Development of a Low-Cost Biosorbent from Daphniphyllum glaucescens Seeds for the Sorption of Methylene Blue

Abstract

Recent years have seen increased interest in using natural adsorbents as alternatives to conventional ones, from both economic and environmental viewpoints. This study aims to produce a natural adsorbent from a locally available plant: Daphniphyllum glaucescens seeds (DG), and to assess its potential for removing Methylene Blue (MB) from wastewater. The biosorbent material was prepared by grinding and pyrolysing DG at three different temperatures: 300 °C, 400 °C, and 500 °C. The material was characterised using XRD, EDX, and SEM. Proximate analysis, including ash, moisture, and carbon content, was conducted in accordance with ASTM-recommended protocols. Results showed that the adsorbent material prepared from DG had an optimal pH value of approximately 9.77. The ash content was 28.57%, and the carbon content was 59.67%. Additionally, the effects of process parameters such as contact time, initial concentration, and temperature on MB biosorption were examined. DG-based material achieved an adsorption efficiency of 96.1 mg/g, demonstrating its potential as an effective, sustainable biosorbent at Room temperature. Furthermore, the adsorption equilibrium data were best fitted to the Langmuir isotherm model (R2 = 0.9875), indicating monolayer adsorption of MB onto DG-based activated carbon. The maximum adsorption capacity was 10.5 mg/g with a Langmuir constant of 1.70 L/mg. This work represents the first detailed investigation of DG seeds as a precursor for adsorbent synthesis, highlighting their untapped potential as a low-cost biosorbent, to the best of our knowledge. Owing to its cost-effectiveness, simple synthesis, and sustainable origin, the developed adsorbent shows potential for practical application in wastewater treatment.