Light-Assisted Synthesis of Silver and Gold Nanoparticles by New Benzophenone Derivatives.

Benzophenone derivatives were evaluated as new photoinitiators in combination with triethylamine (TEA) and iodonium salt (Iod) for very rapid and efficient formation of metal nanoparticles in an organic solvent, by which silver and gold ions were reduced under light at 419 nm (photoreactor) with an irradiation intensity of 250 microwatts/cm2. The new benzophenone derivatives combined with TEA/Iod salt showed good production of metal nanoparticles (Au0 and Ag0) and a small size of nanoparticles of around 4-13 nm. The photochemical mechanisms for the production of initiating radicals were studied using cyclic voltammetry, where a negative ΔG of around -1.96 eV was obtained, which made the process favorable. The obtained results proved the formation of amine and phenyl radicals, which led to the reduction of gold III chloride or silver ions to the gold and silver NPs. The UV-vis spectroscopy technique was used as a very beneficial tool for the surface plasmon resonance band detection of metal nanoparticles. To sum up the results, we have observed that nanoparticles (NPs) were distributed differently in different photoinitiator systems and the particle size also changed by changing the system of initiation. In comparison to the system alone, not only were the nanoparticles smaller but they were also generated within a shorter period of irradiation time for the system BP\Iod\TEA. Finally, the quenching process of benzophenone fluorescence by the gold and silver nanoparticles was investigated.

Production of cellulose from Aegagropila Linnaei macro-algae: Chemical modification, characterization and application for the bio-sorptionof cationic and anionic dyes from water.

Marine algae wereprovedto begoodadsorbentsformany pollutants. In this work, Aegagropila Linnaei (Aegagropila L.) was treated with sodium hydroxideand sodium chlorite. The extracted cellulose content was 18.5%. It was functionalized with Dimethyl diallyl ammonium chloride and diallylamin co-polymer. The products were characterized using Fourier Transform Infra-Red (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and thermogravimetric analyses (TGA). The samples were studied as adsorbents of methylene blue(MB) and acid blue 25(AB25) in a controlled batch system. The effect of salts concentration (KCl, NaCl, and CaCl2), adsorbent dosage, pH, contact time and initial dye concentration on the adsorption mechanism was discussed. At equilibrium, the adsorption of MB and AB25ontoextracted and functionalized cellulose reached 109 mg/g and 139 mg/g, respectively. Under the same conditions, the adsorption capacity of AB25 and MB onto unmodified Aegagropila L. was, only, 32 mg/g and 47 mg/g. The pseudo second-order kinetic equation exhibited the optimal fitting results. The mean free energy (E = 70.71 to 223.6 Kj/mol), calculated from Dubinin-Radushkevich isotherm, suggested a chemi-sorption mechanism. Overall, the results confirmed that the studied products could be considered as valuable bio-sorbents of dyes from contaminated waters.