Faculty Publications
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Item Biological sulfide oxidation using autotrophic Thiobacillus sp.: Evaluation of different immobilization methods and bioreactors(2009) Ravichandra, P.; Gopal, M.; Jetty, A.Aims: Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied. Methods and Results: Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl2 concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations. Conclusions: The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage. Significance and Impact of the Study: Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation. © 2009 The Society for Applied Microbiology.Item One-pot production of 5-(chloromethyl)furfural and levulinic acid from marine carbohydrates(Springer Science and Business Media Deutschland GmbH, 2025) C, P.N.; Yadav, A.K.; Aranha, D.A.; Dutta, S.5-(Chloromethyl)furfural (CMF) and levulinic acid (LA) were produced from marine biomass-derived carrageenan (? and ?) and chitin. CMF was produced in HCl (aq., 35%)-1,2-dichloroethane biphasic reaction within a batch-type glass pressure reactor, whereas LA was produced in the same setup using aqueous HCl (20%) only. The reactions were optimized on temperature, duration, stirring speed, volume of solvent, and feedstock loading. The isolated yield of CMF reached 37.8% starting from ?-carrageenan (80 °C, 2 h), whereas chitin afforded a 21.8% yield of CMF (100 °C, 4 h). LA was obtained in a 52.3% yield from ?-carrageenan (120 °C, 4 h) and 36% from chitin (150 °C, 4 h). The mixture of CMF and LA was then converted into HMF-levulinate, a prospective fuel oxygenate, in a one-pot process, affording a 77.8% isolated yield. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.