Faculty Publications
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Item Source apportionment of PM2.5 particles: Influence of outdoor particles on indoor environment of schools using chemical mass balance(AAGR Aerosol and Air Quality Research hhyang@cyut.edu.tw, 2017) Kalaiarasan, G.; Mohan Balakrishnan, R.M.; Sethunath, N.A.; Manoharan, S.Children have higher lung function than adults and they spend most of their day time in schools. Also, children studying at schools located in the vicinity of busy roadways are vulnerable to childhood asthma and respiratory disorders. The present study is focused on estimating the sources of PM2.5 particles present in the indoor air quality in schools which are located adjacent to urban and suburban roadways. The indoor PM2.5 samples from all the four schools were collected using fine dust sampler from 8 a.m. to 4 p.m. The sampling was carried out for one complete week during various seasons including both working and non-working days. The chemical compositions of the PM2.5 samples were analyzed for certain elements like Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, V and Zn using Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) and ions like F-, Cl-, NO3-, PO43-, SO42-, K+, Ca2+, Mg2+, NH4+, Na+ using Ion Chromatography (IC). Source apportionment study using Chemical Mass Balance was carried out using the species concentration of the collected samples. The major sources were found to be Paved Road Dust, Soil Dust, Gasoline Vehicle Emissions, Diesel Vehicle Emissions and Marine Source Emissions. Among these, vehicular emissions contribution was found to be higher for the schools located close to roadways rather than the school located at a considerable distance from highway. The difference in source type contribution at each school clearly depicts the difference in nature of location and type of activities in the vicinity of the sampling sites. © Taiwan Association for Aerosol Research.Item Kinetic and thermodynamic studies on the adsorption of heavy metals from aqueous solution by melanin nanopigment obtained from marine source: Pseudomonas stutzeri(Academic Press, 2018) Manirethan, V.; Raval, K.; Rajan, R.; Thaira, H.; Mohan Balakrishnan, R.M.The difficulty in removal of heavy metals at concentrations below 10 mg/L has led to the exploration of efficient adsorbents for removal of heavy metals. The adsorption capacity of biosynthesized melanin for Mercury (Hg(II)), Chromium (Cr(VI)), Lead (Pb(II)) and Copper (Cu(II)) was investigated at different operating conditions like pH, time, initial concentration and temperature. The heavy metals adsorption process was well illustrated by the Lagergren's pseudo-second-order kinetic model and the equilibrium data fitted excellently to Langmuir isotherm. Maximum adsorption capacity obtained from Langmuir isotherm for Hg(II) was 82.4 mg/g, Cr(VI) was 126.9 mg/g, Pb(II) was 147.5 mg/g and Cu(II) was 167.8 mg/g. The thermodynamic parameters revealed that the adsorption of heavy metals on melanin is favorable, spontaneous and endothermic in nature. Binding of heavy metals on melanin surface was proved by Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). Contemplating the results, biosynthesized melanin can be a potential adsorbent for efficient removal of Hg(II), Cr(VI), Pb(II) and Cu(II) ions from aqueous solution. © 2018 Elsevier LtdItem Batch and continuous studies on the removal of heavy metals from aqueous solution using biosynthesised melanin-coated PVDF membranes(Springer, 2020) Manirethan, V.; Gupta, N.; Mohan Balakrishnan, R.M.; Raval, K.Heavy metals like mercury, chromium, lead and copper present in groundwater at lower concentrations cause severe health issues and can even be fatal when consumed. The biopigment/biopolymer melanin can be reaped from different sources like bacterium, fungus, and human hair. It has excellent heavy metal ion scavenging property and can be exploited for non-biological applications, substantially including water purification. In this work, melanin nanoparticles were derived from the marine bacterium Pseudomonas stutzeri and were coated onto hydrophobic polyvinylidene fluoride (PVDF) membrane as a support, for batch and continuous removal of heavy metal studies. Batch studies on the effect of pH, temperature and adsorbate dose and continuous adsorption studies on the effect of flow rate, adsorbate and adsorbent mass loadings were carried out by using biosynthesised melanin-coated PVDF membranes for the removal of Hg(II), Cr(VI), Pb(II) and Cu(II). Scanning electron microscope (SEM) images revealed the surface morphology, Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) deciphered the chemical characteristics of melanin-coated PVDF membranes before and after adsorption. Contact angle measurement confirmed the improvement in hydrophilicity of PVDF membrane upon coating with melanin. The maximum removal percentages of heavy metals achieved by melanin-coated PVDF membranes under batch mode operation were 87.6%, 88.45%, 91.8% and 95.8% for mercury, chromium, lead and copper, respectively optimised at 318 K and pH of 3 for chromium and 5 for other metals. However, the continuous mode of operation with a flow rate of 0.5 mL/min having 1 mg/L of heavy metal solution concentration exposed to 50 mg of melanin loading with a working volume of 200 mL showed better removal efficiencies compared with batch mode. The dynamic studies using Thomas and Yoon–Nelson models described the transient stage of the breakthrough curve and the model constants were calculated for column design and scale-up. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Item Fluorometric detection of bisphenol A using ?-cyclodextrin-functionalized ZnO QDs(Springer Science and Business Media Deutschland GmbH, 2021) Kadam, V.V.; Mohan Balakrishnan, R.M.; JagadeeshBabu, J.The estrogenic property of bisphenol A (BPA) leads to potential adverse health and ecological effects. A simple, selective, and cost-effective sensor capable of detecting BPA would have a noteworthy relevance for the environmental system. The present work illustrates the synthesis and characterization of ?-cyclodextrin (?-CD) functionalized zinc oxide (ZnO) quantum dots (QDs) for the selective detection of BPA. BPA has a fluorescence quenching effect on functionalized ZnO QDs, and the decrease in fluorescence intensity is associated with the BPA concentration between 2 and 10 ?M. Under the optimum reaction condition, a good linear correlation was obtained between relative fluorescence-quenching intensity of ?-cyclodextrin-functionalized ZnO QDs and BPA concentration (R2 = 0.9891). The lower detection limit of functionalized QDs for BPA was estimated to be 0.19 ?M, which is lower than the toxic limits in aquatic biota. The fluorescence-based detection of BPA may be ascribed to the electron transfer mechanism, which is elucidated with scientific details from the literature. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Zinc-decorated barium oxide nanorods for the effective sunlight-induced catalytic degradation of Irgalite violet dye(Springer Science and Business Media Deutschland GmbH, 2023) Ilango, I.; Susanna, D.; Gabriella, R.; Mohan Balakrishnan, R.M.; JagadeeshBabu, J.Simple and facile fabrication of barium oxide (BaO) and zinc-decorated barium oxide (ZnBaO) nanocatalysts was accomplished through a co-precipitation technique. Irgalite violet (IV) dye was subjected to sunlight-induced catalytic degradation using novel catalyst ZnBaO nanorods. The synthesized nanocatalysts were subjected to various analytical techniques, including FE-SEM/EDX, XRD and FTIR, for their comprehensive characterization. X-ray diffraction confirmed the crystallinity of BaO and ZnBaO nanocatalysts. The FE-SEM image of the ZnBaO nanocatalyst revealed the occurrence of distinct nanorods with a mean size of 22.5 nm possessing an aspect ratio of 4.95. A characteristic UV absorbance peak was observed at 310 nm for BaO and 380 nm for ZnBaO nanocatalysts. The substitution of Zn to BaO led to a favorable decrease in the band gap energy from 5.315 eV (BaO) to 2.6 eV (ZnBaO). The synthesized BaO and ZnBaO nanocatalysts were used in parametric studies by varying catalyst dosage, irradiation time, pH and initial dye concentration. The ZnBaO nanorods showed a maximum degradation efficiency of 99.9% at pH 11 with a catalyst dosage of 40 mg/50 mL containing 5 mg/L dye concentration. The recyclability studies showed that the ZnBaO nanorods could serve as a potential catalyst for degrading dyes. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.