Synthesis and characterization of methyl pyrazolone functionalized magnetic chitosan composite for visible light photocatalytic degradation of methylene blue.

TiO2/Fe3O4, TiO2/Fe3O4/chitosan and Methylpyrazolone functionalized TiO2/Fe3O4/chitosan (MPyTMChi) were successfully prepared. The chemical structure of the prepared materials was confirmed by FT-IR spectra, XRD, SEM and TEM. BET surface area increased from 2.4 to 3.1m2/g, Eg decreased from 2.58 to 2.25eV and more quenching of PL emission spectra was observed upon functionalization of TMChi by MPy. Moreover, high Ti and oxygen percentages were detected by EDX. Magnetization value (Ms) reached 21 emu.g-1 for MPyTMChi. MPyTMChi showed enhanced photocatalytic degradation rate of methylene blue (MB) dye under visibe light irradiation (99.8% after 40min) as compared with that for TiO2/Fe3O4 (96.7% after 100min) and TMChi (98.9% after 60min), respectively. It was regarded that the photocatalytic degradation of MB dye on MPyTMChi follows apparent pseudo-first-order according to the Langmuir-Hinshelwood (L-H) model and kapp value was 0.089min-1. Active species trapping experiment revealed that h+ and O2- played the main role in the photodegradation of MB dye while OH quenching did not greatly affect photodegradation rate. Additionally, MPyTMChi can be efficiently reused for six repetitive cycles. MPyTMChi showed higher antimicrobial activity against gram-positive, gram- negative bacterial and fungal strains while large inhibition zone was observed for gram-positive bacteria.

Abdelwahab NA ，Morsy EMH 《-》

Facile synthesis of chitosan-La(3+)-graphite composite and its influence in photocatalytic degradation of methylene blue.

Integrated photocatalytic composite adsorbents (IPCA) are used to degrade toxic organic and inorganic compounds in presence of UV/visible light irradiation. The compound preserves all the existing features of individual components and at the same time overcome drawbacks like rapid recombination of photogenerated electrons, low absorptivity and hindrance effect of the photocatalyst. Herein, an integrated Photocatalytic Chitosan-La3+-Graphite composite adsorbent was synthesized and the resultant composites were characterized by FTIR, XRD, TGA, EDX and SEM analysis. The UV-visible diffusion reflectance spectroscopy (UV-vis DRS) was used for the band gap measurement and it was found to be 3.2 eV. An aqueous solution of methylene blue (MB) dye (30 mL of 100 mg/L) was used to study the photocatalytic efficiency of the prepared IPCA. The Chitosan-La3+-Graphite Composite (CS-La-GR) (100 mg of dosage) exhibits enhanced photocatalytic degradation efficiency (93.5% in 40 min) for Methylene blue under UV light irradiation. The highest photodegradation was due to the stronger adsorption of MB dye on the surface of highly porous IPCA. Moreover, the reactive species, ·OH radical and O2·- radical ions play a major role in the photocatalytic degradation of Methylene blue over composite photocatalyst.

Sirajudheen P ，Meenakshi S 《-》

Visible light photo catalytic inactivation of bacteria and photo degradation of methylene blue with Ag/TiO2 nanocomposite prepared by a novel method.

Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite. To confirm the formation, crystal structure, particle size and shape of green synthesized nanoparticles and nanocomposite, they were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The AgNPs, TiO2 and Ag/TiO2 were evaluated for photo degradation of methylene blue (MB) and photo inhibition of Bacteria. The bio-synthesized Ag/TiO2 nanocomposite was observed to have strong catalytic activities for photo reduction of MB and photo inactivation of bacteria as compared to bare AgNPs and TiO2. In the presence of Ag/TiO2, 90% of MB was degraded only in 40min of irradiation. Alternatively the bare AgNPs and TiO2 degraded less than 30% and 80% respectively of MB even in more than 100min of irradiation. Similarly the Ag/TiO2 has very strong photo inhibition efficiency towards Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition of irradiated Ag/TiO2 nanocomposites against E. coli and P. aeruginosa was 19mm and 17mm respectively which was two times higher than in dark. These promising photocatalytic activities of nanocomposite may be due to the highly decorated AgNPs over the surface of TiO2.

Tahir K ，Ahmad A ，Li B ，Nazir S ，Khan AU ，Nasir T ，Khan ZUH ，Naz R ，Raza M ... -  《-》

Crystallinity and lowering band gap induced visible light photocatalytic activity of TiO(2)/CS (Chitosan) nanocomposites.

The inhibition of electrons-holes recombination and enhancement of visible light photocatalytic activity were accomplished by the synthesized TiO2/CS nanocomposites system. In this present work, the different weight ratio of TiO2 and chitosan (75:25, 50:50 and 25:75) nanocomposites were synthesized via two-step method. After that, the existing functional groups, size and structure of the nanocomposites system were characterized via FT-IR, TEM and XRD measurements. The band gap of the prepared materials and its excitation and emission spectra were elevated through UV-vis and PL analyses. Moreover, the MO and MB degradation capability of the synthesized TiO2/CS nanocomposites was optimized, and the outcomes are described in detail.

Saravanan R ，Aviles J ，Gracia F ，Mosquera E ，Gupta VK ... -  《-》

Highly efficient photocatalytic degradation of methylene blue by PoPD/TiO2 nanocomposite.

Yang C ，Zhang M ，Dong W ，Cui G ，Ren Z ，Wang W ... -  《PLoS One》