Zhiqian Jia

Facile synthesis of tin oxide nanocrystals and their photocatalytic activity

Abstract Tin oxide nanocrystals with diameters smaller than 10 nm were synthesized using Na 2 SnO 3 and CO 2 as reactants and cetyltrimethylammonium bromide (CTAB) as stabilizer under mild conditions. As a mild acidic gas, CO 2 is favorable for the accurate adjustment of pH value of Na 2 SnO 3 solution. Stannate salt is stable, cheap and easy in operation. The effects of Na 2 SnO 3 concentration, CTAB concentration, aging temperature, and aging time on the nanocrystals were studied. It was found that, with the increasing Na 2 SnO 3 concentration, aging temperature and aging time, SnO 2 nanocrystals size decreases. The formation of SnO 2 nanocrystals can be interpreted by electrostatic-interaction mechanism. SnO 2 nanocrystals show high photocatalytic activities in the degradation of Rhodamine B solution. The catalytic activity of small nanocrystals is higher than that of large ones.

Preparation of Calcium Carbonate Nanoparticles with a Continuous Gas-liquid Membrane Contactor: Particles Morphology and Membrane Fouling

Abstract Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH) 2 concentration, CO 2 pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH) 2 concentrations, the average size of the particles increased. The effects of Ca(OH) 2 concentration and CO 2 pressure on particles were not apparent under the experimental conditions. When the Ca(OH) 2 concentration and liquid flow velocity were high, or the CO 2 pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.