Department of Chemical Engineering

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Author: search.filters.author.Maheshwari, UtkarshSubject: search.filters.subject.Multiple metal ions

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    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.
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    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.