Faculty Publications

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    Sacrificial polystyrene template assisted synthesis of tunable pore size hollow core-shell silica nanoparticles (HCSNs) for drug delivery application
    (American Institute of Physics Inc. subs@aip.org, 2019) Deepika, D.; JagadeeshBabu, J.
    Hollow core-shell silica nanoparticles (HCSNs) with desirable interior space have attracted intensive interest in the field of controlled drug delivery. In the present research work facile two-step method was employed to synthesize HCSNs by using sacrificial polystyrene (PS) template. Monodispersed spherical polystyrene nanoparticles with size range 200-250 nm were synthesized by emulsion polymerization method. Silica was coated on PS template using TEOS as precursor and cetyltrimethyl ammonium bromide (CTAB) as the shell structure directing agent. Complete removal of the template particles was achieved by calcination at 550 °C confirmed by fourier transform infrared spectroscopy (FTIR). Variation in pore size was attained by altering ethanol/water volume ratio and visualized in scanning electron microscope (SEM). Average specific surface area of HCSNs verified by Brunauer Emmett Teller (BET) method observed to be 842.57 m2/g. Drug release behavior was investigated using doxorubicin as model drug by varying pore size of HCSNs, displayed a pore size dependent release. HCSNs with reduced pore size (2.2 nm) showed maximum delay in the doxorubicin release, demonstrated the potential application of HCSNs in targeted drug delivery. © 2019 Author(s).
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    Synthesis and characterization of microporous hollow core-shell silica nanoparticles (HCSNs) of tunable thickness for controlled release of doxorubicin
    (Springer Netherlands rbk@louisiana.edu, 2018) Deepika, D.; JagadeeshBabu, J.B.
    Hollow core-shell silica nanoparticles (HCSNs) are being considered as one of the most favorable drug carriers to accomplish targeted drug delivery. In the present study, we developed a simple two-step method, employing polystyrene (PS) nanoparticles (150 ± 20 nm) as a sacrificial template for the synthesis of microporous HCSNs of size 230 ± 30 nm. PS core and the wall structure directing agent cetyl trimethyl ammonium bromide (CTAB) were removed by calcination. Monodispersed spherical HCSNs were synthesized by optimising the parameters like water/ethanol volume ratio, PS/tetraethyl orthosilicate (TEOS) weight ratio, concentration of ammonia, and CTAB. Transmission electron microscopy (TEM) revealed the formation of hollow core-shell structure of silica with tunable thickness from 15 to 30 nm while tailoring the concentration of silica precursor. The results obtained from the cumulative release studies of doxorubicin loaded microporous HCSNs demonstrated the dependence of shell thickness on the controlled drug release behavior. HCSNs with highest shell thickness of 30 nm and lowest surface area of 600 m2/g showed delay in the doxorubicin release, proving their application as a drug carrier in targeted drug delivery systems. The novel concept of application of microporous HCSNs of pore size ~ 1.3 nm with large specific surface area in the field of drug delivery is successful. © 2018, Springer Nature B.V.
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    Reusable floating polymer nanocomposite photocatalyst for the efficient treatment of dye wastewaters under scaled-up conditions in batch and recirculation modes
    (John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2019) Das, S.; Mahalingam, H.
    BACKGROUND: In the last decade, research on floating photocatalysts has increased rapidly with polymer substrates being a popular choice. However, most of the published work is on very small volumes and there is very little work on scale-up of such systems. RESULTS: Polystyrene–titanium dioxide nanocomposite floating films were prepared using a facile solvent casting method and tested for the photocatalytic degradation of four different dyes under UV irradiation. The prepared film was characterised by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES) and profilometry. Scale-up studies were done in batch mode under optimised conditions, and for the larger reactor volume, the effect of recirculation was studied. Complete decolourisation of the model dye (Remazol Turquoise Blue) was observed within 80 min in the scaled-up batch process. In the recirculation mode, for a much larger volume of the dye solution, around 75% decolourisation in 6 h was observed. The reusability of the photocatalytic film was tested, and the results promise a minimum decolourisation efficiency of around 70%. Finally, total organic carbon (TOC) and liquid chromatography mass spectrometry (LC-MS) analysis were used to assess the degradation of the dye. The maximum TOC reduction observed was around 25% possibly due to the complex nature of the dye used in this study. The intermediate products of degradation were identified, and a tentative mechanism is suggested. CONCLUSION: This work demonstrates the recirculation aspects of the photocatalytic reactor under the scaled-up conditions for a complex dye. The prepared film showed excellent stability with satisfactory wastewater decontamination under UV irradiation even after repeated use. © 2019 Society of Chemical Industry. © 2019 Society of Chemical Industry
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    Novel immobilized ternary photocatalytic polymer film based airlift reactor for efficient degradation of complex phthalocyanine dye wastewater
    (Elsevier B.V., 2020) Das, S.; Mahalingam, H.
    Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) catalysts were synthesized and a physical admixture of rGO and g-C3N4 along with TiO2 in the ratio of 1:1:1 by weight was immobilized in a polystyrene film using the facile solvent casting method. An internal loop airlift reactor with a working volume of 1.2 litres incorporating the prepared polymer-based photocatalytic film was designed and tested for the photocatalytic degradation of remazol turquoise blue dye synthetic wastewater. The reactor parameters affecting the photocatalytic activity such as airflow rate and Di/Do (ratio of draft tube diameter to outer tube diameter) were evaluated. The successful operation of the reactor obtained using the ternary immobilized catalyst mixture film gave 92.25% total organic carbon reduction and 94% decolourization within 140 min, compared to 91% decolourization by the slurry form within 40 min. Complete and quicker decolourization of the dye was also demonstrated under the influence of O3 or H2O2. The immobilized catalyst was successfully reused four times. The ternary catalyst admixture employed in this work and the unique design of the photocatalytic reactor helps to increase the degradation rate of toxic textile effluents thus making it suitable for larger scales of treatment. © 2019 Elsevier B.V.
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    Understanding of synergy in non-isothermal microwave-assisted in-situ catalytic co-pyrolysis of rice husk and polystyrene waste mixtures
    (Elsevier Ltd, 2022) Sridevi, V.; Suriapparao, D.V.; Tukarambai, M.; Terapalli, A.; Ramesh, R.; Sankar Rao, C.S.; Gautam, R.; Moorthy, J.V.; Suresh Kumar, C.
    Rice husk (RH) and polystyrene (PS) wastes were converted into value-added products using microwave-assisted catalytic co-pyrolysis. The graphite susceptor (10 g) along with KOH catalyst (5 g) was mixed with the feedstock to understand the products and energy consumption. RH promoted the char yield (20–34 wt%) and gaseous yields (16–25 wt%) whereas PS enhanced the oil yield (23–70 wt%). Co-pyrolysis synergy induced an increase in gaseous yields (14–53 wt%) due to excessive cracking. The specific microwave energy consumption dramatically decreased in co-pyrolysis (5–22 kJ/g) compared to pyrolysis (56–102 kJ/g). The pyrolysis index increased (17–445) with the increase in feedstock quantity (5–50 g). The obtained oil was composed of monoaromatics (74%) and polyaromatics (18%). The char was rich in carbon content (79.5 wt%) and the gases were composed of CO (24%), H2 (12%), and CH4 (22%). © 2022 Elsevier Ltd
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    The effect of torrefaction temperature and catalyst loading in Microwave-Assisted in-situ catalytic Co-Pyrolysis of torrefied biomass and plastic wastes
    (Elsevier Ltd, 2022) Ramesh, R.; Suriapparao, D.V.; Sankar Rao, C.S.; Sridevi, V.; Kumar, A.; Shah, M.
    In the current study, the effect of torrefaction temperatures (125–175 °C) and catalyst quantity (5–15 g) on co-pyrolysis of torrefied sawdust (TSD) and polystyrene (PS) are investigated to obtain value-added products. The role of torrefaction in co-pyrolysis of TSD: PS was analyzed to understand the product yields, synergy, and energy consumption. As the torrefaction temperature increases, oil yield (48.3–59.6 wt%) and char yield (24.3–29 wt%) increase while gas yield (27.4–11.4 wt%) decreases. Catalytic co-pyrolysis showed a significant level of synergy when compared to non-catalytic co-pyrolysis. For the conversion (%), a positive synergy maximum (-2.6) exists at a torrefaction temperature of 175 °C and 15 g of KOH catalyst. To develop the model, polynomial regression-based machine learning was used to predict pyrolysis product yields and energy usage variables. The developed models showed significant prediction accuracy (R2 > 0.98), suggesting the experimental values and the predicted values matched well. © 2022 Elsevier Ltd