ABSTRACT
The discharge of wastewater containing dyes into aquatic ecosystems constituents a form of aesthetic pollution, which has significant harmful effects. Conventional adsorbents for treating effluents are frequently efficient but costly, prompting the need for developing effective, economical, and locally sourced adsorbents. A mixed adsorbent prepared from clay and orange peel char has been evaluated to remove methylene blue dye from a simulated wastewater. Clay was collected, screened for impurities, oven dried and pulverized, while Orange Peel were collected, washed with water, dried, then carbonized. A mixture was synthesized from the clay and orange peel char in a 4:1 mass ratio. The adsorption study was carried out under batch mode. The mixture adsorbent was used to treat the synthetic wastewater by varying concentration (50- 250 mg/L) and contact time (10-180 min). The surface morphology of the adsorbent revealed a heterogeneous, porous structure with rough, uneven surface and dispersion. The BET and BJH surface areas, pore volume and pore size were found to be 189.2 m2 /g, 200.8 m2 /g, 0.09721 cc/g, 2.207 nm respectively. The experimental data was fitted using pseudo first order, pseudo second-order, elovich kinetic model and intra-particle diffusion model. The pseudo second-order kinetic model having the highest coefficient of determination value (R2 > 0.99) among the tested kinetic model for all concentrations studied, suggested the PSO model as the best fit model, implying chemisorption as the rate-limiting mechanism. Intra-particle diffusion modelling implied the coexistence of multiple sorption mechanisms, underscoring the complexity of the adsorption process.
