Photocatalytic degradation of methyl orange behavior comparison of titanium species: alkaline biochar and acidic biochar composites

The biochar was produced from wood waste via pyrolysis. The biochar with pH 9.7 was comprised of titanium species named Ti-WB9. After acidification, the acidic biochar with pH 3.66 was also comprised of titanium species named Ti-WB3. Using XRD, the particle sizes of anatase TiO 2 were 7 and 8 nm in Ti-WB9 and Ti-WB3, respectively; these were then synthesized via the solvothermal method at low temperature. The degradation efficiencies of methyl orange were 93.5 and 95.1% in 120 min with Ti-WB9 and Ti-WB3, respectively. During degradation, the by-products were barely observed in the solution when Ti-WB3 was used as a photocatalyst under UV light. However, the by-products exited in another solution that used Ti-WB9 as a photocatalyst for degradation according to the results of UV-Vis and FTIR. Via XPS, the formation of C-Ti in Ti-WB3 played an important role in the enhanced and complete degradation of methyl orange without by-products.