scholarly journals The Role of Carboxyl and Hydroxyl Groups of Humic Acid in Removing AuCl4- from Aqueous Solution

2017 ◽  
Vol 17 (1) ◽  
pp. 95 ◽  
Author(s):  
Sri Sudiono ◽  
Mustika Yuniarti ◽  
Dwi Siswanta ◽  
Eko Sri Kunarti ◽  
Triyono Triyono ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Humic Acid ◽  
Peat Soil ◽  
Sharp Decrease ◽  
Hydroxyl Groups ◽  
Mixed Solution ◽  
Oh Groups ◽  
Characterization Result ◽  
Ft Ir

Humic acid (HA) extracted from peat soil according to the recommended procedure of the International Humic Substances Society (IHSS) has been tested to remove AuCl4- from aqueous solution. The removal was optimum at pH 2.0 and it was mainly dictated by attachment through hydrogen bonding to unionized carboxyl (–COOH) groups and reduction by the action of the hydroxyl (–OH) groups to gold (Au) metal. The removal of AuCl4- improved after HA was purified through repeated immersion and shaking in a mixed solution containing 0.1 M HCl and 0.3 M HF. When the purification led to the sharp decrease in ash content from 39.34 to 0.85% (w/w) and significant increase in both the –COOH and –OH contents from 3240 to 3487 mmol/kg and from 4260 to 4620 mmol/kg, respectively; the removal of AuCl4- improved from 0.105 to 0.133 mmol/g. This improvement of AuCl4- removal by the purified HA was accompanied by higher ability in reduction to Au metal. The attached AuCl4- on –COOH groups of both crude and purified HAs was qualitatively observed by the characterization result of FT-IR spectroscopy, while the presence of Au metal on the surface of those HAs was verified by the characterization result of XRD.

scholarly journals Role of Zingiber Officinale Essential Oil- Chitosan Based Biopolymer Film For Bioactive Packaging

2021 ◽  
Author(s):  
Sawsan A. Al-Hilifi ◽  
Rawdah M. Al-Ali
Keyword(s):  
Essential Oil ◽  
Food Packaging ◽  
Fourier Transforms ◽  
Zingiber Officinale ◽  
Differential Scanning Calorimetric ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Biopolymer Film

Abstract The recent interest in bio-packing at field of food become trending in the development of antimicrobial coatings. The focus of this study was to assess the potential application of zingiber officinale essential oil (GEO) in chitosan films (CHf). The data indicated that there were significant differences(p < 0.05) in the chemical composition of the samples.Forty-seven active compounds of the essential oil were identified from the rhizomes of ginger, which were identified byGC-MS. Fourier transforms infrared spectra (FT-IR) confirmed that an interaction between the hydroxyl groups of the phenolic compounds of the essential oil and the amide groups of polymer matrix. As shown the appearance of peaks at wavenumbers 1639cm-1 and 1558cm-1 Furthermore, X-ray diffraction results suggested a lower crystallintiyin CHf due to GEO effect. Differential Scanning Calorimetric (DSC) analysis revealed that CHf possessed high thermal stability, especially when different concentrations of GEO added. The bioactive CHf showed distinct activity against both positive and negative gram bacteria. They are Staphylococcus aurous, Bacillus subtillis, Streptococcus Sp. Escherichia coli, Salmonella Sp. Pseudomonas erugiosa. This results provides a comprehensive insight on the importance of films incorporated with EOs of interest in food packaging.

scholarly journals The Temperature-Dependent Adsorption Behaviour of Benzene Molecules in ZSM-5 Zeolite Pores: TPD and FT-IR Spectroscopy Studies

2005 ◽  
Vol 23 (2) ◽  
pp. 95-107 ◽  
Author(s):  
Arati Sahasrabudhe ◽  
Salil Varma ◽  
Narendra M. Gupta
Keyword(s):  
Benzene Molecule ◽  
Hydroxyl Groups ◽  
Fixed Amount ◽  
Oh Groups ◽  
Ir Studies ◽  
Ft Ir ◽  
Temperature Programmed ◽  
Spectroscopy Studies ◽  
Ir Spectroscopic

Temperature-programmed desorption (TPD) and in situ Fourier-transform infrared (FT-IR) spectroscopic methods were employed to investigate the effect of loading and sample temperature on the state of benzene molecules inside the channels of NaZSM-5 zeolite. TPD profiles revealed the existence of at least three distinct states of benzene adsorption, characterized by desorption peak maxima at ca. 120°C, 170°C and 220°C, respectively. Based on the growth behaviour of these bands, it is suggested that the benzene molecules occupy sinusoidal channels, straight channels and external surfaces, in that order. A reverse trend was observed during the subsequent flushing of the sample at varying temperatures. A virtually fixed amount of benzene was occluded at these three locations, depending upon the loading. The FT-IR studies revealed that the benzene molecule exists in a compressed state in the zeolitic channels, with the molecular clusters formed in the process dispersing only at temperatures above 150°C. For initial benzene loadings of up to ca. 1.5 molecules/unit cell, the spectrum obtained showed that in the O—H stretch region the bridge-bonded OH groups and hydroxyl groups associated with the internal zeolitic channels were perturbed simultaneously. The results show that even for a loading lower than necessary for saturation, a considerable amount of benzene remains condensed at the external surface of ZSM-5 zeolite.

scholarly journals Thermal modification of wood—a review: chemical changes and hygroscopicity

2021 ◽  
Author(s):  
Callum Hill ◽  
Michael Altgen ◽  
Lauri Rautkari
Keyword(s):  
Cell Wall ◽  
Moisture Content ◽  
Dimensional Stability ◽  
Thermal Modification ◽  
Hydroxyl Groups ◽  
Water Leaching ◽  
Topic Area ◽  
Sorption Behaviour ◽  
Oh Groups

Abstract Thermal modification is a well-established commercial technology for improving the dimensional stability and durability of timber. Numerous reviews of thermally modified timber (TMT) are to be found in the scientific literature, but until now a review of the influence of cell wall moisture content during the modification process on the properties of TMT has been lacking. This paper reviews the current state of knowledge regarding the hygroscopic and dimensional behaviour of TMT modified under dry (cell wall at nearly zero moisture content) and wet (cell wall contains moisture) conditions. After an overview of the topic area, the review explores the literature on the thermal degradation of the polysaccharidic and lignin components of the cell wall, as well as the role of extractives. The properties of TMT modified under wet and dry conditions are compared including mass loss, hygroscopic behaviour and dimensional stability. The role of hydroxyl groups in determining the hygroscopicity is discussed, as well as the importance of considering the mobility of the cell wall polymers and crosslinking when interpreting sorption behaviour. TMT produced under wet processing conditions exhibits behaviour that changes when the wood is subjected to water leaching post-treatment, which includes further weight loss, changes in sorption behaviour and dimensional stability, but without any further change in accessible hydroxyl (OH) content. This raises serious questions regarding the role that OH groups play in sorption behaviour. Graphical abstract

Modelling the role of humic acid in radiocaesium distribution in a British upland peat soil

2002 ◽  
Vol 61 (2) ◽  
pp. 133-147 ◽  
Author(s):  
S. Lofts ◽  
E.W. Tipping ◽  
A.L. Sanchez ◽  
B.A. Dodd
Keyword(s):  
Humic Acid ◽  
Peat Soil

Crystallization time in ZnO: the role of surface OH groups in its photoactivity

2020 ◽  
Vol 44 (42) ◽  
pp. 18216-18224
Author(s):  
Jéssica C. de Almeida ◽  
Mateus T. Corrêa ◽  
Rafaella H. Koga ◽  
Douglas M. S. Del Duque ◽  
Osmando F. Lopes ◽  
...  
Keyword(s):  
Critical Role ◽  
Surface Modifications ◽  
Crystallization Time ◽  
Hydroxyl Groups ◽  
Surface Groups ◽  
Oh Groups

The crystallization time and surface modifications concerning the hydroxyl groups on the ZnO catalyst were studied and the results suggest that there is a balance between the surface groups and morphology playing a critical role in its photoactivity.

scholarly journals ANALYSIS OF INFLUENCE OF PH AND TEMPERATURE IN ADSORPTION METHYLENE BLUE FOR PSEUDOSTEM FIBER BANANA

2013 ◽  
Vol 12 (24) ◽  
pp. 34-41
Author(s):  
Caroline CASTANHETTI ◽  
Ana Paula FIGUEIREDO ◽  
Lucas DOMINGUINI
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Carboxylic Acid ◽  
High Efficiency ◽  
Hydroxyl Groups ◽  
Alkaline Ph ◽  
Banana Fiber ◽  
Ph Values ◽  
Ft Ir ◽  
Influence Of Ph

This study examined the potential for adsorption of methylene blue, in solution of 50 mg.L-1, by banana fiber spray, to 2 g/L of solution. We carried out variations in temperature and pH of the solution. The results indicate that it is possible to use the banana fiber as adsorbent methylene blue in ambient temperature and alkaline pH values with high efficiency. The FT-IR spectrum showed the presence of carboxylic acid and hydroxyl groups on the fiber. Such groups are capable of forming hydrogen bonds with methylene blue and removing it from the aqueous solution. It was concluded that for the conditions tested, the best temperature for adsorption was 25 °C and pH to better efficiency of better temperature was 11.

Adsorption for Au3+ by Persimmon Tannins Immobilized on Collagen Fiber

2013 ◽  
Vol 745-746 ◽  
pp. 39-45 ◽  
Author(s):  
Feng Lei Liu ◽  
Zhong Min Wang ◽  
Jian Cui ◽  
Zhi De Zhou ◽  
Gui Yin Li ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Collagen Fiber ◽  
Adsorption Process ◽  
Ph Value ◽  
Hydroxyl Groups ◽  
Adsorption Behaviour ◽  
Solution Ph ◽  
Initial Concentration ◽  
Ft Ir ◽  
Precious Metal Ions

A novel adsorbent which is effective to adsorb Au3+ was prepared using immobilized persimmon tannin (PT) on collagen fiber by glutaraldehyde crosslinking. The adsorption behaviour of this new adsorbent to Au3+ in aqueous solution was investigated. The effects of various factors such as initial solution pH, temperature, ionic strength and initial concentration of Au3+ on the influence of the adsorption process were studied. The equilibrium adsorption capacity reached 2347 mg/g at 323 K and pH value 2.0 when the initial concentration of Au3+ in aqueous solution was 500 mg/L. The immobilized PT was characterized by FT-IR, XRD and SEM. The results indicated that Au3+ changed to gold by oxidation adjacent phenol hydroxyl groups of persimmon tannin. Experiments also showed that adsorption isotherms of immobilized tannin for Au3+ could be described by Langmuir models. Immobilized PT adsorption provided a new way for the separation of the precious metal ions

Evaluation of Hydroxyl Groups on Hydroxyapatite and Calcium Metaphosphate by Grafting TEOS and APTES

2007 ◽  
Vol 342-343 ◽  
pp. 677-680 ◽  
Author(s):  
Chang Kuk You ◽  
Sung Min Kim ◽  
Myun Whan Ahn ◽  
Seong Yong Kim ◽  
Suk Young Kim
Keyword(s):  
Aqueous Solution ◽  
Ph Value ◽  
Ethanol Solution ◽  
Hydroxyl Groups ◽  
Acidic Media ◽  
Ph Change ◽  
Oh Groups ◽  
Ph Values ◽  
Phosphate Ions ◽  
Ph Increase

OH groups on hydroxyapatite (HA) and calcium metaphosphate (CMP) were evaluated by grafting tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethyloxysilane (3-APTES) which can bond covalently with OH group of ceramic biomaterials. The prepared HA and CMP disks were soaked in pH 2 and 5 of acidic water and ethanol solution respectively, where pH change of each solution was measured during soaking of samples. After grafting TEOS and 3-APTES on HA and CMP disks, samples were ultrasonically cleaned in distilled water and soaked in pH 5 of ethanol solution, and pH measurement was carried out in the same manner. The pH value of HA and CMP in aqueous solution at pH 2 increased with time continuously, resulting from dissolution of HA and CMP by acidic condition on surface. At pH 5 in aqueous solution, it was the same though the pH increase was smaller. In case of ethanol at pH 5 with HA, though pH value went up slightly, the curve became saturated with time, while there was no change in pH with CMP. After grafting TEOS and 3-APTES, pH values were stabilized with few changes, indicating that there was no direct chemical reaction between the acidic media and the surface of samples due to covalently grafted TEOS and 3-APTES layer. In conclusion, it was confirmed that OH group on the surface of HA was crystallographic and chemical one rather than physically adsorbed one by grafting TEOS or 3-APTES and it will serve an effective binding site for calcium and phosphate ions, or minerals.

ROLE OF THE STROMAL CELLULAR COMPONENT IN COMPENSATORY PROCESSES IN DIFFUSE LIVER DAMAGE

2018 ◽  
pp. 32-37 ◽  
Author(s):  
Z. A. Shafigullina ◽  
S. Yu. Medvedeva ◽  
I. G. Danilova
Keyword(s):  
Toxic Hepatitis ◽  
Intraperitoneal Administration ◽  
Sharp Decrease ◽  
Cellular Component ◽  
Ki 67 ◽  
Sinusoidal Cells ◽  
Toxic Damage ◽  
Stromal Component ◽  
Regeneration Processes

The aim of the study was to assess the role of the cellular component of the stroma in liver regeneration after its toxic damage. The experimental model of toxic hepatitis caused by intraperitoneal administration of tetrachloromethane (CCl4) showed that regeneration processes in the liver on the 3rd day are manifested in an increase in binuclear hepatocytes, Ki-67 + cells and hepatocytes dividing by mitosis. The reaction of the stromal component is expressed in an increase in the number of CD45 +, mast and sinusoidal cells (SC). On the 7th day of the development of toxic hepatitis the hepatocyte alteration increases, that is accompanied by a sharp decrease in the mitotic index and the number of Ki-67 + cells. In the stromal component there is a decrease in the number of sinusoidal cells, CD45 + and a significant increase in mast cells with a high secretion granule content.

Kinetic Adsorption of Humic Acids Mixture Obtained from Microalgae on Exfoliated Graphite Nanoplatelets

2018 ◽  
Vol 69 (1) ◽  
pp. 191-195
Author(s):  
Elena Radu ◽  
Elena Emilia Oprescu ◽  
Cristina Emanuela Enascuta ◽  
Catalina Calin ◽  
Rusandica Stoica ◽  
...  
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Alkali Treatment ◽  
Exfoliated Graphite ◽  
Acid Mixture ◽  
Acidic Ph ◽  
Graphite Nanoplatelets ◽  
Mixture Concentration ◽  
Ft Ir ◽  
Exfoliated Graphite Nanoplatelets

The dehydration of polysaccharides fraction in the presence of acid catalysts, is a chemical process in which results as secondary product humic matter. In our work, the humic acid mixture was for the first time based on our knowledge extracted from defatted microalgae biomass rich in polysaccharides by standard alkali treatment, followed by precipitation at acidic pH. The dried humic acid mixture has been characterized using infrared spectroscopic measurements (FT-IR). Exfoliated graphite nanoplatelets (xGnP) were used as new adsorbents for this type of humic acids mixture, their adsorption being investigated. The effect of several parameters such as: contact time, concentration of humic acid mixture, concentration of xGnP, temperature and pH of the solutions were studied. The process of adsorption took place with good results, in the following conditions: at a concentration of humic acid mixture of 18.6 mg L-1, an xGnP amount of 0.01 mg in 25 mL of solution, at a temperature of 25 �� and at acidic pH values, in aqueous solution.

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