524
P. S. Das et al.
Fig. 11 UV-Vis absorption spectra of MB solution a Control solution, b after exposure to direct
sunlight for different times in presence of the DMHNPLA samples, c exploded view of the region
660–670 nm from Fig. 11b. (Reprinted with permission from Das et al. (2018))
the dye adsorbed on the surface. Further, the surface also has higher redox potential
for both electrons as well as hole. When incident sunlight provides energy >E g , the
electrons are excited. These photo-excited electrons can and do jump into conduction
band. As the photo-excited electrons move over to the conduction band, the corresponding positively charged holes remain in the DMHNPLA sample surface (Xu
et al. 2014). It is most likely that the free hydroxyl radical generated by these holes,
degrade the cationic MB dye (Das et al. 2018). The contact with water has no effect
on crystal facets of brucite Mg(OH) 2 (Ou et al. 2014). Therefore, through direct
sunlight-induced photocatalytic activity the phase pure DMHNPLA samples can be
used to degrade MB dye in industrial wastewater. Thus, for futuristic applications
in treatment of industrial wastewater both MHNPL and DMHNPLA samples exhibit
good promise.