Commercial Animal Feeds as Novel Biomass Adsorbents for Methylene Blue Removal from Water: Adsorption Performance and Mechanism

Wastewater from textile industries that contain methylene blue poses a serious environmental problem due to its stability and toxicity. In the current study, calf starter feed (CSF), goat feed (GF), and lamb grower feed (LGF) were investigated as potential adsorbents for methylene blue removal from aqueous solutions. For structure and surface analyses of the adsorbents, EDX analysis was performed with FTIR and SEM, respectively. Parameters such as pH, adsorbent dosage, dye concentration, and time were varied, and optimum pH values of 6.0 and 7.0 were obtained for CSF and both GF and LGF, respectively. It was noted that adsorption increased with adsorbent concentration; conversely, it decreased with an increase in initial dye concentration. Among all the isotherms examined, the Langmuir isotherm yielded the best correlation, with R2 > 0.98. The maximum adsorption capacity was found to be 12.4, 11.5, and 11.01 mg g−1 for CSF, GF, and LGF, respectively. Kinetic analysis showed that the pseudo-second-order model provided the best fit to the experimental data, suggesting that adsorption may involve surface interaction processes. The findings demonstrate that commercial animal feeds can serve as alternative adsorbents for methylene blue removal and provide the first evidence of their potential application in wastewater treatment.