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P.K. Tewari

Bio: P.K. Tewari is an academic researcher from Homi Bhabha National Institute. The author has contributed to research in topics: Desalination & Membrane. The author has an hindex of 16, co-authored 94 publications receiving 856 citations. Previous affiliations of P.K. Tewari include Indian Institute of Technology, Jodhpur & Bhabha Atomic Research Centre.


Papers
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TL;DR: In this article, a substantial amount of work have been carried out with impregnation of CNTs (simply as one of the reinforcements for incorporation of better properties like antibiofouling and/or better strength, etc.) in polymer host matrix.

182 citations

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TL;DR: In this article, the authors summarise first results of review and research on the possible extraction of uranium from the concentrated brine rejected by integrated nuclear desalination systems, which both partners are currently developing in the two organisations.

115 citations

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TL;DR: In this paper, the authors showed that there was no interatomic charge transfer between nano-ZnO and host polyamide matrix, indicating that no formation of chemical bonding occurred between them in the skin layers of the membranes.
Abstract: Inorganic–polymer hybrid, thinfilm nanocomposite nanofiltration (TFN-NF) membranes prepared by in situ interfacial polymerization of branched polyethyleneimine and trimesoyl chloride, with simultaneous impregnation of as-synthesized hexagonal wurtzite ZnO nanocrystals (nano-ZnO), either through aqueous or organic phase, have been extensively characterized. XPS analysis revealed that there was no inter-atomic charge transfer between nano-ZnO and host polyamide matrix, indicating that no formation of chemical bonding occurred between them in the skin layers of the membranes. The type of interaction present within the nanocomposite polyamide matrices of the membranes was through formation of noncovalent type secondary chemical interactions with peripheral hydroxyl groups of nano-ZnO and polyamide network as substantiated through FTIR analysis. SEM revealed the formation of distinct patterns and coils, through multiple-point interactions between the nano-ZnO and the polyamide network in the membranes' skin surfaces when introduced through aqueous amine phase. However, when introduced through the organic phase, nanomaterials remained distributed as discrete clusters within the membranes' skin layers because of lack of polar environment around the reaction zone, further emphasizing the role of the medium in which the nanomaterials are incorporated. AFM showed variation of surface roughness features with change in the precursor medium of introduced nano-ZnO. Nanofiltration performance towards different solutes, providing differential rejections in the order of MgCl2 > NaCl ≥ Na2SO4, revealed that the membranes were distinctly positively charged. Solvent fluxes of the membranes were significantly higher when nanomaterials were introduced through the aqueous phase as compared to the organic phase.

31 citations

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TL;DR: In this paper, a crosslinked polyacrylamides were synthesized by solution polymerization using benzoyl peroxide as the radical initiator, and the water-insoluble polymer obtained was functionalized by reacting with hydroxylamine to convert the amide group into hydroxamic acid group.
Abstract: Crosslinked polyacrylamides were synthesized by solution polymerization using benzoyl peroxide as the radical initiator. The water–insoluble polymer obtained was functionalized by reacting with hydroxylamine to convert the amide group into hydroxamic acid group. The resultant functionalized polymer was characterized in terms of moisture uptake, elemental composition, IR spectra, thermal stability, exchange capacity and heavy metal sorption. The sorbent, obtained in particulate form, was investigated for its sorption properties with respect to uranium from uranyl nitrate solutions under unstirred batch conditions. This paper will concentrate on preparation, characterization and performance evaluation with respect to uranium sorption as a function of concentration, time, solution pH and temperature. The potential of this sorbent for uranium and other heavy metal ion recovery from sea water is ascertained.

27 citations

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TL;DR: In this article, a positively-charged thin film composite (TFC) type nanofiltration membranes, bearing fixed quaternary ammonium moieties, have been developed and studied and the effects of variation of chemical compositions and other experimental conditions such as curing temperature and duration of curing on the performances of the membrane were studied.
Abstract: Thin film composite (TFC) type positively-charged nanofiltration membranes, bearing fixed quaternary ammonium moieties, have been developed and studied. Branched polyethyleneimine (PEI) was functionalized by reaction with glycidyl trimethyl ammonium chloride (GTACl) to introduce quaternary ammonium chloride. Positively-charged TFC membranes were prepared by in situ interfacial polymerization of functionalized PEI and terephthaloyl chloride. The effects of variation of chemical compositions and other experimental conditions such as curing temperature and duration of curing on the performances of the membrane were studied. ATR FT-IR spectroscopy was done to establish the presence of charge-bearing groups in the membrane. The membranes were tested using single solute feed solutions of NaCl, Na2SO4, CaCl2, and MgSO4. Positive charges on the membranes were estimated in terms of their ion-exchange capacities (IEC). The values were also correlated to the solute-rejection properties of the membranes.

25 citations


Cited by
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Journal ArticleDOI
TL;DR: Key parameters of an RO process and process modifications due to feed water characteristics are brought to light by a direct comparison of seawater and brackish water RO systems.

2,665 citations

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TL;DR: In this article, the authors summarized the recent scientific and technological advances in the development of nanocomposite membranes for water treatment and discussed challenges and future research directions in developing high performance nanocomposition membranes.

822 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide an update on recent developments in heat pump systems, and is intended to be a "one-stop" archive of known practical heat pump solutions.

737 citations

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TL;DR: In this article, the authors comprehensively reviewed molecular modeling and experimental aspects of CNT-membrane fabrication and functionalization for the desalination of both sea and brackish water.

725 citations