Institute of Fundamental Technological Research

We present a facile and green approach to produce crystalline TiO2 nanoparticles on a surface of different carbonaceous materials derived from lignocellulosic biomass such as STARBON-800® obtained by carbonization at 800 °C and biochar-SWP700 (Soft Wood Pellets (SWP) obtained by pyrolysis at 700 °C) via novel low-temperature ultrasound-promoted green methodology coupled with citric acid as a cross-linking agent. In comparison to other methods, the developed method has several significant benefits such as simplicity, great ability to get crystalline TiO2 particles (elimination of high-temperature treatment (material calcination at >300 °C) needed in the conventional sol-gel method, which is extremely important in transforming amorphous TiO2 into a photoactive crystalline phase) elimination of risky chemicals and oxidizing agent, and also ability to change some parameters (e. g. ultrasound intensity). Prepared materials were characterized by XRD, DR UV−vis, N2 physisorption, HR-XPS, XRF, HR-TEM, FT-IR and subsequently tested for their photocatalytic activities both in photocatalytic phenol degradation (in water) and oxidation of methanol (in air) under UV and visible light irradiation.

A series of new inorganic-organic hybrid materials based on TiO2 and new biochar-based supports (biochar obtained by pyrolysis of Miscanthus Straw Pellets (MSP) and Soft Wood Pellets (SWP) at 550 and 700 oC) were successfully prepared using ultrasound-assisted
methodology. The resulting composites were characterized by a wide range physicochemical techniques and investigated in water and gas phase photocatalytic test reaction. Our best composite (TiO2/SWP700) achieved phenol degradation of 64.1% (under UV light) and 33.6% (under visible light). In addition, it also showed an extraordinarily high activity (~90%) in selective oxidation of methanol to methyl formate in flow gas phase, high selectivity to
methyl formate (~80 %) and high yield of methyl formate (~88 %) after 240 minutes of illumination. It can be noticed that when TiO2 is supported on biochar, presented a superior photocatalytic ability and could be recycled at least 5 times in both photocatalytic runs tests with reproducible high photocatalytic efficiency.

Biochar,TiO2,Synthesis of composite photocatalysts,Sonication for composite preparation,Phenol degradation,Methanol oxidation