Publications by authors named "Sivaraman Chandrasekaran"

6 Publications

  • Page 1 of 1

Fabrication strategies and surface tuning of hierarchical gold nanostructures for electrochemical detection and removal of toxic pollutants.

J Hazard Mater 2021 Jul 14;420:126648. Epub 2021 Jul 14.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, South Korea. Electronic address:

The intensive research on the synthesis and characterization of gold (Au) nanostructures has been extensively documented over the last decades. These investigations allow the researchers to understand the relationships between the intrinsic properties of Au nanostructures such as particle size, shape, morphology, and composition to synthesize the Au nano/hybrid nanostructures with novel physicochemical properties. By tuning the properties above, these nanostructures are extensively employed to detect and remove trace amounts of toxic pollutants from the environment. This review attempts to document the achievements and current progress in Au-based nanostructures, general synthetic and fabrication strategies and their utilization in electrochemical sensing and environmental remediation applications. Additionally, the applications of Au nanostructures (e.g., as adsorbents, sensing platforms, catalysts, and electrodes) and advancements in the field of electrochemical sensing of different target analytes (e.g., proteins, nucleic acids, heavy metals, small molecules, and antigens) are summarized. The literature survey concludes the existing methods for the detection of toxic contaminants at various concentration levels. Finally, the existing challenges and future research directions on electrochemical sensing and degradation of toxic contaminants using Au nanostructures are defined.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2021.126648DOI Listing
July 2021

Semi-Volatile Organic Compounds in Car Dust: A Pilot Study in Jeddah, Saudi Arabia.

Int J Environ Res Public Health 2021 04 30;18(9). Epub 2021 Apr 30.

Toxicological Center, University of Antwerp, Antwerpen 2610, Belgium.

People may spend a significant amount of their daily time in cars and thus be exposed to chemicals present in car dust. Various chemicals are emitted from during car use, contaminating the car dust. In this study, we compiled published and unpublished data on the occurrence of phthalates, flame retardants (FRs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in Saudi car dust. Phthalates, a class of chemical commonly used as plasticizers in different car parts, were the major pollutants found in car dust, with a median value of ∑phthalates 1,279,000 ng/g. Among other chemicals, organophosphate flame retardants (OPFRs) were found to be between 1500-90,500 ng/g, which indicates their use as alternative FRs in the car industry. The daily exposure to Saudi drivers (regular and taxi drivers) was below the respective reference dose (RfD) values of the individual chemicals. However, the estimated incremental lifetime cancer risk (ILCR) values due to chronic exposure to these chemicals was >1 × 10 for taxi drivers for phthalates and PAHs, indicating that the long-term exposure to these chemicals is a cause of concern for drivers who spend considerable time in cars. The study has some limitations, due to the small number of samples, lack of updated RfD values, and missing cancer slope factors for many studied chemicals. Despite these limitations, this study indicates the possible range of exposure to drivers from chemicals in car dust and warrants further extensive studies to confirm these patterns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijerph18094803DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8124401PMC
April 2021

Synthesis, characterization and photocatalytic performance of W impregnated g-CN for the removal of chlorophenol derivatives in natural sunlight exposure.

Chemosphere 2021 Feb 28;265:129135. Epub 2020 Nov 28.

Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia; Chemistry Department, Faculty of Science, King Abdulaziz University, PO Box 80203, Jeddah, 21589, Saudi Arabia.

The surface of the g-CN was altered by impregnating W ions that transformed to homogeneously coated oxide layer by a calcination process. An enhanced absorption and the suppressed de-excitation in the emission spectra, with the increasing W loading, exposed the supporting role of the coated layer in extending the spectral response as well as the prolonged life span of excitons. The same was further supported by electrochemical impedance spectroscopy (EIS). The XRD and XPS analysis revealed the coated layer as highly crystalline pure phase monoclinic WO with the majority of impregnated tungsten ions in 6+ oxidation state respectively, whereas the FESEM and HRTEM analysis substantiated the uniformity of the coated layer with the interlayer spacing of the 0.369 nm. Additionally, the probable formation of individual WO nanoparticles or clusters was ruled out. The as-synthesized impregnated photocatalysts, in comparison to pure g-CN were subjected to natural sunlight exposure for the photocatalytic removal of chlorophenol derivatives (2-CP, 3-CP, 4-CP, 2,3-DCP, 2,4-DCP, 2,4,6-TCP and PCP) that revealed the 5 wt% coating as the optimum level for significant removal. The progress of the photocatalytic process was monitored by periodic HPLC analysis whereas ion chromatography (IC) was used for the estimation of released ions. The mineralization capability of the as-synthesized W coated catalysts was measured by the time scale TOC measurements. As the formation of intermediates was indicated in HPLC analysis, selected samples were subjected to GC-MS analysis for the identification of the nature of intermediates. The variable degree of removal of chlorophenol derivatives signified the role of the position and orientation of Cl group. The kinetics of the removal process was evaluated with the calculation of rate constants. The results extracted from the analytical tools and the associated band edge potentials were correlated to speculate the probable mechanism as well as the identification of major reactive oxygen species (ROS) involved in the removal process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2020.129135DOI Listing
February 2021

A facile synthesis of metal ferrites and their catalytic removal of toxic nitro-organic pollutants.

Environ Pollut 2021 Feb 11;270:116063. Epub 2020 Nov 11.

Department of Materials Science and Engineering, Hongik University, 2639-Sejong- ro, Jochiwon- eup, Sejong-city, 30016, Republic of Korea. Electronic address:

Nitrocompounds are the major prime water contaminants. In this investigative study, toxic nitrocompounds (4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol) were removed by using magnetic CuFeO, CoFeO, and NiFeO material systems. The metal ferrites were synthesized through hydrothermal method and also followed with calcination process. The properties of metal ferrites were confirmed through using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM) studies and results there on were presented. For the first time, the synthesized CuFeO, CoFeO, and NiFeO material systems were used for the reduction of 4-nitrophenol (NP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP) in aqueous medium. The UV-visible spectrometry was employed to monitor the removal of nitro compounds and formation of aminophenol. Among, the three catalysts, the CuFeO displayed excellent removal activity for nitrocompounds. The CuFeO nanoparticles completely removed the NP, DNP and TNP within 2, 5, 10 min, respectively. The NP reduction reaction follows the pseudo-first-order kinetics. Further, the investigated and proposed CuFeO catalyst has given and demonstrated excellent kinetic rate constants 0.990, 0.317, 0.184 min for 4-NP, DNP and TNP respectively, which was very fast kinetic than the already published reports. Also, the aminophenol formation was confirmed for the above mentioned and select nitrocompounds. The obtained results confirm suggest that CuFeO nanoparticles based material system could be one of the promising catalysts for nitro compounds removal process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2020.116063DOI Listing
February 2021

Synthesis of hierarchically structured ɤ-FeO-PPy nanocomposite as effective adsorbent for cationic dye removal from wastewater.

Environ Pollut 2020 Dec 29;267:115498. Epub 2020 Aug 29.

Department of Materials Science and Engineering, Hongik University, 2639-Sejong- Ro, Jochiwon-eup, Sejong-city, 30016, South Korea. Electronic address:

Industrial dye effluents, which are a major wastage component that enter the natural environment, pose a significant health risk to human and aquatic life. Therefore, the effective removal of dye effluents is a major concern. Against this backdrop, in this study, a low-cost, earth-abundant, and ecofriendly ɤ-FeO-PPy nanocomposite was prepared employing the conventional hydrothermal method. The morphology, functional groups, and elemental composition of ɤ-FeO-PPy were characterized by XRD, SEM, XPS, and FTIR studies. Under optimized conditions, the prepared novel ɤ-FeO-PPy nanocomposite showed a high methylene blue (MB) adsorption capacity of 464 mg/g, which is significantly higher than that of existing adsorbents such as CNTs and polymer-modified CNTs. The adsorption parameters such as pH, adsorbent dosage, and ionic strength were optimized to enhance the MB adsorption capacity. The adsorption results revealed that MB is adsorbed onto the adsorbent surface via electrostatic interactions, hydrogen bonding, and chemical binding interactions. In terms of practical application, the adsorbent's adsorption-desorption ability in conjunction with magnetic separation was investigated; the prepared ɤ-FeO-PPy nanocomposite exhibited excellent adsorption and desorption efficiencies over more than seven adsorption-desorption cycles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2020.115498DOI Listing
December 2020

Biodegradation of crude oil by Pseudomonas aeruginosa and Escherichia fergusonii isolated from the Goan coast.

Mar Pollut Bull 2013 Nov 14;76(1-2):276-82. Epub 2013 Sep 14.

Applied and Environmental Biotechnology Laboratory, Department of Biological Sciences, BITS, Pilani, KK Birla Goa Campus, Zuari Nagar, Goa 403 726, India. Electronic address:

Petroleum hydrocarbons are major pollutants of the marine environment. Bioremediation is a promising approach for treating such contaminated environments. The present study aims at isolating naturally occurring bacteria from the coast of Goa, India and to study their hydrocarbonoclastic capacity. Pseudomonas aeruginosa and Escherichia fergusonii were isolated from a crude oil-contaminated sediment sample using diesel oil as the sole carbon source. The capability of the enriched culture to degrade crude oil was estimated using microcosm studies under saline conditions. Based on GC-MS analysis, the culture was found to degrade n-alkanes at a higher rate compared to polyaromatic hydrocarbons. It was also found that the culture degraded alkylated polyaromatic hydrocarbons much less than unalkylated ones. Alkanes ranging from C12 to C33 were highly degraded compared to n-C34. This study shows bioremediation of crude oil in saline (3% NaCl) conditions by naturally existing bacteria isolated from the marine environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.marpolbul.2013.08.026DOI Listing
November 2013
-->