Faculty Publications
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Item Potential environmental applications of Helianthus annuus (sunflower) residue-based adsorbents for dye removal in (waste)waters(Elsevier, 2022) Anastopoulos, I.; Giannopoulos, G.; Islam, A.; Ighalo, J.O.; Iwuchukwu, F.U.; Pashalidis, I.; Kalderis, D.; Giannakoudakis, D.A.; Nair, N.; Lima, E.C.Under the framework of Circular Economy, agricultural residues that once were considered an unwanted byproduct, are currently gaining popularity as novel bio-based products for environmental applications. This chapter evaluates the potential of Helianthus annuus (sunflower) biomass residues for (waste)water dye removal considering the factors regulating its subsequent chemical processes and equilibria. The initial pH, which affects both the dye speciation in solution and the surface charge of the adsorbent, is one of the most critical parameters and determines the optimum conditions for efficient dye removal. The soluble dyes, that present a high affinity for water, are generally ionized (e.g., possess positive or negative charge), and therefore, the sorption capacities of an adsorbent are strongly affected by the initial pH of the dye solution. The equilibrium data regarding the removal of various dyes from aqueous solutions using sunflower-based adsorbents (in pristine or chemically modified form) are usually better described by the Langmuir equation; however, in some cases, the Freundlich adsorption model seems to better fit the experimental data. The majority of the kinetic data associated with the removal of dyes using sunflower-based adsorbents follows the pseudo-second-order model. In addition to the thermodynamic adsorption data, this chapter summarizes and discusses also data of desorption experiments performed using dye-loaded adsorbents. © 2022 Elsevier Inc. All rights reserved.Item Equilibrium and kinetic study for the removal of malachite green using activated carbon prepared from Borassus flabellofer male flower(2010) JagadeeshBabu, P.E.; Kumar, V.; Visvanathan, R.Activated carbon was prepared from dried Borassus flabellofer male flower and batch adsorption experiments were conducted to study its potential to remove malachite green (MG) dye. The process was further optimized by studying the operating variables like initial pH of the stock solution, activation temperature, initial dye concentration, adsorbent loading and contact time. The optimized pH and activation temperatures were found to be 7.55 and 450.C respectively, where further analysis was made using these optimal variables. Linear, Freundlich and Langmuir isotherms were studied and it was found that the Langmuir isotherms have the highest correlation coefficients compared to the others. Further, the sorption kinetics were analysed using pseudo-first-order and pseudo-second-order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intra-particle diffusion is the rate limiting factor. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.Item Solar light-driven photocatalytic degradation of Anthraquinone dye-contaminated water by engineered Ag@TiO2 core–shell nanoparticles(Bellwether Publishing, Ltd., 2015) Khanna, A.; Shetty K, V.K.Abstract: The Ag core–TiO2 shell (Ag@TiO2) nanoparticles were synthesized by one-pot synthesis method followed by calcination and characterized using X-ray diffraction and transmission electron microscopy. The Ag@TiO2 core–shell-structured nanocatalyst was evaluated for its photocatalytic activity towards the degradation of Acid Blue-129 (AB-129), an Anthraquinone dye under solar light irradiations. The nanoparticles were engineered for efficient photocatalytic degradation of AB-129 by varying the parameters such as catalyst composition, calcination temperature, and calcination time. The catalyst composition with Ag to Ti molar ratio of 1:1.7, calcination temperature of 450°C, and time of 3 h were found to be the optimum for the efficient photocatalytic degradation of AB-129. The efficacy of Ag@TiO2 was compared with commercial TiO2, synthesized nano-TiO2, and Ag-doped TiO2 for the photocatalytic degradation of AB-129 and enhanced dye degradation was obtained with Ag@TiO2. This enhanced activity of Ag@TiO2 may be attributed to the trapping of conduction band electrons in Ag core and subsequent discharge on supply of air. Solar photocatalytic degradation of AB-129 dye using Ag@TiO2 followed Langmuir–Hinshelwood kinetics. Ag@TiO2 can be exploited as an efficient catalyst for the degradation of dye and textile industry wastewater. © 2014, © 2014 Balaban Desalination Publications. All rights reserved.Item Humic Acid Based Biopolymeric Membrane for Effective Removal of Methylene Blue and Rhodamine B(American Chemical Society service@acs.org, 2015) Shenvi, S.S.; Isloor, A.M.; A.F., A.F.; Shilton, S.J.; Al-Ahmed, A.Humic acid was immobilized on a polypropylene supported sodium alginate/hydroxyethyl cellulose blend membrane in the current work. The adsorption property of this membrane for the removal of cationic dyes, namely, methylene blue (MB) and rhodamine B (RhB), was extensively studied. Batch-adsorption experiments were conducted to investigate the adsorption behavior of dyes on the membrane with variation in adsorbent mass, initial dye concentration, pH, time, and temperature. The membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). Prepared membranes showed more than 98% removal capacity for both dyes under optimal conditions. Kinetic experiments revealed that the pseudo second order model exhibited the best correlation with the adsorption data. Dubinin-Radushkevich model indicated that the adsorption of dyes onto the membrane surface was by simple physisorption. The membrane was easily regenerated by simple acid treatment, and its efficiency remained significant even after four adsorption cycles. © 2015 American Chemical Society.Item From Molecular Design to Co-sensitization; High performance indole based photosensitizers for dye-sensitized solar cells(Elsevier Ltd, 2016) Babu, D.D.; Su, R.; El-Shafei, A.; Vasudeva Adhikari, A.V.Herein, we report the molecular design and synthesis of two novel organic co-adsorbers DBA-1((Z)-2-cyano-3-(5-(4-(cyclohexa-1,5-dien-3-ynyl(phenyl)amino)phenyl)-1-hexyl-1H-indol-3-yl)acrylic acid) and (DBA-2) 5-((5-(4-(diphenylamino)phenyl)-1-hexyl-1H-indol-3-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione with D-D-A (donor-donor-acceptor) architecture. We have combined the strong electron donating triphenylamine group with indole moiety attached to different acceptors/anchoring groups, as co-adsorbers for dye-sensitized solar cells and we present for the first time, the role of anchoring/acceptor unit on their co-adsorption properties. In this study, cyanoacetic acid and barbituric acid are employed as anchoring groups in the co-sensitizers DBA-1 and DBA-2, respectively. Their electrochemical and photo-physical properties along with molecular geometries, obtained from Density Functional Theory (DFT) are employed to vindicate the effect of co-sensitizer structures on photovoltaic properties of DSSCs. We have demonstrated that the co-sensitization effect is profoundly dependent upon the anchoring/acceptor unit in the co-adsorber molecule. Devices co-sensitized using DBA-1 and DBA-2 along with HD-2 (Ru-complex of 4, 4?-bis-(1,4-benzodioxan-5-yl-vinyl)-[2,2?]bipyridine), displayed higher power conversion efficiencies (PCEs) than the device sensitized using only HD-2. In the present work, ruthenium based sensitizer, HD-2, has been chosen due to its better solar-to-power conversion efficiency and impressively higher photocurrent densities than that of standard N719. Among them, co-adsorber DBA-2, containing barbituric acid as the acceptor/anchoring group displays promising photovoltaic results and exhibited an enhanced efficiency of 8.06%. Further, good agreement between the calculated and experimental results showcase the precision of the energy functional and basis set utilized in this study. All these findings provide a deeper insight and better understanding into the intricacies involved in the design of superior co-sensitizers for development of highly efficient DSSCs. © 2016 Elsevier Ltd. All rights reserved.Item Solar photocatalytically active, engineered silver nanoparticle synthesis using aqueous extract of mesocarp of Cocos nucifera (Red Spicata Dwarf)(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2017) Sumi, M.B.; Devadiga, A.; Shetty K, V.K.; Saidutta, M.B.Silver nanoparticles synthesised using aqueous extract of Cocos nucifera (CN) mesocarp were evaluated for their photocatalytic activity under solar irradiation. The silver nanoparticles were synthesised by a green method of harnessing bioactive phytocomponents from the mesocarp of Cocos nucifera. Large-scale application of this process necessitates the manoeuvering of the process parameters for increasing the conversion of silver ions to nanoparticles. Process parameters influencing the morphological characteristics of silver nanoparticles such as precursor salt concentration and pH of the synthesis mixture were studied. The crystalline nanoparticles were characterised using UV-vis spectroscopy, XRD, FTIR, SEM and EDX analysis. CN extract and 5 mM silver nitrate solution at a ratio of 1:4 (v/v) in the synthesis mixture was found to be the optimum. Alkaline initial pH of the synthesis mixture was found to favour the synthesis of smaller sized monodispersed silver nanoparticles. Solar energy was harnessed for the photocatalytic degradation of Malachite green dye using silver nanoparticles obtained through the green synthesis method. Overall process aims at utilisation of naturally available resource for the synthesis of silver nanoparticles as well as the degradation of dyes using these nanoparticles, making it useful in the treatment of wastewater. © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Item Highly efficient catalytic reductive degradation of various organic dyes by Au/CeO2-TiO2 nano-hybrid(Springer India sanjiv.goswami@springer.co.in, 2017) Saikia, P.; Miah, A.T.; Das, P.P.Highly improved catalytic reductive degradation of different organic dyes, in the presence of excess NaBH4 over Au/CeO2-TiO2 nano-hybrid as the catalyst is reported in this study. CeO2-TiO2 nanocomposite was prepared by a facile co-precipitation method using ultra-high dilute aqueous solutions. Small amount of Au (only 1 wt%) was loaded onto the nanocomposite material by deposition-precipitation with urea (DPU) method to fabricate the ternary Au/CeO2-TiO2 nano-hybrid. The catalysts were characterized by the representative techniques like XRD, BET surface area, ICP-AES, UV-Vis diffuse reflectance spectroscopy, TEM and XPS. The Au/CeO2-TiO2 nano-hybrid along with NaBH4 exhibited remarkable catalytic activities towards all the probed dyes, namely Methylene Blue, Methyl Orange, Congo Red, Rhodamine B and Malachite Green, with a degradation efficiency of ?100% in a short reaction time. The degradation reaction followed pseudo-first-order kinetics with respect to the concentration of the dye. Different parameters that affect the rate of the reaction are discussed. A plausible mechanism for methylene blue degradation has also been proposed. [Figure not available: see fulltext.] © 2017, Indian Academy of Sciences.Item Model generation and process optimization of microwave-assisted aqueous extraction of anthocyanins from grape juice waste(Blackwell Publishing Inc. subscrip@blackwellpub.com, 2017) Venkatramanan, V.; Shanmugam, S.; Arulvel, A.The microwave-assisted extraction of anthocyanins from grape juice waste was investigated in this study. The optimization was implemented using response surface methodology with Box–Behnken design and genetic algorithm (GA). Anthocyanins from grape juice waste were extracted under various microwave power (100–600 W), exposure time (1–5 min) and solvent/solid ratio (10–50 ml/g). The total monomeric anthocyanin yield was considered as the response for optimization experiments. The results indicated that the quadratic model was significant for the chosen response at p <.0001. The analysis of variance and response surface plots showed a significant interaction of all the selected independent variables over anthocyanin extraction process. The maximum anthocyanin yield of 1.31881 mg/g of grape juice waste was predicted by response surface methodology, and the prediction was improved to 1.32244 mg/g of grape juice waste by GA. A confirmatory experiment performed under optimum conditions showed anthocyanin yield of 1.3215 mg/g of grape juice waste. Hence, this model was successful in predicting anthocyanin extraction from grape juice waste under microwave-assisted extraction conditions. Practical application: Anthocyanin pigments find a broad range of implementation as food colorants, antioxidants, and anticancerous agents. The waste residue obtained during grape juice production and processing is also rich in anthocyanins and can be used as an alternative source for anthocyanin extraction. This study exploits the use of grape juice waste for anthocyanin extraction, and it can be the best way of waste management and cost reduction in grape juice production units. © 2016 Wiley Periodicals, Inc.Item Synthesis and photovoltaic performance of a novel asymmetric dual-channel co-sensitizer for dye-sensitized solar cell beyond 10% efficiency(Elsevier Ltd, 2017) Babu, D.D.; Su, R.; Naik, P.; El-Shafei, A.; Vasudeva Adhikari, A.V.In this paper, we report the design and synthesis of a new bi-anchoring indole based co-sensitizer DBA-8 with A-?-D-A (acceptor-? bridge-donor-acceptor) architecture, carrying indole moiety as a donor and barbituric acid as acceptor/anchoring groups. Its photo-physical and electrochemical properties along with molecular geometries, calculated from Density Functional Theory (DFT) are employed to comprehend the effect of co-sensitizer structure on photovoltaic characteristics of DSSCs. The abovementioned organic dye (DBA-8) was employed as a co-sensitizer along with well-known ruthenium based sensitizer NCSU-10 in order to broaden the spectral responses of the co-sensitized DSSC. In the present work, for the first time we are demonstrating the profound role of a dual-anchoring co-sensitizer that can play in ameliorating the overall performance of a solar cell. The photovoltaic studies indicated that, the co-sensitizer DBA-8 succeeded in increasing the light harvesting ability in the device significantly. Notably, the device co-sensitized using 0.2 mM DBA-8 along with ruthenium based chromophore NCSU-10, showed a maximum efficiency of 10.68% (Jsc = 25.14 mAcm?2, Voc = 0.695 V, ff = 61.2%). Further, the good agreement between the theoretically and experimentally obtained ?max data vindicate that, the energy functional and basis set employed in this study can be successfully utilized for predicting the absorption spectra of new photosensitizers, with great precision before synthesis. Furthermore, all these findings showcase the vast potential of bi-anchoring molecules in improving the overall performance of the dye-sensitized solar cells. © 2017 Elsevier LtdItem Reverse micellar extraction of lactoferrin from its synthetic solution using CTAB/n-heptanol system(Springer India sanjiv.goswami@springer.co.in, 2017) Pawar, S.S.; Iyyaswami, R.; Belur, P.D.The partitioning of Lactoferrin (LF) into the reverse micellar phase formed by a cationic surfactant, cetyltrimethylammonium bromide (CTAB) in n-heptanol from the synthetic solution of LF was studied. The solubilization behaviour of LF into the reverse micellar phase and back extraction using a fresh stripping phase were improved by studying the effect of processing parameters, including surfactant concentration, solution pH, electrolyte salt concentration and addition of alcohol as co-solvent. Forward extraction of 100% was achieved at CTAB concentration of 50 mM in n-heptanol solvent, pH of 10 and 1 M NaCl. The electrostatic force and hydrophobic interaction have major influence on LF extraction during forward and back extraction respectively. The size of the reverse micelles and their corresponding water content were measured at different operating conditions to assess their role on the LF extraction. The present reverse micellar system has potential to solubilise almost all the LF into the reverse micelles during forward extraction and could able to allow back extraction from the reverse micellar phase with addition of small amount of co-solvent. © 2017, Association of Food Scientists & Technologists (India).