Chiral synthons from campholenaldehyde: enantiospecific synthesis of diquinane and linear triquinanes

Enantiospecific syntheses of diquinane and linear triquinanes were accomplished, starting from the readily available α-campholenaldehyde employing a Nazarov reaction as the key step.     

Ultrasound assisted synthesis of polyacrylic acid–nanoclay nanocomposite and its application in sonosorption studies of malachite green dye

Synthesis of nanoclay nanocomposite has been undertaken by using polyacryalic acid (PAA) in aqueous medium and ultrasound environment and its application in dye removal has been investigated. The synthesized product was characterized by using FTIR and XRD techniques. The sonosorption capacity of the product namely PAA–nanoclay composite was determined by choosing malachite green (MG) dye as a model pollutant. The effects of various parameters such as nanocomposite loading, pH, various process conditions etc. have been studied. On comparing the results obtained with that of nanoclay as an adsorbent, it was found for an initial concentration of 500 mg/l, the PAA–nanoclay nanocomposite exhibited higher percentage of pollutant removal (68%) and for nanoclay it was 54%. The adsorption data has been correlated using Langmuir and Freundlich models. The fit of the Freundlich isotherm model was found to be good in the entire range of concentration for the experimental sorption data obtained on the nanoclay nanocomposite. A plausible reaction mechanism for use of PAA–nanoclay nanocomposite as an adsorbent is also proposed.     

反射相移对Faraday电流传感器灵敏度及稳定性影响的理论分析

光学法拉第电流传感器内的反射相移能降低传感器的灵敏度与稳定性。本文对此效应给予了定量的理论分析。     

Combined effect of ultrasound and nanoclay on adsorption of phenol

Sorption of phenol onto organophilic bentonite (nanoclay) by ultrasonic irradiation was investigated. Tetrabutyl ammonium chloride (TBAC), N-acetyl-N,N,N trimethyl ammonium bromide (CTAB) and hexadecyl trimethyl ammonium chloride (HDTMA) were used as intercalating agents. Nanoclay was synthesized using sonication technique. TBAC modified nanoclay shows amorphous exfoliated nature, while CTAB and HDTMA modified nanoclay shows intercalating crystalline nature, which was revealed by XRD gram. Further FTIR reveals the presence of NH(2) and (CH(2))(n) groups onto clay platelet. Due to sonication, adsorption equilibrium was achieved within short period of time (10 min). It was found that intraparticle diffusion resistance has overcome due to sonication. The experimental data obtained obeys both Freundlich isotherm model and Langmuir adsorption isotherm model. HDTMA modified nanoclay shows higher parameter values.