Jayesh P. Ruparelia

Bio: Jayesh P. Ruparelia is an academic researcher from Nirma University of Science and Technology. The author has contributed to research in topics: Electrolysis & Anode. The author has an hindex of 9, co-authored 30 publications receiving 1900 citations. Previous affiliations of Jayesh P. Ruparelia include Indian Institute of Technology Bombay.

Solvent degradation studies using hydrodynamic cavitation

Abstract: Hydrodynamic cavitation for the degradation of organic solvents was investigated in detail using a newer form of cavitating device-vortex diode. The results were also compared with that using conventional cavitating device orifice. Removal of three different organic solvents—acetone, methyl ethyl ketone (MEK), and toluene were studied on a pilot plant with capacity of 1 m3/h. The effect of different operating parameters such as inlet pressure, initial concentration, and reactor type on the degradation rate of solvent was investigated in detail. The results revealed that efficiency of solvent removal varies substantially with the change in physical operating conditions and nature of the solvent. It was found that up to 80% degradation could be achieved for toluene (cavitational yield 32.2 × 10−3 mg/J), substantially higher than that for acetone and MEK indicating the effect of molecular weight/structure in the degradation process. Further, the results clearly indicated chemical oxidation as a predominant mechanism for degradation and not physical destruction. Vortex diode that works on the principle of vortex generation for cavitation, was found to be far superior over conventional cavitating device-orifice- ∼up to eight times higher cavitational yield could be obtained for toluene as compared to orifice. The results of this study provide newer insight into solvent removal using hydrodynamic cavitation and would have bearing on the treatment of solvent containing wastewaters. © 2017 American Institute of Chemical Engineers Environ Prog, 2017

A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

Abstract: Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver–dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules—all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

Antimicrobial activity of metals: mechanisms, molecular targets and applications

Abstract: Metals have been used as antimicrobial agents since antiquity, but throughout most of history their modes of action have remained unclear. Recent studies indicate that different metals cause discrete and distinct types of injuries to microbial cells as a result of oxidative stress, protein dysfunction or membrane damage. Here, we describe the chemical and toxicological principles that underlie the antimicrobial activity of metals and discuss the preferences of metal atoms for specific microbial targets. Interdisciplinary research is advancing not only our understanding of metal toxicity but also the design of metal-based compounds for use as antimicrobial agents and alternatives to antibiotics.

Size-controlled silver nanoparticles synthesized over the range 5–100 nm using the same protocol and their antibacterial efficacy

Abstract: A systematic and detailed study for size-specific antibacterial efficacy of silver nanoparticles (AgNPs) synthesized using a co-reduction approach is presented here. Nucleation and growth kinetics during the synthesis process was precisely controlled and AgNPs of average size 5, 7, 10, 15, 20, 30, 50, 63, 85, and 100 nm were synthesized with good yield and monodispersity. We found the bacteriostatic/bactericidal effect of AgNPs to be size and dose-dependent as determined by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against four bacterial strains. Out of the tested strains, Escherichia coli MTCC 443 and Staphylococcus aureus NCIM 5201 were found to be the most and least sensitive strains regardless of AgNP size. For AgNPs with less than 10 nm size, the antibacterial efficacy was significantly enhanced as revealed through delayed bacterial growth kinetics, corresponding MIC/MBC values and disk diffusion tests. AgNPs of the smallest size, i.e., 5 nm demonstrated the best results and mediated the fastest bactericidal activity against all the tested strains compared to AgNPs having 7 nm and 10 nm sizes at similar bacterial concentrations. TEM analysis of AgNP treated bacterial cells showed the presence of AgNPs on the cell membrane, and AgNPs internalized within the cells.