Somenath Mitra

New Jersey Institute of Technology, Newark, New Jersey, United States

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Publications (155)593.61 Total impact

  • Madhuleena Bhadra · Sagar Roy · Somenath Mitra
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    ABSTRACT: Carbon nanotube (CNT) enhanced direct contact membrane distillation (DCMD) is presented for water desalination. We investigated the immobilization of CNTs on a polytetrafluoroethylene (PTFE) membrane. The presence of CNTs on the hydrophobic membrane favorably altered the water-membrane interactions to promote water vapor transport while preventing salt water penetration into the membrane pores. For a salt concentration of 34,000 mg L-1 and at 70°C, the CNT incorporation led to a 54% enhancement in permeate flux, which was as high as 69 kg/m2.hr.
    No preview · Article · Feb 2016 · Separation and Purification Technology
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    Madhuleena Bhadra · Sagar Roy · Somenath Mitra
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    ABSTRACT: We demonstrate the immobilization of graphene oxide on polytetrafluoroethylene (PTFE) membrane surface for desalination via direct contact membrane distillation. The graphene oxide immobilized membrane significantly enhanced the overall permeate flux with complete salt rejection, and the flux reached as high as 97kg/m2h at 80°C. We attribute this enhancement in flux to multiple factors including selective sorption, nanocapillary effect, reduced temperature polarization as well as the presence of polar functional groups in graphene oxide.
    Full-text · Article · Jan 2016 · Desalination
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    ABSTRACT: Efficient algal harvesting, cell pretreatment and lipid extraction are the major steps challenging the algal biofuel industrialization. To develop sustainable solutions for economically viable algal biofuels, our research aims at devising innovative reactive electrochemical membrane (REM) filtration systems for simultaneous algal harvesting and pretreatment for lipid extraction. The results in this work particularly demonstrated the use of the Ti4O7-based REM in algal pretreatment and the positive impacts on lipid extraction. After REM treatment, algal cells exhibited significant disruption in morphology and photosynthetic activity due to the anodic oxidation. Cell lysis was evidenced by the changes of fluorescent patterns of dissolved organic matter (DOM) in the treated algal suspension. The lipid extraction efficiency increased from 15.2±0.6g-lipidg-algae(-1) for untreated algae to 23.4±0.7g-lipidg-algae(-1) for treated algae (p<0.05), which highlights the potential to couple algal harvesting with cell pretreatment in an integrated REM filtration process.
    Full-text · Article · Dec 2015 · Bioresource Technology
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    ABSTRACT: Microwave induced reaction is presented as a means to generate highly defective and oxidized carbon nanotubes (CNTs) for fabrication of supercapacitor electrodes. CNTs were treated for different durations to generate varying amounts of defects and oxidation levels. This was evidenced by increase in BET surface area, D to G ratio and oxygen content with increase in treatment time. Under the given conditions, a treatment time of 40 min was optimum, beyond which the increase in any of these properties as well as in specific capacitance was minimal. The increase in surface area enhanced the double layer capacitance while the oxygenation might lead to pseudocapacitance. Together these make microwave treatment of CNTs an attractive approach to enhance supercapacitor performance.
    No preview · Article · Sep 2015 · Carbon
  • Sagar Roy · Chaudhery Mustansar Hussain · Somenath Mitra
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    ABSTRACT: This paper describes the development of a carbon nanotube (CNT) immobilized membrane for harvesting pure water from air. The CNTs were incorporated into a layer of super absorbing poly(acrylamide-co-acrylic acid) which was cast over a porous hydrophilized polypropylene support. The super absorbing polymer tended to bind to the water molecules to form water clusters. The incorporation of CNTs led to the interruption of specific water-polymer as well as water-water interactions to generate more free water which permeated more easily through the membrane. The CNTs were functionalized with carboxylic groups to improve the dispersibility into the polymer matrix. The water vapor extraction efficiency reached over 50%, and the presence of CNTs led to an enhancement in water vapor removal by as much as 45% and in mass transfer coefficient by 44%.
    No preview · Article · Aug 2015
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    Sagar Roy · Chaudhery Mustansar Hussain · Somenath Mitra
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    ABSTRACT: This paper describes the development of a carbon nanotube (CNT)-immobilized membrane for harvesting pure water from air. The CNTs were incorporated into a layer of super-absorbing poly(acrylamide-co-acrylic acid) which was cast over a porous hydrophilized polypropylene support. The super-absorbing polymer tended to bind to the water molecules to form water clusters. The incorporation of CNTs led to the interruption of specific water–polymer as well as water–water interactions to generate more free water which permeated more easily through the membrane. The CNTs were functionalized with carboxylic groups to improve the dispersibility into the polymer matrix. The water vapor extraction efficiency reached over 50%, and the presence of CNTs led to an enhancement in water vapor removal by as much as 45% and in the mass transfer coefficient by 44%. Graphical abstract: Carbon nanotube-immobilized super-absorbent membrane for harvesting water from the atmosphere
    Full-text · Article · Aug 2015
  • Zheqiong Wu · Somenath Mitra
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    ABSTRACT: Removal of oxidation debris for generating high purity functionalized carbon nanotubes (CNTs) has been a challenge, where base washing has been found to be an effective purification treatment. In this paper we report microwave induced reactive base wash (MRW) as a fast, green alternate to conventional filtrate washing. Carboxylated CNTs of three different dimensions were subjected to MRW and the results were compared to conventional base-wash. The results showed that MRW was an effective method for the removal of oxidation debris which reduced the reaction time from 4 h to 20 min and alkali consumption by 75%. The CNTs from MRW were similar to those from conventional base wash in terms of dimensions, elemental composition, BET surface area and colloidal stability in aqueous media.
    No preview · Article · Jul 2015 · Carbon
  • Megha Thakkar · Varunpreet Randhawa · Somenath Mitra · Liping Wei
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    ABSTRACT: This study presents the synthesis of diatom-FeOx composite as a novel sorbent for arsenic removal from water. The unique porous architecture of the diatom was utilized to immobilize iron oxide to form the composite. The surface area was as high as 70m(2)/g. The adsorption isotherms for As (III) and As (V) followed the Langmuir, Freundlich and D-R models. Langmuir monolayer adsorption capacity for arsenite (As III) was 10,000μg/g and arsenate (As V) was 12,500μg/g. The pseudo-second order rate equation was found to effectively describe the kinetics of arsenic adsorption. This study opens the door for the development of bio derived materials for environmental remediation. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jul 2015 · Journal of Colloid and Interface Science
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    ABSTRACT: For the first time we present an ultra-low casting of Pt based nano-ink on carbon paste electrodes (CPEs) for electrooxidation of glycerol and ethylene glycol fuels in alkaline medium. The platinum loaded carbon nanotube (Pt-CNT) synthesized by a microwave induced reaction has been extensively characterized by microscopic, spectroscopic and thermal gravimetric techniques. Pt-CNT has shown 6 and 33 fold improved activity for the Glycerol electrooxidation reaction (GOR) and ethylene glycol electrooxidation reaction (EGOR) vis-à-vis the commercial Johnson Matthey Pt-C. The low onset potentials and high current densities achieved using this novel nano ink is indicative of its plausible role in fuel cell applications.
    Full-text · Article · Jun 2015 · Fuel
  • Smruti Ragunath · Somenath Mitra
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    ABSTRACT: This paper reports the development of novel carbon nanotube immobilized composite membranes (CNIM) for the extraction of volatile organics from air. The nanotubes were immobilized onto the selective layer of a composite membrane where they served as sorption sites and provided additional pathways for enhanced solute transport. Depending upon the process conditions, the presence of CNTs led to the organic removal with flux as high as 37.7E-05, 72.9E-05 and 8.22E-05 gm-mol/m2.min and an increase in mass transfer coefficient about 92.2%, 22.7% and 44.3% for toluene, dichloromethane and ethanol, respectively. The CNIM demonstrated several advantages including enhanced recovery at low concentrations and low temperature.
    No preview · Article · May 2015 · The Journal of Physical Chemistry C
  • Megha Thakkar · Zheqiong Wu · Liping Wei · Somenath Mitra
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    ABSTRACT: Frustules or the rigid amorphous silica cell wall of unicellular, photosynthetic microalgae with unique porous architecture has been used to synthesize a composite by immobilizing ZrO2 on its surface and in the pores. This was effective in water defluoridation. The average diameter of the composite was 80±2nm and surface area was 140m(2)/g. The adsorption isotherms followed both Langmuir and Freundlich models, and the composite was regenerable. Adsorption kinetics followed second order model and the adsorption capacity was as high as 11.32mg/g, while the Langmuir maximum adsorption capacity (qm) reached 15.53mg/g. The research findings highlight the potential of diatoms as hosts for nanomaterials for use in water treatment. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Mar 2015 · Journal of Colloid and Interface Science
  • Madhuleena Bhadra · Somenath Mitra
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    ABSTRACT: The availability of freshwater resources is dwindling in many parts of the world, a problem that is anticipated to grow with budding population. One promising source of potable water is the world's virtually limitless supply of seawater, but so far desalination technologies have been too expensive for widespread use. With current advances in nanotechnology and the development of diverse nanomaterials, which can be employed for successful membrane fabrication, nanostructured membrane-based desalination might be ready for the next generation of breakthroughs. Typically, by facilitating the manipulation of matter and control of transport at nanometer length scales, fabrication of nanostructured membranes offers new opportunities to advance water desalination technologies. This chapter will provide a broad discussion on highly promising nanomaterials; their specific morphology, which leads to specific enhanced water permeation, membrane-vapor interactions, their membrane fabrication procedures, and potential applications in leading desalination technologies.
    No preview · Chapter · Dec 2014
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    Sagar Roy · Madhuleena Bhadra · Somenath Mitra
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    ABSTRACT: In this paper, for the first time we report the development of carbon nanotube immobilized membrane (CNIM) on porous polypropylene support for direct contact membrane distillation (DCMD) desalination application. We also describe the effect of specific interaction of functional group of carbon nanotubes (CNTs) with water moisture on the enhancement of water vapor flux in DCMD via alteration of polar–non polar nature of membrane surface. The incorporation of carboxylic acid (−COOH) functional group on carbon nanotubes alters the hydrophilic–hydrophobic interaction of water moistures with the membrane surface that provides additional pathway for enhanced water vapor transport. The water vapor flux was obtained 36.8 kg/m2 h at 70 °C for CNT–COOH–PP, which is 51.5% higher than unmodified polypropylene membrane at salt concentration 10,000 ppm in feed. The salt rejection was found greater than 99.9% at salt concentration 10,000 ppm in feed solution. An increase in mass transfer coefficient about 1.5 times was also observed for CNT–COOH–PP membrane. The CNIM also exhibits higher thermal stability at elevated temperatures.
    Full-text · Article · Nov 2014 · Separation and Purification Technology
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    ABSTRACT: Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and the carbon nanotubes forms studied, functionalization via carboxylation and propyl amine were the most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11) which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar group led to as much as 300% increase in breakthrough volume and a desorption band width was reduced by 2.5 times.This article is protected by copyright. All rights reserved
    No preview · Article · Nov 2014 · Journal of Separation Science
  • Zhiqian Wang · Somenath Mitra
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    ABSTRACT: We present the development of flexible secondary alkaline battery with rechargeability similar to that of conventional secondary alkaline batteries. Multiwalled carbon nanotubes (MWCNTs) were added to both electrodes to reduce internal resistance, and a cathode containing carbon black and purified MWCNTs was found to be most effective. A polyvinyl alcohol-poly (acrylic acid) copolymer separator served the dual functions of electrolyte storage and enhancing flexibility. Additives to the anode and cathode were effective in reducing capacity fades and improving rechargeability.
    No preview · Article · Oct 2014 · Journal of Power Sources
  • Xinbo C. Lau · Zhiqian Wang · Somenath Mitra
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    ABSTRACT: We demonstrate for the first time the efficiency improvement of poly(3-hexylthiophene) (P3HT)-fullerene (C-60) bulk heterojunction photovoltaic cells by the introduction of trace concentrations of carbon black (CB) into the photoactive layer. As compared to control devices with only C-60, the addition of low concentration (12.5 ppm) of CB resulted in 35% improvement in short circuit current density (J(sc)) and 79% improvement in power conversion efficiency (PCE). CB served the dual function of enhancing electron transport as well as optimizing phase separation leading to high current density and PCE. The results indicate that CB is a promising additive for the performance enhancement of polymer photovoltaic cells and may work with diverse donor-acceptor systems.
    No preview · Article · Sep 2014 · Solar Energy Materials and Solar Cells
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    ABSTRACT: Inhaled multiwalled carbon nanotubes (MWCNTs) may cause adverse pulmonary responses due to their nanoscale, fibrous morphology and/or biopersistance. This study tested multiple factors (dose, time, physicochemical characteristics, and administration method) shown to affect MWCNT toxicity with the hypothesis that these factors will influence significantly different responses upon MWCNT exposure. The study is unique in that (1) multiple administration methods were tested using particles from the same stock; (2) bulk MWCNT formulations had few differences (metal content, surface area/functionalization); and (3) MWCNT retention was quantified using a specialized approach for measuring unlabeled MWCNTs in rodent lungs. Male Sprague-Dawley rats were exposed to original (O), purified (P), and carboxylic acid functionalized (F) MWCNTs via intratracheal instillation and inhalation. Blood, bronchoalveolar lavage fluid (BALF), and lung tissues were collected at postexposure days 1 and 21 for quantifying biological responses and MWCNTs in lung tissues by programmed thermal analysis. At day 1, MWCNT instillation produced significant BALF neutrophilia and MWCNT-positive macrophages. Instilled O- and P-MWCNTs produced significant inflammation in lung tissues, which resolved by day 21 despite MWCNT retention. MWCNT inhalation produced no BALF neutrophilia and no significant histopathology past day 1. However, on days 1 and 21 postinhalation of nebulized MWCNTs, significantly increased numbers of MWCNT-positive macrophages were observed in BALF. Results suggest (1) MWCNTs produce transient inflammation if any despite persistence in the lungs; (2) instilled O-MWCNTs cause more inflammation than P- or F-MWCNTs; and (3) MWCNT suspension media produce strikingly different effects on physicochemical particle characteristics and pulmonary responses.
    Full-text · Article · Aug 2014 · ACS Nano
  • Zheqiong Wu · Somenath Mitra
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    ABSTRACT: Length dependent dispersibility of carboxylated multiwalled carbon nanotubes is presented using a novel approach that ensures the same diameter and the degree of functionalization. The longer multiwalled nanotubes were reduced in length by ultrasonication and then their dispersibility was studied in comparison to the original tubes. Colloidal studies showed dependence on the length where the shorter tubes showed higher aggregation in terms of larger particle size, zeta potential and lower critical coagulation concentrations in the presence of electrolytes. It is hypothesized that the longer tubes entangled more leading to a more complex electrostatic double layer that increased their stability.
    No preview · Article · Aug 2014 · Journal of Nanoparticle Research
  • Zheqiong Wu · Somenath Mitra
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    ABSTRACT: Length dependent dispersibility of carboxylated multi-walled carbon nanotubes is presented using a novel approach where a batch of carboxylated nanotubes was size sorted via ultracentrifugation into different fractions with lengths ranging from 150 to 950 nm. The different fractions had the same tube diameter and degree of oxidation. The dispersibility of the nanotube fractions showed dependence on the length where the longer tubes showed more aggregation in terms of larger particle size, zeta potential and lower critical coagulation concentrations (CCC) in the presence of electrolytes. It is hypothesized that the longer tubes formed a more complex electrostatic double layer that increased their entanglement and aggregation.
    No preview · Article · Jul 2014 · Environmental Sciences: Processes and Impacts
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    Madhuleena Bhadra · Sagar Roy · Somenath Mitra
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    ABSTRACT: Recent years have witnessed the emergence of detonation nanodiamonds (DNDs) as a new member of the nanocarbon family. This paper reports the immobilization of DNDs within a hydrophobic membrane for desalination applications. A dispersion of DNDs in polyvinylidene fluoride polymer was injected through a hydrophobic membrane, which incorporated the DNDs within the membrane. Embedding only a minimal quantity of (approximately 2%) the nanocarbon favorably altered the water vapor–membrane interactions to enhance water vapor permeability while preventing liquid penetration into the membrane pores thereby enhancing water vapor flux. Overall, desalination was consistently better with DND immobilized membrane than with conventional polypropylene, with flux enhancement as high as 118% in the sweep gas membrane distillation mode.
    Full-text · Article · May 2014 · Desalination

Publication Stats

3k Citations
593.61 Total Impact Points

Institutions

  • 1992-2016
    • New Jersey Institute of Technology
      • Department of Chemistry and Environmental Science
      Newark, New Jersey, United States
  • 2013
    • Indiana University-Purdue University Indianapolis
      • Department of Cellular and Integrative Physiology
      Indianapolis, Indiana, United States
  • 2007
    • Siena Heights University
      University Heights, Ohio, United States