Department of Chemical Engineering

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Author: search.filters.author.Gupta, SureshSubject: search.filters.subject.Adsorption

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    Experimental, kinetic, equilibrium and regeneration studies for adsorption of Cr(VI) from aqueous solutions using low cost adsorbent (activated flyash)
    (Taylor & Francis, 2012-08-03) Gupta, Suresh
    In the present study, activated flyash — a low-cost adsorbent, is used as for Cr(VI) removal from aqueous solutions. Flyash is activated by giving heat treatment and with the use of concentrated sulfuric acid (98% w/w). Batch adsorption experiments are carried out to investigate the effect of influencing process parameters such as initial pH, change in pH during adsorption, contact time, adsorbent amount, and initial Cr(VI) concentration. The maximum adsorption of Cr(VI) on activated flyash is found at an initial pH value of 1. The value of pH increases with increase in adsorption of Cr(VI). The equilibrium data for adsorption of Cr(VI) on activated flyash is tested with different adsorption isotherm models such as Langmuir, Freundlich, Redlich—Peterson, Koble—Corrigan, Tempkin, Dubinin—Radushkevich and generalized isotherm models. The Koble—Corrigon isotherm model is found to be the most suitable one for Cr(VI) adsorption using activated flyash. The maximum adsorption capacity obtained is 21.9 mg g−1 at a pH value of 1. The adsorption process follows the second order kinetics and the corresponding rate constants are obtained at different initial Cr(VI) concentrations. Desorption of Cr(VI) from activated flyash using acid and base treatment shows a higher desorption efficiency by more than 85%. A feasible methodic solution for the disposal of contaminant (acid and base solutions) containing high concentration of Cr(VI) obtained during the desorption process is proposed.
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    Experimental Investigations and Theoretical Modeling Aspects in Column Studies for Removal of Cr(VI) from Aqueous Solutions Using Activated Tamarind Seeds
    (Scientific Research, 2010) Gupta, Suresh
    Continuous adsorption experiments are conducted using fixed-bed adsorption column to evaluate the performance of the adsorbent developed (from activated tamarind seeds) for the removal of Cr(VI) from aqueous solutions and the results obtained are validated with a model developed in this study. The effects of significant parameters such as flow rate, mass of adsorbent, and initial Cr(VI) concentration are studied and breakthrough curves are obtained. As the flow rate increases from 10 to 20 mL min-1, the breakthrough time decreases from 210 to 80 min. As the mass of adsorbent increases, breakthrough time gets delayed. The breakthrough times are obtained as 110, 115 and 210 min for 15, 20 and 25 g of activated tamarind seeds. As the initial Cr(VI) concentration increases from 100 to 200 mgL-1, the break point time decreases from 210 to 45 min. The process parameters for fixed-bed adsorption such as breakthrough time, total percentage removal of Cr(VI), adsorption exhaustion rate and fraction of unused bed length are calculated and the performance of fixed-bed adsorption column is analyzed. The mechanism for Cr(VI) adsorption on activated tamarind seeds is proposed. At low value of solution pH (= 1), the increase in Cr(VI) adsorption is due to the electrostatic attraction between positively charged groups of activated tamarind seeds and the HCrO4-. A mathematical model for fixed-bed adsorption column is proposed by incorporating the effect of velocity variation along the bed length in the existing model. Pore and surface diffusion models are used to describe the intra-particle mechanism for Cr(VI) adsorption. The breakthrough curve obtained theoretically from pore diffusion model and surface diffusion model are compared with experimental results for different operating conditions. The standard deviation values obtained for pore diffusion model and solid diffusion model are 0.111 and 0.214 respectively.
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    Modeling, simulation, and experimental validation for continuous Cr(VI) removal from aqueous solutions using sawdust as an adsorbent
    (Elsiever, 2009-12) Gupta, Suresh
    Continuous adsorption experiments were performed in a fixed-bed adsorption column to evaluate the performance of low-cost adsorbent (sawdust) developed for the removal of Cr(VI) from aqueous solutions. The effects of influencing parameters such as flow rate, mass of adsorbent, initial Cr(VI) concentration were studied and the corresponding breakthrough curves were obtained. The fixed-bed adsorption process parameters such as breakthrough time, total percentage removal of Cr(VI), adsorption exhaustion rate and fraction of unused bed-length were obtained. A mathematical model for fixed-bed adsorption column was proposed by incorporating the effect of velocity variation along the bed-length in the existing model. Pore and solid diffusion models were used to describe the intra-particle mechanism for Cr(VI) adsorption. The proposed mathematical model was validated with the literature data and the experimental data obtained in the present study and the model was found to be good for explaining the behavior of breakthrough curves.
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    Utilization of waste product (tamarind seeds) for the removal of Cr(VI) from aqueous solutions: Equilibrium, kinetics, and regeneration studies
    (Elsiever, 2009-07) Gupta, Suresh
    In the present study, an adsorbent was prepared from tamarind seeds and used after activation for the removal of Cr(VI) from aqueous solutions. The tamarind seeds were activated by treating them with concentrated sulfuric acid (98% w/w) at a temperature of 150 °C. The adsorption of Cr(VI) was found to be maximum at low values of initial pH in the range of 1–3. The adsorption process of Cr(VI) was tested with Langmuir, Freundlich, Redlich–Peterson, Koble–Corrigan, Tempkin, Dubinin–Radushkevich and Generalized isotherm models. Application of the Langmuir isotherm to the system yielded a maximum adsorption capacity of 29.7 mg/g at an equilibrium pH value ranging from 1.12 to 1.46. The adsorption process followed second-order kinetics and the corresponding rate constants obtained were 2.605 × 10−3, 0.818 × 10−3, 0.557 × 10−3 and 0.811 × 10−3 g/mg min−1 for 50, 200, 300 and 400 mg/L of initial Cr(VI) concentration, respectively. The regenerated activated tamarind seeds showed more than 95% Cr(VI) removal of that obtained using the fresh activated tamarind seeds. A feasible solution is proposed for the disposal of the contaminants (acid and base solutions) containing high concentrations of Cr(VI) obtained during the regeneration (desorption) process.
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    Removal of toxic metal Cr(VI) from aqueous solutions using sawdust as adsorbent: Equilibrium, kinetics and regeneration studies
    (Elsiever, 2009-08-01) Gupta, Suresh
    In the present study, a low-cost adsorbent is developed from the naturally and abundantly available sawdust which is biodegradable. The removal capacity of Cr(VI) from aqueous solutions and from the synthetically prepared industrial effluent of electroplating and tannery industries is obtained. The batch experiments are carried out to investigate the effect of the significant process parameters such as initial pH, change in pH during adsorption, contact time, adsorbent amount, and the initial Cr(VI) concentration. The maximum adsorption of Cr(VI) on sawdust is obtained at an initial pH value of 1. The value of pH increases with increase in contact time and initial Cr(VI) concentration. The equilibrium data for the adsorption of Cr(VI) on sawdust is tested with various adsorption isotherm models such as Langmuir, Freundlich, Redlich–Peterson, Koble–Corrigan, Tempkin, Dubinin–Radushkevich and Generalized equation. The Langmuir isotherm model is found to be the most suitable one for the Cr(VI) adsorption using sawdust and the maximum adsorption capacity obtained is 41.5 mg g−1 at a pH value of 1. The adsorption process follows the second-order kinetics and the corresponding rate constants are obtained. Desorption of Cr(VI) from sawdust using acid and base treatment exhibited a higher desorption efficiency by more than 95%. A feasible solution is proposed, for the disposal of the contaminant (acid and base solutions) containing high concentration of Cr(VI) obtained during the desorption process. The interference of other ions which are generally present in the electroplating and tannery industrial effluent streams on the Cr(VI) removal is investigated.
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    Removal of Cr(VI) from wastewater using activated tamarind seeds as an adsorbent
    (ICE Publishing, 2008-07-30) Gupta, Suresh
    In the present study, an adsorbent was prepared from tamarind seeds and batch studies were conducted for Cr(VI) removal from aqueous solutions. Tamarind seeds were activated by heat treatment and with concentrated sulfuric acid (98% w/w). The parameters investigated include initial pH, contact time, initial Cr(VI) concentration, and adsorbent dosage. The adsorption of Cr(VI) was found to be maximum at low values of initial pH in the range of 1–3. The adsorption process of Cr(VI) was tested with Langmuir and Freundlich isotherm models. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 29.08 mg g–1. The adsorption process followed second order kinetics and the corresponding rate constant was found to be 0.0026 g mg–1 min–1.
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    Modeling And Simulation Of Fixed Bed Adsorption Column: Effect Of Velocity Variation
    (iManager, 2005-08) Gupta, Suresh
    The kinetic behavior of a fixed-bed adsorber can be explained and the characteristic breakthrough curve of the adsorption phenomena can be obtained through mathematical models. In the earlier models, the kinetics is explained using a mathematical model that takes into account of external and internal mass-transfer resistances with a nonideal plug flow behavior. The variation of fluid velocity along the column is an important aspect, which has not been accounted so far. In the present study, a mathematical model is proposed for explaining the kinetic behavior of adsorption phenomena incorporating the fluid velocity variation along the column length also. Internal mass-transfer resistances due to pore diffusion mechanism are considered in the model. The proposed mathematical model for fixed-bed adsorption is solved numerically and compared with earlier model reported in literature. The results show that the breakpoint is obtained earlier which represents the realistic behavior in adsorption phenomena. Initially the sharp front of the breakthrough curve is seen followed by broadening of tail of the breakthrough curve. Simulations are carried out using the present model for a systematic parametric study. The effects of various important and influencing parameters such as flow rate, bed height, inlet adsorbate concentration and particle diameter on breakthrough curve are studied in detail.
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    Characteristics and kinetic study of chitosan prepared from seafood industry waste for oil spills cleanup
    (Taylor & Francis, 2012-05-15) Gupta, Suresh
    Chitosan being a biodegradable material would be an eco-friendly and effective alternative in the cleaning up of oil spills. In the present study, adsorbent (Chitosan) was prepared from the seafood industry waste, prawn shells for removal of oil from aqueous solution. Batch experiments were carried out to study the kinetics for the removal of oil from oil–water solutions using chitosan. The effect of various influencing parameters such as contact time, pH, initial concentration, and mass of adsorbent were studied. The equilibrium time for adsorption of oil on chitosan was obtained as 6 min. The maximum capacity of chitosan to adsorb oil from oil–water solution was found to be 17.96 g g−1 of adsorbent. The removal efficiency was observed to be higher in the acidic medium. The adsorption properties of chitosan have been attributed mainly to its positive charge. The equilibrium data was tested with the Langmuir isotherm and excellent correlation was obtained.
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    Application of Nanomaterials for the Removal of Pollutants from Effluent Streams
    (Bentham Science, 2012) Gupta, Suresh; Maheshwari, Utkarsh
    Rapid industrialization with the increase in the population leads to the water crisis. The number of industries using heavy metals such as copper, chromium, nickel, zinc, etc. in their process is also leaving behind the effluent containing a large amount of heavy metals which discharged directly to the water bodies. There are constraints set by the regulatory bodies of government on the industries to maintain an upper level discharge limit for each of the metal ion. There are various methods available for the removal of metal ions which are selected according to the requirement. Adsorption is one of the optimal solutions for the removal of metal ions from industrial effluent streams. It is helpful in reducing the operational cost and size of equipment along with the increase recovery of metal ions. Adsorption is a surface phenomenon so the foremost property required for a perfect adsorbent is the higher surface area. Nanoparticles are now being preferred to be used as an adsorbent due to their large surface area which is a very important characteristic for a desired adsorbent. Development of nanoparticles has been the subject of enormous interest since the past decade. They have incredible adsorption properties due to the presence of high-energy adsorption sites and they also have excellent binding energies or interaction potentials for physisorption than traditional adsorbents. This study summarized the use of nanomaterial for the removal of metal ions from wastewater streams. It also highlights the various types of nanomaterials, their fabrication method and characteristics. The mechanism of metal adsorption onto various nanomaterials is also described in this study.
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    A novel method to identify optimized parametric values for adsorption of heavy metals from waste water
    (Elsiever, 2016-02) Gupta, Suresh; Maheshwari, Utkarsh
    In the present study, a strategy to obtain the optimum parameters for the removal of metal ions from wastewater is developed. A generalized model is proposed which can be used to represent the dependence of the dependent parameter on the independent parameters. Here, the experimental data from various studies available in the literature are utilized for the development of the model. The experimental data are normalized on the basis of their maximum value considered among all the experiments in the study. The normalized data are further non-linearly regressed to a fourth-order polynomial using Microsoft Excel 2007 to obtain the model equation. The model equation is developed indicating the dependence of dependent parameter (adsorption capacity) on the independent parameters (initial metal concentration, pH, contact time and adsorbent dosage). The proposed generalized equation is validated using various experimental results from the literature and the parameters of the model equation are being estimated. The modeled equation is later being optimized by applying a specific optimization technique (differential evolution). A code of differential evolution is being developed using the platform of MATLAB 7 for the optimization of the models.