One of the concerns in wastewater pollution is the presence of colored
compounds, such as dyes. Acid violet 7 (AV7) and brilliant green (BG) are examples
of synthetic dyes that have been used in various applications. In this work, a
comparison of AV7 and BG dye adsorption was investigated using an adsorbent
prepared from the mixture of rice husk ash (RHA) and coal fly ash (CFA). The
attention was focused on the major batch adsorption parameters, which include
adsorbent dosage, initial dye concentration, contact time, pH, shaking speed, and
temperature. A lesser amount of RHA-CFA adsorbent was found to be used for
adsorbing the same concentration of BG as compared to AV7. In contrast to AV7, the
adsorption of BG rapidly attained equilibrium. The effective pH for BG removal is in
the pH range of 6–8, while the highest AV7 removal was obtained at a low pH value.
The adsorption removal for AV7 and BG increases with rising shaking speed and
temperature. Scanning electron morphology (SEM) analysis showed the morphological
porous structure on the RHA–CFA adsorbent surface. X-ray diffraction (XRD) analysis
indicated the presence of complex compounds containing cristobalite, quartz, and
mullite compounds in the RHA–CFA adsorbent. The study revealed that RHA–CFA
adsorbents can remove AV7 and BG from an aqueous medium.
Keywords: Acid violet 7 (AV7) dye, Adsorbent, Brilliant green dye, Coal fly ash, Rice husk ash.
