32 Combination of two or more metallic particles along with high surface area and porous structur... more 32 Combination of two or more metallic particles along with high surface area and porous structure exhibits 33 enhanced catalytic as well as antibacterial activity. Here, Ag-Cu bimetallic monoliths were synthesized by 34 nanocasting method by strictly adjusting the molar ratio of Ag-Cu. This work is mainly focused on the 35 effect of molar ratio (Ag:Cu) on surface area (14–110 m 2 /g) and porous size of bimetallic monoliths, 36 which has great influence on enhancement of catalytic and antimicrobial activity. The catalytic activity 37 of bimetallic Ag-Cu monoliths was evaluated for the reduction of 4-nitrophenol (4-NP) to 38 4-aminophenol (4-AP) in the presence of excess NaBH 4. The reaction rate follows pseudo-first order 39 for reduction of 4-NP with a reduction efficacy of $95%. The effect of Ag:Cu molar ratio and reaction con-40 ditions on the rate of reaction were investigated. In comparison with novel monometallic silver mono-41 liths, bimetallic Ag-Cu monoliths exhibit high catalytic performance on the reduction of 4-NP. These 42 heterogeneous catalysts were effortlessly recovered and reused (up to 8 cycles) after completion of cat-43 alytic reaction. As bimetallic Ag-Cu particles are well-known for antibacterial activity, so bactericidal 44 properties of synthesized monoliths are tested against E. coli and B. subtilis bacteria by minimum inhibi-45 tory concentration method (MIC). The calculated EC 50 (half maximum effective concentration) after com-46 pletion of incubation period, against E. coli and B. subtilis were 22.87 ± 0.015 and 23.33 ± 0.09 respectively 47 using Ag/Cu-3 bimetallic monolith. 48
A B S T R A C T Mesoporous MgO nanostructures with the high specific surface area (180 m 2 g −1) ... more A B S T R A C T Mesoporous MgO nanostructures with the high specific surface area (180 m 2 g −1) were synthesized via mixed surfactant-templating method. The synthesis of MgO with mixed surfactants system has rarely been discussed in the literature, which motivates us to synthesize MgO in this system. Alteration in catanionic surfactant molar ratio and chain length resulted in a change in surface area. Morphological and physical properties were analyzed using FESEM, HRTEM, FTIR and XRD. Synthesized MgO nanorods showed excellent adsorption properties for dye removal from aqueous solution. The obtained adsorption capacities were 333.33, 250 and 200 mg g −1 for Methylene Blue (MB), Alizarin red (AZ) and Rhodamine B (RD), respectively, which is higher or comparable with other reported methods in literature. Other than adsorption, MgO can act as a good bactericide. The effective antimicrobial activity of MgO was analyzed via minimal inhibitory concentration (MIC) method against E. coli and B. subtilis and obtained IC 50 (half maximal inhibitory concentration) values after 24 h were 71.98 ± 0.03 and 94.01 ± 0.030 respectively.
A B S T R A C T TiO 2 /bentonite nanocomposite was prepared by microwave irradiation method. Diff... more A B S T R A C T TiO 2 /bentonite nanocomposite was prepared by microwave irradiation method. Different quantities of Ag (0.5-3% by weight) were loaded to the nanocomposite by wet impregnation process to investigate their effect on the photocatalytic activity. Morphological and elemental analysis of the as-synthesized nanocomposites were carried out by field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), energy dispersive spectroscopy (EDS), inductively coupled plasma-Auger electron spectroscopy (ICP-AES) and X-ray photoelectron spectroscopy (XPS). Crystallographic studies were carried out by X-Ray diffraction analysis (XRD). From nitrogen adsorption-desorption (BET-Brunauer Emmett Teller) analysis it was found that surface area and pore volume decreased upon Ag loading but pore size distribution was not much affected in the nanocomposites. The absorption edge and band gap of the nanocomposites were found to be red-shifted after Ag loading as observed from UV–vis DRS (diffuse reflectance spectroscopy) spectra. The prepared Ag-TiO 2 /bentonite nanocomposites were found to be effective for photocatalytic degradation of harmful volatile organic compounds (VOCs) like chlorobenzene under both UV and visible light. The nanocomposite containing 1.5% of Ag was found to be highly active in degrading chlorobenzene both in UV and visible light.
In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide mo... more In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide monoliths (through nanocasting method) were synthesized. Porous silica and metal oxide monoliths (MnO 2 and TiO 2) exhibited excellent adsorption for heavy metal ions such as Pb(II) & Cd(II). The morphological and structural study of the synthesized silica and metal oxide monoliths were done by FESEM and XRD analysis. The adsorption studies were conducted in different batches. The maximum adsorption of Pb(II) on SiO 2 , MnO 2 and TiO 2 varied from 91 to 125, 166e200 and 769e857 mg/g respectively depending upon the choice of PEG, which is used as a structure directing/controlling agent. Similarly the maximum adsorption of Cd(II) on SiO 2 , MnO 2 and TiO 2 varied from 90 to 100, 100e125 and 667e770 mg/g respectively. The effects of contact time (0e80 min), temperature (at 303, 313 and 323 K) and pH (3e10) on the Pb(II) & Cd(II) removal were also explored.
To achieve maximum pore diameter and surface area of porous silica monoliths different structure ... more To achieve maximum pore diameter and surface area of porous silica monoliths different structure directing agents (SDAs) (Cationic/anionic/neutral/mixture) were used. BET study showed alteration of SDA's chain length, composition or concentration have a cumulative effect on controlling the surface area and pore size. PEG in combination with other SDAs like CTAB, SDS, BTMAC, Triton-X100 etc. controlled internal agglomeration along with particles size. The maximum amount of surface area was observed by using maximum chain length of PEG and CTAB.
Supply of pure drinking water and air is a perquisite for sustaining of civilization and in this ... more Supply of pure drinking water and air is a perquisite for sustaining of civilization and in this respect the clays are found to have significant importance as a semiconductor support material due to their layered morphology, chemical as well as mechanical stability, cation exchange capacity, non-toxic nature, low cost and availability. In spite of availability of technique very few studies have been done on the effect of clay structure on photocatalytic efficiency of semiconductor/clay nanocomposites. The TiO 2 /clay nano-composites were synthesized from different clays having textural differences (1:1 and 2:1); by a simple and time as well as cost effective method under microwave conditions. Formation of anatase TiO 2 nanoparticles on surface of different clays was achieved at 180 C within 10 min of time. Phase composition, particle morphology, specific surface area, chemical bonding, etc. of those samples were characterized by using XRD, TEM, FESEM, FTIR and nitrogen gas adsorption-desorption (BET) methods. Formation of TiO 2 nanoparticles on clay surface were confirmed by monitoring peaks of anatase TiO 2 with crystallite size 10e20 nm in X-Ray diffraction pattern of TiO 2 /Clay nanocomposites. The TiO 2 /clay nanocomposites exhibited high surface area and uniform pore distribution compared to pure clays and TiO 2 (Degussa P25, Germany). The photocatalytic activities of the nanocomposites were found to be depended on clay texture as well as optical characteristics apart from their surface area. The 2:1 clay (bentonite, kunipia-F) was observed to act as better support for TiO 2 in comparison with 1:1 clay (kaolin); regarding its photo-catalytic degradation of methylene blue (MB) and volatile organic compound (VOC) such as chlorobenzene (CB) due to their different texture and optical properties. TiO 2 / bentonite nanocomposite has high optical absorbance under UV spectrum. It also showed surface area of 112 m 2 /g with high photocatalytic activity with a rate constant 0.02886 and 0.0460 min À1 for MB and CB degradations respectively. It had also been found that, the photocatalytic activity of the TiO 2 /bentonite nanocomposites were 8 and 5 times higher for MB and CB degradation respectively in compare with Degussa P25.
In this study microwave assisted technique has been adopted for the synthesis of different weight... more In this study microwave assisted technique has been adopted for the synthesis of different weight ratios of TiO 2 dispersed on Santa barbara amorphous-15 (SBA-15) support. Morphological study revealed TiO 2 particles (4–10 nm) uniformly distributed on SBA-15 while increases in SBA-15 content results in higher specific surface area (524–237 m 2 /g). The diffraction intensity of 101 plane of anatase poly-morph was seen increasing with increase in TiO 2 ratio. All the photocatalysts were having a mesoporous nature and follow the Langmuir IV isotherm, SBA-15 posses the highest pore volume (0.93 cm 3 g-1) which consistently decreased with TiO 2 content and was lowest (0.50 cm 3 g-1) in case of 5 wt% of TiO 2 followed by P25 (0.45 cm 3 g-1) while pore diameter increased after TiO 2 incorporation due to pore strain. The photocatalytic activity of the nanocomposites were analysed for the photodegradation of alizarin dye and pentachlorophenol under UV light irradiation. The reaction kinetics suggested the highest efficiency (98 % for alizarin and 94 % for PCP) of 5 wt% TiO 2 compared to other photocatalysts, these nanocomposites were reused for several cycles, which is most important for heterogeneous photocat-alytic degradation reaction.
Silver nanoparticles (Ag NPs) were synthesized by one-step process in the presence of kollicoat a... more Silver nanoparticles (Ag NPs) were synthesized by one-step process in the presence of kollicoat as capping, reducing and stabilizing mediator. The synthesized NPs were characterized by using FTIR, TEM, DLS, XRD, EDS and UV-Vis spectroscopy. The resulting Ag NPs had an incom-parable colloidal stability against the salt addition and change of pH. The e®ect of di®erent synthesis parameters and the catalytic property of the NPs were examined.
Use of low-cost heterogeneous renewable catalysts are essential for effective removal of chemical... more Use of low-cost heterogeneous renewable catalysts are essential for effective removal of chemical contaminants like 4-nitrophenol (4-NP) from water bodies. In the present study, for the first time use of surface enhanced (14 m 2 /g) nanocasted mesoporous silver monolith (AgM) through impregnation into silica monoliths (prepared by sol–gel method) has been demonstrated for its catalytic and antibacterial activity. Highly efficient catalytic reduction rate (2.43 min −1) of 4-NP to 4-aminophenol (4-AP) has been demonstrated using 0.2 gL −1 of AgM catalyst. Enhancement of reduction rate is also observed with increase in temperature (from 25 to 40 °C). Removal of microbial contamination from drinking water is also a prime concern for water purification. Mesoporous AgM shows effective antimicrobial activity against gram negative (E. coli) and gram positive (B. subtilis) bacteria with IC 50 values of 75.86 ± 0.173 and 74.56 ± 0.103 respectively at 24 h of incubation. Graphical Abstract Use of low-cost renewable catalysts is essential for effective removal of a chemical contaminant like 4-nitrophenol (4-NP) from water bodies. Nanocasted mesoporous silver monolith (AgM) synthesized via impregnation into silica monoliths (prepared by sol-gel method) has been demonstrated for its catalytic and anti-bacterial activity. Mesoporous AgM also showed effective antimicrobial activity against gram negative and gram positive bacteria.
32 Combination of two or more metallic particles along with high surface area and porous structur... more 32 Combination of two or more metallic particles along with high surface area and porous structure exhibits 33 enhanced catalytic as well as antibacterial activity. Here, Ag-Cu bimetallic monoliths were synthesized by 34 nanocasting method by strictly adjusting the molar ratio of Ag-Cu. This work is mainly focused on the 35 effect of molar ratio (Ag:Cu) on surface area (14–110 m 2 /g) and porous size of bimetallic monoliths, 36 which has great influence on enhancement of catalytic and antimicrobial activity. The catalytic activity 37 of bimetallic Ag-Cu monoliths was evaluated for the reduction of 4-nitrophenol (4-NP) to 38 4-aminophenol (4-AP) in the presence of excess NaBH 4. The reaction rate follows pseudo-first order 39 for reduction of 4-NP with a reduction efficacy of $95%. The effect of Ag:Cu molar ratio and reaction con-40 ditions on the rate of reaction were investigated. In comparison with novel monometallic silver mono-41 liths, bimetallic Ag-Cu monoliths exhibit high catalytic performance on the reduction of 4-NP. These 42 heterogeneous catalysts were effortlessly recovered and reused (up to 8 cycles) after completion of cat-43 alytic reaction. As bimetallic Ag-Cu particles are well-known for antibacterial activity, so bactericidal 44 properties of synthesized monoliths are tested against E. coli and B. subtilis bacteria by minimum inhibi-45 tory concentration method (MIC). The calculated EC 50 (half maximum effective concentration) after com-46 pletion of incubation period, against E. coli and B. subtilis were 22.87 ± 0.015 and 23.33 ± 0.09 respectively 47 using Ag/Cu-3 bimetallic monolith. 48
A B S T R A C T Mesoporous MgO nanostructures with the high specific surface area (180 m 2 g −1) ... more A B S T R A C T Mesoporous MgO nanostructures with the high specific surface area (180 m 2 g −1) were synthesized via mixed surfactant-templating method. The synthesis of MgO with mixed surfactants system has rarely been discussed in the literature, which motivates us to synthesize MgO in this system. Alteration in catanionic surfactant molar ratio and chain length resulted in a change in surface area. Morphological and physical properties were analyzed using FESEM, HRTEM, FTIR and XRD. Synthesized MgO nanorods showed excellent adsorption properties for dye removal from aqueous solution. The obtained adsorption capacities were 333.33, 250 and 200 mg g −1 for Methylene Blue (MB), Alizarin red (AZ) and Rhodamine B (RD), respectively, which is higher or comparable with other reported methods in literature. Other than adsorption, MgO can act as a good bactericide. The effective antimicrobial activity of MgO was analyzed via minimal inhibitory concentration (MIC) method against E. coli and B. subtilis and obtained IC 50 (half maximal inhibitory concentration) values after 24 h were 71.98 ± 0.03 and 94.01 ± 0.030 respectively.
A B S T R A C T TiO 2 /bentonite nanocomposite was prepared by microwave irradiation method. Diff... more A B S T R A C T TiO 2 /bentonite nanocomposite was prepared by microwave irradiation method. Different quantities of Ag (0.5-3% by weight) were loaded to the nanocomposite by wet impregnation process to investigate their effect on the photocatalytic activity. Morphological and elemental analysis of the as-synthesized nanocomposites were carried out by field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), energy dispersive spectroscopy (EDS), inductively coupled plasma-Auger electron spectroscopy (ICP-AES) and X-ray photoelectron spectroscopy (XPS). Crystallographic studies were carried out by X-Ray diffraction analysis (XRD). From nitrogen adsorption-desorption (BET-Brunauer Emmett Teller) analysis it was found that surface area and pore volume decreased upon Ag loading but pore size distribution was not much affected in the nanocomposites. The absorption edge and band gap of the nanocomposites were found to be red-shifted after Ag loading as observed from UV–vis DRS (diffuse reflectance spectroscopy) spectra. The prepared Ag-TiO 2 /bentonite nanocomposites were found to be effective for photocatalytic degradation of harmful volatile organic compounds (VOCs) like chlorobenzene under both UV and visible light. The nanocomposite containing 1.5% of Ag was found to be highly active in degrading chlorobenzene both in UV and visible light.
In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide mo... more In the present study, ordered hierarchically porous silica (by sol-gel method) and metal-oxide monoliths (through nanocasting method) were synthesized. Porous silica and metal oxide monoliths (MnO 2 and TiO 2) exhibited excellent adsorption for heavy metal ions such as Pb(II) & Cd(II). The morphological and structural study of the synthesized silica and metal oxide monoliths were done by FESEM and XRD analysis. The adsorption studies were conducted in different batches. The maximum adsorption of Pb(II) on SiO 2 , MnO 2 and TiO 2 varied from 91 to 125, 166e200 and 769e857 mg/g respectively depending upon the choice of PEG, which is used as a structure directing/controlling agent. Similarly the maximum adsorption of Cd(II) on SiO 2 , MnO 2 and TiO 2 varied from 90 to 100, 100e125 and 667e770 mg/g respectively. The effects of contact time (0e80 min), temperature (at 303, 313 and 323 K) and pH (3e10) on the Pb(II) & Cd(II) removal were also explored.
To achieve maximum pore diameter and surface area of porous silica monoliths different structure ... more To achieve maximum pore diameter and surface area of porous silica monoliths different structure directing agents (SDAs) (Cationic/anionic/neutral/mixture) were used. BET study showed alteration of SDA's chain length, composition or concentration have a cumulative effect on controlling the surface area and pore size. PEG in combination with other SDAs like CTAB, SDS, BTMAC, Triton-X100 etc. controlled internal agglomeration along with particles size. The maximum amount of surface area was observed by using maximum chain length of PEG and CTAB.
Supply of pure drinking water and air is a perquisite for sustaining of civilization and in this ... more Supply of pure drinking water and air is a perquisite for sustaining of civilization and in this respect the clays are found to have significant importance as a semiconductor support material due to their layered morphology, chemical as well as mechanical stability, cation exchange capacity, non-toxic nature, low cost and availability. In spite of availability of technique very few studies have been done on the effect of clay structure on photocatalytic efficiency of semiconductor/clay nanocomposites. The TiO 2 /clay nano-composites were synthesized from different clays having textural differences (1:1 and 2:1); by a simple and time as well as cost effective method under microwave conditions. Formation of anatase TiO 2 nanoparticles on surface of different clays was achieved at 180 C within 10 min of time. Phase composition, particle morphology, specific surface area, chemical bonding, etc. of those samples were characterized by using XRD, TEM, FESEM, FTIR and nitrogen gas adsorption-desorption (BET) methods. Formation of TiO 2 nanoparticles on clay surface were confirmed by monitoring peaks of anatase TiO 2 with crystallite size 10e20 nm in X-Ray diffraction pattern of TiO 2 /Clay nanocomposites. The TiO 2 /clay nanocomposites exhibited high surface area and uniform pore distribution compared to pure clays and TiO 2 (Degussa P25, Germany). The photocatalytic activities of the nanocomposites were found to be depended on clay texture as well as optical characteristics apart from their surface area. The 2:1 clay (bentonite, kunipia-F) was observed to act as better support for TiO 2 in comparison with 1:1 clay (kaolin); regarding its photo-catalytic degradation of methylene blue (MB) and volatile organic compound (VOC) such as chlorobenzene (CB) due to their different texture and optical properties. TiO 2 / bentonite nanocomposite has high optical absorbance under UV spectrum. It also showed surface area of 112 m 2 /g with high photocatalytic activity with a rate constant 0.02886 and 0.0460 min À1 for MB and CB degradations respectively. It had also been found that, the photocatalytic activity of the TiO 2 /bentonite nanocomposites were 8 and 5 times higher for MB and CB degradation respectively in compare with Degussa P25.
In this study microwave assisted technique has been adopted for the synthesis of different weight... more In this study microwave assisted technique has been adopted for the synthesis of different weight ratios of TiO 2 dispersed on Santa barbara amorphous-15 (SBA-15) support. Morphological study revealed TiO 2 particles (4–10 nm) uniformly distributed on SBA-15 while increases in SBA-15 content results in higher specific surface area (524–237 m 2 /g). The diffraction intensity of 101 plane of anatase poly-morph was seen increasing with increase in TiO 2 ratio. All the photocatalysts were having a mesoporous nature and follow the Langmuir IV isotherm, SBA-15 posses the highest pore volume (0.93 cm 3 g-1) which consistently decreased with TiO 2 content and was lowest (0.50 cm 3 g-1) in case of 5 wt% of TiO 2 followed by P25 (0.45 cm 3 g-1) while pore diameter increased after TiO 2 incorporation due to pore strain. The photocatalytic activity of the nanocomposites were analysed for the photodegradation of alizarin dye and pentachlorophenol under UV light irradiation. The reaction kinetics suggested the highest efficiency (98 % for alizarin and 94 % for PCP) of 5 wt% TiO 2 compared to other photocatalysts, these nanocomposites were reused for several cycles, which is most important for heterogeneous photocat-alytic degradation reaction.
Silver nanoparticles (Ag NPs) were synthesized by one-step process in the presence of kollicoat a... more Silver nanoparticles (Ag NPs) were synthesized by one-step process in the presence of kollicoat as capping, reducing and stabilizing mediator. The synthesized NPs were characterized by using FTIR, TEM, DLS, XRD, EDS and UV-Vis spectroscopy. The resulting Ag NPs had an incom-parable colloidal stability against the salt addition and change of pH. The e®ect of di®erent synthesis parameters and the catalytic property of the NPs were examined.
Use of low-cost heterogeneous renewable catalysts are essential for effective removal of chemical... more Use of low-cost heterogeneous renewable catalysts are essential for effective removal of chemical contaminants like 4-nitrophenol (4-NP) from water bodies. In the present study, for the first time use of surface enhanced (14 m 2 /g) nanocasted mesoporous silver monolith (AgM) through impregnation into silica monoliths (prepared by sol–gel method) has been demonstrated for its catalytic and antibacterial activity. Highly efficient catalytic reduction rate (2.43 min −1) of 4-NP to 4-aminophenol (4-AP) has been demonstrated using 0.2 gL −1 of AgM catalyst. Enhancement of reduction rate is also observed with increase in temperature (from 25 to 40 °C). Removal of microbial contamination from drinking water is also a prime concern for water purification. Mesoporous AgM shows effective antimicrobial activity against gram negative (E. coli) and gram positive (B. subtilis) bacteria with IC 50 values of 75.86 ± 0.173 and 74.56 ± 0.103 respectively at 24 h of incubation. Graphical Abstract Use of low-cost renewable catalysts is essential for effective removal of a chemical contaminant like 4-nitrophenol (4-NP) from water bodies. Nanocasted mesoporous silver monolith (AgM) synthesized via impregnation into silica monoliths (prepared by sol-gel method) has been demonstrated for its catalytic and anti-bacterial activity. Mesoporous AgM also showed effective antimicrobial activity against gram negative and gram positive bacteria.
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