Removal of Methylene Blue from Aqueous Solution Using Black Tea Wastes: Used as Efficient Adsorbent

The biosorbent black tea wastes (BTW) after preliminary treatments was used in this study for the removal of methylene blue (M.B) from aqueous solution. The removal of M.B from aqueous solution was studied as a function of time, initial concentration of M.B temperature, pH, and BTW dosage. The optimum time for equilibration was achieved in 3 min. The optimum dosage of adsorbent was found to be 0.4 g. Various kinetic models were applied to the sorption kinetic data in which the obtained data was best explained by the pseudo-second-order model (R-2=0.99) with a rate constant K2 of 0.0714-0.0763 g.mg(-1) min(-1). Additionally, the calculated amount of adsorption was approximately equal to the experimentally determined value. The isotherm data was best fitted to the Langmuir model rather than the Freundlich model. The intraparticle diffusion model exhibited the process to be diffusion dependent. The various organic functional groups on the surface of BTW played a significant role in the sorption of the selected dye. Consequently, BTW has the prospective to act as a potential sorbent for the removal of other contaminants from aquatic media as well.

Automated summary

This study found that the pre-treated black tea wastes (BTW) can effectively remove methylene blue from aqueous solution, with an optimal equilibration time of 3 minutes and an optimal dosage of 0.4 g of adsorbent. The pseudo-second-order kinetics model best explained the experimental data, while the Langmuir model fit the isotherm data better. The various organic functional groups on the surface of BTW played a significant role in the adsorption process, indicating its potential as a sorbent for removing other contaminants from water.