Enhancement of Adsorption-Photocatalysis of Malachite Green Using Oil Palm Biomass-Derived Activated Carbon/ Titanium Dioxide Composite

Background:
Nowadays, effective wastewater treatment has become a hot research topic in the field of environment. A series of novel activated carbon/ titanium dioxide (AC/TiO2) composites at various weight ratio were synthesised using the sol-gel method and were characterised using XRD, SEM-EDX, FT-IR, TGA and surface area analysis.


Method:
TiO2 particles were successfully incorporated on the AC surface and were mainly composed of Ti, O and C atoms. The AC/TiO2 composites were made up of spherical TiO2 particles agglomerated
on the smooth tubular and porous structure of AC. The photocatalytic efficiency was influenced by the weight proportion of AC:TiO2 and the degradation process was attributed to the adsorption and photocatalytic processes.


Results:
It was found that 2.5 g/L AC/TiO2 at a weight ratio of 3:1 on an initial Malachite Green concentration of 10 mg/L at 50°C led to a degradation efficiency of 96.3% in 7.5 minutes under a halogen lamp. A chemical oxygen demand (COD) removal of 96.7% was also recorded. Reusability of the AC/TiO2 composite and kinetic study of the photodegradation of Malachite Green were also investigated. The recycled AC/TiO2 composite achieved high catalytic performance (83.1%) after one catalytic cycle.


Conclusion:
The degradation kinetics of Malachite Green at various solution temperatures were fitted to the pseudo-first-order reactions and the activation energy for the degradation of Malachite Green was 21.48 kJ/mol. This work demonstrated that AC/TiO2 composite is a promising material for photocatalytic degradation of organic dyes.