Synthesis of Magnetic Biosorbent from Bamboo Powders and Their Application for Methylene Blue Removal from Aqueous Solution: Kinetics, Isotherm, and Regeneration Studies.

Abstract

Bamboo is known as the "world's second largest forest". The bamboo industry has become a globally recognized green industry, and the research and development of bamboo-based products have huge economic, ecological, and cultural values. In this study, a biosorbent with magnetically sensitive properties was developed based on natural bamboo powders (BPs) for the removal of methylene blue (MB) dye from aqueous solution. The selected BPs with 60 mesh were magnetized by loading Fe₃O₄ using an in situ co-precipitation process. The adsorption-desorption equilibrium was nearly established after 30 min, achieving a removal efficiency of 97.7% for 5.0 g/L BPs/Fe₃O₄ in a 20 mg/L MB solution. The removal efficiency of MB by 5.0 g/L BPs/Fe₃O₄ exhibited a remarkable enhancement, escalating from 33.9% at pH = 5 to an impressive 93.9% at pH = 11 in a 50 mg/L MB solution. The linear fitting method demonstrated greater suitability for characterizing the adsorption process compared to the nonlinear fitting method, which encompassed both adsorption isotherms and kinetics studies. Among these approaches, the adsorption isotherms were well-fitted to the Langmuir model, while the kinetics were accurately represented by the pseudo-second-order model. The removal efficiency by the recycled BPs/Fe₃O₄ adsorbent remained at 97.3% over five consecutive cycles, proving that BPs/Fe₃O₄ has a high potential for being used as a highly efficient biosorbent. Moreover, the BPs/Fe₃O₄ biosorbent had superparamagnetism with strong magnetic sensitivity, which could facilitate the sustainable removal of hazardous dye from the aqueous solution in practical applications.