Askwar Hilonga | NM-AIST, Arusha, Tanzania (original) (raw)

Papers by Askwar Hilonga

Applied Water Science, 2017

Materials Today Chemistry, Jun 1, 2021

Abstract In this study, the efficacy of inorganic additives in the removal of total ammonia nitro... more Abstract In this study, the efficacy of inorganic additives in the removal of total ammonia nitrogen (TAN) and sulfide in the aqueous phase of slaughterhouse waste undergoing anaerobic digestion in the batch reactor was investigated. A mixture of natural inorganic additives processed from the anthill and red rock soil samples collected from Arusha, Tanzania were used as adsorbents in different ratios. These materials were chosen in regard to their abundance in the local environment, surface properties, and elemental composition. Before analysis, the materials were pulverized and calcined at 700 and 900 °C for 2 h in a furnace and then sieved to 250 μm fine particle size. XRD analysis revealed that the anthill soil sample is endowed with major mineral phases of quartz and hematite while red rock soil contains albite, pyroxene, and quartz as predominant phases. The anthill and red rock soil samples calcined at 900 °C displayed higher BET surface areas of 815.35 and 852.35 m2/g, respectively. The mixture of anthill soil and red rock soil in a ratio of 3:1 had a higher TAN removal efficiency of 92% at a contact time of 30 min compared to other ratios. On the other hand, a ratio of 1:2 showed a higher sulfide removal efficiency of 79% at a contact time of 60 min. Adsorption isotherm studies revealed that the Jovanovich model fitted better to the experimental data than the Langmuir and Freundlich models. The results demonstrated further that inorganic additives have a synergistic effect on stimulating methanogenesis as well as eliminating ammonia and sulfide during anaerobic digestion of slaughterhouse waste. Our findings demonstrate that anthill and red rock soils can be exploited as affordable, ecofriendly, and efficient adsorbents for mitigation of TAN and sulfide from the liquid phase and sustenance of methanogenesis.

Journal of packaging technology and research, Feb 20, 2020

The effects of mixing sequence of starch-chitosan nanocomposite films on antimicrobial properties... more The effects of mixing sequence of starch-chitosan nanocomposite films on antimicrobial properties of vanillin, the release kinetics of vanillin, and physicomechanical changes of films have been reported. Four types of films were prepared based on the order of mixing. SC1: starch-glycerol-MMT-vanillin; SC2: starch-glycerol-chitosan-MMT-vanillin; SC3: starch-MMT-glycerol-vanillin-chitosan and SC4: starch-chitosan-glycerol-vanillin-MMT. All formulation exhibited high antimicrobial activity against E. coli, S. enterica, and Z. bailii, except P. aeruginosa, which showed lower sensitivity. Migration dynamics of vanillin from films into simulants showed high vanillin migrated into water and 10% ethanol at 25 and 40 °C as analyzed by high-performance liquid chromatography (HPLC). The diffusion coefficients of vanillin in water ranged between 0.38 × 10 −13 m 2 s −1 and 4.30 × 10 −13 m 2 s −1 and in 10% ethanol between 1.38 × 10 −13 m 2 s −1 and 5.16 × 10 −13 m 2 s −1 following the Fickian diffusion mechanism and first-order kinetics. The diffusion was temperature-dependent following the Arrhenius equation with high activation energies of 15.00-52.80 kJmol −1 in water and 35.80-56.50 kJ mol −1 in 10% ethanol. The plot of the mass fraction of m t m ∞ against time for each sample shows the burst release of vanillin in between 30 min and 1 h and then attained the steady-state migration over 48 h. The plasticization effect of vanillin reduced the tensile strength and elastic modulus of films, while it increased the elongation at the break by 154% that was reversed after the addition of chitosan. These nanostructured starch films showed promising applications in the antimicrobial packaging industry.

Effluents resulting from the frequent use of industrial azo dyes in textile operations have posed... more Effluents resulting from the frequent use of industrial azo dyes in textile operations have posed great toxicological impacts on man and the environment. The limitations of conventional treatment infrastructure necessitate the use of rapid Fenton-mediated catalytic systematic process to tackle the attendant treatment limitations. The study applied in situ Fenton-mediation process with constructed low power UV-LED reactor for rapid catalytic treatment of dye-laden effluent using enhanced acid and alkali TiO 2-nanoparticles (Nps) (1-5%, i.e. 1-5 M) at definite experimental conditions, respectively. A comprehensive instrumental study was done to access the morphological, functional and elemental constituents of these nanocatalysts. The performance of the respective catalyst was evaluated using methylene blue (MB) dye at definite experimental conditions of pH, dosage, concentration and irradiation time. The results revealed a mesoporous structural nanocatalyst with increasing surface area after enhanced modification. The optimal experimental conditions of pH and concentration were recorded as 5 and 10 mg/L, respectively; while the most efficient nanocatalyst was 3 wt% alkali-modified TiO 2 (3% Ak-TiO 2) having a degradation efficiency of 89.15% at 90 min of irradiation using 50 mg dosage in contrast to higher irradiation time and catalyst dosage for other catalysts.

Journal of Biomimetics, Biomaterials and Biomedical Engineering, May 31, 2023

The aim of this study was to develop and characterize a delivery system for polyphenols from an e... more The aim of this study was to develop and characterize a delivery system for polyphenols from an extract of Carissa spinarum leaves, based on liposomes. Liposomes loaded with Carissa spinarum polyphenols (nanoliposomal CsP) were prepared by ethanol-solvent injection method and characterized in terms of zeta potential, size, and polydipersity index by using Zeta sizer and Fourier Transform Infrared spectrum analysis. Total Phenolic content was measured by using Folin-Ciocalteu method and entrapment efficiency was evaluated. The release behavior was conducted in Phosphate Buffer Saline (PBS) solution at pH, 7.4 and Kinetic model fitted to evaluate mechanism of release. Disc diffusion sensitivity test was used to evaluate antimicrobial activity of free extract and nanoliposomal CsP. The mean diameter of nanoliposomal CsP was 181 ± 1.02 nm and had 0.345 ± 0.014 polydipersity index. Zeta potential value for nanoliposomal CsP was-45.6 ± 8.84 mV. Entrapment efficiency under the optimum conditions was 66.11 ± 1.11%. and the nanoliposomal CsP was stable over 30 days. The antibacterial activity of nanoliposomal CsP exhibited inhibition zone diameter of 14.33 ± 1.53 mm and 12.00 ± 1.23 mm against S. aureus and E. coli respectively The results reveal the Carrisa spinarum liposome can be applied as potential carrier for delivery of polyphenols to improves therapeutic action against bacterial strain.

Materials Letters, Aug 1, 2012

The aim of this study is to identify an acid precursor that is most desirable for the synthesis o... more The aim of this study is to identify an acid precursor that is most desirable for the synthesis of sodium silicate-based silver-doped silica for large-scale industrial production. The final products were developed based on the presence of silver (silver-doped silica) or the absence of silver (pure silica). The properties of the obtained final products were examined using the BET method. This method involves characterization based on N2 physisorption studies to determine the surface area, pore diameter, and pore volume. Various graphs ...

Materials Chemistry and Physics, Jun 1, 2019

Journal of Industrial and Engineering Chemistry, 2013

Chemical Engineering Journal, Aug 1, 2012

h i g h l i g h t s " Titania-silica composites are prepared via peptization sol-gel method. " Si... more h i g h l i g h t s " Titania-silica composites are prepared via peptization sol-gel method. " Silicic acid yielded from water glass is used as a precursor and peptizing agent. " The composite formed by peptizing Ti(OH) 4 gel into silicic acid has anatase phase. " Anatase and rutile form in the composite where nitric acid was a peptizing agent.

Nanotechnology, Science and Applications, Dec 1, 2014

The goal of this study was to explore the effects of spray-drying on w/o/w double emulsions of me... more The goal of this study was to explore the effects of spray-drying on w/o/w double emulsions of methyltestosterone (MT) loaded in a stearic acid matrix. MT-loaded nanoparticles were formulated by a water-in-oil-in-water emulsion technique using 50, 75, and 100 mg of stearic acid, 2% and 3% w/v polyvinyl alcohol, 5% w/v lactose, and 0.2% w/v chitosan. The emulsions were immediately spray-dried based on an optimized model of inlet temperature and pump rate, and characterized for optimized responses with regard to particle size, polydispersity index, and zeta potential, for both emulsion and powder samples. Dynamic light scattering analysis shown that the nanoparticles increased in size with increasing concentrations of polyvinyl alcohol and stearic acid. Scanning electron microscopy indicated that the MT-loaded nanoparticles were spherical in shape, had a smooth surface, and were in an amorphous state, which was confirmed by differential scanning calorimetry. These MT-loaded nanoparticles are a promising candidate carrier for the delivery of MT; however, further studies are needed in order to establish the stability of the system and the cargo release profile under normal conditions of use.

Materials Letters, Feb 1, 2012

Here, we report on the synthesis of silver nanoparticles (Ag-NPs) manipulating the pores of silic... more Here, we report on the synthesis of silver nanoparticles (Ag-NPs) manipulating the pores of silica beads (SBs) with sizes ranging from 0.5 to 1mm. Silver ions were occluded inside the pores of SBs and in situ reduced to Ag-NPs using Sodium borohydride (NaBH4). SBs with different average pore diameters from 3.8 to 20nm were used to assess the effect of their pore sizes and porous structures on the formation of Ag-NPs. Obtained results revealed that the silver amount occluded inside pores increases along with the increase of total pore ...

Powder Technology, 2012

In this study a simple and reproducible method was used to develop silver-doped silica powder wit... more In this study a simple and reproducible method was used to develop silver-doped silica powder with antibacterial properties. Silica matrices were synthesized via a sol–gel route which allows one to easily tailor textural and chemical properties. A wide range of silica-materials/products was obtained via the present route. These are: pure silver nanoparticles (Ag0), silver in ionic state (Ag+), AgCl nanoparticles, and the mixture of Ag0 and AgCl. The efficacy of these products were tested against Escherichia coli and the results ...

Powder Technology, 2013

Abstract Titania silica composites (TSC) with various Ti/Si ratios were synthesized via sol–gel p... more Abstract Titania silica composites (TSC) with various Ti/Si ratios were synthesized via sol–gel process using less expensive precursors; sodium silicate solution as a silica source and titanium oxychloride as a titania source. The influence of varying Ti content in the composites was examined by FTIR, SEM, TEM, DTA/TGA, N 2 physisorption studies, XRF and XRD. The BET surface area of the raw materials increased with increasing Ti/Si ratio up to 2.9 (461 m 2/g) but further increase of Ti content beyond that ratio yielded composites ...

Materials Letters, Aug 1, 2012

ABSTRACT Here we report the preparation of micrometer-sized highly nanoporous, relatively trasper... more ABSTRACT Here we report the preparation of micrometer-sized highly nanoporous, relatively trasperant silica aerogel beads with high surface area as well as large pore volume with sizes ranging from 165 to 395 μm. The wet micrometer-sized silica hydrogel beads were prepared through hydrolysis and polycondensation of sodium silicate as a silica precursor. A hydrophobic micro-silica aerogel nanoporous bead was synthesized by simultaneous solvent exchange surface modification process of as synthesized micron sized silica hydrogel bead at an ambient pressure. Hydrophilic micron-sized silica aerogel beads with relatively more textural properties (surface area, pore volume and pore size) with its counterpart were obtained by heating the synthesized hydrophobic micro-silica aerogel beads at 395 °C for an hour. This study demonstrates a robust approach to high porous hydrophobic and hydrophilic micro-silica aerogel beads with a myriad of potential applications in various fileds such as catalysis, biomolecule immobilization, chromatographic separation, and CO 2 absorption. This proposed synthesis, which exploits a low-cost silica source (water-glass), is suitable for large-scale industrial production of highly porous hydrophobic and hydrophilic micro-silica aerogel beads at an ambient pressure.

Applied Surface Science, Nov 1, 2011

The conventional drying (oven drying) method used for the preparation of precipitated mesoporous ... more The conventional drying (oven drying) method used for the preparation of precipitated mesoporous silica with low surface area (>300 m 2 /g) and small pore volume is often associated with a high production cost and a time consuming process. Therefore, the main goal of this study was to develop a cost-effective and fast drying process for the production of precipitated mesoporous silica using inexpensive industrial grade sodium silicate and spray drying of the precipitated wet-gel silica slurry. The precipitated wet-gel silica slurry was prepared from an aqueous sodium silicate solution through the drop-wise addition of sulfuric acid. Mesoporous precipitated silica powder was prepared by drying the wet-gel slurry with different drying techniques. The effects of the oven drying (OD), microwave drying (MD), and spray drying (SD) techniques on the physical (oil, water absorption, and tapping density), and textural properties (specific BET surface area, pore volume, pore size, and % porosity) of the precipitated mesoporous silica powder were studied. The dried precipitated mesoporous silica powders were characterized with field-emission scanning electron microscopy; Brunauer, Emmett and Teller and BJH nitrogen gas adsorption/desorption methods; Fourier-transform infrared spectroscopy; thermogravimetric and differential analysis; N 2 physisorption isotherm; pore size distribution and particle size analysis. There was a significant effect of drying technique on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the mesoporous silica powder. Additionally, the effect of the microwave-drying period on the physicochemical properties of the precipitated mesoporous silica powder was investigated and discussed.

Powder Technology, Feb 1, 2012

Mesoporous titania-silica composite (MTSC) with a large surface area (387 m 2 /g) and large pore ... more Mesoporous titania-silica composite (MTSC) with a large surface area (387 m 2 /g) and large pore volume was synthesized by a two step condensation sol-gel method. Transparent TiO 2 sol was formed at room temperature through condensation and peptization of titanium oxychloride solution using ammonium hydroxide and aqueous nitric acid respectively. Sodium silicate was used as a silica source to form a composite with the preformed TiO 2 sol. The physical properties of the composite were examined by Fourier Transform infrared (FTIR), BET surface area, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The nitrogen physisorption behavior of the synthesized composite was compared to that obtained from grafting and one-pot co-condensation methods using the same precursors in the presence of cetyltrimethylammonium bromide (CTAB). It was found that MTSC synthesized under this method possessed large pore sizes and pore volume but its thermal stability was comparatively low. FTIR spectra showed the formation of a Ti\O\Si bond at 940 cm − 1 suggesting that titania was incorporated in silica to form a composite. The XRD patterns showed that the major phase of the titania had an anatase phase up to 900°C but it transforms into rutile when calcined at 1000°C. Furthermore the EDS studies of the as-synthesized and calcined samples substantiated the formation of titania-silica composites.

Journal of physics, Mar 1, 2018

View the article online for updates and enhancements. You may also like Optimum parameters for th... more View the article online for updates and enhancements. You may also like Optimum parameters for the production of nano-scale electrospun polycaprolactone to be used as a biomedical material Basma Ekram, Bothaina M Abdel-Hady, Abeer M El-kady et al.-Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

This book demonstrates the potential of developing porous Nanomaterials by using renewable surfac... more This book demonstrates the potential of developing porous Nanomaterials by using renewable surfactant/template obtained from cashew nuts shell liquid. This approach is environmentally friendly and might be considered for the large scale production of Nanomaterials for industrial application. The Nanomaterials obtained could be used for various applications such as water purification, antibacterial agent, thin films, etc. The success of this work will add value to cashew nuts farmers who are currently not benefiting at all from the liquids obtained after processing the cashew nuts. So there is a lot of win-win through the success of this investigation, though it is still in early stages. Dr. Hilonga has developed various Nanomaterials, some of which are suitable for water purification - applied in Nanofilter - a low-cost water purification system developed in Tanzania. With this filter, Hilonga has won several awards as demonstrated on his online presence, eg. www.gongalimodel.com and general Google search with terms like "Hilonga" "Nanofilter", etc

International Research Journal of Pure and Applied Chemistry, Jan 10, 2016

This work was carried out in collaboration between all authors. The design of work was carried un... more This work was carried out in collaboration between all authors. The design of work was carried under direction of author DMK. Author NM involved in synthesis of the work and writing layout of the manuscript. All authors involved in writing, editing and proofing the manuscript and approved the final manuscript.

Applied Water Science, 2017

Materials Today Chemistry, Jun 1, 2021

Abstract In this study, the efficacy of inorganic additives in the removal of total ammonia nitro... more Abstract In this study, the efficacy of inorganic additives in the removal of total ammonia nitrogen (TAN) and sulfide in the aqueous phase of slaughterhouse waste undergoing anaerobic digestion in the batch reactor was investigated. A mixture of natural inorganic additives processed from the anthill and red rock soil samples collected from Arusha, Tanzania were used as adsorbents in different ratios. These materials were chosen in regard to their abundance in the local environment, surface properties, and elemental composition. Before analysis, the materials were pulverized and calcined at 700 and 900 °C for 2 h in a furnace and then sieved to 250 μm fine particle size. XRD analysis revealed that the anthill soil sample is endowed with major mineral phases of quartz and hematite while red rock soil contains albite, pyroxene, and quartz as predominant phases. The anthill and red rock soil samples calcined at 900 °C displayed higher BET surface areas of 815.35 and 852.35 m2/g, respectively. The mixture of anthill soil and red rock soil in a ratio of 3:1 had a higher TAN removal efficiency of 92% at a contact time of 30 min compared to other ratios. On the other hand, a ratio of 1:2 showed a higher sulfide removal efficiency of 79% at a contact time of 60 min. Adsorption isotherm studies revealed that the Jovanovich model fitted better to the experimental data than the Langmuir and Freundlich models. The results demonstrated further that inorganic additives have a synergistic effect on stimulating methanogenesis as well as eliminating ammonia and sulfide during anaerobic digestion of slaughterhouse waste. Our findings demonstrate that anthill and red rock soils can be exploited as affordable, ecofriendly, and efficient adsorbents for mitigation of TAN and sulfide from the liquid phase and sustenance of methanogenesis.

Journal of packaging technology and research, Feb 20, 2020

The effects of mixing sequence of starch-chitosan nanocomposite films on antimicrobial properties... more The effects of mixing sequence of starch-chitosan nanocomposite films on antimicrobial properties of vanillin, the release kinetics of vanillin, and physicomechanical changes of films have been reported. Four types of films were prepared based on the order of mixing. SC1: starch-glycerol-MMT-vanillin; SC2: starch-glycerol-chitosan-MMT-vanillin; SC3: starch-MMT-glycerol-vanillin-chitosan and SC4: starch-chitosan-glycerol-vanillin-MMT. All formulation exhibited high antimicrobial activity against E. coli, S. enterica, and Z. bailii, except P. aeruginosa, which showed lower sensitivity. Migration dynamics of vanillin from films into simulants showed high vanillin migrated into water and 10% ethanol at 25 and 40 °C as analyzed by high-performance liquid chromatography (HPLC). The diffusion coefficients of vanillin in water ranged between 0.38 × 10 −13 m 2 s −1 and 4.30 × 10 −13 m 2 s −1 and in 10% ethanol between 1.38 × 10 −13 m 2 s −1 and 5.16 × 10 −13 m 2 s −1 following the Fickian diffusion mechanism and first-order kinetics. The diffusion was temperature-dependent following the Arrhenius equation with high activation energies of 15.00-52.80 kJmol −1 in water and 35.80-56.50 kJ mol −1 in 10% ethanol. The plot of the mass fraction of m t m ∞ against time for each sample shows the burst release of vanillin in between 30 min and 1 h and then attained the steady-state migration over 48 h. The plasticization effect of vanillin reduced the tensile strength and elastic modulus of films, while it increased the elongation at the break by 154% that was reversed after the addition of chitosan. These nanostructured starch films showed promising applications in the antimicrobial packaging industry.

Effluents resulting from the frequent use of industrial azo dyes in textile operations have posed... more Effluents resulting from the frequent use of industrial azo dyes in textile operations have posed great toxicological impacts on man and the environment. The limitations of conventional treatment infrastructure necessitate the use of rapid Fenton-mediated catalytic systematic process to tackle the attendant treatment limitations. The study applied in situ Fenton-mediation process with constructed low power UV-LED reactor for rapid catalytic treatment of dye-laden effluent using enhanced acid and alkali TiO 2-nanoparticles (Nps) (1-5%, i.e. 1-5 M) at definite experimental conditions, respectively. A comprehensive instrumental study was done to access the morphological, functional and elemental constituents of these nanocatalysts. The performance of the respective catalyst was evaluated using methylene blue (MB) dye at definite experimental conditions of pH, dosage, concentration and irradiation time. The results revealed a mesoporous structural nanocatalyst with increasing surface area after enhanced modification. The optimal experimental conditions of pH and concentration were recorded as 5 and 10 mg/L, respectively; while the most efficient nanocatalyst was 3 wt% alkali-modified TiO 2 (3% Ak-TiO 2) having a degradation efficiency of 89.15% at 90 min of irradiation using 50 mg dosage in contrast to higher irradiation time and catalyst dosage for other catalysts.

Journal of Biomimetics, Biomaterials and Biomedical Engineering, May 31, 2023

The aim of this study was to develop and characterize a delivery system for polyphenols from an e... more The aim of this study was to develop and characterize a delivery system for polyphenols from an extract of Carissa spinarum leaves, based on liposomes. Liposomes loaded with Carissa spinarum polyphenols (nanoliposomal CsP) were prepared by ethanol-solvent injection method and characterized in terms of zeta potential, size, and polydipersity index by using Zeta sizer and Fourier Transform Infrared spectrum analysis. Total Phenolic content was measured by using Folin-Ciocalteu method and entrapment efficiency was evaluated. The release behavior was conducted in Phosphate Buffer Saline (PBS) solution at pH, 7.4 and Kinetic model fitted to evaluate mechanism of release. Disc diffusion sensitivity test was used to evaluate antimicrobial activity of free extract and nanoliposomal CsP. The mean diameter of nanoliposomal CsP was 181 ± 1.02 nm and had 0.345 ± 0.014 polydipersity index. Zeta potential value for nanoliposomal CsP was-45.6 ± 8.84 mV. Entrapment efficiency under the optimum conditions was 66.11 ± 1.11%. and the nanoliposomal CsP was stable over 30 days. The antibacterial activity of nanoliposomal CsP exhibited inhibition zone diameter of 14.33 ± 1.53 mm and 12.00 ± 1.23 mm against S. aureus and E. coli respectively The results reveal the Carrisa spinarum liposome can be applied as potential carrier for delivery of polyphenols to improves therapeutic action against bacterial strain.

Materials Letters, Aug 1, 2012

The aim of this study is to identify an acid precursor that is most desirable for the synthesis o... more The aim of this study is to identify an acid precursor that is most desirable for the synthesis of sodium silicate-based silver-doped silica for large-scale industrial production. The final products were developed based on the presence of silver (silver-doped silica) or the absence of silver (pure silica). The properties of the obtained final products were examined using the BET method. This method involves characterization based on N2 physisorption studies to determine the surface area, pore diameter, and pore volume. Various graphs ...

Materials Chemistry and Physics, Jun 1, 2019

Journal of Industrial and Engineering Chemistry, 2013

Chemical Engineering Journal, Aug 1, 2012

h i g h l i g h t s " Titania-silica composites are prepared via peptization sol-gel method. " Si... more h i g h l i g h t s " Titania-silica composites are prepared via peptization sol-gel method. " Silicic acid yielded from water glass is used as a precursor and peptizing agent. " The composite formed by peptizing Ti(OH) 4 gel into silicic acid has anatase phase. " Anatase and rutile form in the composite where nitric acid was a peptizing agent.

Nanotechnology, Science and Applications, Dec 1, 2014

The goal of this study was to explore the effects of spray-drying on w/o/w double emulsions of me... more The goal of this study was to explore the effects of spray-drying on w/o/w double emulsions of methyltestosterone (MT) loaded in a stearic acid matrix. MT-loaded nanoparticles were formulated by a water-in-oil-in-water emulsion technique using 50, 75, and 100 mg of stearic acid, 2% and 3% w/v polyvinyl alcohol, 5% w/v lactose, and 0.2% w/v chitosan. The emulsions were immediately spray-dried based on an optimized model of inlet temperature and pump rate, and characterized for optimized responses with regard to particle size, polydispersity index, and zeta potential, for both emulsion and powder samples. Dynamic light scattering analysis shown that the nanoparticles increased in size with increasing concentrations of polyvinyl alcohol and stearic acid. Scanning electron microscopy indicated that the MT-loaded nanoparticles were spherical in shape, had a smooth surface, and were in an amorphous state, which was confirmed by differential scanning calorimetry. These MT-loaded nanoparticles are a promising candidate carrier for the delivery of MT; however, further studies are needed in order to establish the stability of the system and the cargo release profile under normal conditions of use.

Materials Letters, Feb 1, 2012

Here, we report on the synthesis of silver nanoparticles (Ag-NPs) manipulating the pores of silic... more Here, we report on the synthesis of silver nanoparticles (Ag-NPs) manipulating the pores of silica beads (SBs) with sizes ranging from 0.5 to 1mm. Silver ions were occluded inside the pores of SBs and in situ reduced to Ag-NPs using Sodium borohydride (NaBH4). SBs with different average pore diameters from 3.8 to 20nm were used to assess the effect of their pore sizes and porous structures on the formation of Ag-NPs. Obtained results revealed that the silver amount occluded inside pores increases along with the increase of total pore ...

Powder Technology, 2012

In this study a simple and reproducible method was used to develop silver-doped silica powder wit... more In this study a simple and reproducible method was used to develop silver-doped silica powder with antibacterial properties. Silica matrices were synthesized via a sol–gel route which allows one to easily tailor textural and chemical properties. A wide range of silica-materials/products was obtained via the present route. These are: pure silver nanoparticles (Ag0), silver in ionic state (Ag+), AgCl nanoparticles, and the mixture of Ag0 and AgCl. The efficacy of these products were tested against Escherichia coli and the results ...

Powder Technology, 2013

Abstract Titania silica composites (TSC) with various Ti/Si ratios were synthesized via sol–gel p... more Abstract Titania silica composites (TSC) with various Ti/Si ratios were synthesized via sol–gel process using less expensive precursors; sodium silicate solution as a silica source and titanium oxychloride as a titania source. The influence of varying Ti content in the composites was examined by FTIR, SEM, TEM, DTA/TGA, N 2 physisorption studies, XRF and XRD. The BET surface area of the raw materials increased with increasing Ti/Si ratio up to 2.9 (461 m 2/g) but further increase of Ti content beyond that ratio yielded composites ...

Materials Letters, Aug 1, 2012

ABSTRACT Here we report the preparation of micrometer-sized highly nanoporous, relatively trasper... more ABSTRACT Here we report the preparation of micrometer-sized highly nanoporous, relatively trasperant silica aerogel beads with high surface area as well as large pore volume with sizes ranging from 165 to 395 μm. The wet micrometer-sized silica hydrogel beads were prepared through hydrolysis and polycondensation of sodium silicate as a silica precursor. A hydrophobic micro-silica aerogel nanoporous bead was synthesized by simultaneous solvent exchange surface modification process of as synthesized micron sized silica hydrogel bead at an ambient pressure. Hydrophilic micron-sized silica aerogel beads with relatively more textural properties (surface area, pore volume and pore size) with its counterpart were obtained by heating the synthesized hydrophobic micro-silica aerogel beads at 395 °C for an hour. This study demonstrates a robust approach to high porous hydrophobic and hydrophilic micro-silica aerogel beads with a myriad of potential applications in various fileds such as catalysis, biomolecule immobilization, chromatographic separation, and CO 2 absorption. This proposed synthesis, which exploits a low-cost silica source (water-glass), is suitable for large-scale industrial production of highly porous hydrophobic and hydrophilic micro-silica aerogel beads at an ambient pressure.

Applied Surface Science, Nov 1, 2011

The conventional drying (oven drying) method used for the preparation of precipitated mesoporous ... more The conventional drying (oven drying) method used for the preparation of precipitated mesoporous silica with low surface area (>300 m 2 /g) and small pore volume is often associated with a high production cost and a time consuming process. Therefore, the main goal of this study was to develop a cost-effective and fast drying process for the production of precipitated mesoporous silica using inexpensive industrial grade sodium silicate and spray drying of the precipitated wet-gel silica slurry. The precipitated wet-gel silica slurry was prepared from an aqueous sodium silicate solution through the drop-wise addition of sulfuric acid. Mesoporous precipitated silica powder was prepared by drying the wet-gel slurry with different drying techniques. The effects of the oven drying (OD), microwave drying (MD), and spray drying (SD) techniques on the physical (oil, water absorption, and tapping density), and textural properties (specific BET surface area, pore volume, pore size, and % porosity) of the precipitated mesoporous silica powder were studied. The dried precipitated mesoporous silica powders were characterized with field-emission scanning electron microscopy; Brunauer, Emmett and Teller and BJH nitrogen gas adsorption/desorption methods; Fourier-transform infrared spectroscopy; thermogravimetric and differential analysis; N 2 physisorption isotherm; pore size distribution and particle size analysis. There was a significant effect of drying technique on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the mesoporous silica powder. Additionally, the effect of the microwave-drying period on the physicochemical properties of the precipitated mesoporous silica powder was investigated and discussed.

Powder Technology, Feb 1, 2012

Mesoporous titania-silica composite (MTSC) with a large surface area (387 m 2 /g) and large pore ... more Mesoporous titania-silica composite (MTSC) with a large surface area (387 m 2 /g) and large pore volume was synthesized by a two step condensation sol-gel method. Transparent TiO 2 sol was formed at room temperature through condensation and peptization of titanium oxychloride solution using ammonium hydroxide and aqueous nitric acid respectively. Sodium silicate was used as a silica source to form a composite with the preformed TiO 2 sol. The physical properties of the composite were examined by Fourier Transform infrared (FTIR), BET surface area, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The nitrogen physisorption behavior of the synthesized composite was compared to that obtained from grafting and one-pot co-condensation methods using the same precursors in the presence of cetyltrimethylammonium bromide (CTAB). It was found that MTSC synthesized under this method possessed large pore sizes and pore volume but its thermal stability was comparatively low. FTIR spectra showed the formation of a Ti\O\Si bond at 940 cm − 1 suggesting that titania was incorporated in silica to form a composite. The XRD patterns showed that the major phase of the titania had an anatase phase up to 900°C but it transforms into rutile when calcined at 1000°C. Furthermore the EDS studies of the as-synthesized and calcined samples substantiated the formation of titania-silica composites.

Journal of physics, Mar 1, 2018

View the article online for updates and enhancements. You may also like Optimum parameters for th... more View the article online for updates and enhancements. You may also like Optimum parameters for the production of nano-scale electrospun polycaprolactone to be used as a biomedical material Basma Ekram, Bothaina M Abdel-Hady, Abeer M El-kady et al.-Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

This book demonstrates the potential of developing porous Nanomaterials by using renewable surfac... more This book demonstrates the potential of developing porous Nanomaterials by using renewable surfactant/template obtained from cashew nuts shell liquid. This approach is environmentally friendly and might be considered for the large scale production of Nanomaterials for industrial application. The Nanomaterials obtained could be used for various applications such as water purification, antibacterial agent, thin films, etc. The success of this work will add value to cashew nuts farmers who are currently not benefiting at all from the liquids obtained after processing the cashew nuts. So there is a lot of win-win through the success of this investigation, though it is still in early stages. Dr. Hilonga has developed various Nanomaterials, some of which are suitable for water purification - applied in Nanofilter - a low-cost water purification system developed in Tanzania. With this filter, Hilonga has won several awards as demonstrated on his online presence, eg. www.gongalimodel.com and general Google search with terms like "Hilonga" "Nanofilter", etc

International Research Journal of Pure and Applied Chemistry, Jan 10, 2016

This work was carried out in collaboration between all authors. The design of work was carried un... more This work was carried out in collaboration between all authors. The design of work was carried under direction of author DMK. Author NM involved in synthesis of the work and writing layout of the manuscript. All authors involved in writing, editing and proofing the manuscript and approved the final manuscript.