Se produjeron biocarbones a partir de tres tipos de biomasa residual: coronta de maíz, cáscara de... more Se produjeron biocarbones a partir de tres tipos de biomasa residual: coronta de maíz, cáscara de café y exoesqueleto de langostino, para estudiar la influencia de diferentes dosis de los mismos en la germinación y crecimiento en vivero de semillas de la especie forestal Capparis scabrida (Sapote). Se realizó una exhaustiva caracterización de los biocarbones obtenidos en base a sus propiedades texturales, morfológicas, estructurales y química superficial. Semillas viables de sapote fueron colocadas en sustratos con dosis de 0, 15 y 30 %wt de cada uno de los tres tipos de biocarbones obtenidos y se colocaron en bolsas de 2 kg en condiciones de vivero. Se evaluaron los parámetros de germinación: tiempo y % de germinación; y de crecimiento de las plántulas: crecimiento de raíz y tallo, engrosamiento de tallo, incremento de masa de raíz y parte aérea y la carga microbiana en la raíz. Se determinó que el tipo de biocarbón tuvo influencia solamente en el tiempo de germinación y la dosis de biocarbón tuvo influencia en el incremento de masa de parte aérea durante el crecimiento de las plántulas. El resto de parámetros evaluados no fueron afectados ni por el tipo ni por la dosis de biocarbón. Palabras clave: biocarbón; especies forestales; germinación; peligro de extinción; vivero.
International Journal of Chemical Reactor Engineering, Apr 7, 2017
The application of nanofiltration membranes to remove sulfate and arsenic from wastewaters was in... more The application of nanofiltration membranes to remove sulfate and arsenic from wastewaters was investigated. The influence of operating parameters on the rejection and permeate flux was determined. The nanofiltration experiments carried out with NF90 and NF270 membranes showed a high rejection of sulfate ( 90 %) and arsenic ( 97 %) under the given set of experimental conditions. Better permeate flux values were obtained by NF270 membrane with a minor drop in rejections, but it proved to be better in water recovery. In FESEM analysis, the sulfate deposition on the membrane surface confirmed its well-known precipitation in desalination types of equipment. The experimental results were successfully predicted by using theoretical framework available in the literature. The simulation was carried out by using Levenberg-Marquardt with Gauss-Newton algorithm in MATLAB and the prime important parameters, viz. membrane resistance(𝑅 ), permeability coefficient P m , and mass transfer coefficient (k) were established separately for each membrane. The gel layer thickness was determined to better understand the hydrodynamics over the membrane surface and it validated the assumption of negligible fouling.
Contamination of water by heavy metal ions is a severe environmental problem. In this study, star... more Contamination of water by heavy metal ions is a severe environmental problem. In this study, starch-or waste-starch-based binding agents were used to bind heavy metal ions in aqueous solutions in order to prevent the precipitation of metals in alkaline conditions (pH 10). This is a useful feature, e.g. when ultrafiltration is used as a purification technique for a low metal concentration containing wastewaters. The studied binding agents were water-soluble cationized depolymerized barley starch (CDS) prepared by depolymerization and subsequent cationization, sulphonylated starch (SS) and cationized depolymerized potato peel waste (CW), all of which have not been used previously as binding agents. The studied modified starches were investigated in the binding of Fe(III), Cu(II), Zn(II), or Ni(II) ions in aqueous solutions by utilizing inductively coupled plasma-optical emission spectrometry (ICP-OES) as an analytical method. Cationized depolymerized starch bound 80-100% of Fe(III), Zn(II), and Cu(II) ions and SS bound 85-95% of Fe(III), Zn(II), and Ni(II) ions when 0.5 mM metal ions solutions and molar ratio of starch:metal 0.66:1 were used. Cationized depolymerized waste starch bound Cu(II) ions 78-94% (0.25-2.5 mM metal ion solutions prepared with distilled or lake water) in aqueous solution with molar ratio of starch:metal varying from 1:1 to 3:1.
The porous structure and dissolution of phiogopite, as a fun&ton of the condittons of acid-leachi... more The porous structure and dissolution of phiogopite, as a fun&ton of the condittons of acid-leaching, ace discussed. Sutface areas and pore disitibutfons of the products from HNO,-. HCi-and H,SO,-leaching3 of the mica from the apatite mine of Siilinjiirvi, Finland were ailalszed. The pores formed during leaching were found to bc slit-shaped or ink-bottle type. as indicated by adsorption-desorption isotherms of nitrogen. The pores formed an selL=tive dissolutbn of potassium from phlogopitc were so narrow that not even nitrogen could penetrate them. The products of leaching with HMO, were much more microporous than the products of leaching with HCI and H,SO,. The maximum values obtained for totally lrached phlogopite were 820 m' g-' and 0.46 cm' g-* for surface area ar.d total pore volrrme, reopectivety, The temperature of leaching, acid concentration and acid nature affected the results. Surface areas anrl pore distributions for leached phlogopite samptes obtained were similar to those of the active coal and active kaolin used as reference materials, In order to investigate the effect of leaching temperature, the surface areas and pore distributions were determined foi samples leached with HNO, under thz conditions shown in Table
Journal of Nanoscience and Nanotechnology, Oct 1, 2005
A lanthanum molybdate aerogel, La2Mo2O9, with a mean particle size in the range from 100 to 150 n... more A lanthanum molybdate aerogel, La2Mo2O9, with a mean particle size in the range from 100 to 150 nm, was synthesized by the sol-gel method and high-temperature supercritical drying. In this communication it is shown that control over the crystallinity of product aerogels can be exercised by changing the amount of water used for hydrolysis and the temperature for subsequent heat treatment. Methoxy species are formed on the surface during synthesis. The new aerogel may prove useful as a catalyst for the oxidation of hydrocarbons to oxygenated organic compounds.
Butanol has potential to become an important renewable transportation fuel and feedstock chemical... more Butanol has potential to become an important renewable transportation fuel and feedstock chemical in the future. However, low yield and high separation costs are the main obstacles in feasible industrial scale biobutanol production by the acetone-butanol-ethanol (ABE) fermentation process. Both problems can be overcome by using pervaporation as the product removal technique. The performance of a polydimethylsiloxane (PDMS) membrane with a support layer of polyacrylonitrile (PAN) was studied for the removal of acetone, butanol and ethanol from dilute aqueous model solutions. The effect of feed composition on permeation fluxes, permeances, separation factors and pervaporation separation indices was investigated by using binary aqueous solutions of acetone, butanol and ethanol followed by experiments with different aqueous ternary mixtures and quaternary ABE-water mixture. At feed temperature of 42 1C, partial fluxes and permeate concentrations were found to be in the order of acetoneE butanol4 ethanol, while the permeance order was butanol 4ethanol E acetone. Separation factors were in the range of 21-26, 22-29 and 5-7 for acetone, butanol and ethanol, respectively. Results indicate that the tested membrane has potential to be used in the ABE fermentation process.
In this study, a novel approach combining different techniques, including Fourier transform infra... more In this study, a novel approach combining different techniques, including Fourier transform infrared (FT-IR) spectroscopy, photoacoustic spectroscopy (PAS) with an interferometric cantilever microphone, and principal component analysis (PCA) along with a proper data preprocessing procedure, have been used in the investigation of hair samples for cocaine abuse. Hair fibers from cocaine-overdose patients have been measured using a simple procedure involving cantilever-enhanced photoacoustic Fourier transform infrared spectroscopy. In addition, a reference group of hair samples from subjects with no cocaine abuse has been measured. We present a first approach to discriminate the cocaine users from the reference group with the photoacoustic method and PCA. With proper data preprocessing methods, the two groups were successfully separated according to their spectra. The results were confirmed with two different classification methods independent of the principal component data analysis.
An attached fungal growth has appeared in a fixed biofilm process at the waste water treatment pl... more An attached fungal growth has appeared in a fixed biofilm process at the waste water treatment plant of the City of Oulu, Finland. Due to the filamentous morphology of the fungi, biofilm support material is easily washed out. The appearance is believed to be the result of the unbalanced availability of nutrients, where phosphorus has been identified as the key component. Experimental work concentrated on the influence of phosphorus on the fungal growth. Bench scale experiments showed that a higher uptake of phosphorus for the removal of organic material is possible, which also resulted in a suppression of the fungal growth by bacterial biomass. The results were confirmed by experimentation in a full-scale biofilter. Addition of extra phosphoric acid to the biofilter influent resulted in a biofilm where the fungal growth is less pronounced. The fungal growth is believed to be competitive with the desired bacterial growth. It is possible to keep the fungal growth within limits by changing the conditions in favour of the bacterial growth, thus avoiding the operational problems connected with the filamentous fungi.
A multiscale modeling procedure is introduced in this paper for modeling continuous high-shear we... more A multiscale modeling procedure is introduced in this paper for modeling continuous high-shear wet granulation. Flow inside the granulator is accounted using the discrete element method (DEM) and particle-level interactions with population balance (PB). The developed DEM-PB model is validated against experiments, particle size distribution (PSD), and residence time distribution (RTD). It was observed that the model gave good correspondence to the experimental values. The developed methodology can be used when designing continuous granulation processes.
In this paper CAS-OB ladle process has been studied with three-phase CFD model. Model was validat... more In this paper CAS-OB ladle process has been studied with three-phase CFD model. Model was validated against the literature, where similar system was studied with physical model and industrial setup. The simulations were performed with the OpenFOAM R -2.3.0 CFD software package. Multifluid CFD model was used instead of traditional Volume of Fluid (VOF) formulation to capture the produced bubble plume and the slag-steel interface features with the same model. Turbulence was take into account with Large Eddy Scale (LES) turbulence model. As a result, the used computational mesh together with argon injection the produced bubble plume is presented. The obtained plume velocity profile and the slag-free open-eye area are also presented and compared against the experimental data from the literature, which were found to be in good agreement. In the future the presented model could be used to study the details of the CAS-OB process, like wearing of the refractory lining.
in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu,... more in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu, Zn) using the co-precipitation-oxidation method. The band gap calculated from UV-Visible diffuse reflectance spectra were found in the range of 1.11-1.81 eV. These ferrite nanocatalysts were studied for the photocatalytic degradation of multiple organic dyes in a 32 W UV-C/H 2 o 2 system. All the four ferrites showed an excellent dye degradation rate in the range of 2.065-2.417 min -1 at neutral pH. in the optimized condition, NiF was found to degrade 89%, 92%, 93%, and 78% of methylene blue, methyl orange, bromo green, and methyl red, respectively within 1 min of UV-irradiation. A 40% TOC removal was recorded after 5 min of degradation reaction, which increased to 60% after 50 min. Mechanism elucidated by scavenger studies and fluorescence spectroscopy revealed that • oH and holes were the primary reactive radicals responsible for the degradation process. ferrite photocatalysts showed an insignificant performance loss in seven consecutive cycles. The photocatalyst was found efficient in the presence of a high concentration of salts. thus, it was concluded that these photocatalysts are highly suitable for the remediation of dye-contaminated wastewater.
Revista de la Sociedad Química del Perú, Mar 31, 2016
Carbones activados y carbones activados modificados con nanopartículas de ZnO fueron preparados m... more Carbones activados y carbones activados modificados con nanopartículas de ZnO fueron preparados mezclando residuos agroindustriales como coronta de maíz o pepa de ciruela con ZnCl 2 , como agente químico activador en una proporción en peso 1:1, o con ZnCl 2 , y acetato de zinc, en una proporción en peso 1:1:0,5 en medio acuoso, respectivamente. Con la masa pastosa resultante se hicieron pellets, los cuales fueron secados para luego ser carbonizados. El material resultante fue lavado varias veces con una solución HCl 0,5 M y abundante agua destilada para luego ser secado a 100°C durante 12 h. Finalmente, los pellets fueron molidos y tamizados dejando pasar tamaños menores a 0,25 mm. Microscopía electrónica de barrido de emisión de campo fue utilizada para la caracterización de las diferentes morfologías de las nanopartículas de ZnO en la superficie del carbón activado modificado que dependió de la materia prima empleada para la obtención del carbón activado, sin embargo en ambas se determinó la presencia del ZnO por difracción de rayos X. Los estudios cinéticos de adsorción con azul de metileno mostraron que el carbón activado modificado con ZnO procedente de la coronta de maíz mejora su proceso cinético con la presencia de la radiación UV. Sin embargo los carbones activados tienen mejores propiedades de adsorción que los modificados con ZnO debido a que las nanopartículas de ZnO cubrirían los sitios activos del carbón activado.
In 2016, the United Nations (UN) Member States adopted a decision on the role of the UN Education... more In 2016, the United Nations (UN) Member States adopted a decision on the role of the UN Educational, Scientific and Cultural Organization (UNESCO) in encouraging girls and women to be leaders in science, technology, engineering, and mathematics (STEM) and in science, technology, engineering, arts, and mathematics (STEAM). This decision poses a special challenge for many sectors in society and posits unique opportunities for women's leadership in higher education institutions (HEIs). This chapter opens by presenting views on overcoming gender segregation in STEM. The roles of women in leadership positions in the higher education STEM research areas of a large multidisciplinary university in a Nordic country are explored. The unique paths in which four of these women have progressed in their profession, position, and promotion of equality through their diverse and multiple roles within their HEI are examined. From this collection, intertwined opportunities in assuming M. Heikkinen (B) Gender Studies/Values, Ideologies and Social Contexts of Education (VISE),
Simultaneous poisoning of sulfur + phosphorus on a platinum-based diesel oxidation catalyst was s... more Simultaneous poisoning of sulfur + phosphorus on a platinum-based diesel oxidation catalyst was studied to gain a deeper understanding on the catalyst deactivation. Compared to a single poisoning (sulfur or phosphorus), the simultaneous poisoning had a severe effect on the catalyst activation: light-off temperature for 90% conversion of propene was not reached, this of carbon monoxide was much higher than expected, and the maximum conversion of nitrogen monoxide collapsed. With very comprehensive structural characterization by various methods (e.g. STEM-EDS, XPS, DRIFTS) used, we achieved to conclude an explanation for this. In the case of the S + P-poisoning of the catalyst, formed aluminum phosphate was found to block adsorption sites for sulfur species on alumina and sulfur adsorbs mainly on cerium oxides. In addition, sulfur species remain with and in the vicinity of the platinum particles blocking active sites.
Se produjeron biocarbones a partir de tres tipos de biomasa residual: coronta de maíz, cáscara de... more Se produjeron biocarbones a partir de tres tipos de biomasa residual: coronta de maíz, cáscara de café y exoesqueleto de langostino, para estudiar la influencia de diferentes dosis de los mismos en la germinación y crecimiento en vivero de semillas de la especie forestal Capparis scabrida (Sapote). Se realizó una exhaustiva caracterización de los biocarbones obtenidos en base a sus propiedades texturales, morfológicas, estructurales y química superficial. Semillas viables de sapote fueron colocadas en sustratos con dosis de 0, 15 y 30 %wt de cada uno de los tres tipos de biocarbones obtenidos y se colocaron en bolsas de 2 kg en condiciones de vivero. Se evaluaron los parámetros de germinación: tiempo y % de germinación; y de crecimiento de las plántulas: crecimiento de raíz y tallo, engrosamiento de tallo, incremento de masa de raíz y parte aérea y la carga microbiana en la raíz. Se determinó que el tipo de biocarbón tuvo influencia solamente en el tiempo de germinación y la dosis de biocarbón tuvo influencia en el incremento de masa de parte aérea durante el crecimiento de las plántulas. El resto de parámetros evaluados no fueron afectados ni por el tipo ni por la dosis de biocarbón. Palabras clave: biocarbón; especies forestales; germinación; peligro de extinción; vivero.
International Journal of Chemical Reactor Engineering, Apr 7, 2017
The application of nanofiltration membranes to remove sulfate and arsenic from wastewaters was in... more The application of nanofiltration membranes to remove sulfate and arsenic from wastewaters was investigated. The influence of operating parameters on the rejection and permeate flux was determined. The nanofiltration experiments carried out with NF90 and NF270 membranes showed a high rejection of sulfate ( 90 %) and arsenic ( 97 %) under the given set of experimental conditions. Better permeate flux values were obtained by NF270 membrane with a minor drop in rejections, but it proved to be better in water recovery. In FESEM analysis, the sulfate deposition on the membrane surface confirmed its well-known precipitation in desalination types of equipment. The experimental results were successfully predicted by using theoretical framework available in the literature. The simulation was carried out by using Levenberg-Marquardt with Gauss-Newton algorithm in MATLAB and the prime important parameters, viz. membrane resistance(𝑅 ), permeability coefficient P m , and mass transfer coefficient (k) were established separately for each membrane. The gel layer thickness was determined to better understand the hydrodynamics over the membrane surface and it validated the assumption of negligible fouling.
Contamination of water by heavy metal ions is a severe environmental problem. In this study, star... more Contamination of water by heavy metal ions is a severe environmental problem. In this study, starch-or waste-starch-based binding agents were used to bind heavy metal ions in aqueous solutions in order to prevent the precipitation of metals in alkaline conditions (pH 10). This is a useful feature, e.g. when ultrafiltration is used as a purification technique for a low metal concentration containing wastewaters. The studied binding agents were water-soluble cationized depolymerized barley starch (CDS) prepared by depolymerization and subsequent cationization, sulphonylated starch (SS) and cationized depolymerized potato peel waste (CW), all of which have not been used previously as binding agents. The studied modified starches were investigated in the binding of Fe(III), Cu(II), Zn(II), or Ni(II) ions in aqueous solutions by utilizing inductively coupled plasma-optical emission spectrometry (ICP-OES) as an analytical method. Cationized depolymerized starch bound 80-100% of Fe(III), Zn(II), and Cu(II) ions and SS bound 85-95% of Fe(III), Zn(II), and Ni(II) ions when 0.5 mM metal ions solutions and molar ratio of starch:metal 0.66:1 were used. Cationized depolymerized waste starch bound Cu(II) ions 78-94% (0.25-2.5 mM metal ion solutions prepared with distilled or lake water) in aqueous solution with molar ratio of starch:metal varying from 1:1 to 3:1.
The porous structure and dissolution of phiogopite, as a fun&ton of the condittons of acid-leachi... more The porous structure and dissolution of phiogopite, as a fun&ton of the condittons of acid-leaching, ace discussed. Sutface areas and pore disitibutfons of the products from HNO,-. HCi-and H,SO,-leaching3 of the mica from the apatite mine of Siilinjiirvi, Finland were ailalszed. The pores formed during leaching were found to bc slit-shaped or ink-bottle type. as indicated by adsorption-desorption isotherms of nitrogen. The pores formed an selL=tive dissolutbn of potassium from phlogopitc were so narrow that not even nitrogen could penetrate them. The products of leaching with HMO, were much more microporous than the products of leaching with HCI and H,SO,. The maximum values obtained for totally lrached phlogopite were 820 m' g-' and 0.46 cm' g-* for surface area ar.d total pore volrrme, reopectivety, The temperature of leaching, acid concentration and acid nature affected the results. Surface areas anrl pore distributions for leached phlogopite samptes obtained were similar to those of the active coal and active kaolin used as reference materials, In order to investigate the effect of leaching temperature, the surface areas and pore distributions were determined foi samples leached with HNO, under thz conditions shown in Table
Journal of Nanoscience and Nanotechnology, Oct 1, 2005
A lanthanum molybdate aerogel, La2Mo2O9, with a mean particle size in the range from 100 to 150 n... more A lanthanum molybdate aerogel, La2Mo2O9, with a mean particle size in the range from 100 to 150 nm, was synthesized by the sol-gel method and high-temperature supercritical drying. In this communication it is shown that control over the crystallinity of product aerogels can be exercised by changing the amount of water used for hydrolysis and the temperature for subsequent heat treatment. Methoxy species are formed on the surface during synthesis. The new aerogel may prove useful as a catalyst for the oxidation of hydrocarbons to oxygenated organic compounds.
Butanol has potential to become an important renewable transportation fuel and feedstock chemical... more Butanol has potential to become an important renewable transportation fuel and feedstock chemical in the future. However, low yield and high separation costs are the main obstacles in feasible industrial scale biobutanol production by the acetone-butanol-ethanol (ABE) fermentation process. Both problems can be overcome by using pervaporation as the product removal technique. The performance of a polydimethylsiloxane (PDMS) membrane with a support layer of polyacrylonitrile (PAN) was studied for the removal of acetone, butanol and ethanol from dilute aqueous model solutions. The effect of feed composition on permeation fluxes, permeances, separation factors and pervaporation separation indices was investigated by using binary aqueous solutions of acetone, butanol and ethanol followed by experiments with different aqueous ternary mixtures and quaternary ABE-water mixture. At feed temperature of 42 1C, partial fluxes and permeate concentrations were found to be in the order of acetoneE butanol4 ethanol, while the permeance order was butanol 4ethanol E acetone. Separation factors were in the range of 21-26, 22-29 and 5-7 for acetone, butanol and ethanol, respectively. Results indicate that the tested membrane has potential to be used in the ABE fermentation process.
In this study, a novel approach combining different techniques, including Fourier transform infra... more In this study, a novel approach combining different techniques, including Fourier transform infrared (FT-IR) spectroscopy, photoacoustic spectroscopy (PAS) with an interferometric cantilever microphone, and principal component analysis (PCA) along with a proper data preprocessing procedure, have been used in the investigation of hair samples for cocaine abuse. Hair fibers from cocaine-overdose patients have been measured using a simple procedure involving cantilever-enhanced photoacoustic Fourier transform infrared spectroscopy. In addition, a reference group of hair samples from subjects with no cocaine abuse has been measured. We present a first approach to discriminate the cocaine users from the reference group with the photoacoustic method and PCA. With proper data preprocessing methods, the two groups were successfully separated according to their spectra. The results were confirmed with two different classification methods independent of the principal component data analysis.
An attached fungal growth has appeared in a fixed biofilm process at the waste water treatment pl... more An attached fungal growth has appeared in a fixed biofilm process at the waste water treatment plant of the City of Oulu, Finland. Due to the filamentous morphology of the fungi, biofilm support material is easily washed out. The appearance is believed to be the result of the unbalanced availability of nutrients, where phosphorus has been identified as the key component. Experimental work concentrated on the influence of phosphorus on the fungal growth. Bench scale experiments showed that a higher uptake of phosphorus for the removal of organic material is possible, which also resulted in a suppression of the fungal growth by bacterial biomass. The results were confirmed by experimentation in a full-scale biofilter. Addition of extra phosphoric acid to the biofilter influent resulted in a biofilm where the fungal growth is less pronounced. The fungal growth is believed to be competitive with the desired bacterial growth. It is possible to keep the fungal growth within limits by changing the conditions in favour of the bacterial growth, thus avoiding the operational problems connected with the filamentous fungi.
A multiscale modeling procedure is introduced in this paper for modeling continuous high-shear we... more A multiscale modeling procedure is introduced in this paper for modeling continuous high-shear wet granulation. Flow inside the granulator is accounted using the discrete element method (DEM) and particle-level interactions with population balance (PB). The developed DEM-PB model is validated against experiments, particle size distribution (PSD), and residence time distribution (RTD). It was observed that the model gave good correspondence to the experimental values. The developed methodology can be used when designing continuous granulation processes.
In this paper CAS-OB ladle process has been studied with three-phase CFD model. Model was validat... more In this paper CAS-OB ladle process has been studied with three-phase CFD model. Model was validated against the literature, where similar system was studied with physical model and industrial setup. The simulations were performed with the OpenFOAM R -2.3.0 CFD software package. Multifluid CFD model was used instead of traditional Volume of Fluid (VOF) formulation to capture the produced bubble plume and the slag-steel interface features with the same model. Turbulence was take into account with Large Eddy Scale (LES) turbulence model. As a result, the used computational mesh together with argon injection the produced bubble plume is presented. The obtained plume velocity profile and the slag-free open-eye area are also presented and compared against the experimental data from the literature, which were found to be in good agreement. In the future the presented model could be used to study the details of the CAS-OB process, like wearing of the refractory lining.
in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu,... more in this study, we report a surfactant-mediated synthesis of ferrites (Mfe 2 o 4 : M = co, ni, cu, Zn) using the co-precipitation-oxidation method. The band gap calculated from UV-Visible diffuse reflectance spectra were found in the range of 1.11-1.81 eV. These ferrite nanocatalysts were studied for the photocatalytic degradation of multiple organic dyes in a 32 W UV-C/H 2 o 2 system. All the four ferrites showed an excellent dye degradation rate in the range of 2.065-2.417 min -1 at neutral pH. in the optimized condition, NiF was found to degrade 89%, 92%, 93%, and 78% of methylene blue, methyl orange, bromo green, and methyl red, respectively within 1 min of UV-irradiation. A 40% TOC removal was recorded after 5 min of degradation reaction, which increased to 60% after 50 min. Mechanism elucidated by scavenger studies and fluorescence spectroscopy revealed that • oH and holes were the primary reactive radicals responsible for the degradation process. ferrite photocatalysts showed an insignificant performance loss in seven consecutive cycles. The photocatalyst was found efficient in the presence of a high concentration of salts. thus, it was concluded that these photocatalysts are highly suitable for the remediation of dye-contaminated wastewater.
Revista de la Sociedad Química del Perú, Mar 31, 2016
Carbones activados y carbones activados modificados con nanopartículas de ZnO fueron preparados m... more Carbones activados y carbones activados modificados con nanopartículas de ZnO fueron preparados mezclando residuos agroindustriales como coronta de maíz o pepa de ciruela con ZnCl 2 , como agente químico activador en una proporción en peso 1:1, o con ZnCl 2 , y acetato de zinc, en una proporción en peso 1:1:0,5 en medio acuoso, respectivamente. Con la masa pastosa resultante se hicieron pellets, los cuales fueron secados para luego ser carbonizados. El material resultante fue lavado varias veces con una solución HCl 0,5 M y abundante agua destilada para luego ser secado a 100°C durante 12 h. Finalmente, los pellets fueron molidos y tamizados dejando pasar tamaños menores a 0,25 mm. Microscopía electrónica de barrido de emisión de campo fue utilizada para la caracterización de las diferentes morfologías de las nanopartículas de ZnO en la superficie del carbón activado modificado que dependió de la materia prima empleada para la obtención del carbón activado, sin embargo en ambas se determinó la presencia del ZnO por difracción de rayos X. Los estudios cinéticos de adsorción con azul de metileno mostraron que el carbón activado modificado con ZnO procedente de la coronta de maíz mejora su proceso cinético con la presencia de la radiación UV. Sin embargo los carbones activados tienen mejores propiedades de adsorción que los modificados con ZnO debido a que las nanopartículas de ZnO cubrirían los sitios activos del carbón activado.
In 2016, the United Nations (UN) Member States adopted a decision on the role of the UN Education... more In 2016, the United Nations (UN) Member States adopted a decision on the role of the UN Educational, Scientific and Cultural Organization (UNESCO) in encouraging girls and women to be leaders in science, technology, engineering, and mathematics (STEM) and in science, technology, engineering, arts, and mathematics (STEAM). This decision poses a special challenge for many sectors in society and posits unique opportunities for women's leadership in higher education institutions (HEIs). This chapter opens by presenting views on overcoming gender segregation in STEM. The roles of women in leadership positions in the higher education STEM research areas of a large multidisciplinary university in a Nordic country are explored. The unique paths in which four of these women have progressed in their profession, position, and promotion of equality through their diverse and multiple roles within their HEI are examined. From this collection, intertwined opportunities in assuming M. Heikkinen (B) Gender Studies/Values, Ideologies and Social Contexts of Education (VISE),
Simultaneous poisoning of sulfur + phosphorus on a platinum-based diesel oxidation catalyst was s... more Simultaneous poisoning of sulfur + phosphorus on a platinum-based diesel oxidation catalyst was studied to gain a deeper understanding on the catalyst deactivation. Compared to a single poisoning (sulfur or phosphorus), the simultaneous poisoning had a severe effect on the catalyst activation: light-off temperature for 90% conversion of propene was not reached, this of carbon monoxide was much higher than expected, and the maximum conversion of nitrogen monoxide collapsed. With very comprehensive structural characterization by various methods (e.g. STEM-EDS, XPS, DRIFTS) used, we achieved to conclude an explanation for this. In the case of the S + P-poisoning of the catalyst, formed aluminum phosphate was found to block adsorption sites for sulfur species on alumina and sulfur adsorbs mainly on cerium oxides. In addition, sulfur species remain with and in the vicinity of the platinum particles blocking active sites.
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Papers by Riitta Keiski