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Author: search.filters.author.Manirethan, V.Subject: search.filters.subject.water treatment

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    Insights on the advanced processes for treatment of inorganic water pollutants
    (Elsevier, 2020) Mohan Balakrishnan, R.M.; Uddandarao, P.; Manirethan, V.; Raval, K.
    A remarkable increase in the discharge of inorganic pollutants globally from various sources such as mines, industries, or agricultural lands is a major threat to the environment. Development of novel methodologies to mitigate the effects caused by inorganic pollutants in water is crucial in addressing environmental issues. In this regard, various biological sources as nanosorbents and biosensors are venerated as superior entities for the detection and removal of inorganic contaminants. This chapter summarizes the utility of marine bacterial melanin- and fungal-based selenium nanoparticles for the adsorption and further reports endophytic fungal–based ZnS and PbS nanoparticles for the detection of inorganic pollutants from the aqueous systems; moreover, it gives a perspective on current challenges for the removal of contaminants. © 2020 Elsevier Inc. All rights reserved.
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    Adsorptive removal of trivalent and pentavalent arsenic from aqueous solutions using iron and copper impregnated melanin extracted from the marine bacterium Pseudomonas stutzeri
    (Elsevier Ltd, 2020) Manirethan, V.; Raval, K.; Mohan Balakrishnan, R.M.
    The metalloid arsenic is one of the most conspicuous groundwater contaminants in the Indian subcontinent and its removal from aqueous medium is the main focus of this study. The study aims at functionalising melanin using iron and copper for the efficient removal of arsenic and rendering water fit for consumption. Melanin obtained from the marine bacteria Pseudomonas stutzeri was functionalised by iron impregnation (Fe-melanin) and copper impregnation (Cu-melanin). Morphological studies using FESEM portrayed the impregnated iron and copper granules on the surface of melanin, while XRD analysis confirmed the presence of Fe2O3 and CuO on melanin. Adsorption studies on As (V) and As (III) were conducted using Fe-melanin and Cu-melanin for different operating variables like pH, temperature and contact time. More than 99% per cent of As (III) and As (V) from water was removed at a pH range between 4 and 6 within 50 min in the case of Fe-melanin and 80 min for Cu-melanin. Adsorption equilibrium studies showed better fit with Langmuir adsorption isotherm and had good agreement with Redlich-Peterson's three-parameter model. The maximum adsorption capacities of Fe-melanin and Cu-melanin obtained from Langmuir adsorption model are 50.12 and 20.39 mg/g, respectively, for As (V) and similarly 39.98 and 19.52 mg/g, respectively, for As (III). Arsenic-binding to the functionalised melanin was confirmed using FT-IR and the XPS analysis. Reuse of the adsorbent was effectively done by desorbing the iron and copper together with the bound As (III) and As (V) and further re-impregnation of iron and copper in melanin. Re-functionalised melanin showed 99% adsorption efficiency up to four cycles of adsorption/desorption. A novel iron and copper impregnated melanin was synthesized to remove As (III) and As (V) from groundwater and the adsorption process was optimized. © 2019 Elsevier Ltd
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    Photocatalytic Degradation of Chlorpyrifos and Tetracycline in Aqueous Medium Using Silver Titanate Perovskite Nanoparticles
    (Springer Science and Business Media Deutschland GmbH, 2024) Joseph, A.; Raval, K.; Manirethan, V.
    Near-infrared (NIR) active silver titanate perovskite (AgTiO3)-based photocatalysis is a potential method for degrading organic pollutants due to its unique structural features, compositional flexibility, and affordability. Herein, we have synthesized novel NIR-active AgTiO3 nanoparticles with a low band gap of 0.92 eV via the hydrothermal method using Ananas comosus leave extract, which is a major agricultural waste worldwide. The produced AgTiO3 nanoparticles were characterized using Fourier Transform Infrared (FTIR) spectroscopy investigations, X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDS). The photocatalytic activities of the AgTiO3 nanoparticles toward the degradation of tetracycline and chlorpyrifos under UV, visible, NIR, and solar light irradiation were carefully examined, and the photocatalytic mechanism was proposed using liquid chromatography-mass spectrometry (LC-MS) and high-performance liquid chromatography (HPLC). AgTiO3 nanoparticles completely degraded tetracycline and chlorpyrifos within 27 min and 21 min, respectively. The increased efficiency of AgTiO3 nanoparticles produced by green synthesis over conventional photocatalysts points to a potential advancement avenue for water treatment systems. Furthermore, using agricultural waste like leftover pineapple leaves not only lessens the impact on the environment but also solves the issue of cost when putting these technologies into practice on a larger scale. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.