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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Cleaning of Wastewater from Total Coliform Using Chitosan–Grafted–Poly(2-methylaniline)

The preparation and characterization of a low-cost solid materials chitosan–graft–poly(2-methylaniline) as anti-coliform present in wastewater are confirmed by FTIR, TGA, XRD and SEM. The preparation is performed using ammonium persulphate as an oxidant. The data reveals that the grafting process enhances the efficiency of both chitosan and homo-poly(2-methylaniline) to remove coliform present in wastewater. The used wastewater contains 1600 colonies on testing total coliform using classical membrane filter techniques. The total coliform present in wastewater becomes zero by using 50 ppm of the graft, 100 ppm of chitosan and 1000 ppm of poly(2-methylaniline).

36 MATERIALS SCIENCE↗
DOE OSTI2018

Chitosan Depolymerization and Nanochitosan Production Using a Single Physical Procedure

The many applications of the chitosan biopolymers in the areas of nanotechnology and nanomaterials have led to the need to develop novel techniques suitable for the production of nanochitosan. At present these typically involve the use of chemical agents to form chitosan nanoparticles. Physical, chemical, and enzymatic methods have been described for the depolymerizatiton of chitosan. In this work, evaluation was made of the efficiency of a combination of physical methods, including milling of the raw material and drying of the final chitosan, in order to obtain nanochitosan with low molar mass. The results revealed the effectiveness of the combination of milling the raw material under controlled conditions for 4.5 h and drying of the chitosan by thermal shock, which provided depolymerization of up to 10× and resulted in chitosan with M{sub v} less than 21 kDa and hydrodynamic diameter below 30 nm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Environmentally Friendly Chitosan-g-poly(acrylic acid-co-acrylamide)/Ground Basalt Superabsorbent Composite for Agricultural Applications

This paper investigates on the preparation of a novel eco-friendly composite hydrogel, chitosan-g-poly(acrylic acid-co-acrylamide)/ground basalt and its potential application as a soil ameliorant. Synthesis was undergone using microwave irradiation. N,N′-methylene bisacrylamide MBA was used as a cross-linker, whereas potassium peroxydisulfate KPS and N,N,N′,N′-tetramethylene diamine TEMED were used as radical initiator and reaction accelerator, respectively. The incorporation of ground basaltic rocks into the hydrogel was very beneficial: (i) It lowers the cost of the final hydrogel, (ii) It enhances the mechanical strength of the hydrogel, (iii) It boosts the maximum water absorbency of the composite, 650 g/g versus 450 g/g for the hydrogel without basalt and (iv) It promotes the thermal stability of the composite in comparison with the hydrogel alone. The prepared composite hydrogel was characterized by FTIR, X-ray diffractometer and scanning electron microscope SEM. The effects of pH and ionic strength on water absorbency were also investigated. The role of the prepared composite as a soil conditioner is performed using eggplant (Solanum melongena) as a model.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Development of Nanofibers Composed of Chitosan/Nylon 6 and Tannin/Nylon 6 for Effective Adsorption of Cr(VI)

In this study, novel nanofiber materials composed of chitosan/nylon 6 and tannin/nylon 6 were synthesized by the Forcespinning® method and were used as adsorbents for effective removal of chromium(VI) from aqueous solutions. The nanofibers showed similar production rates of 3.5 g h{sup −1}. The diameters of the nanofibers ranged from 100 to 800 nm. Under the experimental conditions tested, chromium(VI) adsorption was favored at pH 3 (chitosan/nylon 6 nanofibers) and pH 2 (tannin/nylon 6 nanofibers), at a temperature of 328 K. The most suitable models for description of the kinetic data were the pseudo-second order model (chitosan/nylon 6 nanofibers) and the Elovich model (tannin/nylon 6 nanofibers). For both nanofibers, the equilibrium isotherms could be fitted by the Langmuir model. The maximum adsorption capacities were 23.9 and 62.7 mg g{sup −1} for the chitosan/nylon 6 and tannin/nylon 6 nanofibers, respectively. The thermodynamic parameters showed that the adsorption was spontaneous, favorable, and endothermic. The findings indicated that these nanofibers produced using a centrifugal technique offer excellent potential as adsorbents, with high adsorption capacities for chromium(VI).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Chitosan Functionalization with Amino Acids Yields to Higher Copper Ions Adsorption Capacity

Chitosan (Chi) beads were conjugated with three different amino acids [namely, glutamic acid (GLU), methionine (MET), and taurine (TAU)] aiming to increase the divalent copper ions uptake in aqueous media. Scanning Electron Microscopy evidenced the development of a large porous structure after amino acid functionalization, associated with the increase in a number of amino groups in the polymer backbone. X-Ray Photoelectron Spectroscopy and Fourier-Transform Infrared Spectra analyses were also employed to assess the conjugation of these three different amino acids in chitosan backbone. Adsorption experiments were conducted in a batch process, at 298 K, and kinetic data indicated a slightly better fitting for the pseudo-first-order model when compared to pseudo-second order. Intraparticle diffusion model suggested a three-step mechanism for Cu(II) adsorption kinetics, limited by the third step, the intraparticle diffusion. The isotherm data fitting to the traditional Langmuir and Freundlich models indicated a better fit for the former case. The amino acid conjugation resulted in the increase of the maximum adsorption capacity for Cu(II) from 1.30 mmol g{sup −1} prior to amino acid conjugation to values as high as 2.31 mmol g{sup −1}, 2.40 mmol g{sup −1} and 2.68 mmol g{sup −1} for Chi–TAU, Chi–GLU, and Chi–MET, respectively. These results are attributed to the introduction of additional amino groups and new carboxylate and amino acid residues into the chitosan backbone, which might also be explored for amino acid demanding applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Chemical Modifications of Cyclodextrin and Chitosan for Biological and Environmental Applications: Metals and Organic Pollutants Adsorption and Removal

New advances in polymer science and their possible applications have increased in recent years highlighting their important and desired properties. Regarding cyclodextrin and chitosan polymers, they are used in many fields such as agriculture, pharmaceutical, food industry, medicine and in electrochemical sensors. Carefully designed studies are therefore required in order to understand the toxicology, the ways of interaction, biodegradation rate and other parameters of these compounds before using them. This review presents the finding of studies of these polymers applications mainly on drug delivery system and pollutants removal. In addition, modifications are made to enhance their properties and enable some reactions, here it is discussed the most used modification techniques and how they change chitosan and cyclodextrin structure. Although there has been an increase in the number of studies in these areas, further progress is needed to improve understanding of the interaction between the polymers and the compounds of interest, besides their mechanism.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Keratin and Chitosan Biosorbents for Wastewater Treatment: A Review

Heavy metal ions and their toxic complexes with minerals and organic matter significantly affect the quality of water bodies. Such metallic complexes and excessive minerals are of non-biodegradable nature posing a serious threat to fauna, flora, and human health. Therefore, removal of metal ions and organic matters from water is highly desirable in benign chemistry. Over the years, biomaterials have increasingly become important in green chemistry and they have been trialed to eradicate heavy metals from water successfully. Nevertheless, mechanistic understanding of biosorption process still requires investigation in laboratories before the process is applied in industries. In this review, we elaborated exclusively chemistry and applications of most common biomaterials such as keratin, chitosan, and their derivatives for reclamation of water polluted by heavy metals. Biosorption efficiency is increased by changing the surficial morphology of applied biopolymer by chemical modification. Keratin and chitosan operate through active polar sites on their surface to attract the charged metal ions via physical and chemical surficial mechanism. This review can be noteworthy for chemists, biologists and environmentalists working in the research area of water quality and related disciplines.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Polymer Based Palladium Nanocatalyst for the Degradation of Nitrate and Congo Red

In this study, the Pd catalyst based on chitosan-tannin (CT) framework as support was prepared and characterized. The CT support and Pd catalyst were characterized by attenuated total reflection (ATR) spectroscopy and Raman spectroscopy, Scanning electron microscopy-energy dispersive X-ray analyzer (SEM–EDX) and transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Attenuated total reflection (ATR) spectra revealed the coordination of Pd via hydroxyl and amino functional groups. Raman spectral analysis was carried out to give information about the structural defect of the catalyst compared to CT support. The SEM–EDX results revealed regular surface morphology and presence of Pd in the catalyst as compared to CT support. TEM analysis revealed that the deposition of Pd on organic support with a spherical shape possessing size in the range of 6.01 nm–20.7 nm (average particle size = 12.65 ± 3.14 nm). The XRD results revealed the amorphous nature of the catalyst compared to CT support. TGA analysis revealed that the catalyst is highly thermally-stable compared to CT support. The catalytic activity of Pd catalyst was investigated for the reduction of nitrate and Congo red in the presence and absence of H{sub 2}. The catalytic activities exhibited 71.11% and 23% removal of nitrate and Congo red in 20 and 60 min, respectively. Thus, results suggested that Pd catalyst has a potential of catalytic activity toward reduction of nitrate and Congo red in presence H{sub 2}.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Chemically Modified Chitosan Bio-Sorbents for the Competitive Complexation of Heavy Metals Ions: A Potential Model for the Treatment of Wastewaters and Industrial Spills

Heavy metal pollution of water sources has become one of the most serious environmental and health problems nowadays. Chitosan (CHI) and derivatives can be used in the complexation and adsorption of heavy metals in water. Hence, this study compared the influence of CHI and carboxymethyl chitosan (CMC) ligands on the competitive complexation between toxic heavy metal ions with opposite charges Cr(VI) and Cd(II) at different pH values as an alternative and ecologically sustainable proposal for industrial spills of heavy metals into aquatic environments. The properties of the synthesized products and CHI were extensively characterized by several spectroscopy techniques, the competitive kinetics of complexation of metal ions with CHI and two type of CMC (with methanol, CMC 40-ME, and with ethanol, CMC 60-ET) was evaluated by wavelength dispersive X-ray fluorescence spectroscopy (WDXRF). The results clearly indicated the influence of the pH and ligands on the competitive complexation of the cationic or anionic ions. The results demonstrated that O-carboxymethylation of chitosan has occurred with a degree of functionalization of (1.20 ± 0.02) and (0.88 ± 0.02) for CMC 40-ME and CMC 60-ET, respectively, leading to the formation of CMC soluble in alkaline medium (pH range of 3.5 ≤ pH ≤ 6.5 and 4.0 ≤ pH ≤ 8.0 for CMC 40-ME and CMC 60-ET, respectively). In alkaline media, complexation of CMC 40-ME is approximately 10% higher (147.2 ± 0.9 mg g{sup −1}) than CMC 60-ET (99.8 ± 2.9 mg g{sup −1}) with Cd{sup 2+} ions at pH 8.5, and approximately 21% lower [(95 ± 2 mg g{sup −1}) and (96.3 ± 2.8 mg g{sup −1}) for CMC 40-ME and CMC 60-ET, respectively] than CHI (121 ± 6 mg g{sup −1}) for Cr{sub x}O{sub y}{sup z−} ions at pH 3.0. The kinetic analysis showed variations for each ion and a significant difference regarding the complexant towards the negatively charged ions. The CMC 40-ME, in any analyzed pH, the complexation occurred during the first 45 min of the process. These results showed that CMC, as polydentate functional ligand, was more efficient than CHI especially for the complexation of cations in basic media. Therefore, these systems appear to be attractive alternatives for the containment of industrial spills of heavy metals in wastewater.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Treatment of Fat-Containing Wastewater Using Binary Flocculant Mixtures Based on Chitosan and Quaternary Salt of Poly(2-dimethylamino)ethyl Methacrylate

The flocculating capability of a mixture of chitosan and poly(2-dimethylamino)ethyl methacrylate) methyl sulfate quaternary salt in fat-containing waters was studied. A synergistic effect was determined that involves a significant increase in the degree of clarification and a simultaneous decrease in the fat and organic impurity contents compared with the use of individual flocculants. The prospects of using the studied mixture of similarly charged polyelectrolytes when treating actual sewage from a milk processing plant are described.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Removal of Nitrate from Water by Alginate-Derived Carbon Aerogel Modified by Protonated Cross-Linked Chitosan

In this study, a carbonaceous aerogel with superior structural properties was synthesized from sodium alginate with a specific surface area and density of about 470 m{sup 2} g{sup −1} and 0.05 g cm{sup −3}, respectively. In order to adsorb nitrate from water, the surface of the aerogel was modified by protonated cross-linked chitosan. To investigate the morphology, elemental composition, crystalline phases and surface functional groups of the adsorbent, various techniques such as field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy were employed. To study the performance of this green adsorbent in nitrate removal process, the effect of nitrate initial concentration, adsorbent dosage, pH of solutions were investigated in batch mode. It was revealed that the Langmuir isotherm model could properly describe the experimental equilibrium data and the maximum adsorption capacity was evaluated to be about 18 mg g{sup −1} at neutral pH and room temperature. Besides, the kinetic data perfectly followed the pseudo-second order model. Thermodynamic analysis showed that the adsorption reaction was spontaneous, exothermic with decreased randomness at the solid–liquid interface. The macroscopic size of the adsorbent allowed its facile separation from the solution.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Microfluidic Fabrication of Nanoparticles Based on Ethyl Acrylate-Functionalized Chitosan for Adsorption of Methylene Blue from Aqueous Solutions

The adsorption of nanoparticle (NP)-based adsorbents especially those made of polymers to remove dyes as toxic substances from pollutants is yet remained as a critical issue. The objective of this work was to prepare microfluidic (MF) fabrication of NPs based on ethyl acrylate (EA)-functionalized chitosan (CS) for methylene blue (MB) dye removal from aqueous solutions. For this purpose, a series of experiments such as FTIR, SEM alongside DLS, and UV–vis spectrophotometry were carried out to investigate the physicochemical properties of the samples. The FTIR spectra showed that the amine (–NH{sub 2}) and hydroxyl (–OH) groups on CS structure were replaced with EA, appropriately. The SEM and DLS results depicted that EA-functionalized CS NPs fabricated using MF technique had uniform shapes, and the diameters as small as 70 nm compared to those samples produced via bulk mixing (BM) method (~ 300 nm). Moreover, the surface charge of MF-assisted CS NPs after functionalization exhibited the lower zeta potential value (~ + 11) than that of samples based on BM (~ + 14) due to occurring the laminar flow through the micro-channels embedded in the MF chip, leading to an increase in the MB adsorption. Subsequently, at the optimized amounts of the dye concentration (89.12 mg L{sup −1}), the adsorbent concentration (1.38 g L{sup −1}), and pH (10.58) by means of Box-Behnken design (BBD) method, the maximum percentage of MB removal by the use of MF-fabricated EA-functionalized CS NPs was 98.4%. By fitting the obtained adsorption data to the isotherm models such as Lagmuir, Freundlich, and Temkin, it has been found that the adsorption mechanism followed the Langmuir model (maximum capacity of the adsorption 384.61 mg/g), which assumed a monolayer coverage of MB molecules as adsorbates over a homogeneous adsorbent surface.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Bioactivity Potentials of Biodegradable Chitosan/Gelatin Film Forming Solutions Combined with Monoterpenoid Compounds

Novel food packaging systems including biodegradable/edible films have been introduced to the market for consumers who desire natural products for their nutrition. Biochemically active plant compounds are added to the biopolymer-based films to improve their functionality. Within the present study, chitosan (1%) and gelatin (4%) biopolymer-based film forming solutions (FFSs) combined with 1, 2, 5 and 10% (v/v) eugenol, pulegone and carvacrol, monoterpenoid compounds, were evaluated for their antimicrobial and antioxidative potential. Antioxidant activities and total phenolic contents (TPC) of the FFSs were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and Folin–Ciocalteau assays, respectively. Screening the antimicrobial activity of FFSs were performed against food spoilage microorganisms including Bacillus cereus, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes and a fungi, Candida albicans by using agar well diffusion method. The chitosan FFS containing 10% carvacrol had greater TPC (3857.3 ± 0.07 mg gallic acid equivalent/L). The highest antioxidative capacity was observed for the chitosan FFS containing 10% eugenol as 97.92 ± 0.01%. FFSs with monoterpenoids showed promising antimicrobial activities against tested microorganisms. Based on antioxidative and antimicrobial potentials of the FFSs, it can be envisaged to use monoterpenoid incorporation to biopolymer films for food packaging applications.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Fabrication and Properties of a Novel Porous Material from Biopolymer and Natural Rubber for Organic Compound Absorption

Maleate poly (vinyl alcohol) (PVAM)-graft water soluble polymer with deproteinized natural rubber (DPNR) porous materials were prepared using the freeze drying technique. The effect of the water soluble polymer type (chitosan (CS) and gelatin (GT)) and the DPNR content was studied. The mechanical properties of the porous materials were improved by the addition of the DPNR. The results showed that the addition of the DPNR improved the water resistance of the porous material. Many micro-voids were formed after the PVAM was grafted with the water soluble polymers as observed under SEM, leading to changes in porosity and density. The highest number of micro-voids was found in the PVAM-graft-chitosan (sPVAM-g-CS) sample while the minimum number of microvoids was found in the maleate poly (vinyl alcohol) (sPVAM). The swelling ratio of the nPVAM significantly improved after the freeze drying process. The PVAM-graft-gelatin (sPVAM-g-GT) gave the maximum swelling ratio in water. After the DPNR was added to the sPVAM-g-GT, the pore size of the porous material significantly decreased and the size distribution became narrower. The moisture absorption, moisture content and swelling ratio of the porous material decreased after blending with the DPNR but the tear strength and rebound resilience of the porous material was enhanced. The macroporous material was able to be reused the maximum number of over 30 times as organic compound-absorbent material and it easily decomposed in nature.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Preparation of Chitooligosaccharide by Hydrogen Peroxide Degradation of Chitosan and Its Effect on Soybean Seed Germination

Chitooligosaccharides (COS) were prepared by hydrogen peroxide (1%) degradation of chitosan solution (3%) in dilute lactic acid at ambient temperature. The molecular weights of degraded chitosan were measured by gel permeation chromatography, and the chemical structure of resultant COS were characterized by Fourier transform infrared spectra. The decrease of chitosan Mw followed the first-order kinetics with the rate constant of 5.71 × 10{sup −7} mol/g/h. As a result, the COS with Mw of 4500 g/mol was obtained at 360 h of the reaction time and its chemical structure almost remained the same as initial chitosan. Germination ability of soybean seeds pre-soaking in COS (4500 g/mol) solution with different concentrations, particularly 0 (control), 50, 100 and 200 mg/L was investigated. Results indicated that germination rate increased significantly for all soybean seeds treated with COS compared to the control. Thus, COS prepared by this method can be potentially applied to large-scale production with reasonably low cost and used as an effective biostimulant for sustainable agriculture.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Effective Adsorption of Cr(VI) by High Strength Chitosan/Montmorillonite Composite Hydrogels Involving Spirulina Biomass/Microalgae

The “3-in-1 type” biopolymer composite (chitosan/montmorillonite clay/biosorbent) hydrogels were produced and used as adsorbents for Cr(VI) ion. Na-Montmorillonite (NaMMT) clay was modified with Spirulina (Sp) biosorbent by using lyophilization based “cryoscopic expansion” (C-XP) method. The Sp immobilized MMT (SpMMT) clay containing hydrogels were found to have an open/extended form of Sp structure on their pores’ walls, presenting all possible receptor groups for adsorption of Cr(VI) ions. SpMMT loaded hydrogels showed higher adsorption capacities than NaMMT loaded ones. The physically crosslinked hydrogel including only 1% SpMMT (1SpM-H) clay exhibited 150% higher adsorption capacity as compared to neat chitosan hydrogel even in 50 ppm Cr(VI) solution. The same composite hydrogel was found to adsorp about 780% Cr(VI) with respect to the clay’s weight while individual uses of Sp and MMT can remove only about 4.80 and 0.36% Cr(VI) with respect to their weights. The pseudo-first order model was found to be the most suitable for the kinetic data of NaMMT loaded hydrogels while that of SpMMT containing hydrogels followed the pseudo-second order kinetics. The isotherm data of all the hydrogels exhibited a better fit to the Freundlich and Sips model. The maximum adsorption capacity (3333 mg g{sup −1}) calculated by Sips model was achieved via the hydrogel having 1% SpMMT which is in good agreement with the experimental kinetic data. The highest adsorption with the lowest amount of SpMMT clay could be attributed to its looser Sp network structure whose functional groups are in long-distance, releasing more adsorption sites for the Cr(VI). The highest compression modulus and toughness were also obtained with the 1SpM-H hydrogel which is probably due to increased physical and reversible interactions between chitosan molecules and SpMMT clay layers at optimum clay loading (1%).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Correction to: Treatment of Fat-Containing Wastewater Using Binary Flocculant Mixtures Based on Chitosan and Quaternary Salt of Poly(2-dimethylamino)ethyl Methacrylate

The original version of this article unfortunately contained an error in the article title of Ref. [22]. The correct reference is given below: Bigogno RG, Rodríguez RJS, Abreu MF (2018) Quaternized chitosan for ecological treatment of bauxite mining effluents. J Polym Environ 26:4169.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Enhancing the Anti-biofouling Properties of Polyethersulfone Membrane Using Chitosan-Powder Activated Carbon Composite

Biofouling is one of the major challenges of membrane technology in water and wastewater treatments. In this work, we investigated the potential of chitosan/chitosan powder activated carbon (PAC) composite to reduce biofouling of membrane. Polyethersulfone (PES) membrane was modified with chitosan/chitosan-PAC composite and the performance of the modified membrane in river water treatment was evaluated. The effect of different concentration of polymer [(chitosan: 2.0% (w/v), 1.0% (w/v), 0.5% (w/v), 0.1% (w/v), and chitosan-PAC composite: 1.5% (w/v) − 1.0 (w/v), 0.5% (w/v) − 0.2% (w/v)] on the membrane performance was examined. The properties of the modified membrane such as roughness, morphology, surface functional groups wettability, swelling ration and contact angle were analyzed. The membrane water flux increased with increasing chitosan concentration from 0.1% (w/v) (7.36 mL/cm{sup 2} m) to 1.0% (w/v) (9.46 mL/cm{sup 2} m), but decreased at (2.0 w/v) (5.30 mL/cm{sup 2} m). However, the water flux for chitosan-PAC-modified membrane was about 6.86 mL/cm{sup 2} m, which was slightly lower than unmodified membrane (7.36 mL/cm{sup 2} m). The chitosan-modified membrane resulted in 28% reduction in total coliform bacteria while the chitosan-PAC-modified membrane reduced 45% of the total coliform bacteria. These results indicated that chitosan and chitosan-PAC composite could enhance the anti-microbial properties of PES membrane, which would prevent biofilm formation during water treatment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗