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Dhamodharan Raghavachari

Bio: Dhamodharan Raghavachari is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Self-healing hydrogels & Copolymer. The author has an hindex of 6, co-authored 13 publications receiving 202 citations.

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Journal ArticleDOI
TL;DR: In this article, six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety were synthesized and characterized, and they were fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid.
Abstract: Six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety are synthesized and characterized. Dye-sensitized solar cells are fabricated using these dyes with and without a co-adsorbent, chenodeoxychloicacid. Simple molecular engineering around the phenothiazine moiety enabled a maximum of 12% photoconversion efficiency with one of the dyes.

96 citations

Journal ArticleDOI
TL;DR: In this article, the extent of epoxidation is controlled in such a manner that the NR does not lose its elasticity while retaining to a significant degree its oil absorbing property.
Abstract: New, eco-friendly nanocomposite materials have been synthesized from natural rubber (NR) and magnetite nanoparticles for the first time The poor oil resistance of natural rubber is exploited for the removal of oil spills Towards this purpose, mildly epoxidized natural rubber (ENR)–magnetite nanoparticle (MN) nanocomposites are prepared and the absorption of petrol (gasoline) is studied The extent of epoxidation is controlled in such a manner that the NR does not lose its elasticity while retaining to a significant degree its oil absorbing property Epoxidation also serves as a means for binding sufficient quantity of MNs so that the composite can be recovered using a magnetic field ENR with 5 mol% of epoxidation served as the best absorbent among all the absorbents studied as it was stable in petrol even after many days of immersion It is observed that the ENR–MN nanocomposite absorbs 7 g of petrol per gram without any mass loss The material was reused for several cycles without much loss in the capacity The petrol uptake of ENR–MN is greater than that of butyl rubber which is the most commercially used rubber for oil spill removal Porous rubber was also synthesized for the first time as oil uptake is facilitated not only by the hydrophobicity but also by the capillary absorption Porous ENR absorbed a relatively larger amount of oil and exhibited the highest stability in oil All the sorbents have quite high absorption capacities to be applied practically with a very low water uptake and a few of the absorbents could be satisfactorily reused The model studies promise their potential use in the environmental field

69 citations

Journal ArticleDOI
TL;DR: A seedless, one pot, green and selective synthesis of triangular gold nanoplates (NPs) by the reduction of chloroauric acid using Aegle marmelos gum (bael fruit derived gum; BG), with control over size is reported in this article.
Abstract: A seedless, one pot, green and selective synthesis of triangular gold nanoplates (NPs) by the reduction of chloroauric acid using Aegle marmelos gum (bael fruit derived gum; BG), with control over size is reported The size of the NPs is found to be dependent critically on the concentration of the BG with triangular, triangular with truncation at the apex and hexagonal plates being the predominant shapes over a wide concentration range, at room temperature At very high concentration of BG and at room temperature, the shape of the particles is spherical A fine-tuning of the temperature, at a particular concentration of BG, results in the formation of perfect triangular NPs Increasing the temperature of reduction to 90 °C and especially above a particular BG concentration, Au nanoparticles that are elongated spheres are obtained as the major product The possible mechanism for the Au NPs formation is investigated using techniques such as HR-TEM, SEM, XRD and UV–visible spectroscopy The formation of sing

25 citations

Journal ArticleDOI
TL;DR: The present method offers a simple means of preparing macroporous chitosan of any shape and size in very large scale with soft foam-like morphology, and could find applications in drug delivery, biodegradable super water absorbency and haemostatic applications.

16 citations

Journal ArticleDOI
TL;DR: In this article, the effect of naphthalimide as auxiliary acceptor in the PTz-based dyes for dye-sensitised solar cell (DSSC) application is reported.
Abstract: The effect of naphthalimide as auxiliary acceptor in the PTz-based dyes for dye-sensitised solar cell (DSSC) application is reported. In this regard, two new organic dyes with N-alkylated phenothiazine (PTz) core were synthesized by substitution of naphthalimide at C-3 of the PTz via triple bond and incorporation of an electron acceptor at C-7 position. Photophysical and electrochemical studies were carried out to assess the performance of the dyes on spectral coverage and to determine the redox energy levels, respectively. Charge distribution and electron transfer process of the optimized dyes were rationalised via theoretical studies. DSSCs fabricated with these dyes showed an optimal efficiency of 4.9 % for a device fabricated with iodide/triiodide electrolyte.

15 citations


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Journal ArticleDOI
TL;DR: Some additional properties are emphasized, which are required by oil sorbents to cope with oil spills under extreme conditions or to facilitate the oil-collection processes.
Abstract: Oil sorbents play a very important part in the remediation processes of oil spills. To enhance the oil-sorption properties and simplify the oil-recovery process, various advanced oil sorbents and oil-collecting devices based on them have been proposed recently. Here, we firstly discuss the design considerations for the fabrication of oil sorbents and describe recently developed oil sorbents based on modification strategy. Then, recent advances regarding oil sorbents mainly based on carbon materials and swellable oleophilic polymers are also presented. Subsequently, some additional properties are emphasized, which are required by oil sorbents to cope with oil spills under extreme conditions or to facilitate the oil-collection processes. Furthermore, some oil-collection devices based on oil sorbents that have been developed recently are shown. Finally, an outlook and challenges for the next generation of oil-spill-remediation technology based on oil-sorbents materials are given.

509 citations

Journal ArticleDOI
TL;DR: The aim of this review is to clarify and give an unifying view of the complex interplay between the NP's surface with their nanoenvironment, which has not been addressed in a comprehensive way in the literature.
Abstract: The physico-chemical properties of colloidal nanoparticles (NPs) are influenced by their local environment, as, in turn, the local environment influences the physico-chemical properties of the NPs. In other words, the local environment around NPs has a profound impact on the NPs, and it is different from bulk due to interaction with the NP surface. So far, this important effect has not been addressed in a comprehensive way in the literature. The vicinity of NPs can be sensitively influenced by local ions and ligands, with effects already occurring at extremely low concentrations. NPs in the Huckel regime are more sensitive to fluctuations in the ionic environment, because of a larger Debye length. The local ion concentration hereby affects the colloidal stability of the NPs, as it is different from bulk owing to Debye Huckel screening caused by the charge of the NPs. This can have subtle effects, now caused by the environment to the performance of the NP, such as for example a buffering effect caused by surface reaction on ultrapure ligand-free nanogold, a size quenching effect in the presence of specific ions and a significant impact on fluorophore-labelled NPs acting as ion sensors. Thus, the aim of this review is to clarify and give an unifying view of the complex interplay between the NP's surface with their nanoenvironment.

310 citations

Journal ArticleDOI
TL;DR: It is revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents or combination of both prior to cross-linking.

202 citations

Journal ArticleDOI
TL;DR: This review aimed to provide an overview of the three main classes of DSSC photosensitizers, namely ruthenium(II) polypyridyl complexes, Zn-porphyrin derivatives and metal-free organic dyes.
Abstract: Dye sensitized solar cells (DSSC) are considered one of the most promising photovoltaics technologies alternative to the traditional silicon based solar cells because of their compatibility with low cost manufacture methodologies, their peculiar optical and mechanical properties and their high indoor efficiency. Photosensitizers represent one of the most important part in a DSSC device and probably the most thoroughly investigated in the last twenty years, with thousands of dyes that have been proposed and tested for this kind of application. In this review we aimed to give an overview of the three main classes of DSSC photosensitizers, namely ruthenium (II) polypyridyl complexes, Zn-porphyrin derivatives and metal free organic dyes. After a brief introduction on the architecture and operational principles of a DSSC and on the state of the art of the other main components of this kind of device, we focused our discussion on photosensitizers. We defined the several requirements DSSC photosensitizers should fulfil and provided an excursus about their historical development along the years; by examining specific dyes reported in the literatures, we attempted to highlight the molecular design strategies that have been established for the optimization of their performance in actual devices both for what concerns efficiency (that recently reaches an outstanding 14.3 %) and operational stability. We finally discussed, in the last section, about the possible future developments of this intriguing technology.

184 citations

Journal ArticleDOI
Jian Li1, Long Yan1, Xiaohua Tang1, Hua Feng1, Dongcheng Hu1, Fei Zha1 
TL;DR: In this paper, a bag is made from superhydrophobic fabric and stuffed with pristine polyurethane (PU) sponge, which can quickly absorb and collect a large amount of oil from a polluted water surface with the separation efficiency always above 98.2%.
Abstract: Removal of oil from water has become an increasingly important field due to the frequent oil spill accidents as well as industrial oily wastewater. In this study, a bag is made from superhydrophobic fabric and stuffed with pristine polyurethane (PU) sponge just utilizing the synergetic effect of the superhydrophobic and superoleophilic selective absorption of oil from water of the fabric and the excellent large volume-based oil storage capacity of the PU sponge. The superhydrophobic filling bag can quickly absorb and collect a large amount of oil from a polluted water surface with the separation efficiency always above 98.2% for a series of oil/water mixtures. In addition, the filled orignial sponges exhibit large volume-based absorption capacity up to 20–36 times its own weight, keeping nearly the same absorption capacity with the previous reported hydrophobic modified sponges. Furthermore, the superhydrophobic bag filled with PU sponges can continuously and efficiently absorb oils from water surfaces with high-speed, removing about 40 L of kerosene in 150 min under a continuous vacuum regime. Moreover, the as-prepared superhydrophobic filling bag also shows high selectivity and excellent oil storage stability; and no oil escapes from the bag even under harsh conditions, including strong acidic, alkaline, salt aqueous solutions, hot water, and mechanical abrasion.

177 citations