: In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of... more : In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of organic pollutants from tainted water using photodegradation, since the available chemical, physical, and biological methods often are time consuming, involve high cost and dumping complications, sometimes posing serious threat to both human health and environmental elements. Use of nanomaterials is less expensive and does not, in general, form aggregated macromolecules. In addition, nanotechnology for waste-water treatment demolishes or alters the risky chemical wastes to harmless end products like H2O and CO2. Nanomaterials synthesized from natural resources or prepared using green synthetic routes are receiving surge of interest as our consciousness to ecological environment and safety rises. ‘Green’ materials of this kind might also show unique strength features and exceptional biodegradability, along with their other notable advantageous properties like minimum threat to environment, efficient recyclablity and low cost compared to synthetic nanomaterials. Such green nanomaterials can also serve as nanocatalysts to treat toxic organic pollutants in a safer way, including photodegradation to less or non-toxic products. This article reviews latest developments on the synthesis of some promising green nanomaterials aiming towards their efficient uses as photocatalysts for degradation of organic pollutants. Strategies to find new green materials as photocatalysts by modification of technologies, and development of novel methodologies for safer treatment of organic pollutants will also be discussed.
ABSTRACT Electrochemical behaviour of cobalt salt was carried out on a glassy carbon electrode an... more ABSTRACT Electrochemical behaviour of cobalt salt was carried out on a glassy carbon electrode and a copper electrode (CuE) using aqueous cobalt(II) nitrate solution. The electrochemical behaviour was also studied on CuE using a hydrophilic ionic liquid, 1-ethyl-3-methylimidazolium ethylsulphate ([emim][EtSO4]). The [emim][EtSO4] has been found to be electroinactive in the reduction potential range of cobalt(II) ion, and electrodeposition could be successfully performed from [emim][EtSO4] at ambient condition. Scanning electron microscopic images of the deposited cobalt show that cobalt is deposited from [emim][EtSO4] in nanodimension, and the thickness of the deposited film depends on the time of electrolysis retaining the dimension of the electrodeposited cobalt on CuE.
Background: Honey is known for its various physical properties, chemical contents and as a topica... more Background: Honey is known for its various physical properties, chemical contents and as a topical therapeutic agent. However its potential use in diagnostic radiology has not been reported.Aims: To establish radio opacity of honey as its unique physical property, to establish its relationship with other physical properties, chemical contents and to determine if honey has any potential as diagnostic contrast media.Material and Methods: CT scanner was used to calculate radio density in Hounsfield Unit (HU) on six honey samples, honey samples of different dilutions, Iopamidol, 25% glucose and agents containing Calcium, Iron, Magnesium and Potassium. Plain X-ray was obtained on honey samples, honey filled plastic tubes, and honey impregnated cotton gauze. Radio density of honey samples was compared with four selected physical properties of honey.Results: Radio density of six honey samples ranged between 287±3.4 HU and 329±5.3 HU. Radio density of 2% Iopamidol, a commonly used radio con...
Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a cont... more Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a contrasting structure; it consists of a rigid and brittle 1 st network with dilute, densely cross-linked short chains and a soft and ductile 2 nd network with concentrated, loosely cross-linked long chains. In this work, we focus on how the brittle gel changes into a tough one by increasing the amount of ductile component. By comparing the molecular structures of the individual first network and second network gels, we found that the true key factor that controls the brittleductile transition is the density of elastically effective polymer strands of the two networks, and. When / < 1, the second network fractures right after the fracture of the first network, and the gels are brittle. When / > 1, only the first network fractures. As a result, the brittle first network serves as sacrificial bonds, imparting toughness of DN gels. This result provides essential information to design tough materials based on the double network concept. Scheme 1: Illustration of super-tough double network (DN) gels with a contrasting structure. The blue and pink lines represent the 1 st and 2 nd networks respectively and the filled circles indicate chemical cross-linking points. The two networks do not have internetwork chemical bond, creating a truly interpenetrating network (IPN) structure. The chemical structures of PAMPS and PAAm as first and second networks, respectively, is shown on the right.
Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from... more Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from the internal fracture of the brittle network during deformation, which dissipates energy as sacrificial bonds. In this study, we intend to elucidate the detailed internal fracture process of DN gels. We quantitatively analysed the tensile hysteresis and re-swelling behaviour of a DN gel that shows a well-defined necking and strain hardening, and obtained the following new findings: 1) Fracture of the 1 st network PAMPS starts far below the yielding strain, and 90% of the initially load-bearing PAMPS chains already breaks at the necking point. 2) The dominant internal fracture process occurs in the necking and hardening region although the softening mainly occurs before necking. 3) The internal fracture efficiency is very high, 85% of the work is used for the internal fracture and 9% of all PAMPS chains break at sample failure. 4) The internal fracture is anisotropic, fracture occurs preferentially perpendicular to the tensile direction than other two directions, but the fracture anisotropy decreases in the hardening region. Result 1) and 2) is in agreement with a hierarchical structural model of PAMPS network. Based on these findings, we present a revised description of the fracture process of DN gels.
: In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of... more : In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of organic pollutants from tainted water using photodegradation, since the available chemical, physical, and biological methods often are time consuming, involve high cost and dumping complications, sometimes posing serious threat to both human health and environmental elements. Use of nanomaterials is less expensive and does not, in general, form aggregated macromolecules. In addition, nanotechnology for waste-water treatment demolishes or alters the risky chemical wastes to harmless end products like H2O and CO2. Nanomaterials synthesized from natural resources or prepared using green synthetic routes are receiving surge of interest as our consciousness to ecological environment and safety rises. ‘Green’ materials of this kind might also show unique strength features and exceptional biodegradability, along with their other notable advantageous properties like minimum threat to environment, efficient recyclablity and low cost compared to synthetic nanomaterials. Such green nanomaterials can also serve as nanocatalysts to treat toxic organic pollutants in a safer way, including photodegradation to less or non-toxic products. This article reviews latest developments on the synthesis of some promising green nanomaterials aiming towards their efficient uses as photocatalysts for degradation of organic pollutants. Strategies to find new green materials as photocatalysts by modification of technologies, and development of novel methodologies for safer treatment of organic pollutants will also be discussed.
ABSTRACT Electrochemical behaviour of cobalt salt was carried out on a glassy carbon electrode an... more ABSTRACT Electrochemical behaviour of cobalt salt was carried out on a glassy carbon electrode and a copper electrode (CuE) using aqueous cobalt(II) nitrate solution. The electrochemical behaviour was also studied on CuE using a hydrophilic ionic liquid, 1-ethyl-3-methylimidazolium ethylsulphate ([emim][EtSO4]). The [emim][EtSO4] has been found to be electroinactive in the reduction potential range of cobalt(II) ion, and electrodeposition could be successfully performed from [emim][EtSO4] at ambient condition. Scanning electron microscopic images of the deposited cobalt show that cobalt is deposited from [emim][EtSO4] in nanodimension, and the thickness of the deposited film depends on the time of electrolysis retaining the dimension of the electrodeposited cobalt on CuE.
Background: Honey is known for its various physical properties, chemical contents and as a topica... more Background: Honey is known for its various physical properties, chemical contents and as a topical therapeutic agent. However its potential use in diagnostic radiology has not been reported.Aims: To establish radio opacity of honey as its unique physical property, to establish its relationship with other physical properties, chemical contents and to determine if honey has any potential as diagnostic contrast media.Material and Methods: CT scanner was used to calculate radio density in Hounsfield Unit (HU) on six honey samples, honey samples of different dilutions, Iopamidol, 25% glucose and agents containing Calcium, Iron, Magnesium and Potassium. Plain X-ray was obtained on honey samples, honey filled plastic tubes, and honey impregnated cotton gauze. Radio density of honey samples was compared with four selected physical properties of honey.Results: Radio density of six honey samples ranged between 287±3.4 HU and 329±5.3 HU. Radio density of 2% Iopamidol, a commonly used radio con...
Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a cont... more Tough double network (DN) hydrogels are a kind of interpenetrating network (IPN) gels with a contrasting structure; it consists of a rigid and brittle 1 st network with dilute, densely cross-linked short chains and a soft and ductile 2 nd network with concentrated, loosely cross-linked long chains. In this work, we focus on how the brittle gel changes into a tough one by increasing the amount of ductile component. By comparing the molecular structures of the individual first network and second network gels, we found that the true key factor that controls the brittleductile transition is the density of elastically effective polymer strands of the two networks, and. When / < 1, the second network fractures right after the fracture of the first network, and the gels are brittle. When / > 1, only the first network fractures. As a result, the brittle first network serves as sacrificial bonds, imparting toughness of DN gels. This result provides essential information to design tough materials based on the double network concept. Scheme 1: Illustration of super-tough double network (DN) gels with a contrasting structure. The blue and pink lines represent the 1 st and 2 nd networks respectively and the filled circles indicate chemical cross-linking points. The two networks do not have internetwork chemical bond, creating a truly interpenetrating network (IPN) structure. The chemical structures of PAMPS and PAAm as first and second networks, respectively, is shown on the right.
Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from... more Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from the internal fracture of the brittle network during deformation, which dissipates energy as sacrificial bonds. In this study, we intend to elucidate the detailed internal fracture process of DN gels. We quantitatively analysed the tensile hysteresis and re-swelling behaviour of a DN gel that shows a well-defined necking and strain hardening, and obtained the following new findings: 1) Fracture of the 1 st network PAMPS starts far below the yielding strain, and 90% of the initially load-bearing PAMPS chains already breaks at the necking point. 2) The dominant internal fracture process occurs in the necking and hardening region although the softening mainly occurs before necking. 3) The internal fracture efficiency is very high, 85% of the work is used for the internal fracture and 9% of all PAMPS chains break at sample failure. 4) The internal fracture is anisotropic, fracture occurs preferentially perpendicular to the tensile direction than other two directions, but the fracture anisotropy decreases in the hardening region. Result 1) and 2) is in agreement with a hierarchical structural model of PAMPS network. Based on these findings, we present a revised description of the fracture process of DN gels.
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