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The concentration and bioaccumulation of heavy metals were investigated in four distinct components (water, sediment, benthic organisms, and fish) in the Ennore estuary. The average concentration of studied metals in water is 2-5 times higher in the sediment. The geoaccumulation index in the sediment, particularly for Cd, 55 folds greater than WHO and USEPS standards. The indices like MI, C deg , PLI, and PERI demonstrated low contamination levels, whereas I geo and C f revealed elevated levels of cadmium (Cd), signifying a moderate degree of contamination. Human health indices like Target Hazard Quotation (THQ) values generally fell within permissible limits (<1), except for lead (Pb) and iron (Fe). However, HI values exceeded 1, indicating a non-carcinogenic health risk for consumers. The Target Risk for lead (TR Pb ) value for Oreochromis urolepis was 1.0 × 10 -5 , suggesting a significant cancer risk and may leads to other fish species in future if carcinogenic metals bioaccumulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In the present study, biomass from the Chromolaena odorata plant's stem was activated using sulfuric acid to adsorb crystal violet (CV) dye. The adsorption operation of CV dye was studied considering the effect of variables like pH, initial dye concentration, time, adsorbent dosage, and temperature. The pseudo-second-order equation best fitted the kinetic study. The thermodynamic parameters such as activation energy (9.56 kJ/mol), change in Gibbs energy (81.43 to 96.7 kJ/mol), enthalpy change (6.89 kJ/mol), and entropy change (-254.4 J/mol K) were calculated. Response surface methodology estimated that at pH (4.902), adsorbent dosage (8.33 g/L), dye concentration (82.30 ppm), and temperature (300.13 K) dye removal of 97.53% is possible. FTIR, SEM, XRD, BJH, and BET confirmed adsorption operation. The adsorbent can be reused for 3 cycles effectively. Langmuir isotherm which best fitted the adsorption operation was used for designing a theoretical single-stage batch adsorber for large-scale operation., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Nowadays, fast-growing industrialization has resulted in the release of enormous amounts of contaminants such as toxic dyes into water bodies and leading to cause health and environmental risks. In this regard, we prepared inorganic nanocomposites for the treatment of toxic dyes. Hence, we synthesized TiO 2 /PAni/GO nanocomposites and examined them by using XRD, SEM, TEM, UV-Vis spectroscopy, BET analysis, and a photoluminescence investigation. In addition, band gap energies of the nanocomposites were determined, and Total Organic Carbon (TOC) testing was used to determine dye degradation levels. The photocatalytic degradations of Thymol Blue and Rose Bengal dyes were investigated at different dye concentrations, illumination periods, solution pH values, and photocatalyst dosages. By using TiO 2 /PAni/GO, TiO 2 /PAni, and TiO 2 at neutral pH, a photocatalyst dose of 1600 mg/L, and exposure to visible light, Thymol Blue and Rose Bengal were photodegraded 85-99%, 60-97%, and 10-20%, respectively, at a concentration of 25 ppm (180 min). Reductions in the TOCs confirmed their photodegradation, and a kinetic study revealed photodegradation followed first-order kinetics. This study shows the coating of polyaniline (PAni) and graphene oxide (GO) on TiO 2 improved its ability to photodegrade Thymol Blue and Rose Bengal dye., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Water pollution is a serious problem that threatens both developed and developing countries. Several methods have been used to purify contaminated water, among which the photocatalytic decomposition approach is widely used to purify contaminated water from organic pollutants. In this work, biomass derived SiO 2 nanoparticles composite with TiO 2 semiconductors used as an efficient photocatalyst for degradation of RhB dye molecules under UV-visible light irradiation is proclaimed. The different weight percentages of Arundo donax L. ash-derived SiO 2 nanoparticles combined with TiO 2 nanoparticles were prepared through the wet impregnation method. The photocatalytic degradation ability of the as-prepared samples has been scrutinized against the degradation of Rh B dye in which the pronounced photocatalytic degradation efficiency 93.7% is successfully achieved on 50 wt % SiO 2 -50 wt % TiO 2 nanocomposite photocatalyst. The catalytic performance of the nanocomposite decreases with an increase of 50%-75% in SiO 2 nanoparticles. There could have been a decrease in degradation efficiency due to an excess amount of SiO 2 covering TiO 2 nanoparticles, which prevented photons from reaching the nanoparticles. The efficiency of cyclic decomposition of the 50 wt% SiO 2 -50 wt% TiO 2 composite showed only a slight change in photocatalytic capacity compared to the first cycle, which ensures the durability of the sample. However, the hydroxyl radical species play the main role in the degradation process, which has been confirmed by the scavenger test. The probable reaction mechanism is also deliberated in detail. The high photocatalytic performance of novel eco-friendly SiO 2 -TiO 2 photocatalyst make it ideal for water purification applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The importance of microplastic (MPs) contamination in marine environments is reflected by increasing number of studies in fish species. Some even dedicated to the toxicological effects from the ingestion. Microplastics (MPs) and their trace metal composition were examined in the muscle and intestine of five commercially important fish species (i.e., Sufflamen fraenatus, Heniochus acuminatus, Atropus atropos, Pseudotriacanthus and Leiognathus brevirostris) from Thoothukudi at the Gulf of Mannar coast in south India. The abundance and morphology of MPs (size, shape, and texture) in muscle and intestinal were investigated by micro-Fourier Transform Infrared Spectroscopy (μ-FT-IR) and atomic force microscope (AFM). ICP-OES was used to investigate the adsorption/leaching of trace metals in microplastics in order to assess health risk for adults and children. Particles of 100-250 μm and white color dominated, and the mean abundances (items/100 g) of total MPs were more in Pseudotriacanthus (muscle: 51.2; intestine: 50.1) compared to Heniochus acuminatus (muscle: 9.6; intestine: 15), Leiognathus brevirostris (muscle: 12; intestine: 13.2) and Atropus atropus (muscle: 15.2; intestine: 44.1). Polyethylene (35.3%), polypropylene (27.2%), polyamide (nylon) (22.2%) and fiber (15.3%) represented the MPs present in muscles, and polyamide (nylon) (30.2%), polyethylene (28.1%), polypropylene (25.9%), and fiber (15.8%) composed the intestine MPs. We estimated possible consumption of 121-456 items of MPs/week by adults and about 19-68 items of MPs/week by children by considering the sizes of safe meals. Zn, Cu, Mn and Cr in these fish species reflected influence of the sewage waste. However, the non-carcinogenic risk evaluated through EDI, THQ, HI, and CR did not suggest any immediate health problem for the consumers., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In the present study, filamentous algae, an emerging candidate for biofuel and other useful chemical production, has been investigated as a biological adsorbent for the removal of contaminants from synthetic wastewater. Operational parameters were optimized in batch phytoremediation experiments. The adsorption equilibrium isotherm models such as Langmuir, Freundlich, and Dubinin-Radushkevitch and kinetics models such as pseudo-1st and pseudo-2nd order in methylene blue decolorization and Cr(VI) removal were also investigated. The D-R isotherm theory provided the best fit. The pseudo-2nd order model accurately described the adsorption kinetic data. Maximum adsorption capacities were observed to 5.03 mg.g -1 and 0.77 mg.g -1 along with removal efficiencies were achieved to 91.3% and 91.4% for methylene blue and Cr(VI) remediation, respectively. Moreover, intra-particle diffusion kinetic theory was used to describe the mechanism. These outcomes are significant in the development of algae-based zero-cost pollutants removal technology in wastewater treatment., (Copyright © 2021 Elsevier Ltd. All rights reserved.)