Abstract:
Synthetic dyes have provided many advantages, one of which is that they have good
compared to natural dyes. As for the negative impacts given by synthetic dyes is the threat
of cancer and being non degradable, thus endangering envirotment. One of the synthetic
dyes that is often used is methylene blue. Methylene blue has a thiazine group and can be
classified as a toxic compound. The photocatalyst method has been considered as an
effective method for degrade organic compounds. Therefore this study aims to make a
composite material namely MnO2/fly ash to degrade methylene blue. The synthesis of the
MnO2/fly ash composite was made by directly reactiong KMnO4 with citric acid and
adding HCl activated fly ash through the precipitation method with a molar ratio of 3 : 1.
The results of XRD characterization showed that MnO2/fly ash composite succeeded in
forming high crystallinity, the crystal size of the MnO2/fly ash composite was 4.23 nm
and resulted in a cryptomelane type of structure. The photocatalyst application was
carried out using pH 11 for 120 minutes by irradiating with a UV A lamp and measuring
the absorbance using a visible spectofotometer. The result showed that the % degradation
at pH 11 was around 52.97% for 120 minutes.
