Elephant Apple Leaf-Derived Adsorbent for Efficient Methylene Blue Removal: A Combined Batch and Fixed-Bed Column Approach

In the present study, Elephant Apple leaf powder (EALP) was investigated for its adsorptive potential for the removal of methylene blue (MB) from aqueous solutions. The treated EALP were prepared by simply boiling the EALP in distilled water and characterized by FTIR, SEM and BET analyses which revealed the presence of abundant functional groups responsible for adsorption and mesoporous surface structure suitable for adsorption. Batch adsorption experiments were carried out to study the effect of solution pH, adsorbent dosage, contact time, initial dye concentration and temperature. The maximum adsorption capacity of treated EALP under optimized conditions was 751.9 mg/g, which was much higher than that of untreated EALP as well as many agricultural biomass reported in the literature. The high adsorption capacity observed for treated EALP may be associated with improvements in surface characteristics following treatment, including increased surface area, enhanced pore accessibility, and increased heterogeneity of active sites that favor interactions between the adsorbent and methylene blue molecules. Equilibrium data fitted well to the Langmuir isotherm model and kinetic data fitted well to the pseudo-second-order model. Further evaluation of Temkin isotherm indicated that interaction between adsorbate and adsorbent was significant during adsorption process. Thermodynamic parameters showed that the adsorption of MB was spontaneous and endothermic in the temperature range studied. Fixed-bed column studies were performed to evaluate the practical applicability and maximum removal efficiency of 91.3% and the bed adsorption capacity of 247.3 mg/g were obtained under the experimental operating conditions. Compared with many reported biomass-derived adsorbents, EALP has the advantages of low cost, simple preparation and effective dye removal performance. The present findings indicate the potential use of biosorbents derived from Elephant Apple leaves as sustainable materials in wastewater treatment applications.