METHYLENE BLUE SORPTION CAPACITY OF SOME COMMON WASTE PLANT MATERIALS

Abstract

Honey tree and peepul leaves showed tremendous potential in sorbing methylene blue (MB) from aqueous solution, with q_max values of 417 and 402 mg g⁻¹, respectively. But other tested biomass had considerably lower q_max (mg g⁻¹): mango leaves (301), guava leaves (295), black gram husk (278), coir fibers (273), neem leaves (265), Indian elm leaves (264), Indian rosewood leaves (253), bermuda grass clippings (247), banyan leaves (239), groundnut husk (206), citrus leaves (204), tea leaves (203), banana peels (184), wheat straw (171), sugarcane baggasse (154), rice husk (126), teak leaves (120), and teak sawdust (96). MB sorption by honey tree leaves attained equilibrium within 20–30 min, but a slightly slower attainment of equilibrium of MB sorption was noticed in the case of peepul leaves. Both the pseudo-first-order and the pseudo-second-order rate equations suitably fitted to the time course data of MB sorption by honey tree and peepul leaves. However, the latter fitted better because its estimated values of equilibrium MB sorption (q_E) were closer to the experimental values. MB sorption by honey tree and peepul leaves was adversely affected by the presence of divalent cations. Nevertheless, both honey tree and peepul leaves efficiently sorbed MB from solution in the presence of the monovalent cation Na⁺.

Keywords:

• Biosorption
• Methylene blue
• Sorption capacity
• Sorption isotherm
• Waste plant material

Acknowledgments

We thank Coordinators of Center of Advanced Study in Botany and Environmental Sciences and Head, Department of Botany, Banaras Hindu University, for facilities. D. K. thanks the Council of Scientific and Industrial Research, New Delhi, for financial support in the form of a Senior Research Fellowship.

Notes

^a Mean ± SD of three replicates. Data in parentheses show standard error of model parameter estimation. The q _em is the experimental maximum MB sorption.

^a Means ± SD of three replicates. Data in parentheses show the standard error of model parameter estimation. The q _exp and r _sor(i) are the experimental MB sorption at equilibrium and the initial MB sorption rate, respectively.