Light-assisted adsorption of methylene blue dye onto Luffa cylindrica

This paper reports an investigation into the adsorption of methylene blue (MB – as representative of a group of potentially polluting chemicals) by modified Luffa cylindrica (LC). A simple and efficient preparation was employed to treat LC which then successfully and rapidly adsorbed methylene blue in the presence of light. The combination of photodegradation and adsorption of MB occurred simultaneously. The effects of contact time, solution pH, temperature, and initial adsorbate concentration are described. The LC was characterized by Brunauer–Emmett–Teller, Fourier transform infra-red, and scanning electron microscopy with energy-dispersive X-ray analyses. The treated LC adsorbed methylene blue dye from aqueous solution within 5 min at an optimum pH of 7. The experimental data best fitted the Freundlich model, with R2 = 0.998 and a maximum adsorption capacity of 98.5% at pH 7. There is a difference in adsorption capacity in dark and light conditions. The kinetic data was represented by the pseudo-second-order (PSO) model. This study shows the potential of chemically modified LC to treat wastewater contaminated by methylene blue dye and similar chemicals.