RESUMEN
Robust and reusable magnetic chitosan/calcium alginate double-network hydrogel beads (CSMAB) with an environmentally benign biocomposite material synthesis approach were used adsorption of surfactant and removal of methylene blue dye sequentially for the first time. Double network hydrogel structure with sodium alginate and chitosan and acidification of the surface with HCl provided the reusability of the beads at the pollutant removal in water. The CSMAB beads were characterized for structural analysis by FESEM, EDX, BET, VSM, and FTIR techniques. They were used for the adsorption of cationic hexadecylpyridinium chloride (HDPCl) and anionic sodium dodecyl sulfate (SDS) surfactants and reused in the removal of cationic methylene blue dye without any pretreatment. The effect of pH, adsorbent dose, and temperature on surfactant removal efficiency was analyzed and pH was found the statistical significance. The adsorption capacity of CSMAB beads with a surface area of 0.65 m2 g-1 was calculated as 1.9 mg g-1 for HDPCl, and 1.2 mg g-1 for SDS, respectively. The SDS and HDPCl adsorption followed the pseudo-second-order kinetic and Freundlich isotherm model. The thermodynamic results showed that the surfactant adsorption process is an exothermic and spontaneous process. SDS-reacted CSMAB beads showed higher efficiency with 61 % in the removal of methylene blue dye.
Asunto(s)
Quitosano , Contaminantes Químicos del Agua , Hidrogeles/química , Quitosano/química , Adsorción , Azul de Metileno/química , Alginatos/química , Tensoactivos/química , Fenómenos Magnéticos , Contaminantes Químicos del Agua/química , Cinética , Concentración de Iones de HidrógenoRESUMEN
Ficus carica (common fig) dried fruit extract was used to synthesize iron oxide nanoparticles in this study. Biomaterials in the common fig dried fruit extract synthesized the iron nanoparticles by reducing the iron precursor salt and then acted as capping and stabilizing agents. The nanoparticles were produced smaller than 20 nm diameters and oxidized due to the high phenolic compound content in the common fig dried fruit extract. Nanoparticles were characterized by energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS). First, color change and pH reduction occurred immediately due to the iron nanoparticle synthesis. TEM images showed that the nanoparticles were at 9 ± 4 nm diameters and the metallic core-oxide shell form. The nanoparticles were in spherical shapes with a monodisperse distribution. EDX, XRD and FTIR analysis signals showed the iron oxyhydroxide/oxide formation. Absorption peaks were detected at 205 nm and 291 nm due to the iron metallic core hydrolysis products. The intensity-average diameter of nanoparticles was calculated at 475 nm diameter by DLS analysis. Colloid stability was determined as moderate at 20.7 mV.
Asunto(s)
Compuestos Férricos/química , Compuestos Férricos/síntesis química , Ficus/química , Tecnología Química Verde/métodos , Nanopartículas del Metal/química , Extractos Vegetales/química , Biocatálisis , Coloides/síntesis química , Coloides/química , Desecación , Frutas/química , Microscopía Electrónica de Transmisión , Tamaño de la Partícula , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos XRESUMEN
Biogas production from food waste has been used as an efficient waste treatment option for years. The methane yields from decomposition of waste are, however, highly variable under different operating conditions. In this study, a statistical experimental design method (Taguchi OA9) was implemented to investigate the effects of simultaneous variations of three parameters on methane production. The parameters investigated were solid content (SC), carbon/nitrogen ratio (C/N) and food/inoculum ratio (F/I). Two sets of experiments were conducted with nine anaerobic reactors operating under different conditions. Optimum conditions were determined using statistical analysis, such as analysis of variance (ANOVA). A confirmation experiment was carried out at optimum conditions to investigate the validity of the results. Statistical analysis showed that SC was the most important parameter for methane production with a 45% contribution, followed by F/I ratio with a 35% contribution. The optimum methane yield of 151 l kg-1 volatile solids (VS) was achieved after 24 days of digestion when SC was 4%, C/N was 28 and F/I were 0.3. The confirmation experiment provided a methane yield of 167 l kg-1 VS after 24 days. The analysis showed biogas production from food waste may be increased by optimization of operating conditions.
Asunto(s)
Biocombustibles , Biotecnología/métodos , Alimentos , Metano/biosíntesis , Análisis de Varianza , Biotecnología/instrumentación , Carbono/metabolismo , Modelos Estadísticos , Nitrógeno/metabolismo , Eliminación de Residuos/métodos , Turquía , ResiduosRESUMEN
The present study examines the effects of an effluent from a fat plant (FP) on zebrafish (Danio rerio) embryos and larvae using the whole effluent toxicity testing methods (WET). The method is based on acute toxicity using 96-h larval mortality and chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim-up failure, accumulative mortality, and sex ratio. On the basis of larval mortality the 96-h LC(50) (the concentration was lethal to 50% of newly hatching zebrafish larvae) was 68.9%. In chronic toxicity test, newly fertilized embryos (<5-h old) were exposed to 1, 6, 12, 25, 50% effluent concentrations in a 24-h static renewal system at (27 +/- 0.5) degrees C until 15-day posthatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution. Embryos began to show lesions on third day at higher concentrations (12, 25, 50% FP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. Morphological abnormalities were observed in newly hatched larvae at 25 and 50% FP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. On the basis of the study, the FP effluent tested here may cause increasing embryotoxicity in the zebrafish embryos. We conclude that the test using zebrafish is feasible to evaluate both acute and chronic toxicities of industrial effluents.
Asunto(s)
Residuos Industriales/efectos adversos , Contaminantes Químicos del Agua/toxicidad , Pez Cebra/crecimiento & desarrollo , Animales , Bioensayo , Relación Dosis-Respuesta a Droga , Embrión no Mamífero/efectos de los fármacos , Monitoreo del Ambiente , Femenino , Industria de Alimentos , Larva/efectos de los fármacos , Masculino , Óvulo/efectos de los fármacos , Razón de Masculinidad , Eliminación de Residuos Líquidos , Contaminación Química del AguaRESUMEN
In this paper, Taguchi method was applied to determine the optimum dye removal from aqueous solution by electrocoagulation using aluminum electrodes. An orthogonal array (OA(16)) experimental design that allows to investigate the simultaneous variations of five parameters (initial dye concentration, initial pH of the solution, supporting electrolyte concentration, supporting electrolyte type and current density) having four levels was employed to evaluate the effects of experimental parameters. Performance measure analysis was followed by performing a variance analysis, in order to determine the optimum levels and relative magnitude of the effect of parameters. Because the desired characteristic for response has been maximum decolorization, Taguchi's 'the larger the better' performance formula was used. While the optimum conditions were found to be initial dye concentration of 100 mg/L, initial pH of the solution of 3, supporting electrolyte concentration of 0.0 mM, supporting electrolyte type of CaCl(2) and current density of 0.50 mA/cm(2). Under these optimum conditions, energy consumption is 0.607 kWh/kg dye, when the system evaluated also based on the energy consumptions it can be said that optimum conditions should be modified as follows: supporting electrolyte concentration of 2.5 mM; supporting electrolyte type NaCl, for 100 mg/L initial dye concentration; initial pH of the solution of 3; current density of 0.50 mA/cm(2).
Asunto(s)
Colorantes/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Aluminio/química , Electroquímica , Electrodos , Concentración de Iones de Hidrógeno , Residuos Industriales , Soluciones , Industria TextilRESUMEN
The aim of this investigation is to evaluate the treatability of synthetically prepared water with high concentration of humic substances by electrocoagulation in batch mode using iron cast electrodes. Effects of applied potential, initial humic substance concentration and supporting electrolyte type on humic substance removal efficiency were investigated. NaNO3, Na2SO4 and NaCl were used as supporting electrolyte. Among these supporting electrolytes, Na2SO4 and NaCl have provided high removal efficiencies, whereas in the experiments using NaNO3 as supporting electrolyte have been observed no flock formation. The highest removal rate is obtainable with NaCl as supporting electrolyte. Removal efficiencies for initial humic substance concentration of 500 mg L-1 with NaCl and Na2SO4 equal to 97.95% for 35 min and 92.69% for 70 min, respectively. This behavior of the system has been derived from oxidation products, available in the bulk solution, of chloride ions. When NaCl is used as supporting electrolyte, there is an advantage of providing the disinfection of water, but humic substances and chloride ions are available in the bulk solution with risk of formation undesirable organo-chlorine compounds, so the Na2SO4 is the most favorable supporting electrolyte.
Asunto(s)
Productos Biológicos/aislamiento & purificación , Sustancias Húmicas , Hierro/química , Purificación del Agua/métodos , Agua/química , Electroquímica , Electrodos , Electrólitos/química , Nitratos/química , Cloruro de Sodio/química , Sulfatos/química , Purificación del Agua/instrumentaciónRESUMEN
In this study, the effect of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes has been investigated. For this aim, experiments have been carried out controlled initial pH values within the range of 3-9. Effects of initial pH have been analyzed on efficiencies of phosphate removal and energy consumptions. From obtained results, it was found that optimal initial pH is 3. Besides, experiments have been carried out controlled system pH. Effects of system variables have been analyzed on constant pH. From obtained results in these experiments, it was found that optimal system pH is 7.