Optimization of orange G and indigo carmine dye sequestration by incense stick ash: characterisation, isotherm, and kinetic analysis

The sequestration of orange G (OG) and indigo carmine (IC) dye by utilizing novel incense stick (IS) ash adsorbent was examined in the current study. The dye uptake capacity of the adsorbent was explored through several batch experiments. The efficiency of the adsorbent was studied by different factors viz. adsorbent dose, agitation time, pH, temperature, and dye concentration. The study of the kinetic model described that the pseudo-second-order model was more effective for orange G and indigo carmine dye removal. Adsorption equilibrium was examined by the Langmuir and Freundlich model. The data obtained from the isotherm study for both dyes were well described and fitted to the Langmuir model. The incense stick ash adsorbent material was characterized by SEM, EDAX, BET, and FTIR techniques. The porosity of the adsorbent surface is described by the BET surface area of 6.934 m 2 /g and the micropore surface area of 4.550 m 2 /g. At a dye concentration of 50 mg/L and adsorbent dosage of 200 mg, the maximum dye uptake for orange G and indigo carmine was found 26.10 mg/g and 20.53 mg/g, respectively. For OG dye, the values of the thermodynamic parameters ∆H 0 and ∆S 0 were 40.99 kJ/mol and 0.015 kJ/mol, and for IC dye, 58.81 kJ/mol and 0.191 kJ/mol respectively. Regeneration performance of the used adsorbent was investigated by alkaline treatment. In comparison to the IC dye, the OG dye desorbs at a greater rate of 42.56%. According to this study, using incense stick ash to remove textile dyes would be a cost-effective and environmentally friendly green alternative.