Search

Herein, we report the existence of a novel semiconductor–metal–semiconductor type transition in Fe3O4 nanoparticles by employing impedance spectroscopy techniques.

1,5 Diphenylcarbazide (DPC) functionalized sol–gel silicas (DPCSG) were prepared and investigated for the solid phase extraction of Hg(II) from aqueous solution by a batch equilibrium technique. The metal sorption properties of DPCSG were examined to evaluate their performance toward metal extraction under different controlling factors, such as pH of solutions, equilibration shaking times, effect of foreign ions and complexing agents. The equilibration was fast and was achieved within 30 min. Maximum extraction capacity of Hg(II) ions onto the DPCSG from non-competitive solutions was 5.6 mg/g (0.028 mmol/g) at 28 ± 2 °C and the enhancement factor was found to be 560 at optimized pH 6 when compared with control and commercial silica gel. The adsorption data obtained as a function of mercury concentration were fitted to a Langmuir adsorption model. The stripping and regeneration of the sorbent were reported and it was further observed that extraction and regeneration were indicated by the dark violet colouration and decoloration of the extractant, respectively. It is concluded from the extraction data that DPCSG is a promising material for the extraction of mercury.

1-(2-Pyridylazo)-2-Naphthol (PAN) doped sol-gel silica has been investigated for removal of metal ions from aqueous media. In the doped sol-gel silica, the large reagent molecules are entrapped inside the pores while small metal ions can diffuse into the pores where they are complexed by the reagent and retained inside the pores. This new solid sorbent was applied for removal of Cd(II) from aqueous solutions. The kinetics, adsorption isotherm, equilibration time and pH effect on the removal were studied to optimize the conditions to be utilized on a large scale. It was observed that a sol gel loaded with 0.09 mmol PAN/g, had a capacity of 0.044 mmol Cd/g. The desorption of metal ions was carried by 1 M HCl and the sol-gel silica sorbent could be regenerated and reused repeatedly.

1-Naphthylthiocarbamide (ANTU) doped xerogel was prepared and investigated for removal of mercury ions from aqueous media. Physicochemical parameters such as effect of pH, equilibration time, and adsorption isotherm on the removal of mercury were evaluated to optimize the conditions to utilize the data on a large scale. It was observed that uptake and retention of mercury ions inside the pores take place by the formation of a complex with the entrapped reagent molecules. The data show that a xerogel doped with 0.2 mmol ANTU/g of sorbent can remove 0.096 mmol Hg. The probable composition of the mercury complex has been deduced and a removal mechanism is suggested. The regeneration and reuse of doped gel for the removal of targeted metal has been discussed.

The title compound, C21H24N2O2, is a phenyl hydrazine derivative of the well known anthelminthic agent α-santonin, which is composed of three fused rings (benzodieneone, cyclohexane and γ-lactone). The cyclohexadienone ring adopts a boat conformation, the cyclohexane ring is in a chair conformation and the trans-fused γ-lactone ring adopts a C-envelope conformation. In the crystal, molecules are linked by N—H...O and C—H...O hydrogen bonds, forming chains along the a axis.

A TAR [4-(2-thiazolylazo)resorcinol] doped sol–gel silica sorbent (red colour, porous, stable, hard, non-swelling) was prepared, characterized and investigated for the removal of Co(II) from aqueous solutions. The kinetics, adsorption isotherm, equilibration time and effect of pH on such removal were studied to optimize the conditions necessary for large-scale application. Rapid equilibration was observed with adsorption equilibria being attained within 10 min. The adsorption of cobalt ions onto the plain (undoped) sol–gel silica was negligible. The maximum adsorption of Co(II) ions onto the TAR-doped sol–gel silica from single solutions was 12.6 mmol/g. The TAR-doped sol–gel silica could be regenerated by washing with a 0.1 M HCl solution to give a maximum regeneration value as high as 98.5%. The TAR-doped sol–gel silica could be used for more than three consecutive adsorption/desorption cycles without experiencing any considerable loss of adsorption capacity. The adsorption process and the nature of the Co–TAR complex were discussed.

The title compound, C21H23NO3, is a phenylimine derivative of the well known anthelmintic agent α-santonin. The trans-fused cyclohexane and γ-lactone rings of the α-santonin ring system adopt chair and envelope conformations, respectively, whereas the hexadiene ring is approximately planar [maximum deviation = 0.029 (4) Å] and forms a dihedral angle of 62.30 (11)° with the benzene ring. An intramolecular O—H...N hydrogen bond is observed.