Separation of furans and carboxylic acids from sugars in dilute acid rice straw hydrolyzates by nanofiltration.

This work studied the concentration of hydrolyzates obtained from dilute acid hydrolysis of rice straw using nanofiltration (NF). In order to minimize the Donnan exclusion effect of the membrane, the hydrolyzate solution was controlled at low pH value. Negative retentions of both furans and carboxylic acids were observed. The maximum separation factor of acetic acid over xylose was 49, while the maximum separation factor of acetic acid over arabinose was 52, when the system was operated at pH 2.9 and an applied pressure of 24.5-34.3 bar. The separation factors of inhibitors over glucose became infinity due to the complete retention of glucose. The separation performance decreased when the operating temperature was increased from 25 to 40 degrees C. The flux deterioration was recovered by flushing with 0.01 N of NaOH and water.

Synthesis and characterizations of nanometric-sized TiO2 powders as a photocatalyst for water splitting.

Nanometric-sized titanium oxide (TiO2) powders were synthesized through two emulsions method. In which two solutions of reverse emulsion, one containing Ti4+ chelated with citric acid/cellulose aqueous droplets and the other aqueous ammonia droplets, with the same water/oil (w/o) ratio are mixed together to form a slurry of titanium citrate precursor. Then the precursors were recovered and calcined to form TiO2 at various temperatures. The powders prepared from volume ratio of w/o at 1/100 had a relatively uniform and spherical with less aggregation. When the volume ratio of w/o was increased, the particle size had more aggregation and bigger. The particle sizes of powders obtained from volume ratio of 1/100 were estimated to be 6-8 nm. Finally, photocatalytic experiments for water splitting and producing hydrogen was examined in methanol solution by utilizing 65 mg nanometric-sized Pt (0.6 wt%)/TiO2 powder, and about 70 micromol hydrogen was produced in 6 h.