scholarly journals Cyanides and Their Attenuation in Wastewaters Using Green Chemistry

2021 ◽  
Author(s):  
Andrews Quashie
Keyword(s):  
Environmental Pollutants ◽  
Chemical Properties ◽  
Cyanide Solution ◽  
Industrial Processes ◽  
Waste Waters ◽  
Naturally Occurring ◽  
Catalysed Oxidation ◽  
Physico Chemical ◽  
Cyanide Degradation ◽  
Hydrolysis Of

Cyanides, though naturally occurring, are environmental pollutants when not treated properly. Some methods used to attenuate cyanides in waste waters from industrial processes are based simply on changing the physico-chemical properties of the waste water such as the pH and temperature. The effectiveness of these methods are based on hydrolysis of the cyanide and volatilization of the hydrogen cyanide formed. Another reaction which takes place simultaneously is ultraviolet-catalysed oxidation which converts the cyanide to bicarbonates and carbonates.The changes in the cyanide degradation rate approaches a minimum faster if the cyanide solution is maintained at a higher than ambient constant temperature.

scholarly journals The Simultaneous Removal of Zinc and Cadmium from Multicomponent Aqueous Solutions by Their Sorption onto Selected Natural and Synthetic Zeolites

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 343 ◽  
Author(s):  
Bożena Kozera-Sucharda ◽  
Barbara Gworek ◽  
Igor Kondzielski
Keyword(s):  
Aqueous Solutions ◽  
Low Cost ◽  
Environmental Pollutants ◽  
Chemical Properties ◽  
Simultaneous Removal ◽  
Physico Chemical ◽  
Synthetic Zeolites ◽  
Sorption Mechanisms ◽  
Synthetic Aluminosilicate ◽  
Natural And Synthetic

Natural and synthetic aluminosilicate minerals, in particular zeolites, are considered to be very useful in remediation processes, such as purification of waters polluted with heavy metals. That is due to their unique and outstanding physico-chemical properties, rendering them highly efficient, low-cost, and environmentally friendly sorbents of various environmental pollutants. The aim of this study was to examine the sorption capacity of four selected zeolites: A natural zeolite and three synthetic zeolites (3A, 10A, and 13X), towards zinc and cadmium present in multicomponent aqueous solutions, in relation to identified sorption mechanisms. It was stated that synthetic zeolites 3A and 10A were the most efficient in simultaneous removal of zinc and cadmium from aqueous solutions. Additionally, zeolite 10A was demonstrated to be the mineral best coping with prolonged pollution of water with those elements. The mechanism of sorption identified for tested minerals was physisorption.

scholarly journals Tryptic phosphopeptides from whole casein. II. Physicochemical properties related to the solubilization of calcium

1989 ◽  
Vol 56 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Rafael Berrocal ◽  
Serge Chanton ◽  
Marcel A. Juillerat ◽  
Blaise Favillare ◽  
Jean-Claude Scherz ◽  
...  
Keyword(s):  
Binding Sites ◽  
Calcium Phosphates ◽  
Chemical Properties ◽  
Sodium Caseinate ◽  
Ph Values ◽  
Physico Chemical ◽  
Casein Phosphopeptides ◽  
Hydrolysis Of ◽  
Phosphate Solutions ◽  
Tryptic Hydrolysis

SummaryCasein phosphopeptides (GPP) were produced by tryptic hydrolysis of sodium caseinate and further purified by precipitation and chromatography on QAE-Sephadex A-25. Their physico-chemical properties were compared with the properties of an enzymically dephosphorylated equivalent preparation (DPP). Binding of Ca2+ to the peptides was measured using a Ca selective electrode and was found to increase with pH and to show 1/1 stoicheiometry Ca/Porg in CPP at pH 6·5 a.nd 7·6. Klotz plots indicated equivalent binding sites at these two pH values, but some heterogeneity was seen at pH 3·5. In contrast, DPP did not bind significant amounts of Ca2+.CPP effectively inhibited the formation of insoluble calcium phosphates at different Ca/P ratios. The effective CPP concentration was 10 mg/1 and complete stability of calcium phosphate solutions was obtained at about 100 mg/1. This stabilizing effect was dependent on the presence of organic P.

scholarly journals Lactoperoxidase: physico-chemical properties, occurrence, mechanism of action and applications

2000 ◽  
Vol 84 (S1) ◽  
pp. 19-25 ◽  
Author(s):  
Klaas D. Kussendrager ◽  
A. C. M. van Hooijdonk
Keyword(s):  
Mammalian Cells ◽  
Bovine Milk ◽  
Chemical Properties ◽  
Mechanisms Of Action ◽  
Industrial Processes ◽  
Physico Chemical ◽  
Lactoperoxidase System ◽  
Wide Range ◽  
Occurrence Mechanism ◽  
Micro Organisms

Lactoperoxidase (LP) is one of the most prominent enzymes in bovine milk and catalyses the inactivation of a wide range of micro-organisms in the lactoperoxidase system (LP-s). LP-systems are also identified as natural antimicrobial systems in human secretions such as saliva, tear-fluid and milk and are found to be harmless to mammalian cells. The detailed molecular structure of LP is identified and the major products generated by the LP-s and their antimicrobial action have been elucidated for the greater part. In this paper several aspects of bovine LP and LP-s are discussed, including physico-chemical properties, occurrence in milk and colostrum and mechanisms of action. Since the introduction of industrial processes for the isolation of LP from milk and whey the interest in this enzyme has increased considerably and attention will be paid to potential and actual applications of LP-systems as biopreservatives in food and other products.

Effects of non-ionic surfactants on the uptake and hydrolysis of fluoresceindiacetate by alkane-oxidizing bacteria

2000 ◽  
Vol 46 (4) ◽  
pp. 387-390 ◽  
Author(s):  
Per Bruheim ◽  
Kjell Eimhjellen
Keyword(s):  
Cell Surface ◽  
Uptake Rate ◽  
Biological Effects ◽  
Quantitative Difference ◽  
Chemical Properties ◽  
Ionic Surfactants ◽  
Physico Chemical ◽  
Hydrolysis Of

Biological effects of non-ionic surfactants on alkane-oxidizing bacteria were studied by assessing their influence on the uptake of prefluorochrome fluoresceindiacetate (FDA) and its intracellular hydrolysis to fluorescein. Both decreasing and increasing rates of hydrolysis as a consequence of the presence of surfactants were observed. The surfactants influenced the uptake of FDA, but not its intracellular hydrolysis. The effects of the surfactants on the uptake rate depended strongly on the structure and physico-chemical properties of the surfactants. There was no qualitative or significant quantitative difference in surfactant susceptibility between induced (alkane grown) and non-induced bacteria (acetate grown), even though the induced cells possess greater cell surface hydrophobicity.Key words: fluoresceindiacetate, bacteria, surfactants, alkane.

The Effect of Calcinations Temperature on the Performance of TiO2 Aggregates-Based Dye Solar Cells (DSCs)

2011 ◽  
Vol 364 ◽  
pp. 248-253 ◽  
Author(s):  
Nur Azella Zaine Siti ◽  
Muti Mohamed Norani ◽  
Mohamad Azmi Bustam
Keyword(s):  
Conversion Efficiency ◽  
Chemical Properties ◽  
Energy Conversion Efficiency ◽  
Synthesis Process ◽  
Solar Simulator ◽  
Electron Generation ◽  
Physico Chemical ◽  
Vis Spectroscopy ◽  
Dye Solar Cells ◽  
Hydrolysis Of

Development of novel TiO2 nanostructures as the photo-electrode material is one possible solution to control the competition between electron generation and recombination which is the main constraint of obtaining higher conversion efficiency of dye solar cell (DSC). By manipulating the synthesis process, desired TiO2 nanostructure with specific properties can be obtained to enhance solar energy conversion efficiency. In this study, the effect of calcinations temperature towards physico-chemical properties of synthesized TiO2 aggregates and their influence on overall light conversion efficiency of DSC has been investigated. TiO2 aggregates (0.45 µm) composing of nanocrystallites (10-40 nm), were synthesized through hydrolysis of dilute titanium alkoxide in ethanol. The synthesized samples have been characterized using FESEM, XRD and UV-Vis spectroscopy. DSCs were then assembled and evaluated using solar simulator under 100 mW/cm2 illuminations. The size of nanocrystallites was found to increase with increasing calcinations temperature where the 500°C produced the 21 nm sized nanocrystallites, the optimum size for highest absorption of the dye resulting in the highest efficiency. TiO2 aggregates-based DSC demonstrated better performance compared to nanoparticles (P-25)-based DSC. This is attributed to the enhanced scattering introduced by micron-sized aggregates.

scholarly journals Organosolv lignin properties and their effects on enzymatic hydrolysis

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 8909-8924
Author(s):  
Yang Huang ◽  
Chenhuan Lai ◽  
Shaolong Sun ◽  
Qiang Yong ◽  
Brian K. Via ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Distribution Coefficient ◽  
Chemical Properties ◽  
Structural Features ◽  
Hydrolysis Yield ◽  
Pure Cellulose ◽  
Organosolv Lignin ◽  
Physico Chemical ◽  
Enzyme Distribution ◽  
Hydrolysis Of

Lignin plays a crucial role in enzymatic hydrolysis of lignocellulosic biomass. To evaluate the correlation between lignin properties and its effects on enzymatic hydrolysis, five organosolv lignins (OLs) were isolated from woody biomass, and their physico-chemical properties and structural features were characterized. The effects of OL addition on enzymatic hydrolysis of microcrystalline cellulose (pure cellulose) were assessed first, which showed their disparate effects. The addition of three OLs increased the 72 h hydrolysis yield by 7.4% to 10.1%, while the addition of other two OLs reduced the 72 h hydrolysis yield by 3.2% to 20.4%. A strong correlation between the enzyme distribution coefficient on lignins and the 72 h hydrolysis yields indicated that the enzyme-lignin interaction played a significant role in determining the lignin effects. More importantly, a correlation between lignin properties (hydrophobicity, zeta potential, and particle size) and the enzyme distribution coefficient was established. Identifying the key lignin properties will give insights to reduce the lignin inhibition by altering the lignin properties, thereby promoting enzymatic hydrolysis of lignocellulose.

Consequences of Fluoride Incorporation on Properties of Apatites

2006 ◽  
Vol 309-311 ◽  
pp. 697-700 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
Dindo Q. Mijares ◽  
Fang Yao ◽  
John P. LeGeros ◽  
T. Bromage ◽  
...  
Keyword(s):  
Crystal Size ◽  
Chemical Properties ◽  
Calcium Deficiency ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Lower Solubility ◽  
Ft Ir ◽  
Hydrolysis Of ◽  
Ft Ir Spectroscopy

Fluoride, when incorporated in the apatite, stabilizes the structure. The purpose of this study was to determine the consequences of fluoride (F) substitution on the physico-chemical properties of apatites. F-containing apatites were prepared by precipitation or by hydrolysis of CaHPO4 in solutions containing different F concentrations and characterized using x-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, thermogravimetry and chemical analyses. Results showed that F incorporation have the following effects: (a) decrease in a-axis dimension, (b) increase in crystal size and thickness, (c) decrease in calcium deficiency, and (d) lower solubility.

scholarly journals Nanoantioxidants: Pioneer Types, Advantages, Limitations, and Future Insights

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7031
Author(s):  
Basma Omran ◽  
Kwang-Hyun Baek
Keyword(s):  
Oxidative Stress ◽  
Free Radical ◽  
Transition Metal Oxides ◽  
Targeted Delivery ◽  
Antioxidant Properties ◽  
Environmental Pollutants ◽  
Chemical Properties ◽  
Volume Ratio ◽  
Cellular Damage ◽  
Physico Chemical

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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