Candelaria Tejada-Tovar

Adsorción de metales pesados en aguas residuales usando materiales de origen biológico

Biosorption is a process that allows active or passive uptake of metal ions due to the property that different living or dead biomass have to bind and accumulate these pollutants by different mechanisms. The application of low-cost materials obtained from different biomass from microbial flora, agro-industrial waste and algae has been investigated to replace the use of conventional methods for the removal of contaminants such as heavy metals. Some of the metals of greatest impact to the environment due to its high toxicity and difficult to remove are chromium, nickel, cadmium, lead, and mercury. In this paper, an overview of adsorption as an alternative process for the removal of contaminants in solution and biomass commonly used in these processes, as well as some of the modifications made to improve the efficiency of adsorption of these materials is presented. It was concluded that the use of adsorption in the removal of pollutants in aqueous solution using waste biomass is applicable to these decontamination processes avoiding subsequent problems such as the generation of chemical sludge, and generating an alternative to use materials considered as waste. It is further identified that such factors as the pH of the solution, particle size, temperature, and concentration of metal effect on the process.

Removal of Lead (II) of waters from Anticona Cerro de Pasco River (Perú) through the use of orange mesocarpactivated carbon (Citrus sinensis)

The objective of this study was to evaluate the use of activated carbon obtained from orange peel (Citrus sinensis) in the removal of Pb (II) ions present in the waters of the Anticona-Cerro de Pasco River.Activated carbon with phosphoric acid was prepared as an activating agent in an impregnation ratio of 0.70 g H3PO4 per gram of material.The physicochemical properties of the adsorbent were studied using the isothermal adsorption of nitrogen (BET), electron microscopy (SEM) and infrared spectrophotometry with Fourier transform (FTIR).The most influential factors in the adsorption process were the pH of the solution, contact time, porous structure and acidity of the carbon.The results indicate that Freundlichs model is the one that best adjusts the experimental data, reaching a bioadsorption capacity of 478.5 mgLPb (II), which represents 95.70% lead removal (II). Keyword Adsorption, bio-carbon, Freundlich’s isothermal.

Kinetic and dynamic study of Cr (VI) adsorption onto chemically modified corn cob

Low-cost materials have been widely investigated to be used for removing water pollutants as heavy metals. The kinetic and dynamic of adsorption Cr (VI) onto corn cob and chemically modified corn cob biosorbents were studied. Batch adsorption experiments were performed under solution pH=2 and the results were used for determining kinetic model (pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion) that best describes adsorption process over time. In addition, adsorption process was carried out in packed-bed columns to construct concentration-like profile and calculate parameters of dynamic models as Thomas, Adams-Bohart, Yoon-Nelson and dose-response. Desorption-adsorption cycles were also performed to analysis capacity of biomass to be regenerated. It was found that pseudo-second order best fitted experimental data for corn cob biomass with k2 = 0.00098 g/mg min and qe,2 = 15.05 mg/g. The reduction in adsorption capacity after chemical modification indicated that corn cob biosorbent is recommended for further studies. Dynamic process using corn cob biosorbent obeyed Thomas model with kTh = 0.039 mL/mg min and qo = 2.1 mg/g. The desorption study revealed that this biomass can be regenerated and reused in consecutive cycles, which make it attractive for being applied in industrial-scale processes. 1384 Ángel Villabona-Ortíz et al.

Optimization of variables in fixed-bed column using the response surface methodology

Heavy metal removal technologies in industrial wastewater bodies are being implemented more frequently, due to the increasing demand for treatment of water contaminated with metals. Adsorption becomes important due to its profitability and use of organic waste. The objective of this research was to optimize the most incidental variables of the cadmium biosorption process with cocoa shell (Theobroma cacao L.) in fixed-bed column with the response surface methodology. The hypothesis of the study was that bed height is the most influential variable in the continuous adsorption process. The experimental design was 3 multilevel factorial , the information corresponds to the behavior of the bed and influence of feed flow, initial metal concentration in the solution and the height of the packed bed. A second-order polynomial model was generated with a correlation coefficient of 0.9072, which indicates that this makes a good adjustment of the experimental data. The theoretical and operational optimal conditions were determined. The optimal configuration of the actual and theoretical bed operating parameters were: 5 g biomass, 4.5 mL min flow rate and 100 mg L initial metal concentration for real conditions and 10.79 g, 4.50 mL min flow rate and 40 mg L for theoretical flow rate. It concluded that the height of the bed had a proportional influence on the removal rate, while the initial metal concentration in the synthetic solution and the increase in flow rate did not have a significant effect on the system. 1122 Candelaria Tejada-Tovar et al.

Influence of the bed height on the dynamic behavior of a fixed-bed column during mercury biosorption

espanolSe determino el impacto de la altura del lecho en la remocion de Hg (II), presente en solucion sobre biomasa residual de cascara de cacao en sistema continuo de lecho fijo, evaluando el rendimiento de la densidad de empaque. El trabajo experimental estuvo fundamentado en: preparacion de la biomasa, diseno y montaje de la unidad de adsorcion y modelado matematico, considerando como variables intervinientes en el proceso la concentracion inicial del metal, pH, velocidad de flujo y tamano de particula y como variable independiente incidente la densidad de empaque mg biomasa/volumen del lecho, traducido en altura en cm de empaque. Los analisis FTIR de la cascara muestran la presencia de grupos funcionales que favorecen la adsorcion de iones metalicos. La concentracion de Hg (II) se midio por espectroscopia UV/vis; se obtuvo una capacidad maxima de adsorcion fue de 99.62 % para el lecho de 10g (7.5 cm). Ademas, el modelo de Thomas fue el que mejor ajusto los datos experimentales. A partir de estos resultados, se concluye que la cascara de cacao tiene potencial para ser utilizado como bioadsorbente de Hg (II) en solucion y que el aumento de la altura del lecho en el sistema continuo favorecio la remocion del contaminante. EnglishThis study evaluated the packing density of residual biomass of cocoa bean husk as adsorbent of Hg (II) dissolved in an aqueous solution inside a continuous fixed-bed system. The effects of the height of the bed on the removal of the pollutant were evaluated. This experimental work was based on biomass preparation, adsorber design and assembly, and mathematical modelling. The variables considered in the process were initial concentration of the metal, pH, flow rate and particle size. The incident-independent variable was the packing density (mg biomass/bed volume), which translated into the height (cm) of the packing. The FTIR analyses of the husk revealed the presence of functional groups in the spectrum that favour the adsorption of the metal. The residual concentration of the solution was measured by UV/Vis spectroscopy; the maximum adsorption capacity was 99.62%, by the 10g (7.5 cm) bed. In addition, the Thomas model was the best-fitting for the experimental data. On the basis of these results, we concluded that cocoa bean husk has potential to be used as bioadsorbent of Hg (II) from aqueous solutions and that the increase in bed height in the continuous system favours the removal of the pollutant.This study evaluated the packing density of residual biomass of cocoa bean husk as adsorbent of Hg (II) dissolved in an aqueous solution inside a continuous fixed-bed system. The effects of the height of the bed on the removal of the pollutant were evaluated. This experimental work was based on biomass preparation, adsorber design and assembly, and mathematical modelling. The variables considered in the process were initial concentration of the metal, pH, flow rate and particle size. The incident-independent variable was the packing density (mg biomass/bed volume), which translated into the height (cm) of the packing. The FTIR analyses of the husk revealed the presence of functional groups in the spectrum that favour the adsorption of the metal. The residual concentration of the solution was measured by UV/Vis spectroscopy; the maximum adsorption capacity was 99.62%, by the 10g (7.5 cm) bed. In addition, the Thomas model was the best-fitting for the experimental data. On the basis of these results, we concluded that cocoa bean husk has potential to be used as bioadsorbent of Hg (II) from aqueous solutions and that the increase in bed height in the continuous system favours the removal of the pollutant.