Aportes desde la gestión integral del recurso hídrico para la determinación de la capacidad de carga turística en destinos insulares. caso de estudio Islas de Providencia y Santa Catalina

Los procesos turísticos que no son adecuadamente planificados generan presión sobre los sistemas ambientales, generando conflictos, problemas y decisiones difíciles de abordar por su complejidad enmarcada en la relación sociedad-naturaleza. Es evidente que estos procesos además de atentar contra el patrimonio natural, representan una gran amenaza para el patrimonio social y cultural. De acuerdo con la Organización Mundial del Turismo, este sector presenta un crecimiento importante en los últimos años y se prevé, que siga creciendo en los próximos. Es necesario entonces, estudiar de qué manera se pueden gestionar los destinos turísticos para ofrecer servicios de calidad garantizando la sostenibilidad. Los Estudios de Capacidad de Carga Turística representan uno de los instrumentos de mayor importancia para lograr estos propósitos, donde a través de un proceso sistemático se analizan variables que tienen influencia directa sobre el territorio y la prestación de servicios turísticos, con el fin de determinar la cantidad de visitantes que puede recibir y/o atender un destino sin alterar de manera significativa sus dinámicas naturales, sociales y culturales

Antimicrobial effects of carbonaceous material functionalized with silver

Carbonaceous materials as well as its form functionalized with metallic silver have been prepared by hydrothermal carbonization of fructose. Results are presented to show that nanostructured silver was obtained through the functionalization process. The carbonaceous materials were characterized by: nitrogen adsorption/desorption measurement, XRD, SEM/EDS and FTIR. Samples functionalized with silver were analyzed by: XRD and SEM/EDS. The XRD analysis showed that the carbonaceous materials functionalized with silver by hydrothermal carbonization process were successfully performed. Size of silver particles was found to be approximately 32 nm, indicating formation of nanostructure. All samples were tested as an antimicrobial agent for water disinfection. Presence of nanostructured silver in the sample containing 1 mg/mL carbonaceous materials significantly decreased the number of CFU (dCFU = 97.33 %) if compared to the same sample containing the same amount of carbonaceous materials but without of silver (dCFU 65.33 %)

The effect of gamma radiation on the properties of activated carbon cloth

Activated carbon cloth dressing is an appropriate wound healing material due to its biocompatibility and adsorption characteristics. The influence of gamma radiation as a sterilization process on the adsorption and mechanical properties of activated carbon cloth was investigated. The specific surface area, micropore volume, pore size distribution, surface chemistry as well as the breaking load of activated carbon cloth before and after gamma radiation were examined. Characterization by nitrogen adsorption showed that the activated carbon cloth was a microporous material with a high specific surface area and micropores smaller than 1 nm. Gamma radiation decreased the specific surface area and micropore volume but increased the pore width. The sterilization process changed the surface chemistry quantitatively, but not qualitatively. In addition, the breaking load decreased but without any influence considering the further application of this material

Preparation and Characterization of Active Carbon Microspheres Obtained from Fructose and Adsorption Application

A carbon-rich solid product has been synthesized by hydrothermal treatment from fructose with phosphoric acid (H3 PO4 ) at temperature of 250°C and pH value of 0.65. The concentration of the precursor was constant, i.e. 2M of fructose in form of aqueous solution. The formation of the carbon-rich solid material through the hydrothermal carbonization of fructose is the consequence of dehydration reactions. Obtained carbon material is made of spherical micrometer-sized particles with the diameter in the 4-7 μm. The structure and surface chemical properties of obtained material were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectra. Investigation of surface area was determined by gravimetric McBain method where adsorption and desorption isotherms of N2 were measured on carbon material at -196 °C. Adsorption of Methylene Blue (MB) onto prepared carbon material were conducted by changing concentration of MB from 200-500 mg/dm 3 from aqueous solutions of investigated dye. Kinetic results were determined by a pseudo second-order equation.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Preparation and Characterization Of Active Carbon Microspheres Obtained From Fructose And Adsorption Application

Carbon material with active surface properties have been synthesized by hydrothermal method from fructose using 40% and 80% phosphoric acid (H3 PO4 ) solution, at temperature of 260°C and fructose concentration of 2M. The aim of this investigation was active carbon material synthesis which is completed by one step reaction, which was not the case in our previous works. Thus, compared with other samples from our works, this way is more economic and faster since both reaction of carbonization and activation was finished in one step. The hydrothermal process, in general, includes heat treatment of carbohydrate solutions under autogenous pressure at low temperatures (150–260 °C). Obtained solid carbon material has uniform morphology, amorphous structure and high content of oxygen functional groups. Prepared active carbon material is made up of spherical microsphere particles with the diameter in the range of 0.6-2.7 μm. The morphology and surface properties of obtained material were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectra. Adsorption and desorption isotherms of N2 were measured on carbon containing material at -196 °C using the gravimetric McBain method. Adsorption from aqueous solutions of Methylene Blue (MB) onto prepared carbon material was conducted by changing concentration of MB from 200-500mg/dm3 . The best fit of the kinetic results was achieved by a pseudo second-order equation. Also, this nature of material is applicable in other systems regarding environmental protection and dye pollution prevention.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Hydrothermal Synthesized and Alkaline Activated Carbons Prepared from Glucose and Fructose—Detailed Characterization and Testing in Heavy Metals and Methylene Blue Removal

In the presented paper, activated carbons were prepared from fructose and glucose, and activating agents (KOH, NaOH, LiOH) by hydrothermal treatment (HTC) treatment. After preparation, samples were characterized in details. Different techniques were used: x-ray powder diffraction analysis, Raman spectral analysis, elemental analysis, and determination of textural and morphological properties. Obtained results showed dependence of investigated properties and the nature of precursors (glucose or fructose) as well as the type of hydroxides used as activating agents. After characterization, samples were tested as materials for heavy metals (Pb2+, Cd2+and Zn2+) and methylene blue removal. Also, adsorption experiments were performed on wastewaters taken from tailings of the lead and zinc mine and kinetic of the methylene blue removal was studied. The factors which distinguished the KOH activated samples were high yield (~14%), content of organic carbon (63–74%), porosity and specific surface area (SBET~700–1360 m2/g), a low degree of the crystal phase, indications that potassium ions may be included in heavy metals removal, good removal of the heavy metal ions (~47–59 mg/g for Pb2+, ~21–27 mg/g for Cd2+and ~6–10 mg/g for Zn2+) and fast (~10–30 min) and good methylene blue (~60–200 mg/g) removal

Ammonia adsorption on chemically modified activated carbon cloth

The effect of CuCl2, CuSO4, and H2SO4 impregnation of activated carbon cloth on ammonia adsorption at 303 K were examined. Cellulose based activated carbon cloth of various activities were used as the starting materials. The carbon cloth surface area and porous structure parameters were determined by N-2 adsorption at 77 K using the gravimetric McBain method. Ammonia adsorption was significantly increased on impregnated samples, at low relative pressure (low NH3 concentration). Ammonia adsorption at high concentration was found to be directly influenced by the available micropore valume of the activated carbon cloth

Ammonia adsorption on chemically modified activated carbon cloth

The effect of CuCl2, CuSO4, and H2SO4 impregnation of activated carbon cloth on ammonia adsorption at 303 K were examined. Cellulose based activated carbon cloth of various activities were used as the starting materials. The carbon cloth surface area and porous structure parameters were determined by N-2 adsorption at 77 K using the gravimetric McBain method. Ammonia adsorption was significantly increased on impregnated samples, at low relative pressure (low NH3 concentration). Ammonia adsorption at high concentration was found to be directly influenced by the available micropore valume of the activated carbon cloth

The effect of partially carbonized fibers on the mechanical properties of carbon/carbon composites

The carbon/carbon (C/C) composite with satisfactory mechanical properties were obtained through introduction of partially carbonized fibers as a precursor. Applying this procedure the production cost of C/C composites may be significantly reduced. Stabilized PAN fibers were partially carbonized at temperatures ranging from 400 to 1000 degrees C and reinforced with phenolic resin, resole type. Cured composite were carbonized up to 1000 degrees C in an inert atmosphere. Monofilament tensile test strength, Youngs modulus and tensile strength of partially carbonized fibers were determined. Mechanical properties of carbon/carbon composites (flexural strength and flexural modulus) determined by using three-point bending test. The effect of partially carbonized fibers on the mechanical properties of C/C composites was examined by scanning electron microscope (SEM) through analysis of the fracture surface. The C/C composite reinforced with partially carbonized fibers at 600 degrees C showed quite satisfactory flexural strength. This confirms assumptions that through co-carbonization of partially carbonized fibers and resin C/C composite with suitable mechanical properties could be obtained. (C) 2011 Elsevier B.V. All rights reserved

Electrooxidation of hydrogen on nanostructured Pt/C catalysts for polymer electrolyte fuel cells

Mesoporous carbon cryogel synthesized by sol-gel polycondensation and freeze-drying with specific surface area (BET) of 517 m(2) g(-1) was used as a catalyst support. Pt/C catalysts were prepared by a modified ethylene glycol method (EG). Transmission electron microscopy (TEM) images show that the dispersion of the catalyst is very uniform with a mean particle size of about 2.65 nm. Hydrogen oxidation reaction (HOR) was studied on Pt/C catalyst in 0.5 mol dm(-3) HClO4 acid solution. It has been found that HOR appears as a reversible two-electron direct discharged reaction (Tafel slope for this reaction is approximate to 30mV dec(-1)) and that Pt/C catalyst exhibits a very high catalytic activity. However, the corresponding value of the exchange current density obtained by dividing the exchange current by the active surface area of Pt particles has the same order of magnitude as those for the HOR in acidic solution at single crystal and polycrystalline Pt.Recent Developments in Advanced Materials and Processes, 7th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 12-16, 2005, Herceg Novi, Montenegr