Browsing by Author "Maheshwari, Utkarsh"

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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.
Efficient adsorbent for simultaneous removal of Cu(II), Zn(II) and Cr(VI): Kinetic, thermodynamics and mass transfer mechanism
(Elsiever, 2015-11) Gupta, Suresh; Maheshwari, Utkarsh
Present study deals with the development of a nano-porous adsorbent using neem bark for the simultaneous removal of Cu(II), Cr(VI) and Zn(II). The developed adsorbent is characterized using SEM, EDS and TGA. The effect of initial metal concentration, contact time, adsorbent dosage, temperature and pH are studied to see the performance of nANB for the metal ions removal. Various isotherm, kinetic and mass transfer models are validated with the experimental data and corresponding parameters are estimated. The maximum adsorption capacity of the developed adsorbent for Cu(II) and Zn(II) adsorption are found to be 21.23 and 11.904 mg g−1, respectively. The optimum parameter values for contact time, adsorbent dosage, temperature and pH are obtained as 48 h, 6 g L−1, 35 °C and 1.2, respectively, from the experimental results of Cu(II) and Zn(II) removal using nANB. The performance of nANB on the industrial effluent is evaluated by performing equilibrium batch experiments for the simultaneous removal of Cu(II), Cr(VI) and Zn(II) from an aqueous solution. The overall adsorption capacity of the nANB for the removal of multiple metal ions at 200 mg L−1 of each is obtained as 38.95 mg g−1 which is more than double for that obtained for individual metal ions.
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.
Performance evaluation of activated neem bark for the removal of Zn(II) and Cu(II) along with other metal ions from aqueous solution and synthetic pulp & paper industry effluent using fixed-bed reactor
(Elsiever, 2016-05-20) Gupta, Suresh; Maheshwari, Utkarsh
The fixed-bed adsorption experiments are performed for the removal of copper [Cu(II)] and zinc [Zn(II)] by utilizing activated neem bark as an adsorbent. The present study demonstrated the effect of various parameters such as inlet concentration, adsorbent mass and inlet flowrate for the removal of Cu(II) and Zn(II) from aqueous solutions. Various kinetic parameters such as EBRT, stoichiometric capacity, breakthrough time, etc. are evaluated using the experimental data. Yoon–Nelson and Yan model available in the literature are also validated with the experimental data. The developed adsorbent is also tested for the simultaneous removal of multiple metal ions [Cr(VI), Cu(II), Zn(II), Pb(II), Ni(II) and Cd(II)] from the synthetically prepared pulp & paper industrial effluent
Removal of Cr(VI) from Wastewater Using a Natural Nanoporous Adsorbent: Experimental, Kinetic and Optimization Studies
(Sage, 2015-01-01) Gupta, Suresh; Maheshwari, Utkarsh
In the present work, a nanoporous adsorbent prepared from low-cost neem bark is used for the removal of chromium (VI) ions from wastewater. The adsorbent is characterized by scanning electron microscopy, energy-dispersive spectroscopy, BET surface area, infrared analysis and X-ray diffraction analysis. The effect of various parameters such as adsorbent dosage, pH, initial concentration and contact time for the removal of chromium (VI) ions has been studied. The data obtained have been tested with various isotherm and kinetic models. Langmuir model is found to be the best suited isotherm model giving maximum adsorption capacity as 26.95 mg g−1 for the removal of chromium (VI) ions. Effluent from a plating industry was also used to evaluate the performance of the developed adsorbent. Weber and Morris and Boyd models show that both intra-particle and film diffusion are the controlling mechanism for adsorption of chromium (VI) ions on the developed adsorbent. The mathematical model is developed to optimize the adsorption capacity (q) in terms of the influencing parameters with the help of differential evolution (DE) technique.
Removal of Cr(VI) from wastewater using activated neem bark in a fixed-bed column: interference of other ions and kinetic modelling studies
(Taylor & Francis, 2015-04-07) Gupta, Suresh; Maheshwari, Utkarsh
Continuous adsorption experiments are carried out in a fixed-bed to evaluate the performance of a newly developed low-cost adsorbent (activated neem bark, ANB) for the removal of Cr(VI) along with other metal ions (Cu & Zn) from aqueous solutions. The effect of initial Cr(VI) concentration, mass of adsorbent and flow rate on the breakthrough curve are studied. It is observed that as there is an increase in the initial concentration of Cr(VI) from 50 to 100 mg L−1, the mass of the adsorbent from 25 to 175 g, and flow rate from 5 to 15 mg L−1, the breakthrough time decreases from 24.78 to 13.875 h, increase from 9.25 to 111.66 h and decrease from 35.09 to 8.26 h, respectively. The effect on the performance of the ANB for Cr(VI) adsorption is also studied in the presence of Cu and Zn. The breakthrough time is achieved earlier in the presence of Cu and Zn in the feed stream. The fixed-bed adsorption process parameters such as saturation loading capacity, breakthrough time, total percentage removal of Cr(VI), the fraction of unused bed length, adsorption exhaustion rate and empty bed residence time are calculated for different experimental runs. The experimental results are likewise applied to the Yoon–Nelson and the Yan kinetic models. The kinetic parameters for both the models are calculated and reported in this study.
Removal of Metal Ions from Wastewater using Adsorption: Experimental and Theoretical Studies
(BITS, Pilani, 2015) Maheshwari, Utkarsh
Synthesis and use of alumina nanoparticles as an adsorbent for the removal of Zn(II) and CBG dye from wastewater
(Springer, 2014-12-18) Gupta, Suresh; Maheshwari, Utkarsh
In the present study, an alumina nanoparticle adsorbent is developed using solution combustion synthesis method and is further utilized for the removal of zinc (Zn(II)) and color black G (CBG) from wastewater. The developed adsorbent is characterized using SEM–EDS technique. The effect of various parameters such as the initial concentration, the contact time, the mass of adsorbent and the solution pH are studied for the removal of Zn(II) and CBG. The equilibrium time for both, Zn(II) and CBG is obtained to be approximately 4.5 h. The maximum adsorption of Zn(II) is found at pH value of 7 while the maximum removal of CBG is obtained at pH value of 2. The Langmuir isotherm model is found suitable for explaining the adsorption behavior of Zn(II) (R 2 = 0.976) and CBG (R 2 = 0.974) onto alumina nanoparticles, which supports the monolayer formation of Zn(II) and CBG during the adsorption process. The maximum adsorbent capacity of alumina nanoparticles for the removal of Zn(II) and CBG are obtained as 1,047.83 and 263.16 mg g−1, respectively. The kinetic data obtained during the experiments are better fitted with the pseudo-first-order model for both, Zn(II) (R 2 = 0.989) and CBG (R 2 = 0.971). A statistical analysis is also carried out to develop the mathematical equation which relates the different independent parameters (initial metal concentration, pH, time and mass of adsorbent) with the dependent parameter (adsorption capacity). The optimum values of independent parameters are estimated using Microsoft Solver.