36 research outputs found
Adsorptive Removal of Acid Blue 80 Dye from Aqueous Solutions by Cu-TiO 2
The adsorption performance of a Cu-TiO2 composite for removing acid blue 80 (AB80) dye from aqueous solutions was investigated in terms of kinetics, equilibrium, and thermodynamics. The effect of operating variables, such as solution pH, initial dye concentration, contact time, and temperature, on AB80 adsorption was studied in batch experiments. AB80 adsorption increased with increasing contact time, initial dye concentration, and temperature and with decreasing solution pH. Modeling of adsorption kinetics showed good agreement of experimental data with the pseudo-second-order kinetics model. The experimental equilibrium data for AB80 adsorption were evaluated for compliance with different two-parameter, three-parameter, and four-parameter isotherm models. The Langmuir isotherm model best described the AB80 adsorption equilibrium data. The thermodynamic data revealed that the AB80 adsorption process was endothermic and nonspontaneous. Kinetics, equilibrium, and thermodynamic results indicate that Cu-TiO2 adsorbs AB80 by a chemical sorption reaction
Editorial 6(22) AyTBUAP. Sustancias poliméricas extracelulares microbianas con propiedades floculantes: una alternativa al empleo de copolÃmeros de acrilamida
La operación de coagulación-floculación para la remoción de partÃculas suspendidas es muy utilizada en el tratamiento de aguas residuales. Entre los floculantes más empleados actualmente se encuentran los copolÃmeros de acrilamida, sin embargo, el uso extensivo de estas moléculas recalcitrantes podrÃa ocasionar efectos indeseables en los ecosistemas. En estudios recientes se han reportado sustancias poliméricas extracelulares de origen microbiano con propiedades floculantes semejantes a los polÃmeros sintéticos. Estos hallazgos muestran el gran potencial de los polÃmeros microbianos en el área ambiental y la importancia de estudios adicionales que permitan su producción a gran escala
Selección y caracterización de un biomaterial capaz de remover cromo hexavalente y cromo total de soluciones acuosas
Tesis (Doctorado en Ciencias Quimicobiológicas), Instituto Politécnico Nacional, SEPI, ENCB, 2009, 1 archivo PDF, (255 páginas). tesis.ipn.m
Revisión sobre la ocurrencia de triclosán en aguas subterráneas y tendencias tecnológicas para su remoción
Debido a la importancia como fuente de abastecimiento de agua potable, las aguas subterráneas deben garantizar seguridad en cuanto a su composición quÃmica. Sin embargo, en años recientes una gran cantidad de micro-contaminantes orgánicos tóxicos no regulados se han detectado en aguas subterráneas. El triclosán (TCS) es una sustancia desinfectante que debido a sus propiedades tóxicas y alta movilidad en el medio ambiente ha sido una molécula indicadora de procesos contaminantes de origen antropogénico. El análisis de estudios de monitoreo de contaminación de aguas subterráneas con triclosán muestra que su presencia en estas fuentes de agua potable se encuentra principalmente en zonas urbanas y en menor medida en zonas rurales. Y fundamentalmente, se debe a tres problemáticas: 1) la infiltración de aguas residuales domésticas sin tratamiento, 2) la infiltración de aguas residuales domésticas tratadas en cuyo tren de tratamiento no se contemplan operaciones avanzadas para la eliminación de micro-contaminantes orgánicos y 3) la infiltración de lixiviados provenientes de rellenos sanitarios. Las tecnologÃas más prometedoras para la remoción de triclosán de sistemas acuosos con bajo contenido de materia orgánica son: oxidación y oxidación avanzada, adsorción y biosorción, remoción metabólica microbiana, transformación enzimática y fitofiltración. La mayorÃa de los estudios para la remoción de triclosán se han realizado a nivel de laboratorio poniendo énfasis tanto en la eficiencia del proceso como en el mecanismo de remoción del contaminante, estos estudios son de gran importancia para el diseño de sistemas de tratamiento de aguas residuales y naturales
Chromium Recovery from Chromium-Loaded <i>Cupressus lusitanica</i> Bark in Two-Stage Desorption Processes
Hexavalent chromium (Cr(VI)) contamination poses serious health and environmental risks. Chromium biosorption has been employed as an effective means of eradicating Cr(VI) contamination. However, research on chromium desorption from chromium-loaded biosorbents is scarce despite its importance in facilitating industrial-scale chromium biosorption. In this study, single- and two-stage chromium desorption from chromium-loaded Cupressus lusitanica bark (CLB) was conducted. Thirty eluent solutions were evaluated first; the highest single-stage chromium desorption efficiencies were achieved when eluent solutions of 0.5 M NaOH, 0.5 M H2SO4, and 0.5 M H2C2O4 were used. Subsequently, two-stage kinetic studies of chromium desorption were performed. The results revealed that using 0.5 M NaOH solution in the first stage and 0.5 M H2C2O4 in the second stage enabled the recovery of almost all the chromium initially bound to CLB (desorption efficiency = 95.9–96.1%) within long (168 h) and short (3 h) desorption periods at each stage. This study clearly demonstrated that the oxidation state of the recovered chromium depends on the chemical nature and concentration of the eluent solution. The results suggest the possible regeneration of chromium-loaded CLB for its subsequent use in other biosorption/desorption cycles
Chromium Biosorption from Cr(VI) Aqueous Solutions by Cupressus lusitanica Bark: Kinetics, Equilibrium and Thermodynamic Studies.
The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g(-1). Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater
Scanning electron micrographs of CLB at (a) 85×, (b) 500× and (c) 3000× magnification.
<p>Scanning electron micrographs of CLB at (a) 85×, (b) 500× and (c) 3000× magnification.</p
Comparison of maximum total Cr adsorption capacity predicted by the Langmuir model for various adsorbents.
<p>Comparison of maximum total Cr adsorption capacity predicted by the Langmuir model for various adsorbents.</p
Kinetic parameters of the Elovich, fractional power, pseudo-first-order and pseudo-second-order models for total Cr biosorption onto <i>Cupressus lusitanica</i> bark at different temperatures. Initial Cr(VI) concentration: 100 mg L<sup>-1</sup>.
<p>Kinetic parameters of the Elovich, fractional power, pseudo-first-order and pseudo-second-order models for total Cr biosorption onto <i>Cupressus lusitanica</i> bark at different temperatures. Initial Cr(VI) concentration: 100 mg L<sup>-1</sup>.</p
Parameters of the Langmuir and Freundlich isotherm models for total Cr biosorption onto <i>C</i>. <i>lusitanica</i> bark.
<p>Parameters of the Langmuir and Freundlich isotherm models for total Cr biosorption onto <i>C</i>. <i>lusitanica</i> bark.</p