Faculty Publications

Now showing 1 - 3 of 3

Investigation on leaching behaviour of toxic metals from biomedical ash and its controlling mechanism
(Springer Verlag service@springer.de, 2019) Krishnamurthy, K.M.; Devatha, C.P.
It is comprehensible that disposal of biomedical ash (BMA) is a serious threat to human life and to the environment compared to any other type of waste without proper treatment. In the present study, it is focused in studying the leaching behaviour and its controlling mechanism to predict the contamination levels of BMA. Experimental investigation was carried out to determine the physico-chemical properties of BMA. The morphological and mineralogical composition was performed by SEM equipped with EDAX and XRD. A leaching pattern was identified for various heavy metals simultaneously (Hg, Se, As, Fe, Cd, Zn, Pb, Ca, Co, Ni, Cr and Cu) by varying pH (3, 5, 7, 9, and 11) via a pH-dependent batch leaching test using AAS and ICP. Major oxidation states of leached mineral/metal were established by Visual MINTEQA 3.1. Leaching test results show that a high concentration of Hg (9.3 mg/l), Se (2.4 mg/l) and As (9.7 mg/l) at pH 11 was obtained. Characterisation studies substantiate 60% of calcium silicate presence and major minerals like ettringite, calcite and thermonatrite. Geochemical modelling reveals that leached elements were solubility controlled except As and Se. It is inferred that, presence/formation of ettringite, calcite and thermonatrite minerals are responsible for immobilizing/reduced leaching of toxic heavy metals in alkaline environment except for Hg, Se and As as they are highly mobile in an alkaline condition which can be reduced by adopting a suitable pretreatment option so as to reduce the contamination levels of handling even untreated waste disposal. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Novel application of maghemite nanoparticles coated bacteria for the removal of cadmium from aqueous solution
(Academic Press, 2020) Devatha, C.P.; S, S.
Heavy metals are classified as persistent pollutants owing to their nature of bioaccumulation and affect human life and environment, even in minor concentrations. Divalent Cadmium (Cd2+) is one of the heavy metal pollutants that are highly toxic. The present study investigates the novel application of maghemite nanoparticles coated Bacillus subtilis for the removal of Cd2+ ions from its aqueous solution by batch adsorption studies. Surface characterization of the biosorbent done by Scanning Electron Microscope (SEM) and the presence of maghemite nanoparticle coat was confirmed. Parameters like pH, initial metal ion concentration, contact time, and temperature that affect the biosorption of cadmium ions are analyzed, and the equilibrium adsorption capacity expressed as a function of each of the parameters. The mechanism of biosorption was studied by plotting adsorption isotherms, and it follows pseudo-second-order kinetics. Thermodynamic studies showed the process to be spontaneous and endothermic. At optimum conditions of pH 4, 30 °C, 120 rpm, maximum removal percentage of 83.5%, which accounts for an equilibrium adsorption capacity of 32.6 mg/g of biosorbent. There was a recovery of 76.4% of the biosorbent after adsorption studies. Based on the adsorptive capacity and good recovery of the biosorbent, maghemite coated Bacillus subtilis proves to be an efficient adsorbent for the removal of Cd2+ ions from its aqueous solution. © 2019 Elsevier Ltd
Experimental investigation for treating ibuprofen and triclosan by biosurfactant from domestic wastewater
(Academic Press, 2023) Jayalatha, N.A.; Devatha, C.P.
The presence of emerging pollutants of pharmaceutical products and personal care products (PPCPs) in the aquatic environment overspreads the threat on living beings. Bioremediation is a promising option for treating wastewater. In the present study, an experimental investigation was carried out to produce a biosurfactant by Pseudomonas aeruginosa (MTCC 1688) for the removal of Ibuprofen (IBU) and Triclosan (TCS) from domestic wastewater. It was performed in three stages. Firstly, the production and optimization of biosurfactant was carried out to arrive at the best combination of crude sunflower oil, sucrose and ammonium bicarbonate (10%: 5.5 g/L: 1 g/L) to yield effective biosurfactant production (crude biosurfactant) and further extended to achieve critical micelle concentration (CMC) formation by dilution (biosurfactant at 10.5%). The stability of the biosurfactant was also confirmed. Biosurfactant showed a reduction in the surface tension to 41 mN/m with a yield concentration of 11.2 g/L. Secondly, its effectiveness was evaluated for the removal of IBU and TCS from the domestic wastewater collected during the dry and rainy seasons. Complete removal of IBU was achieved at 36 h & 6 h and TCS at 6 h & 1 h by crude biosurfactant and biosurfactant at CMC formation for the dry season sample. IBU removal was achieved in 2 h by both crude and biosurfactant at CMC and no TCS was detected in the rainy season sample. Thirdly, biotransformation intermediates of IBU and TCS formed during the application of the biosurfactant and degradation pathways are proposed based on the Liquid Chromatography-Mass Spectrometry (LC-MS) and it indicates that there is no formation of toxic by-products. Based on the results, it is evident that biosurfactant at CMC has performed better for the removal of IBU and TCS than crude biosurfactants without any formation of toxic intermediates. Hence, this study proved to be an eco-friendly, cost-effective and sustainable treatment option for domestic wastewater treatment. © 2022 Elsevier Ltd

Faculty Publications

Browse

Filters

Settings

Sort By

Results per page

Search Results