Solar light assisted degradation of dyes and adsorption of heavy metal ions from water by CuO–ZnO tetrapodal hybrid nanocomposite

We report a facile and economic hydrothermal process for multifunctionally engineered copper oxide/zinc oxide-tetrapods (CuO/ZnO-T) nanocomposite for wastewater treatment. The resultant CuO/ZnO-T nanocomposite possesses high porosity, large surface area, and low band gap. All these properties are advantageous for photocatalyst and adsorbent for dyes and heavy metal ions removal. The morphology of synthesized nanocomposite was characterized using X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy, and UV–Visible absorption spectroscopy. The results confirmed the attachment of CuO on the ZnO-T surface, forming a hybrid nanocomposite. The concentration of heavy metal ions was monitored using the atomic absorption spectroscopy technique. The synthesized CuO/ZnO-T nanocomposite was investigated for the decontamination of anionic and cationic dyes, Reactive yellow-145 (RY-145) and Basic violet-3 (BV-3) and heavy metal ions (Chromium (VI) and Lead (II)). The CuO/ZnO-T nanocomposite exhibited superior photocatalytic efficiency (80% RY-145 dye removal and 86% BV-3 dye removal) and adsorption capacity (99% Chromium (VI) removal and 97% Lead (II) removal) as compared to pristine ZnO-T. The mechanism for the reduction of dyes and heavy metal ions was discussed by different kinetics and isotherm models. The current study inferred that CuO/ZnO-T nanocomposite is a potential candidate as a proficient photocatalyst/adsorbent for the removal of various wastewater contaminants.     

Bioconversion of Sodium Dodecyl Sulphate to Rhamnolipid by Pseudomonas aeruginosa: A Novel and Cost-Effective Production Strategy

The utility of rhamnolipids in industry is currently limited due to the high constraints in its economic production. In this scenario, the novel utility of sodium dodecyl sulphate (SDS) as carbon source could serve as promising cost-effective strategy. Screening of effective SDS biodegraders led to the isolation of Pseudomonas aeruginosa S15 capable of concomitant SDS degradation and biosurfactant synthesis. SDS-based rhamnolipid production was proved on SDS minimal agar plates using cetyl trimethylammonium bromide–methylene blue method and optimised in SDS-based minimal salt (SBS) medium. SDS proved to be an ideal carbon source for rhamnolipid synthesis with a high substrate to product conversion rate yielding 6.9 g/l of rhamnolipids from 1 g/l SDS in 5 days. Fast atom bombardment mass spectroscopy analysis of the purified biosurfactant proved the presence of mono- and di-rhamnolipids, viz., Rha-C₁₀-C₁₀, Rha-C₁₀-C₁₂ and Rha-Rha-C₁₀-C₁₀ with surface active properties. The secreted rhamnolipids were not utilised by S15 as a carbon source, but it caused a dispersion of bacterial biofilms in SBS medium. To the best of our knowledge, this is the first report on bioconversion of synthetic detergent to biodetergent. This SDS-based novel methodology presents a more economised mode of rhamnolipid synthesis utilising SDS as sole carbon source.     

X-ray crystal structure of [VO(DPA)(H2O)2]·2H2O (DPA=Dipicolinate dianion)

The X-ray crystal structure of the trans-diaqua complex [VO(DPA)(H2O2)]·2H2O (1) (DPA=dipicolinate dianion) has been determined. Comparison with the known structure of [VO(DPA)(o-phen)]·3H2O (2), obtained from (1) by displacement of the two coordinated aqua molecules, shows that the coordination sphere around vanadium is reorganised during this reaction.     

Lucas sequences and Fibonacci triads of graphs in PMO calculation on the charge-transfer bands of a series of EDA complexes: Correlation with experimental and AM1 results

The use of Lucas sequences and Fibonacci triads of graphs in a complete PMO calculation on a series of phenols is shown. The results were correlated with charge-transfer absorption maxima of a series of molecular EDA complexes of p-chloranil with these phenols as donors. The correlation brings out the PMO parameters in a straightforward way. The graph theoretical results are also shown to correlate well with the donor ionization potentials calculated by the AM1 method, and this correlation yields a value of the sp²-C Coulomb integral, α, which agrees well with the one obtained from photoelectron spectroscopic results. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 817–825, 1997     

Method for construction of characteristic polynomials via graph linearization

A new method for construction of characteristic polynomials (CP) of complicated graphs having arbitrary edge and vertex weights has been developed. The method first converts the graph into isospectral linear chains with weighted vertices and edges and then builds up the CP coefficients recursively. Two types of graphs have been used for illustration, viz., (i) graphs that can be linearized by symmetry factorization and (ii) graphs without symmetry which are to be linearized by an algorithm involving walks of unit length. Both types have been illustrated, of which type (i) includes the Schlegel of fullerene fragment C₂₀ and another large graph with many fused rings. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65 : 199–204, 1997