aqueous solutions.

Study on Preparation of Water-Soluble Chitosan with Varying Molecular Weights and Its Antioxidant Activity

Advances in Materials Science and Engineering ◽

10.1155/2019/8781013 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Dang Xuan Du ◽

Bui Xuan Vuong

Keyword(s):

Molecular Weight ◽

Antioxidant Activity ◽

Dose Range ◽

Chitosan Solution ◽

Water Soluble ◽

Molecular Weights ◽

Ph Level ◽

The One

The preparation of water-soluble chitosan (WSC) with various molecular weights by gamma Co-60 irradiation of chitosan solution (5%) in the presence of hydrogen peroxide (1%) combined with acetylated reaction was carried out. The average molecular weight (Mw) of chitosan was measured by gel permeation chromatography (GPC). The chemical structure and the crystallinity of chitosan and WSC were characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), respectively. The antioxidant activity of WSC and chitosan was investigated using the free radical 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+). Obtained results showed that chitosan with Mw of 18–90 kDa could be efficiently prepared by this technique in the dose range from 10 to 24.5 kGy. After the acetylated process, the resulting WSC possesses good solubility in a wide pH level of 2–12, and WSC with low molecular weight exhibited significantly higher antioxidant activity than the one with high molecular weight. In detail, the antioxidant activity was 14.7%, 70.5%, 84.2%, 89.4%, and 97.5% for WSC samples prepared from chitosan with Mw of 140.2 kDa, 91.4 kDa, 51.2 kDa, 35.3 kDa, and 18.1 kDa, respectively, at the same reaction time of 90 min. Moreover, the antioxidant activity of WSC was higher than that of chitosan. Thus, WSC prepared by gamma Co-60 irradiation and acetylated process can be potentially applied as a natural antioxidant agent.

Chitosan Nanocarrier Entrapping Hydrophilic Drugs as Advanced Polymeric System for Dual Pharmaceutical and Cosmeceutical Application: A Comprehensive Analysis Using Box-Behnken Design

Polymers ◽

10.3390/polym13050677 ◽

2021 ◽

Vol 13 (5) ◽

pp. 677

Author(s):

Sara A. Abosabaa ◽

Aliaa N. ElMeshad ◽

Mona G. Arafa

Keyword(s):

Particle Size ◽

Sodium Tripolyphosphate ◽

Chitosan Nanoparticles ◽

Optimization Procedure ◽

Entrapment Efficiency ◽

Chitosan Solution ◽

Polydispersity Index ◽

Successful Implementation ◽

Solution Ph ◽

Box Behnken Design

The objective of the present research is to propose chitosan as a nanocarrier for caffeine—a commonly used drug in combating cellulite. Being a hydrophilic drug, caffeine suffers from insufficient topical penetration upon application on the skin. Chitosan nanoparticles loaded with caffeine were prepared via the ionic gelation technique and optimized according to a Box–Behnken design. The effect of (A) chitosan concentration, (B) chitosan solution pH, and (C) chitosan to sodium tripolyphosphate mass ratio on (Y1) entrapment efficiency percent, (Y2) particle size, (Y3) polydispersity index, and (Y4) zeta potential were studied. Subsequently, the desired constraints on responses were applied, and validation of the optimization procedure was confirmed by the parameters exhibited by the optimal formulation. A caffeine entrapment efficiency percent of 17.25 ± 1.48%, a particle size of 173.03 ± 4.32 nm, a polydispersity index of 0.278 ± 0.01, and a surface charge of 41.7 ± 3.0 mV were attained. Microscopical evaluation using transmission electron microscope revealed a typical spherical nature of the nanoparticles arranged in a network with a further confirmation of the formation of particles in the nano range. The results proved the successful implementation of the Box–Behnken design for optimization of chitosan-based nanoparticles in the field of advanced polymeric systems for pharmaceutical and cosmeceutical applications.

Adsorption Characteristics of Phosphate Ions by Pristine, CaCl2 and FeCl3-Activated Biochars Originated from Tangerine Peels

Separations ◽

10.3390/separations8030032 ◽

2021 ◽

Vol 8 (3) ◽

pp. 32 ◽

Cited By ~ 1

Author(s):

Changgil Son ◽

Wonyeol An ◽

Geonhee Lee ◽

Inho Jeong ◽

Yong-Gu Lee ◽

...

Keyword(s):

Adsorption Kinetics ◽

Chemical Activation ◽

Isotherm Models ◽

Order Model ◽

Phosphate Ions ◽

Adsorption Capacities ◽

Adsorption Isotherm Models ◽

Endothermic Reactions ◽

Pseudo Second Order ◽

Adsorption Kinetics And Isotherm

This study has evaluated the removal efficiencies of phosphate ions (PO43−) using pristine (TB) and chemical-activated tangerine peel biochars. The adsorption kinetics and isotherm presented that the enhanced physicochemical properties of TB surface through the chemical activation with CaCl2 (CTB) and FeCl3 (FTB) were helpful in the adsorption capacities of PO43− (equilibrium adsorption capacity: FTB (1.655 mg g−1) > CTB (0.354 mg g−1) > TB (0.104 mg g−1)). The adsorption kinetics results revealed that PO43− removal by TB, CTB, and FTB was well fitted with the pseudo-second-order model (R2 = 0.999) than the pseudo-first-order model (R2 ≥ 0.929). The adsorption isotherm models showed that the Freundlich equation was suitable for PO43− removal by TB (R2 = 0.975) and CTB (R2 = 0.955). In contrast, the Langmuir equation was proper for PO43− removal by FTB (R2 = 0.987). The PO43− removal efficiency of CTB and FTB decreased with the ionic strength increased due to the compression of the electrical double layer on the CTB and FTB surfaces. Besides, the PO43− adsorptions by TB, CTB, and FTB were spontaneous endothermic reactions. These findings demonstrated FTB was the most promising method for removing PO43− in waters.

Probing the molecular weights of sweetgum and pine kraft lignin fractions

TAPPI Journal ◽

10.32964/tj20.6.381 ◽

2021 ◽

Vol 20 (6) ◽

pp. 381-391

Author(s):

JULIANA M. JARDIM ◽

PETER W. HART ◽

LUCIAN LUCIA ◽

HASAN JAMEEL

Keyword(s):

Molecular Weight ◽

Black Liquor ◽

Systematic Investigation ◽

Kraft Pulping ◽

Molecular Weights ◽

Lignin Recovery ◽

Lignin Reactivity ◽

Kinetics Of

The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physicochemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to deter- mine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weightlignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.

Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

BioResources ◽

10.15376/biores.10.3.4137-4151 ◽

2015 ◽

Vol 10 (3) ◽

pp. 4137-4151 ◽

Cited By ~ 5

Author(s):

Aikfei Ang ◽

Zaidon Ashaari ◽

Edi Suhaimi Bakar ◽

Nor Azowa Ibrahim

Keyword(s):

Molecular Weight ◽

Chemical Structure ◽

Solubility Parameters ◽

Low Molecular Weight ◽

Sequential Fractionation ◽

Weight Average Molecular Weight ◽

Solvent Fractionation ◽

Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization

Pure and Applied Chemistry ◽

10.1515/pac-2015-0607 ◽

2015 ◽

Vol 87 (11-12) ◽

pp. 1085-1097 ◽

Cited By ~ 2

Author(s):

Li Wang ◽

Stefan Baudis ◽

Karl Kratz ◽

Andreas Lendlein

Keyword(s):

Magnetic Nanoparticles ◽

Ring Opening ◽

Polymer Networks ◽

Degree Of Crystallinity ◽

Scanning Calorimetry ◽

H Nmr ◽

Transmission Electron

AbstractA versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)2 as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto- and thermo-sensitive polymer networks were prepared via two subsequent surface-initiated ring-opening polymerizations (ROPs) with ω-pentadecalactone and ε-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85°C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and 1H-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(ω-pentadecalactone) (OPDL) and oligo(ε-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few ω-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)2 was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP.

Preparation and Characterization of a Novel Flame Retardant

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.47-50.294 ◽

2008 ◽

Vol 47-50 ◽

pp. 294-297 ◽

Cited By ~ 1

Author(s):

Xiu Wei Jia ◽

Min Zhi Rong ◽

Ming Qiu Zhang

Keyword(s):

Flame Retardant ◽

Sol Gel ◽

Regular Structure ◽

Helical Conformation ◽

Infrared Spectrometry ◽

Resonance Spectroscopy ◽

X Ray Diffraction

A novel flame retardant polymethylsilsesquioxane (PMSQ) was successfully obtained via combination of non-hydrolytic and hydrolytic sol-gel routes. Chemical structure of the resultant PMSQ was determined by nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectrometry and powder X-ray diffraction, respectively. All the measurements demonstrated that the product possessed regular structure with chain-to-chain width of 0.87nm and chain thickness of 0.40nm. Weight average molecular weight of PMSQ was measured to be 3.5×105 using gel permeation chromatography. Numerical simulations of the molecular structure suggested that PMSQ should exhibit cis-isotactic configuration and double helical conformation at undisturbed condition.

Kinetic Studies on the Curing Reactions of Fluoroepoxy Oligomer and Cycloaliphatic Amine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.747.753 ◽

2013 ◽

Vol 747 ◽

pp. 753-756 ◽

Cited By ~ 1

Author(s):

Thitinun Chongtum ◽

Wunpen Chonkaew

Keyword(s):

Kinetic Studies ◽

Equivalent Weight ◽

Number Average Molecular Weight ◽

Polymeric Systems ◽

Acid Titration ◽

Curing Kinetic ◽

Gel Permeation

The curing kinetic analysis is an important technique for the characterization of the curing behavior of reactive polymeric systems. In this study, fluoroepoxy oligomer was synthesized from trifluoromethyl aniline and epichlorohydrin. The epoxide equivalent weight (EEW) and the number average molecular weight (Mn) of the systhesized fluroepoxy oligomer determined from acid titration and gel permeation chromatography were found to be 312.16 g/eq and 534 g/mol, respectively. The mixtures of the fluoroepoxy oligomer were mixed with the cycloaliphatic amine in various stiochiometric ratios (1:1, 1: 1.5 and 1:2). The effects of the stiochiometric ratio on the curing behaviors were studied using both isothermal and non-isothermal DSC methods. Ozawas, Kissingers and Friedmans methods were employed to investigate the kinetic parameters. The results showed that the peak temperature (Tp) increased with the increasing heating rate. The activation energy (Ea) calculated from Ozawas and Kissingers methods were much larger than that from Friedmans method.

Water defluoridation by alumina modified Turkey clinoptilolite: equilibrium, kinetic models and experimental design approaches

Water Science & Technology Water Supply ◽

10.2166/ws.2017.081 ◽

2017 ◽

Vol 18 (1) ◽

pp. 14-22 ◽

Cited By ~ 2

Author(s):

Selim Selimoglu ◽

Esra Bilgin Simsek ◽

Ulker Beker

Keyword(s):

Natural Zeolite ◽

Kinetic Studies ◽

Order Reaction ◽

Operating Conditions ◽

Second Order Reaction ◽

Freundlich Model ◽

Box Behnken Design ◽

Fluoride Adsorption ◽

Exothermic Process ◽

Pseudo Second Order

Abstract In the current work, alumina modified natural zeolite (Z-Al) was used for fluoride adsorption in aqueous solution. Effects of process parameters such as pH, temperature, initial concentration and contact time were investigated. Box–Behnken design was found effective in defining the operating conditions for fluoride sorption onto Z-Al. Confirmatory experiments were conducted to examine the reliability of the regression equation. The predicted (2.261 mg g−1) and experimental (2.289 mg g−1) capacities were found to be similar, demonstrating the accuracy of the model. The fluoride adsorption onto Z-Al was well described by the Freundlich model. Kinetic studies revealed that the adsorption followed a pseudo-second-order reaction. Thermodynamic parameters depicted that the fluoride adsorption on the alumina modified zeolite was a spontaneous and exothermic process. The co-existing ions affected the defluoridation performance significantly. Regeneration of exhausted Z-Al was achieved with H2SO4.

Purification, Characterization, Prebiotic Preparations and Antioxidant Activity of Oligosaccharides from Mulberries

Molecules ◽

10.3390/molecules24122329 ◽

2019 ◽

Vol 24 (12) ◽

pp. 2329 ◽

Cited By ~ 6

Author(s):

Erna Li ◽

Shiyuan Yang ◽

Yuxiao Zou ◽

Weiwei Cheng ◽

Bing Li ◽

...

Keyword(s):

Antioxidant Activities ◽

Radical Scavenging Activity ◽

Radical Scavenging ◽

Lactobacillus Rhamnosus ◽

Water Soluble ◽

Gas Chromatography Mass Spectrometry ◽

Trolox Equivalent Antioxidant Capacity ◽

Antioxidant Power

A water-soluble oligosaccharide termed EMOS-1a was prepared by enzymatic hydrolysis of polysaccharides purified from mulberries by column chromatography. The chemical structure of the purified fraction was investigated by ultraviolet spectroscopy, Fourier-transform infrared spectroscopy, and gas chromatography–mass spectrometry, which indicated that galactose was the main constituent of EMOS-1a. Chemical analyses showed that the uronic acid and sulfate content of EMOS-1a were 5.6% and 8.35%, respectively, while gel permeation chromatography showed that EMOS-1a had an average molecular weight of 987 Da. The antioxidant activities of EMOS-1a were next investigated, and EMOS-1a exhibited concentration-dependent 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, Trolox equivalent antioxidant capacity, and ferric reducing antioxidant power. The level of proliferation of Lactobacillus rhamnosus reached 1420 ± 16% when 4% (w/v) EMOS-1a was added, where the number of colonies in MRS (de Man, Rogosa, and Sharpe) medium with no added oligosaccharide was defined as 100% proliferation. These results indicate that the oligosaccharide EMOS-1a could be used as a natural antioxidant in prebiotic preparations.