Anais do XX Congresso Brasileiro de Engenharia Química, 2015
Sericin is a protein present in the cocoon of silkworm silk (Bombyx mori), usually discarded in t... more Sericin is a protein present in the cocoon of silkworm silk (Bombyx mori), usually discarded in the effluent from the spinning process. The use of blends provides an improvement in the physical characteristics of the materials produced with the protein, and the use of alginate has the advantage because it has affinity for a variety of cations. The objective of this study is to evaluate the process of thermal crosslinking of the particles produced from the blend between sericin and alginate and metal affinity of these particles with zinc and copper metals. For this purpose, we evaluated the crosslinking temperatures of 40, 100, 125 and 150 °C. Subsequently, the particles were analyzed for the water solubility and its ability to adsorb metals in aqueous solution. The results indicated that the particles cross-linked at 100 ºC had smaller percentage of solubilized matter comparing with other temperatures. The results indicated that sericin/alginate particles had greater affinity to Cu 2+ than to Zn 2+ ions.
The Canadian Journal of Chemical Engineering, 2016
This work aims to evaluate different eluents in cycles of nickel adsorption/desorption on calcine... more This work aims to evaluate different eluents in cycles of nickel adsorption/desorption on calcined Bofe clay. The following eluents were used sequentially for nickel desorption: H 2 SO 4 0.25 mol/L, NaCl 1.0 mol/L, CaCl 2 0.10 mol/L, and EDTA 0.10 mol/L. Physical-chemical characterization analyses of Bofe clay samples were carried out under different conditions to evaluate the effect of the remaining metal on the adsorbent submitted to adsorption/desorption cycles. The adsorbent material was characterized by the following techniques: energy dispersive X-ray spectroscopy (EDX), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and N 2 physisorption (BET). Statistica 5.0 was used as a computational tool to adjust the rate quasi-chemical solution to the experimental data of the breakthrough curves. From the new function obtained, breakthrough curves for different bed heights could be also simulated. An increase of the clay surface area and a reduction of real density after the passage of the four eluents were observed. Among the tested eluents, NaCl (1 mol/L) presented the highest percentage of desorption (88.08 %). The nickel adsorption/desorption cycles study showed that Bofe clay retains the same nickel adsorption capacity throughout the four evaluated cycles.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Neste trabalho foram sintetizadas, por eletrodeposição, ligas de tungstênio usando o ferro como m... more Neste trabalho foram sintetizadas, por eletrodeposição, ligas de tungstênio usando o ferro como metal indutor. Os ensaios de eletrodeposição foram realizados segundo um planejamento experimental 2 3 com 3 pontos centrais, de modo que foi analisada a influência da densidade de corrente elétrica, concentração do ferro no banho eletrolítico e temperatura sobre a eficiência de eletrodeposição. As melhores ligas obtidas foram caracterizadas utilizando microscopia eletrônica de varredura (MEV), difração de Raios X (DRX) e espectroscopia de absorção de infravermelho (FTIR). A maior eficiência de deposição obtida foi de aproximadamente 50% e as ligas caracterizadas apresentaram alto grau de pureza e baixa cristalinidade, sendo predominantemente amorfas.
Mass Transfer - Advancement in Process Modelling, 2015
Ion exchange is a stoichiometric phenomenon commonly used in water treatment as an end-of-pipe te... more Ion exchange is a stoichiometric phenomenon commonly used in water treatment as an end-of-pipe technique. Such process is highly influenced by mass transfer conditions and may be modeled by adsorption equations. Although widely applied in industries its theory has not been completely understood and depends on the exchanger characteristics. Moreover, competitive systems may add complexity and decrease removal efficiency and exchanger selectivity mainly in dynamic systems. In this chapter some general theory was presented and some detailed examples involving alginate biopolymer, bonechar and zeolite in single and competitive systems were discussed in batch and continuous state.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Os autores agradecem a FAPESP e ao CNPq pelo suporte financeiro para a realização da pesquisa e a... more Os autores agradecem a FAPESP e ao CNPq pelo suporte financeiro para a realização da pesquisa e a BRATAC pelo fornecimento dos casulos.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Os autores agradecem ao CNPq e à FAPESP pelo apoio financeiro, e à empresa BRATAC pelo fornecimen... more Os autores agradecem ao CNPq e à FAPESP pelo apoio financeiro, e à empresa BRATAC pelo fornecimento dos casulos.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015
Abstract In this work, the physicochemical and morphological characterization of fish scales and ... more Abstract In this work, the physicochemical and morphological characterization of fish scales and an evaluation of their adsorption of reactive blue 5G (RB5G) dye were performed. The analysis of N2 physisorption, pHZPC, SEM–EDX, XRD and FTIR was carried out. Adsorption experiments were performed in batch and closed system. From N2 physisorption studies, we obtained values of the specific surface area, total pore volume and average pore diameter as 2.6 m2 g−1, 0.003 cm3 g−1 and 20.6 A, respectively. The pHZPC was estimated as 7.6. The presence of hydroxyapatite and collagen fibres in the structure of the scales was observed in SEM–EDX, XRD and FTIR results. Furthermore, leaching of mineral phase mainly occurs during the adsorption process in acid medium (pH 2), although, in neutral and alkaline media (pH 7 and 10), it is less pronounced. The FTIR spectra indicate that the amides functional groups from collagen structure are responsible for RB5G dye adsorption. Comparing the RB5G dye uptake at different initial pH values (2, 7, 10), a higher capacity was achieved in acidic medium. The equilibrium adsorption data of RB5G dye at pH 2 showed a maximum capacity of 241.20 mg g−1 with fast kinetics.
Adsorption is currently recognized as an efficient and economical process for the treatment of to... more Adsorption is currently recognized as an efficient and economical process for the treatment of toxic metals from wastewater. This process provides flexibility in the design and operation of treatment systems and in many cases generates a high-quality treated effluent. Furthermore, due to the reversibility of the adsorption adsorbents are sometimes regenerated by desorption suitable. Among the adsorbent materials, clays are characterized by their wide availability and low cost, which aggregates the potential they represent, especially when modified, resulting in scientific and industrial interest. Bentonite or smectite clays are widely used in industry, where applications are associated with their characteristic adsorbent and these properties can be improved by thermal and chemical treatments. Copper sorption behavior of calcined Bofe clay in consecutive adsorption-desorption cycles has been investigated in a packed-bed flow-through column during a continuous removal of copper from a 1.57 mmol/L aqueous solution at pH 5. The eluent used was HCl 0.1 mol/L. The adsorption and desorption were carried out for an average of 15 and 4 h, respectively, representing more than 2 days of continuous use of the adsorbent. The weight loss of mass after this time was 0.6 %. The Cu-sorption capacity of the calcined clay, based on the initial dry weight, was approximately 0.11 mmol/g. Sorption performance was indicated by shortening breakthrough time and a broadening mass-transfer zone. The column useful time, considered up to 1 mg Cu/L in the effluent, keeping aproximately in 100 min for all cycles. The mass-transfer zone, decreased almost linearly from 10 to 9 cm. Regeneration with HCl provided elution efficiencies up to 100%.
ABSTRACT In this work, the copper removal in fixed-bed of Bofe calcined clay was realized, in whi... more ABSTRACT In this work, the copper removal in fixed-bed of Bofe calcined clay was realized, in which the adsorption and desorption of copper ions, the time of equilibrium and kinetic curves were investigated. Different types of eluents were utilized for calcined clays bed regeneration. Desorption tests were performed using a NaCl solution at 1% and seawater both at pH 3. The results indicated that the regeneration of the bed with NaCl/HCl or saline water at pH 3 is very efficient and the elution was verified as 50%. Also, it was observed an increase in removal after exposure of the bed to the eluent. The highest adsorption capacities of copper were ≈0.3 mmol/g, on the Bofe calcined clay. The equilibrium time increased from 120 min to 400 min considering the first to the last cycle. During the regeneration process, the mass-transfer zone decreased almost linearly from 9.8 to 3.4 cm with the use of NaCl and from 9.9 to 6.7 cm with seawater. In addition, those eluents provide the ideal breakthrough behavior. The recovery efficiency of the water showed that the desorption of copper ions with NaCl or seawater is feasible and has great potential.
In this study, it was evaluated the potential use of commercial sodium bentonitic clay, called Fl... more In this study, it was evaluated the potential use of commercial sodium bentonitic clay, called Fluidgel, chemically and thermally treated, as an adsorbent in the removal of zinc ions from aqueous effluents. The chemical treatment was carried out with 10 g of clay dispersed in 100 mL of acetic acid 4 %. The heat treatment was obtained by calcination at 750 °C for 24 hours in muffle. The adsorption experiments were performed in thermostatic bath system and fixed bed, both based on preliminary study of metallic cationic speciation. The kinetics of zinc ions adsorption by acid-treated clay was rapid, requiring a minimum time of 60 min to reach equilibrium. The adsorbed amount and percentage of total zinc removal, at equilibrium time, was 0.06 mmol/g and 45 %, respectively, using the acid-treated clay. There was no removal of zinc by Fluidgel calcined clay in bath system, but in fixed bed it was obtained the total amount of zinc removal of 0.11 mmol/g and 41 % of percentage of removal.
This paper describes the adsorption of Cd 2+ and Pb 2+ ions using sodic bentonite clay type Fluid... more This paper describes the adsorption of Cd 2+ and Pb 2+ ions using sodic bentonite clay type Fluidgel modified. The Fluidgel before and after chemical modification and thermal activation was characterized by different techniques including X-ray diffraction, thermal analysis, Fourier transform infrared, surface area, helium pycnometry, cation exchange capacity and scanning electron microscopy. Pseudo-first order, pseudo-second order and intra-particle diffusion models were used to analyze the kinetic curves. Equilibrium data were analyzed using Langmuir and Freundlich models. The thermodynamic study indicated that lead adsorption process is endothermic and interactions between clays and solutions of lead occurred spontaneously, while cadmium adsorption revealed an exothermic and spontaneous nature. The maximum removal efficiencies were 97.62% for Cd(II) using Fluidgel modified chemically and 91.08% for lead by Fluidgel modified chemical and thermally.
Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" h... more Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" has been studied by batch and fixed-bed in static and dynamic systems, respectively. Analyses were performed for physicochemical characterization of clays using the techniques: X-ray fluorescence (XRF), thermogravimetry (TG), N 2 adsorption (BET) and Cationic Exchange Capacity (CEC). Batch experiments were performed at a constant temperature, adjusting the pH of the solution in contact with clays. Adsorption assays in fixed bed were conducted at the flow rate determined through mass transfer zone (MTZ). Langmuir and Freundlich models were adjusted to equilibrium data. The results of characterization indicated that the temperature of 500 °C is best suited for the calcination of the clays. The maximum adsorption capacity was higher for dynamic system than fixed bed compared to static system, enhancing from 0.0748 to 0.1371 and from 0.0599 to 0.22 mmol.g-1 of clay for "Bofe" and "Verde-lodo", respectively.
Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" h... more Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" has been studied by batch and fixed-bed in static and dynamic systems, respectively. Analyses were performed for physicochemical characterization of clays using the techniques: X-ray fluorescence (XRF), thermogravimetry (TG), N 2 adsorption (BET) and Cationic Exchange Capacity (CEC). Batch experiments were performed at a constant temperature, adjusting the pH of the solution in contact with clays. Adsorption assays in fixed bed were conducted at the flow rate determined through mass transfer zone (MTZ). Langmuir and Freundlich models were adjusted to equilibrium data. The results of characterization indicated that the temperature of 500 °C is best suited for the calcination of the clays. The maximum adsorption capacity was higher for dynamic system than fixed bed compared to static system, enhancing from 0.0748 to 0.1371 and from 0.0599 to 0.22 mmol.g-1 of clay for "Bofe" and "Verde-lodo", respectively.
Bentonite clays have been showing good adsorbing characteristics and are used as an alternative m... more Bentonite clays have been showing good adsorbing characteristics and are used as an alternative material in the removal of heavy metals. The purpose of this study is to evaluate the removal of nickel on Bofe bentonite calcined clay in porous bed. Firstly, a study was conducted to define the operation outflow, based on the minimum mass transfer zone (MTZ) obtained, useful (q U) and total adsorbed (q T) removal amounts and total nickel removal percentage (Rem (%)). Assays of nickel adsorption on clay were conducted according to a 2 2 factorial design with three central points to evaluate the effect of the particle diameter and initial adsorbate concentration on variables q U , q T and Rem (%). Tests to obtain the adsorbent physical and chemical characteristics were performed on samples of Bofe clay in natura, calcined, and calcined submitted to nickel adsorption. This clay was characterized according to the following techniques: Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Physisorption of N 2 (BET), Helium Picnometry and Scanning Electron Microscope (SEM) with metal mapping.
Bentonite clays have been showing good adsorbing characteristics and are used as an alternative m... more Bentonite clays have been showing good adsorbing characteristics and are used as an alternative material in the removal of heavy metals. The purpose of this study is to evaluate the removal of nickel on Bofe bentonite calcined clay in porous bed. Firstly, a study was conducted to define the operation outflow, based on the minimum mass transfer zone (MTZ) obtained, useful (q U) and total adsorbed (q T) removal amounts and total nickel removal percentage (Rem (%)). Assays of nickel adsorption on clay were conducted according to a 2 2 factorial design with three central points to evaluate the effect of the particle diameter and initial adsorbate concentration on variables q U , q T and Rem (%). Tests to obtain the adsorbent physical and chemical characteristics were performed on samples of Bofe clay in natura, calcined, and calcined submitted to nickel adsorption. This clay was characterized according to the following techniques: Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Physisorption of N 2 (BET), Helium Picnometry and Scanning Electron Microscope (SEM) with metal mapping.
In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were... more In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were studied. The clay was characterized through EDX, surface area (BET) and XRD analysis. The influence of parameters (pH, amount of adsorbent, adsorbate concentration and temperature) was investigated. Kinetic models were evaluated in order to identify potential adsorption process mechanisms. The Langmuir and Freundlich models were utilized for the analysis of adsorption equilibrium. Thermodynamic parameters were assessed as a function of the process temperature. The kinetics data were better represented by the second-order model. The process was found to be strongly influenced by the factors studied. The Bofe clay removed nickel with maximum adsorption capacity of 1.91 mg metal/g of clay (20 • C; pH 5.3) and that the thermodynamic data indicated that the adsorption reaction is spontaneous and of an exothermal nature. The Langmuir model provided the best fit for sorption isotherms.
In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were... more In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were studied. The clay was characterized through EDX, surface area (BET) and XRD analysis. The influence of parameters (pH, amount of adsorbent, adsorbate concentration and temperature) was investigated. Kinetic models were evaluated in order to identify potential adsorption process mechanisms. The Langmuir and Freundlich models were utilized for the analysis of adsorption equilibrium. Thermodynamic parameters were assessed as a function of the process temperature. The kinetics data were better represented by the second-order model. The process was found to be strongly influenced by the factors studied. The Bofe clay removed nickel with maximum adsorption capacity of 1.91 mg metal/g of clay (20 • C; pH 5.3) and that the thermodynamic data indicated that the adsorption reaction is spontaneous and of an exothermal nature. The Langmuir model provided the best fit for sorption isotherms.
This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions re... more This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions removal by adsorption in zeolite Baylith WE984. The experiments were conducted in a fluidised-bed rig with 300 grams of zeolite particles having diameter in the range 1 - 4mm. The volumetric flow rate of the fluidizing solution was 4.1 lmin(-1). Metal concentrations in the solution were measured by atomic absorption and the breakthrough curves were obtained for concentrations of metals ranging from 5 to 30 ppm (pH= 2). Experimental results obtained were fitted to the Renken model for analysis of the mass transfer resistance and the kinetic of adsorption. It was verified that the kinetic of adsorption was the limiting factor for the metallic ion retention in fluidised bed. Competitiveness of the metals adsorbed into Baylith zeolite were also analyzed being found the following order of preference for the metal removals: nickel > zinc > lead. The competitiveness was evaluated simultaneously in the combination of 2 x 2 and the three metals.
This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions re... more This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions removal by adsorption in zeolite Baylith WE984. The experiments were conducted in a fluidised-bed rig with 300 grams of zeolite particles having diameter in the range 1 - 4mm. The volumetric flow rate of the fluidizing solution was 4.1 lmin(-1). Metal concentrations in the solution were measured by atomic absorption and the breakthrough curves were obtained for concentrations of metals ranging from 5 to 30 ppm (pH= 2). Experimental results obtained were fitted to the Renken model for analysis of the mass transfer resistance and the kinetic of adsorption. It was verified that the kinetic of adsorption was the limiting factor for the metallic ion retention in fluidised bed. Competitiveness of the metals adsorbed into Baylith zeolite were also analyzed being found the following order of preference for the metal removals: nickel > zinc > lead. The competitiveness was evaluated simultaneously in the combination of 2 x 2 and the three metals.
Anais do XX Congresso Brasileiro de Engenharia Química, 2015
Sericin is a protein present in the cocoon of silkworm silk (Bombyx mori), usually discarded in t... more Sericin is a protein present in the cocoon of silkworm silk (Bombyx mori), usually discarded in the effluent from the spinning process. The use of blends provides an improvement in the physical characteristics of the materials produced with the protein, and the use of alginate has the advantage because it has affinity for a variety of cations. The objective of this study is to evaluate the process of thermal crosslinking of the particles produced from the blend between sericin and alginate and metal affinity of these particles with zinc and copper metals. For this purpose, we evaluated the crosslinking temperatures of 40, 100, 125 and 150 °C. Subsequently, the particles were analyzed for the water solubility and its ability to adsorb metals in aqueous solution. The results indicated that the particles cross-linked at 100 ºC had smaller percentage of solubilized matter comparing with other temperatures. The results indicated that sericin/alginate particles had greater affinity to Cu 2+ than to Zn 2+ ions.
The Canadian Journal of Chemical Engineering, 2016
This work aims to evaluate different eluents in cycles of nickel adsorption/desorption on calcine... more This work aims to evaluate different eluents in cycles of nickel adsorption/desorption on calcined Bofe clay. The following eluents were used sequentially for nickel desorption: H 2 SO 4 0.25 mol/L, NaCl 1.0 mol/L, CaCl 2 0.10 mol/L, and EDTA 0.10 mol/L. Physical-chemical characterization analyses of Bofe clay samples were carried out under different conditions to evaluate the effect of the remaining metal on the adsorbent submitted to adsorption/desorption cycles. The adsorbent material was characterized by the following techniques: energy dispersive X-ray spectroscopy (EDX), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and N 2 physisorption (BET). Statistica 5.0 was used as a computational tool to adjust the rate quasi-chemical solution to the experimental data of the breakthrough curves. From the new function obtained, breakthrough curves for different bed heights could be also simulated. An increase of the clay surface area and a reduction of real density after the passage of the four eluents were observed. Among the tested eluents, NaCl (1 mol/L) presented the highest percentage of desorption (88.08 %). The nickel adsorption/desorption cycles study showed that Bofe clay retains the same nickel adsorption capacity throughout the four evaluated cycles.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Neste trabalho foram sintetizadas, por eletrodeposição, ligas de tungstênio usando o ferro como m... more Neste trabalho foram sintetizadas, por eletrodeposição, ligas de tungstênio usando o ferro como metal indutor. Os ensaios de eletrodeposição foram realizados segundo um planejamento experimental 2 3 com 3 pontos centrais, de modo que foi analisada a influência da densidade de corrente elétrica, concentração do ferro no banho eletrolítico e temperatura sobre a eficiência de eletrodeposição. As melhores ligas obtidas foram caracterizadas utilizando microscopia eletrônica de varredura (MEV), difração de Raios X (DRX) e espectroscopia de absorção de infravermelho (FTIR). A maior eficiência de deposição obtida foi de aproximadamente 50% e as ligas caracterizadas apresentaram alto grau de pureza e baixa cristalinidade, sendo predominantemente amorfas.
Mass Transfer - Advancement in Process Modelling, 2015
Ion exchange is a stoichiometric phenomenon commonly used in water treatment as an end-of-pipe te... more Ion exchange is a stoichiometric phenomenon commonly used in water treatment as an end-of-pipe technique. Such process is highly influenced by mass transfer conditions and may be modeled by adsorption equations. Although widely applied in industries its theory has not been completely understood and depends on the exchanger characteristics. Moreover, competitive systems may add complexity and decrease removal efficiency and exchanger selectivity mainly in dynamic systems. In this chapter some general theory was presented and some detailed examples involving alginate biopolymer, bonechar and zeolite in single and competitive systems were discussed in batch and continuous state.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Os autores agradecem a FAPESP e ao CNPq pelo suporte financeiro para a realização da pesquisa e a... more Os autores agradecem a FAPESP e ao CNPq pelo suporte financeiro para a realização da pesquisa e a BRATAC pelo fornecimento dos casulos.
Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015
Os autores agradecem ao CNPq e à FAPESP pelo apoio financeiro, e à empresa BRATAC pelo fornecimen... more Os autores agradecem ao CNPq e à FAPESP pelo apoio financeiro, e à empresa BRATAC pelo fornecimento dos casulos.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015
Abstract In this work, the physicochemical and morphological characterization of fish scales and ... more Abstract In this work, the physicochemical and morphological characterization of fish scales and an evaluation of their adsorption of reactive blue 5G (RB5G) dye were performed. The analysis of N2 physisorption, pHZPC, SEM–EDX, XRD and FTIR was carried out. Adsorption experiments were performed in batch and closed system. From N2 physisorption studies, we obtained values of the specific surface area, total pore volume and average pore diameter as 2.6 m2 g−1, 0.003 cm3 g−1 and 20.6 A, respectively. The pHZPC was estimated as 7.6. The presence of hydroxyapatite and collagen fibres in the structure of the scales was observed in SEM–EDX, XRD and FTIR results. Furthermore, leaching of mineral phase mainly occurs during the adsorption process in acid medium (pH 2), although, in neutral and alkaline media (pH 7 and 10), it is less pronounced. The FTIR spectra indicate that the amides functional groups from collagen structure are responsible for RB5G dye adsorption. Comparing the RB5G dye uptake at different initial pH values (2, 7, 10), a higher capacity was achieved in acidic medium. The equilibrium adsorption data of RB5G dye at pH 2 showed a maximum capacity of 241.20 mg g−1 with fast kinetics.
Adsorption is currently recognized as an efficient and economical process for the treatment of to... more Adsorption is currently recognized as an efficient and economical process for the treatment of toxic metals from wastewater. This process provides flexibility in the design and operation of treatment systems and in many cases generates a high-quality treated effluent. Furthermore, due to the reversibility of the adsorption adsorbents are sometimes regenerated by desorption suitable. Among the adsorbent materials, clays are characterized by their wide availability and low cost, which aggregates the potential they represent, especially when modified, resulting in scientific and industrial interest. Bentonite or smectite clays are widely used in industry, where applications are associated with their characteristic adsorbent and these properties can be improved by thermal and chemical treatments. Copper sorption behavior of calcined Bofe clay in consecutive adsorption-desorption cycles has been investigated in a packed-bed flow-through column during a continuous removal of copper from a 1.57 mmol/L aqueous solution at pH 5. The eluent used was HCl 0.1 mol/L. The adsorption and desorption were carried out for an average of 15 and 4 h, respectively, representing more than 2 days of continuous use of the adsorbent. The weight loss of mass after this time was 0.6 %. The Cu-sorption capacity of the calcined clay, based on the initial dry weight, was approximately 0.11 mmol/g. Sorption performance was indicated by shortening breakthrough time and a broadening mass-transfer zone. The column useful time, considered up to 1 mg Cu/L in the effluent, keeping aproximately in 100 min for all cycles. The mass-transfer zone, decreased almost linearly from 10 to 9 cm. Regeneration with HCl provided elution efficiencies up to 100%.
ABSTRACT In this work, the copper removal in fixed-bed of Bofe calcined clay was realized, in whi... more ABSTRACT In this work, the copper removal in fixed-bed of Bofe calcined clay was realized, in which the adsorption and desorption of copper ions, the time of equilibrium and kinetic curves were investigated. Different types of eluents were utilized for calcined clays bed regeneration. Desorption tests were performed using a NaCl solution at 1% and seawater both at pH 3. The results indicated that the regeneration of the bed with NaCl/HCl or saline water at pH 3 is very efficient and the elution was verified as 50%. Also, it was observed an increase in removal after exposure of the bed to the eluent. The highest adsorption capacities of copper were ≈0.3 mmol/g, on the Bofe calcined clay. The equilibrium time increased from 120 min to 400 min considering the first to the last cycle. During the regeneration process, the mass-transfer zone decreased almost linearly from 9.8 to 3.4 cm with the use of NaCl and from 9.9 to 6.7 cm with seawater. In addition, those eluents provide the ideal breakthrough behavior. The recovery efficiency of the water showed that the desorption of copper ions with NaCl or seawater is feasible and has great potential.
In this study, it was evaluated the potential use of commercial sodium bentonitic clay, called Fl... more In this study, it was evaluated the potential use of commercial sodium bentonitic clay, called Fluidgel, chemically and thermally treated, as an adsorbent in the removal of zinc ions from aqueous effluents. The chemical treatment was carried out with 10 g of clay dispersed in 100 mL of acetic acid 4 %. The heat treatment was obtained by calcination at 750 °C for 24 hours in muffle. The adsorption experiments were performed in thermostatic bath system and fixed bed, both based on preliminary study of metallic cationic speciation. The kinetics of zinc ions adsorption by acid-treated clay was rapid, requiring a minimum time of 60 min to reach equilibrium. The adsorbed amount and percentage of total zinc removal, at equilibrium time, was 0.06 mmol/g and 45 %, respectively, using the acid-treated clay. There was no removal of zinc by Fluidgel calcined clay in bath system, but in fixed bed it was obtained the total amount of zinc removal of 0.11 mmol/g and 41 % of percentage of removal.
This paper describes the adsorption of Cd 2+ and Pb 2+ ions using sodic bentonite clay type Fluid... more This paper describes the adsorption of Cd 2+ and Pb 2+ ions using sodic bentonite clay type Fluidgel modified. The Fluidgel before and after chemical modification and thermal activation was characterized by different techniques including X-ray diffraction, thermal analysis, Fourier transform infrared, surface area, helium pycnometry, cation exchange capacity and scanning electron microscopy. Pseudo-first order, pseudo-second order and intra-particle diffusion models were used to analyze the kinetic curves. Equilibrium data were analyzed using Langmuir and Freundlich models. The thermodynamic study indicated that lead adsorption process is endothermic and interactions between clays and solutions of lead occurred spontaneously, while cadmium adsorption revealed an exothermic and spontaneous nature. The maximum removal efficiencies were 97.62% for Cd(II) using Fluidgel modified chemically and 91.08% for lead by Fluidgel modified chemical and thermally.
Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" h... more Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" has been studied by batch and fixed-bed in static and dynamic systems, respectively. Analyses were performed for physicochemical characterization of clays using the techniques: X-ray fluorescence (XRF), thermogravimetry (TG), N 2 adsorption (BET) and Cationic Exchange Capacity (CEC). Batch experiments were performed at a constant temperature, adjusting the pH of the solution in contact with clays. Adsorption assays in fixed bed were conducted at the flow rate determined through mass transfer zone (MTZ). Langmuir and Freundlich models were adjusted to equilibrium data. The results of characterization indicated that the temperature of 500 °C is best suited for the calcination of the clays. The maximum adsorption capacity was higher for dynamic system than fixed bed compared to static system, enhancing from 0.0748 to 0.1371 and from 0.0599 to 0.22 mmol.g-1 of clay for "Bofe" and "Verde-lodo", respectively.
Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" h... more Cu (II) removal equilibrium from aqueous solutions using calcined clays "Bofe" and "Verde-lodo" has been studied by batch and fixed-bed in static and dynamic systems, respectively. Analyses were performed for physicochemical characterization of clays using the techniques: X-ray fluorescence (XRF), thermogravimetry (TG), N 2 adsorption (BET) and Cationic Exchange Capacity (CEC). Batch experiments were performed at a constant temperature, adjusting the pH of the solution in contact with clays. Adsorption assays in fixed bed were conducted at the flow rate determined through mass transfer zone (MTZ). Langmuir and Freundlich models were adjusted to equilibrium data. The results of characterization indicated that the temperature of 500 °C is best suited for the calcination of the clays. The maximum adsorption capacity was higher for dynamic system than fixed bed compared to static system, enhancing from 0.0748 to 0.1371 and from 0.0599 to 0.22 mmol.g-1 of clay for "Bofe" and "Verde-lodo", respectively.
Bentonite clays have been showing good adsorbing characteristics and are used as an alternative m... more Bentonite clays have been showing good adsorbing characteristics and are used as an alternative material in the removal of heavy metals. The purpose of this study is to evaluate the removal of nickel on Bofe bentonite calcined clay in porous bed. Firstly, a study was conducted to define the operation outflow, based on the minimum mass transfer zone (MTZ) obtained, useful (q U) and total adsorbed (q T) removal amounts and total nickel removal percentage (Rem (%)). Assays of nickel adsorption on clay were conducted according to a 2 2 factorial design with three central points to evaluate the effect of the particle diameter and initial adsorbate concentration on variables q U , q T and Rem (%). Tests to obtain the adsorbent physical and chemical characteristics were performed on samples of Bofe clay in natura, calcined, and calcined submitted to nickel adsorption. This clay was characterized according to the following techniques: Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Physisorption of N 2 (BET), Helium Picnometry and Scanning Electron Microscope (SEM) with metal mapping.
Bentonite clays have been showing good adsorbing characteristics and are used as an alternative m... more Bentonite clays have been showing good adsorbing characteristics and are used as an alternative material in the removal of heavy metals. The purpose of this study is to evaluate the removal of nickel on Bofe bentonite calcined clay in porous bed. Firstly, a study was conducted to define the operation outflow, based on the minimum mass transfer zone (MTZ) obtained, useful (q U) and total adsorbed (q T) removal amounts and total nickel removal percentage (Rem (%)). Assays of nickel adsorption on clay were conducted according to a 2 2 factorial design with three central points to evaluate the effect of the particle diameter and initial adsorbate concentration on variables q U , q T and Rem (%). Tests to obtain the adsorbent physical and chemical characteristics were performed on samples of Bofe clay in natura, calcined, and calcined submitted to nickel adsorption. This clay was characterized according to the following techniques: Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Physisorption of N 2 (BET), Helium Picnometry and Scanning Electron Microscope (SEM) with metal mapping.
In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were... more In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were studied. The clay was characterized through EDX, surface area (BET) and XRD analysis. The influence of parameters (pH, amount of adsorbent, adsorbate concentration and temperature) was investigated. Kinetic models were evaluated in order to identify potential adsorption process mechanisms. The Langmuir and Freundlich models were utilized for the analysis of adsorption equilibrium. Thermodynamic parameters were assessed as a function of the process temperature. The kinetics data were better represented by the second-order model. The process was found to be strongly influenced by the factors studied. The Bofe clay removed nickel with maximum adsorption capacity of 1.91 mg metal/g of clay (20 • C; pH 5.3) and that the thermodynamic data indicated that the adsorption reaction is spontaneous and of an exothermal nature. The Langmuir model provided the best fit for sorption isotherms.
In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were... more In this paper the kinetics and dynamics of nickel adsorption on calcined Bofe bentonite clay were studied. The clay was characterized through EDX, surface area (BET) and XRD analysis. The influence of parameters (pH, amount of adsorbent, adsorbate concentration and temperature) was investigated. Kinetic models were evaluated in order to identify potential adsorption process mechanisms. The Langmuir and Freundlich models were utilized for the analysis of adsorption equilibrium. Thermodynamic parameters were assessed as a function of the process temperature. The kinetics data were better represented by the second-order model. The process was found to be strongly influenced by the factors studied. The Bofe clay removed nickel with maximum adsorption capacity of 1.91 mg metal/g of clay (20 • C; pH 5.3) and that the thermodynamic data indicated that the adsorption reaction is spontaneous and of an exothermal nature. The Langmuir model provided the best fit for sorption isotherms.
This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions re... more This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions removal by adsorption in zeolite Baylith WE984. The experiments were conducted in a fluidised-bed rig with 300 grams of zeolite particles having diameter in the range 1 - 4mm. The volumetric flow rate of the fluidizing solution was 4.1 lmin(-1). Metal concentrations in the solution were measured by atomic absorption and the breakthrough curves were obtained for concentrations of metals ranging from 5 to 30 ppm (pH= 2). Experimental results obtained were fitted to the Renken model for analysis of the mass transfer resistance and the kinetic of adsorption. It was verified that the kinetic of adsorption was the limiting factor for the metallic ion retention in fluidised bed. Competitiveness of the metals adsorbed into Baylith zeolite were also analyzed being found the following order of preference for the metal removals: nickel > zinc > lead. The competitiveness was evaluated simultaneously in the combination of 2 x 2 and the three metals.
This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions re... more This work presents an experimental study of nickel (II), lead (II) and zinc (II) metallic ions removal by adsorption in zeolite Baylith WE984. The experiments were conducted in a fluidised-bed rig with 300 grams of zeolite particles having diameter in the range 1 - 4mm. The volumetric flow rate of the fluidizing solution was 4.1 lmin(-1). Metal concentrations in the solution were measured by atomic absorption and the breakthrough curves were obtained for concentrations of metals ranging from 5 to 30 ppm (pH= 2). Experimental results obtained were fitted to the Renken model for analysis of the mass transfer resistance and the kinetic of adsorption. It was verified that the kinetic of adsorption was the limiting factor for the metallic ion retention in fluidised bed. Competitiveness of the metals adsorbed into Baylith zeolite were also analyzed being found the following order of preference for the metal removals: nickel > zinc > lead. The competitiveness was evaluated simultaneously in the combination of 2 x 2 and the three metals.
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Papers by M. Alonso-vale