Decolorization of wastewater by photocatalysis using cornstalk biochar embedded titanium dioxide

Dye-containing wastewater has caused environmental issues due to its toxicity, ability to block sunlight,
and potential carcinogenicity. In this study, TiO2 photocatalyst was synthesized by hydrolysis technique,
while biochar was prepared from corn stalks using a pyrolysis process. To create a composite
biochar/photocatalyst with a better pollutant removal efficiency, biochar and TiO2 were mixed during the
photocatalyst preparation process. According to the BET study, biochar (CB500) has a surface area and
porosity of 13.73 m2/g and 0.042 cm3/g, respectively. The XRD scan shows that the synthesized TiO2 had
anatase as the major crystalline, which had a greater anatase phase than the commercial TiO2 (P25).
Commercial P25 only had 70% anatase compared to synthetic TiO2, which was 87.4%. Due to the direct
transitions of photogenerated electrons, the indirect band gap anatase has a longer lifetime of photoexcited
electrons and holes than the direct band gap rutile and brookite. The biochar and photocatalyst samples were tested for their removal efficiency by adsorption and photocatalysis of methylene blue (MB). The best
adsorption efficiency is obtained from the composite material of biochar and TiO2 (CB-TiO2), which can
remove MB within 5 minutes 􀂲 synthesized TiO2 shows promising results, with a decolorization efficiency
of 30%. Commercial P25, on the other hand, lacks the capacity to efficiently remove trace quantities of
methylene blue in water without UV-A. Under UV-A, the CB500 and CB-TiO2 catalysts could degrade
methylene effectively. Methylene blue was removed almost completely in the first five minutes of the
photocatalysis reaction, faster than P25. The synergetic effect of biochar and TiO2 indicated considerably
increased methylene blue removal.