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Since the sulfur specific cleavage is vital for the organic sulfur removal from fossil fuel, we explored potential bacterial strains of MTCC (Microbial Type Culture Collection) to desulfurize the Dibenzothiophene (DBT) through C-S bond cleavage (4-S pathway). MTCC strains Rhodococcus rhodochrous (3552), Arthrobacter sulfureus (3332), Gordonia rubropertincta (289), and Rhodococcus erythropolis (3951) capable of growing in 0.5 mM DBT were examined for their desulfurization ability. The presence of dsz genes as well as the metabolites was screened by polymerase chain reaction (PCR) and HPLC, respectively. All these strains showed > 99% DBT desulfurization with 10 days of incubation in minimal salt medium. From the HPLC analysis it was further revealed that these MTCC strains show differences in the end metabolites and desulfurize DBT differently following a variation in the regular 4-S pathway. These findings are also well corroborating with their respective organization of dszABC operons and their relative abundance. The above MTCC strains are capable of desulfurizing DBT efficiently and hence can be explored for biodesulfurization of petrochemicals and coal with an eco-friendly and energy economical process. [ABSTRACT FROM AUTHOR]

In hydrometallurgical and mineral processing operations, slurries are often prepared at very small grind sizes and high solids concentrations. The presence of yield stress or flow limits results in flow anomalies as the slurry tends to stagnate close to vessel bottom, walls, and at any internal surface. The preparation of high-concentration slurries preferably in low shear rate ranges consuming less power is an integral part of high-concentration slurry transportation systems. Therefore, during mixing of such concentrated slurries, the selection of appropriate agitation equipment for preparation of a homogeneous suspension requires a thorough investigation. The rheological behavior of ground manganese nodule samples in solids concentration range of 55–65% by weight using both distilled water and sea water as mediums have been evaluated and the discrepancy in yield stress and plastic viscosity values affected by solids concentration and medium has been discussed and presented in the paper. The performance characteristics of a helical ribbon mixer influenced by fluid rheology, medium, and agitator rotational speed were evaluated. The appropriateness of the agitator for preparation of high-concentration manganese nodule slurry was further substantiated by comparing the experimental power consumption data with the theoretical power consumption values computed using Bakker and Gates correlations. [ABSTRACT FROM AUTHOR]

Mine backfilling with power plant ash is gaining increasing attention from the power and mining industries for its bulk disposal. In the USA and other countries, mine backfilling with ash is considered as a viable option for stability improvement, subsidence control, and mine site rehabilitation. This paper presents the results of rheological studies conducted on fly ash and mixtures of fly ash and bottom ash samples collected from NTPC Talcher, Odisha. The complex hydro-mixture slurry indicated non-Newtonian pseudo-plastic behavior in the mass concentration range of 60–67.5%. A non-Newtonian power law head loss model was used to evaluate the head loss of ash slurry in pipelines having nominal bores in the range of 100–300 mm. The results indicated that the addition of bottom ash to fly ash slurry at a given solids concentration has a beneficial effect in reducing the pumping power requirement. A design chart for the fly ash mixture slurry has been formulated indicating the variation in backfilling rate with relative head requirements for a given length of pipeline for a range of pipe sizes and transport velocities. This is expected to provide relevant pipe flow and operational conditions for bulk disposal of fly ash for mine backfilling purpose. [ABSTRACT FROM AUTHOR]

The present study encompasses the first ever attempt of the usage of cow dung as a reductant in the reduction roasting of an Indian iron ore slime containing 56.2% Fe. The resultant reduced mass generated a concentrate of ~ 64% Fe with a weight recovery ~ 66% after being subjected to low intensity magnetic separation (LIMS). The optimum conditions of roasting as determined by the Taguchi statistical design were found to be temperature: 700 °C, time: 45 min and reductant to feed ratio: 0.25:1. Under similar conditions, the conventional reductant charcoal (fixed carbon: 93.5%, volatile matter: 1.2%) could result in a product of ~ 66% Fe at ~ 35% weight recovery proving cow dung (fixed carbon: 8.66%, volatile matter: 41.27%) to be a better reductant. The cow dung cake and some of the reduced products were subjected to integrated instrumental techniques such as X-ray Diffraction (XRD), Scanning Electron Microscope attached with an Energy Dispersive Spectroscopy (SEM-EDS) and Electron Probe Micro-Analysis (EPMA), which revealed the formation of new phases such as hercynite, corundum, iron aluminium silicate along with magnetite and wustite, at different levels of operating parameters, thereby explaining the role of different reduction variables. [ABSTRACT FROM AUTHOR]

Indian low grade iron ores mostly contain quartz, gibbsite, and clay as the major impurities. Depending upon the ore characteristics, in many instances froth flotation has to be used to recover the hematite and other iron oxides from the ground ores. In this context, the difference in silica and alumina content in low grade iron ores is brought to bear on the prospects of iron ore flotation. For this purpose, pure minerals like hematite, quartz, gibbsite, and clay have been used to prepare synthetic mixtures and analyzed to determine the difference in floatability. The results are compared against natural iron ores with variations in silica and alumina content. The flotation results with oleic acid and dodecylamine show better recovery of iron values in the hematite–quartz mixture as well as in the naturally occurring high silica ore compared to the hematite–clay mixture and the high alumina ore respectively. Similarly results on a variety of iron ores show that high silica content as quartz in the ore causes less hindrance in the flotation of iron ore, whereas the presence of silica as clay inhibits the flotation response of iron ore. The scanning electron microscopic (SEM) studies indicate that clay particles cover the surface of hematite, making it less selective for interaction with the collector. The surface potential studies of clay and quartz suggest that charge reversal takes place for quartz treated with dodecylamine (DDA), but for the DDA adsorption on clay, negative potential values are noted beyond a pH of 4.6. [ABSTRACT FROM AUTHOR]

This study illustrates a density functional theory (DFT) based approach to design the amine collectors with regards to their interaction with the quartz surface. Mechanism of interaction of primary aliphatic amines and their ether and ester derivatives with the quartz surface has been established. Hydrogen bond geometries and adsorption energies as calculated using DFT reveal that ester amines are stronger surfactants compared to the ether amines and primary alkyl amines. Simulation studies carried out for the different amines with number of carbon atoms varying from 10 to 18 suggest that increasing the number of carbon atoms in the alkyl chain enhances the interaction, but not beyond C 14 for primary amines and C 16 for its ether and ester derivatives. Presence of both ether and ester group in the alkyl chain facilitates its interaction strength. Adsorption strength of C 12 amine containing both ether and ester amine is almost equivalent to that of C 16 ester amine. [ABSTRACT FROM AUTHOR]

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of Ag(+) ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of Ag(+) ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

A series of experiments were carried out with three native strains of microalgae to measure growth rates, biomass, and lipid productivities. Scenedesmus sp. IMMTCC-6 had better biomass growth rate and higher lipid production. The growth, lipid accumulation, and carbon dioxide (CO2) consumption rate of Scenedesmus sp. IMMTCC-6 were tested under different NaOH concentrations in modified BBM. The algal strain showed the maximum specific growth rate (0.474/day), biomass productivity (110.9 mg l(-1) d(-1)), and CO2 consumption rate (208.4 mg l(-1) d(-1)) with an NaOH concentration of 0.005 M on the 8(th) day of cultivation. These values were 2.03-, 6.89-, and 6.88-fold more than the algal cultures grown in control conditions (having no NaOH and CO2). The CO2 fixing efficiency of the microalga with other alternative carbon sources like Na2CO3 and NaHCO3 was also investigated and compared. The optimized experimental parameters at shake-flask scale were implemented for scaling up the process in a self-engineered photobioreactor. A significant increase in lipid accumulation (14.23% to 31.74%) by the algal strain from the logarithmic to stationary phases was obtained. The algal lipids were mainly composed of C16/C18 fatty acids, and are desirable for biodiesel production. The study suggests that microalga Scenedesmus sp. IMMTCC-6 is an efficient strain for biodiesel production and CO2 biofixation using stripping solution of NaOH in a cyclic process.