Hexavalent chromium removal from aqueous solutions using biogenic iron nanoparticles: Kinetics and equilibrium study.

Green mediated biosynthesis of iron oxide nanoparticles utilising Rosa indica flower petal extracts (RIFP-FeONPs) was used in this investigation. The RIFP-FeONPs were evaluated by the UV-Visible Spectroscopy, FTIR, SEM, EDX, XRD, Zeta potentials, and DLS, and been engaged than for the elimination of Cr (VI) from the contaminated environments. At 269 nm, the RIFP-FeONPs surface plasmon vibration bands were observed, which attributed to the Fe3+. XRD patterns of RIFP-FeONPs depicted the intense diffraction peak of face-centered cubic (fcc) iron at a 2θ value of 45.33° from the (311) lattice plane indisputably revealed that the particles are constituted of pure iron. The fabricated nanomaterials are spherical and polydisperse with a diameter of 70-120 nm, and various agglomeration clusters are attributable to intermolecular interaction. Zeta potential measurement and particle size distribution of RIFP-FeONPs showed a mean average size of 115.5 ± 29 nm and a polydispersity index (PDI) of 0.420. The study aims to analyse the appropriateness of RIFP-FeONPs for removing hexavalent chromium from the aqueous environment and the application of adsorption isotherm and statistical models in the experiment. The sorption of Cr (VI) on RIFP-FeONPs was observed to fit well with the isothermal models (R2 = 0.98). The linear correlation between processing parameters and time demonstrated that the adsorption efficiency of Cr (VI) well correlated with the pseudo-first order kinetic model and isothermal adsorption with the Langmuir and Freundlich isothermal models, so that the RIFP-FeONPs could be a prospective nanosorbent for hexavalent chromium removal from industrial waste.

(6'R*,7'R*)-7'-(1,3,-Diphenyl-1H-pyrazol-4-yl)-1,2,5',6',7',7a',3'',4''-octa-hydro-1'H,2''H-dispiro-[acenaphthyl-ene-1,5'-pyrrolo-[1,2-c][1,3]thia-zole-6',3''-[1]benzopyran]-2,4''-dione.

In the title compound, C40H29N3O3S, the pyran ring adopts a sofa conformation, the thia-zolidine ring adopts a twisted conformation and the pyrrolidine ring adopts an envelope conformation with the N atom as the flap. The pyrazole ring is essentially planar [maximum deviation = 0.002 (2) Å] and forms dihedral angles of 4.8 (1) and 39.0 (1)°, respectively, with the benzene rings attached to the N and C atoms. The acenapthylene ring system is approximately planar [maximum deviation = 0.058 (2) Å] and forms dihedral angles of 85.9 (1) and 48.5 (1)°, respectively, with the pyrollothia-zole and chromene ring systems. The mol-ecular conformation is stabilized by three weak intra-molecular C-H⋯O hydrogen bonds, which generate one S(8) and two S(6) ring motifs. In the crystal, pairs of C-H⋯O hydrogen bonds link centrosymmetrically related mol-ecules into dimers, generating R 2 (2)(14) ring motifs. The crystal packing also features pairs of C-H⋯π inter-actions, which link the dimers into a supra-molecular chain along the b axis.