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1.
Food Chem ; 340: 128185, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33010647

RESUMO

In this study, sodium tripolyphosphate (STP) and tetrasodium pyrophosphate (TSPP) were utilized to modify duck egg white protein (EWP). The phosphorylated EWP was prepared as egg white gel (EWG) by adding sodium hydroxide. The phosphorus content of EWP reached 2.18 mg/g and 2.07 mg/g with the addition of STP and TSPP, respectively, after 2 h phosphorylation. The average particle size, absolute zeta potential value, and surface hydrophobicity of EWP increased significantly during phosphorylation. FTIR results indicate that phosphorylation reduced the random structure and α-helical content while increasing the content of ß-sheets and ß-turn. The mechanical and rheological properties of EWG decreased obviously after phosphorylation. A three-dimensional porous network microstructure was formed, and the gel with added TSPP had larger pores. Adding STP and TSPP to EWG weakened its salt and solvent sensitivity. The findings provide a direction for the exploration of gel properties after protein modification.


Assuntos
Álcalis/química , Patos , Proteínas do Ovo/química , Animais , Difosfatos/química , Géis , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Fosforilação , Reologia , Cloreto de Sódio/química , Hidróxido de Sódio/química
2.
J Chromatogr A ; 1634: 461659, 2020 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-33166890

RESUMO

Excess bilirubin can accumulate in body organs and has serious effects on human health. In this work, a simple engineering strategy, based on cellulose-assisted high-quality dispersion of carbon nanotubes (CNTs), is proposed to produce high-performance bilirubin adsorbents. By dispersing cellulose and CNTs in NaOH/thiourea aqueous solution, a homogeneous and stable cellulose/CNTs solution is achieved. The obtained cellulose/CNTs solution is applied for the fabrication of cellulose/CNTs microspheres (CCMs), in which cellulose serves as a base material and guarantees the blood compatibility of the composite material, and CNTs contribute to the improved mechanical strength and high adsorption capacity. To further improve blood compatibility and adsorption capacity, lysine is immobilized on the CCMs. The obtained lysine-modified CCMs (LCCMs) exhibit a large surface area (171.31 m2/g) and hierarchically porous structure. Experimental results demonstrate LCCMs have high bilirubin adsorption capacity (204.12 mg/g) that is significantly higher than most of the reported adsorbents. The combination of high strength, blood compatibility, and high adsorption capacity positions the LCCMs as a promising candidate for bilirubin removal.


Assuntos
Bilirrubina/metabolismo , Celulose/química , Microesferas , Nanotubos de Carbono/química , Adsorção , Bilirrubina/sangue , Bilirrubina/isolamento & purificação , Humanos , Porosidade , Hidróxido de Sódio/química , Tioureia/química , Água/química
3.
PLoS One ; 15(11): e0240634, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33176336

RESUMO

Bismuth(III) oxide is included as a radio-opacifier in dental materials, including hydraulic silicate cements, the material of choice for several endodontic procedures. It has been implicated in tooth discoloration after contact with endodontic irrigants, in particular NaOCl solution, To date, there has been no work on the chemistry: all reports have been of clinical findings only. The purpose now was to report the reactions leading to colour change from Bi2O3 in contact with solutions used in routine endodontic practice. Ten-gram portions of Bi2O3 were immersed in either water, NaOH, NaCl, NaOCl or HCl solution, either in the dark or exposed to visible light, and samples retrieved at 1, 4, 12 and 24 weeks. After washing, these were exposed to either added CO2 or not, for 1 week while drying, and under the same dark or light conditions. Changes in appearance were monitored by photography and colour measurement, and chemically by X-ray diffraction and Fourier-transform infrared spectroscopy. 24-week material was studied using electron paramagnetic resonance and Raman spectroscopy; NaOCl-treated material was also examined by scanning electron microscopy. With water, NaCl and NaOH, bismuth subcarbonate was formed. With or without added carbon dioxide, discoloration occurred from pale yellow to light brown when exposed to light, and to a lesser extent in the dark, intensifying with time. In contrast, exposure to NaOCl rapidly formed a dark brown-black sodium bismuthate. With HCl, white BiOCl was formed. Bi2O3 is not at all inert in this context as is commonly believed, denying its principle of use. Previously unreported solution-mediated reaction occurs readily even in water and NaCl solution, forming new compounds that discolour. In contact with NaOCl sodium bismuthate is formed; severe darkening occurs rapidly. The reactivity is such that Bi2O3 is not indicated for dental materials and should be withdrawn from use.


Assuntos
Bismuto/química , Materiais Dentários/química , Soluções/química , Cor , Humanos , Ácido Clorídrico/química , Luz , Cloreto de Sódio/química , Hidróxido de Sódio/química , Hipoclorito de Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
4.
PLoS One ; 15(8): e0237612, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790731

RESUMO

Seventeen glass vessels and twenty glass beads recovered from the excavations at the ancient city of Malindi and the archaeological site of Mambrui in Kenya, east Africa were analysed using electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results show that all of the glass samples are soda-lime-silica glass. They belong to the high alumina -plant ash glass type, characterised by high alumina and relatively low calcium contents, widely distributed in eastern (10th- 16th centuries AD) and southern Africa (13th - 15th centuries AD), Central Asia (9th- 14th centuries AD) and southeast Asia (12th- 13th centuries AD), made with plant ashes and sands. This is an understudied glass type for which previous research has indicated there were three types. When compared with published research on such glasses using Zr, Ti, Ba, Cr, La, Li, Cs, Na2O, MgO and CaO we have identified at least four different compositional groups of v-Na-Al glass: Types A, B, C and D. By comparing the results with contemporary v-Na-Al glass vessels and beads from Central Asia, Africa, and southeast Asia we show that most of the Malindi and Mambrui glass share similar characteristics to the compositions of Mapungubwe Oblate and some of the Madagascar glass beads from southern Africa. They belong to Type A v-Na-Al glass which is characterised by an elevated level of Ti and Ba and a relatively high ratios of Cr/La, relatively low Zr concentrations and low ratios of Zr/Ti. Differences in Zr, Li, MgO and Na2O concentrations in Type A glass indicates that there are subgroups which might derive from different glass workshop(s) specialising in Type A v-Na-Al glass production. Comparison with the chemical compositions of glass from Ghazni, Afghanistan and Termez, Uzbekistan, and by using lead isotope analysis, we suggest v-Na-Al glass was manufactured in Central Asia and possibly worked into vessels and beads there.


Assuntos
Compostos de Cálcio/química , Vidro/química , Óxidos/química , Plantas/química , Dióxido de Silício/química , Hidróxido de Sódio/química , Oligoelementos/análise , Oligoelementos/história , África Oriental , Óxido de Alumínio , Arqueologia , História do Século XV , História do Século XVI , Oceano Índico , Marcação por Isótopo/métodos , Quênia , Espectrometria de Massas
5.
J Chromatogr A ; 1627: 461390, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823096

RESUMO

A dispersive solid phase extraction method was combined with deep eutectic solvent-based solidification of floating organic drop-dispersive liquid-liquid microextraction and used for the extraction/preconcentration of some organophosphorus pesticides residues from edible oil samples. The extracted analytes were quantified with gas chromatography-nitrogen phosphorous detector. In this procedure, the sample lipids are saponified with a sodium hydroxide solution and then the analytes are adsorbed onto a primary secondary amine sorbent. After that the analytes are desorbed with acetone as an elution/dispersive solvent and mixed with choline chloride: 3,3-dimethyl butyric acid deep eutectic solvent and the mixture is rapidly dispersed into deionized water. Then, the obtained cloudy solution is centrifuged and placed into an ice bath. The extraction solvent is solidified on the top of the solution. Finally, it is removed and dissolved in acetonitrile, and 1 µL of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.06-0.24 and 0.20-0.56 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 170-192 and 68-77%, respectively. The method had an acceptable precision with relative standard deviations less than ≤9.2% for intra- (n=6) and inter-day (n=6) precisions at four concentrations (3, 10, 50, and 250 ng mL-1, each analyte). Finally the method was used for determination of the analytes in five edible oil samples.


Assuntos
Microextração em Fase Líquida/métodos , Compostos Organofosforados/análise , Praguicidas/análise , Óleos Vegetais/química , Extração em Fase Sólida/métodos , Solventes/química , Acetonitrilos/química , Reprodutibilidade dos Testes , Hidróxido de Sódio/química , Soluções , Sonicação , Fatores de Tempo
6.
J Chromatogr A ; 1626: 461350, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797830

RESUMO

In ionexchange chromatography, the pH gradient mode becomes more and more popular today for the analysis of therapeutic proteins as this mode can provide higher or alternative selectivity to the commonly used salt gradient mode. Ideally, a linear pH response is expected when performing linear gradients. However up to now, only a very few buffer systems have been developed and are commercially available which can perform nearly linear pH responses when flowing through a given column. It is also known that a selected buffer system (mobile phase) can work well on one column but can fail on other column. The goal of this study was to practically evaluate the effects that ionexchange columns (weak and strong exchangers) might have on effluent pH, when performing linear pH gradient separations of therapeutic monoclonal antibodies. To attain this objective, the pH was monitored on-line at the column outlet using a specific setup. To make comprehensive observations of the phenomenon, four different mobile phase conditions and five cation exchange columns (weak and strong exchangers) were employed. The obtained pH responses were systematically compared to responses measured in the absence of the columns. From this work, it has become clear that both the column and mobile phase can have significant effects on pH gradient chromatography and that their combination must be considered when developing a new method. Phase systems (column + mobile phase) providing linear pH responses are indeed the most suitable for separating mAbs with different isoelectric points and, with them, it is possible to elute mAbs across wide retention time ranges and with high selectivity.


Assuntos
Cromatografia por Troca Iônica/métodos , Anticorpos Monoclonais/análise , Cátions/química , Ácido Cítrico/química , Concentração de Íons de Hidrogênio , Troca Iônica , Força Próton-Motriz , Hidróxido de Sódio/química , Taurina/análogos & derivados , Taurina/química
7.
Carbohydr Polym ; 240: 116318, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32475581

RESUMO

Cellulose is a natural material with dissolution-regeneration property and numerous hydrogen bonds in the molecule. By utilizing these properties, this paper reported the development of a multi-functional fabric consisting of cellulose and commercial cotton fabric. The morphology, mechanical and thermal properties along with the oil-water separation performance of the developed material were studied. The results showed that the cellulose dissolved in NaOH/urea solution was regenerated in a salt solution, and attached tightly onto the cotton fabric, forming a sandwich structure for the material. Such modification significantly enhanced the strength, thermal stability and hydrophilic performance of the fabrics. Interestingly, the prepared material exhibited a unique underwater oleophobic performance, and had the capability to separate highly emulsified oil-water mixtures. The relatively low cost for the material preparation, enhanced mechanical property and high separation performance distinguished the developed material a suitable candidate for the separation of emulsified oil from water in practical applications.


Assuntos
Celulose/química , Fibra de Algodão , Óleos/química , Água/química , Emulsões , Interações Hidrofóbicas e Hidrofílicas , Polissorbatos/química , Hidróxido de Sódio/química , Solventes/química , Tensoativos/química , Resistência à Tração , Ureia/química
8.
Trop Anim Health Prod ; 52(5): 2433-2441, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32297043

RESUMO

The aim of this study was to evaluate the effect of adding different concentrations of either urea or NaOH in dehydrated acerola (Malpighia emarginata) fruit residue (DAFR) on chemical composition, in vitro rumen degradability, and gas and methane production. A completely randomized design was used with the following seven treatments: control, without chemical treatment, or pretreatment of DAFR with urea or NaOH at 20, 40, or 60 g/kg dry matter (DM). DM degradability and gas and methane production of DAFR were evaluated by semi-automated in vitro gas production technique. DAFR treated with urea or NaOH at concentrations of 40 and 60 g/kg DM decreased its neutral detergent fiber (P = 0.0115) and lignin (P < 0.0001) content, and this reduction was greater with the highest concentration (60 g/kg DM). In all tested concentrations, urea and NAOH were effective to increase the DM effective degradability of DAFR compared with the control treatment, although treatments with a concentration of 60 g/kg DM presented the highest values (P < 0.0001). Treatment of DAFR with NaOH or urea at 60 g/kg DM promotes greater lignin solubilization and DM degradability and lower gas and methane production in in vitro rumen fermentation.


Assuntos
Digestão , Malpighiaceae/química , Metano/biossíntese , Rúmen/metabolismo , Hidróxido de Sódio/química , Ureia/química , Ração Animal/análise , Animais , Brasil , Dieta/veterinária , Digestão/efeitos dos fármacos , Relação Dose-Resposta a Droga , Fermentação , Frutas/química , Técnicas In Vitro , Masculino , Distribuição Aleatória , Carneiro Doméstico
9.
Sci Rep ; 10(1): 6760, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317739

RESUMO

To improve the performance of bamboo and increase its utilization value, this study aimed at investigating the effects of impregnation pretreatment and thermal treatment on the structural changes of bamboo. The samples were pretreated in sodium hydroxide or zinc chloride solution, and then treated at 160 °C. The pretreated and control samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), and Fourier transform infrared spectroscopy (FTIR). The results showed that the cellulose crystallinity and intensity of samples pretreated by ZnCl2 could be reduced, but the crystal structure remained the same. As for samples pretreated in NaOH, the crystal structure of fiber was destroyed and the crystallinity was increased significantly. High temperature treatment has little effect on the thermal stability of bamboo. However, after treatment with NaOH and ZnCl2, the thermal degradation temperature changed obviously and moved to a lower temperature. ZnCl2 pretreatment had influence on the chemical structure of bamboo, while NaOH pretreatment had greater influence on the chemical structure of bamboo.


Assuntos
Celulose/química , Fibras na Dieta/metabolismo , Sasa/química , Ácidos/farmacologia , Álcalis/farmacologia , Celulose/ultraestrutura , Temperatura Alta , Hidrólise/efeitos dos fármacos , Sasa/ultraestrutura , Hidróxido de Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
10.
PLoS One ; 15(4): e0231623, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32294115

RESUMO

Biogenic CBM is an important component of detected CBM, which is formed by coal biodegradation and can be regenerated by anaerobic microorganisms. One of the rate-limiting factors for microbial degradation is the bioavailability of coal molecules, especially for anthracite which is more condense and has higher aromaticity compared with low-rank coal. In this paper, NaOH solution with different concentrations and treating time was employed to pretreat anthracite from Qinshui Basin to alter the coal structure and facilitate the biodegradation. The results showed that the optimal pretreatment conditions were 1.5 M NaOH treating for 12 h, under which the biomethane production was increased by 17.65% compared with untreated coal. The results of FTIR and XRD showed that NaOH pretreatment mainly reduced the multi-substituted aromatics, increased the C-O in alcohols and aromatic ethers and the branching degree of aliphatic chain, and decreased the aromatic ring structure, resulting in the improvement of coal bioavailability and enhancement of biomethane yield. And some organics with potential to generate methane were released to filtrate as revealed by GC-MS. Our results suggested that NaOH was an effective solution for pretreating coal to enhance biogenic methane production, and anthracite after treating with NaOH could be the better substrate for methanogenesis.


Assuntos
Archaea/metabolismo , Reatores Biológicos , Carvão Mineral/microbiologia , Metano/biossíntese , Hidróxido de Sódio/química , Biodegradação Ambiental , Metano/análise , Energia Renovável , Espectroscopia de Infravermelho com Transformada de Fourier , Desenvolvimento Sustentável , Difração de Raios X
11.
Appl Biochem Biotechnol ; 191(1): 125-134, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31960368

RESUMO

Glycerol conversion to lactic acid (LA) was investigated in aqueous alkali over eight unsupported copper compounds (CuBr2, CuBr, CuCl2, CuCl, CuF2, Cu(NO3)2,CuO, and Cu2O) for studying the effects of anion and valence. Powder X-ray diffraction and scanning electron microscopy measurements indicated that these copper compounds were reduced to metallic copper with different morphologies. Divalent copper compounds exhibited much better performances than the corresponding univalent species, ascribed to their greater reduction heat and higher local reaction temperature. Divalent copper species activity, ionic radius, and the reported reduction potential decreased in the same order: bromide > chloride > floride ≫ nitrate. With increasing reaction temperature, catalyst amount, NaOH concentration and reaction time, glycerol conversion, and LA selectivity increased (due to by-product conversions to LA). Kinetic studies indicated that glycerol disappearance rate was first-order with respect to its concentration. CuBr2 had greater activation energy and therefore exhibited better performance than CuO when reaction temperature was greater than 155 °C. At 185 °C, CuBr2 reached 95.7% lactic acid yield and 98.65% glycerol conversion.


Assuntos
Brometos/química , Cobre/química , Glicerol/química , Ácido Láctico/síntese química , Hidróxido de Sódio/química , Temperatura Alta
12.
Molecules ; 25(3)2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31979336

RESUMO

This study selected three representative protein-rich biomass-brewer's spent grain (BSG), pasture grass (PG), and cyanobacteria (Arthrospira platensis; AP) for protein extraction with different extraction methods (alkaline treatment, aqueous extraction, and subcritical water extraction). The yield, purity, molecular weight, oil-water interfacial tension, and thermal stability of the obtained proteins derived from different biomass and extraction methods were comprehensively characterized and compared. In the view of protein yield and purity, alkaline treatment was found optimal for BSG (21.4 and 60.2 wt.%, respectively) and AP (55.5 and 68.8 wt.%, respectively). With the decreased oil-water interfacial tension, the proteins from all biomass showed the potential to be emulsifier. BSG and AP protein obtained with chemical treatment presented excellent thermal stability. As a novel method, subcritical water extraction is promising in recovering protein from all three biomass with the comparable yield and purity as alkaline treatment. Furthermore, the hydrolyzed protein with lower molecular weight by subcritical water could promote its functions of foaming and emulsifying.


Assuntos
Cianobactérias/química , Grão Comestível/química , Proteínas de Grãos/isolamento & purificação , Poaceae/química , Proteínas/isolamento & purificação , Biomassa , Cianobactérias/metabolismo , Grão Comestível/metabolismo , Proteínas de Grãos/química , Proteínas de Grãos/metabolismo , Temperatura Alta , Hidrólise , Peso Molecular , Poaceae/metabolismo , Proteínas/química , Proteínas/metabolismo , Saccharomyces cerevisiae , Hidróxido de Sódio/química , Água/química
13.
Molecules ; 25(3)2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31979363

RESUMO

The increasing population creates excess pressure on the plantation and production of fruits and vegetables across the world. Consumption demand during the whole year has made production compulsory in the covered production system (greenhouse). Production, harvesting, processing, transporting, and distribution chains of fruit and vegetables have resulted in a huge amount of wastes as an alternative source to produce biofuels. In this study, optimization of two pretreatment processes (NaOH and HCl assisted thermal) was investigated to enhance methane production from fruit and vegetable harvesting wastes (FVHW) that originate from greenhouses. NaOH concentration (0-6.5%), HCl concentration (0-5%), reaction temperature (60-100 °C), solid content (1-5%), time of reaction (1-5 h), and mixing speed (0-500 rpm) were chosen in a wide range of levels to optimize the process in a broad design boundary and to evaluate the positive and negative impacts of independent variables along with their ranges. Increasing NaOH and HCl concentrations resulted in higher COD solubilization but decreased the concentration of soluble sugars that can be converted directly into methane. Thus, the increasing concentrations of NaOH and HCl in the pretreatments have resulted in low methane production. The most important independent variables impacting COD and sugar solubilization were found to be chemical concentration (as NaOH and HCl), solid content and reaction temperature for the optimization of pretreatment processes. The high amount of methane productions in the range of 222-365 mL CH4 gVS-1 was obtained by the simple thermal application without using chemical agents as NaOH or HCl. Maximum enhancement of methane production was 47-68% compared to raw FVHW when 5% solid content, 1-hour reaction time and 60-100 °C reaction temperature were applied in pretreatments.


Assuntos
Reatores Biológicos , Carboidratos/química , Frutas/química , Metano/síntese química , Eliminação de Resíduos/métodos , Verduras/química , Anaerobiose , Biocombustíveis , Análise da Demanda Biológica de Oxigênio , Ácido Clorídrico/química , Metano/química , Microscopia Eletrônica de Varredura , Hidróxido de Sódio/química , Propriedades de Superfície , Temperatura
14.
Int J Biol Macromol ; 148: 688-695, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954786

RESUMO

Lignins are among the most abundant renewable resources on the planet. However, their application is limited by the lack of efficient dissolution and extraction methodologies. In this work, a systematic and quantitative analysis of the dissolution efficiency of different alkaline-based aqueous systems (i.e. lithium hydroxide, LiOH; sodium hydroxide, NaOH; potassium hydroxide, KOH; cuprammonium hydroxide, CuAOH; tetrapropylammonium hydroxide, TPAOH and tetrabutylammonium hydroxide, TBAOH) is reported, for the first time, for kraft lignin. Phase maps were determined for all systems and lignin solubility was found to decrease in the following order: LiOH > NaOH > KOH > CuAOH > TPAOH > TBAOH, thus suggesting that the size of the cation plays an important role on its solubility. The π∗ parameter has an opposite trend to the solubility, supporting the idea that cations of smaller size favor lignin solubility. Dissolution was observed to increase exponentially above pH 9-10 being the LiOH system the most efficient. The soluble and insoluble fractions of lignin in 0.1 M NaOH were collected and analyzed by several techniques. Overall, data suggests a greater amount of simple aromatic compounds, preferentially containing sulfur, in the soluble fraction while the insoluble fraction is very similar to the native kraft lignin.


Assuntos
Hidróxidos/química , Lignina/química , Cátions/química , Compostos de Lítio/química , Compostos de Potássio/química , Hidróxido de Sódio/química , Solubilidade , Água/química
15.
Chemosphere ; 242: 125202, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31677512

RESUMO

The potential effect of base on Raney Ni-catalyzed hydrodechlorination (HDC) of chlorophenol was studied. Compared to weak inorganic bases, strong inorganic bases (NaOH and KOH) and triethylamine (Et3N) were more favorable to promote Raney Ni-catalyzed HDC reaction. Moreover, a stoichiometric amount of NaOH/Et3N was found to be optimal for the HDC reaction, and up to 100% conversion of 4-chlorophenol was achieved within 30 min. Catalyst characterization (SEM, EDXS, and XRD) combined with ICP-OES analysis were introduced to better understand the mechanism for the promoted effect of base on the HDC reaction. The results showed that the optimal amount of strong inorganic bases and Et3N efficiently eliminated HCl corrosion to Raney Ni, greatly reduced the active phase Ni and Al leaching, and avoided collapse of the catalyst framework. Based on the mechanism, the best bases and their optimal amount were developed for further disposal of polychlorinated phenols, and excellently stepwise HDC of polychlorinated phenols was achieved. Recycling tests showed that Raney Ni could be reused at least 5 times for the HDC reaction with the stoichiometric amount of NaOH, which was a promising option for the HDC of wastewater containing chlorophenols over Raney Ni.


Assuntos
Clorofenóis/química , Níquel/química , Hidróxido de Sódio/química , Águas Residuárias/química , Purificação da Água/métodos , Catálise , Halogenação , Reciclagem
16.
Int J Biol Macromol ; 145: 795-803, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31739019

RESUMO

Waste rice straw (RS) was fractionated to extract the lignin using alkaline (sodium hydroxide) treatment (SHT) and organic acid (Formic acid/Acetic acid) treatment (OAT) process. Rice straw fractionation by the acetic OAT and alkaline SHT methods resulted in the recovery of OAT-lignin and SHT-lignin respectively. The structural characterization of the extracted lignin fractions was done by UV-vis spectroscopy, FTIR and 1H NMR technique. Total phenolic content (TPC) present in SHT-lignin and OAT-lignin were determined to be 28.87 mg GAE/g and 24.75 mg GAE/g respectively. The DPPH radical scavenging activity 59.50% was observed in SHT-lignin and 45.74% in OAT-lignin using the DPPH test for 30 min of incubation. Surface characterization of untreated rice straw (UT-RS) and treated rice straw (SHT-RS and OAT-RS) were carried out by XRD, FTIR and SEM. X-ray photoelectron spectroscopy (XPS) survey, C1s, and O1s spectra were used to determined the surface carbon and oxygen composition changes in RS after SHT and OAT. These structural characterizations of lignin and biomass are beneficial for further processing in bio-refinery industry.


Assuntos
Lignina/química , Oryza/química , Ácido Acético/química , Biomassa , Compostos de Bifenilo/química , Carbono/química , Formiatos/química , Oxigênio/química , Fenóis/química , Picratos/química , Hidróxido de Sódio/química
17.
Int J Biol Macromol ; 147: 931-936, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31739062

RESUMO

The effect of NaOH/urea solution freeze-thaw pretreatment to the chitosan of purity and the degree of deacetylation from the crab shell was examined. Higher purity chitosan (CS1) was prepared. On this basis, the raw materials after the first demineralization were pretreated with NaOH/urea solution freeze-thaw under different freeze-thaw situations. The produced chitosans (CS1-CS4) were characterized in the ash content, solubility, protein content, degree of deacetylation, viscosity average molecular weight, SEM, FTIR, XRD, antimicrobial activity. The results showed that the freeze-thaw process had advantageous influence on decreasing the ash content and increasing degree of deacetylation and antibacterial activity. Moreover, the antibacterial property of the extracted chitosans seemed to be positively related to their degree of deacetylation. It is concluded that CS4 had the lowest ash content (0.052%), the highest degree of deacetylation (86.02%) and the greatest antibacterial activity. Therefore, we recommend CS4 as agent for industrial and pharmaceutical applications.


Assuntos
Braquiúros/química , Quitosana , Hidróxido de Sódio/química , Ureia/química , Animais , Quitosana/química , Quitosana/isolamento & purificação , Congelamento
18.
Carbohydr Polym ; 229: 115524, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826475

RESUMO

Structure and properties of pectin can be affected by extraction methods. In this study, grapefruit peel pectins extracted by HCl (at pH 1 [P1], 2 [P2], and 3 [P3]) and NaOH (at pH 9 [P9], 10 [P10], and 11 [P11]) were prepared and characterized. Atomic force microscopy (AFM) provided direct evidence of complex nano-structural patterns of pectins and revealed cross-linked networks of P10 and P11. Small-angle X-ray scattering (SAXS) demonstrated that P1, P2, and P3 possessed a relatively extended conformation, whereas P9, P10, and P11 displayed a three-dimensional structure and folded conformation. The compact and extended conformations of P3 contributed to its high viscosity in solution and the stability of the formed emulsion (75%). Porous surface and larger three-dimensional nanostructure (Dmax: 23 nm) of P10 facilitated its ion-binding capacity. Our results provide valuable insight into relationship between extraction methods and structure-properties of pectin, facilitating design of functional pectins.


Assuntos
Citrus paradisi/metabolismo , Ácido Clorídrico/química , Pectinas/química , Hidróxido de Sódio/química , Emulsões/química , Frutas/metabolismo , Concentração de Íons de Hidrogênio , Nanoestruturas/química , Extratos Vegetais/metabolismo , Porosidade , Reologia , Espalhamento a Baixo Ângulo , Viscosidade , Difração de Raios X
19.
Colloids Surf B Biointerfaces ; 185: 110567, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31654889

RESUMO

A peptide (FFACD) can form hydrogels in DMSO-H2O mixtures (G1), NaOH (G2) and L-arginine (G3) aqueous solutions, respectively. Methyl thiazolyl tetrazolium (MTT) assays demonstrated that G1 and G3 exhibited excellent biocompatibility against HEK293 epithelial cells while G2 had an obvious cytotoxicity. G1 and G3 were used as drug carriers with the high drug loading capacity (DLC). Both hydrophilic DOX and hydrophobic PTX were completely loaded into G1 without destroying the hydrogel, while G3 could only encapsulate DOX. The strong electrostatic interaction between DOX and FFACD molecules could destroy the microstructure of G3 to produce precipitate with a high DOX DLC of 93%. The cytotoxicity assay of G1/DOX against K562 leukemia cells indicated that G1 did not inhabit the efficacy of DOX. In vitro release experiments demonstrated DOX of G3/DOX precipitates could be released 76% at pH = 6.0 of the tumor cells and only about 13% at pH = 7.4 of normal cells.


Assuntos
Liberação Controlada de Fármacos , Hidrogéis/química , Peptídeos/química , Morte Celular , Dimetil Sulfóxido/química , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Células K562 , Fígado/metabolismo , Reologia , Hidróxido de Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
20.
Carbohydr Polym ; 227: 115380, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590848

RESUMO

Old corrugated containers with low recyclability were used as raw materials to synthesize a series of aerogels with varying cellulose concentrations in NaOH/urea solution via a freeze-drying process. The resulting aerogels had a rich porous structure with specific surface areas in the range of 132.72-245.19 m2.g-1 and mesopore volumes in the range of 0.73-1.53 cm3.g-1, and were tested for CO2 sorption at ambient temperature and pressure, displaying excellent CO2 adsorption capacities in the range of 1.96-11.78 mmol.g-1. Furthermore, the CO2/N2 selectivity of aerogels decreased with decreasing specific surface area, which was mainly caused by the decrease in CO2 capture. In addition, the CO2 sorption capacity of the sample with 2% cellulose content, CA-2, exceeded the values reported so far for many other sorbents with higher specific surface areas, and showed reasonable cyclic stability for CO2 capture. Therefore, this adsorbent represents an attractive prospect for CO2 uptake at room temperature.


Assuntos
Dióxido de Carbono/química , Sequestro de Carbono , Celulose/química , Adsorção , Géis , Papel , Porosidade , Reciclagem , Hidróxido de Sódio/química , Ureia/química
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