Punica granatum husk (PGH), a powdered biowaste material for the adsorption of methylene blue dye from aqueous solution

Abstract

In this study, Punica granatum husk (PGH), an agricultural powdered biowaste, was used as adsorbent for the removal of methylene blue (MB) dye from aqueous solutions. The effects of initial pH of solution, adsorbent dosage, contact time, and initial dye concentration on the MB adsorption were evaluated in batch adsorption mode at 298 K. Kinetic data were evaluated by pseudo-first-order, pseudo-second-order, and Elovich models. The equilibrium adsorption was evaluated by Langmuir, Freundlich, and Sips isotherm models. The applicability of PGH was also evaluated for simulated effluents. The results revealed that pseudo-second-order model agreed well with the experimental kinetic data. The adsorption of MB onto PGH was better fitted using Sips isotherm. The maximum adsorption capacity obtained by Sips model was 68.40 mg g⁻¹. Regeneration of PGH adsorbent was possible using 1.0 mol L⁻¹ of HCl as eluent. PGH adsorbent is adequate for removal of MB from simulated textile and river effluents. The results obtained in this work show that PGH can be used as alternative adsorbent for MB removal from effluents.

Keywords:

• Punica granatum husk
• Methylene blue
• Textile effluents
• Batch adsorption

Acknowledgments

The authors are grateful to Reitoria de Pesquisa da Universidade Federal do Pampa, to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), to Ministério de Ciência e Tecnologia (MCT) for financial support and fellowships.