Study of methylene blue dye removal using biochar derived from leaf and stem of Lantana camara L.

The discharge of dye containing effluents into the water bodies has raised concern due to potential hazards related to their toxicity in the environment. The removal of dye from the aqueous solution can be efficiently performed using different kinds of adsorbents. The main objective of the current study is to determine the potential of biochar (BC) prepared from Lantana camara L. at 600 ℃ for the removal of methylene blue (MB) dye from aqueous solution as a function of contact time, pH (3–12), adsorbent dose (100–400 mg L⁻¹), and the initial dye concentration (5–20 mg L⁻¹). The BC prepared using leaf ( \({\text{BC}}_{\text{L}}600\) ${\text{BC}}_{\text{L}}600$ ) and stem ( \({\text{BC}}_{\text{S}}{60}0\) ${\text{BC}}_{\text{S}}600$ ) of Lantana was characterized for elemental analysis, infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and zeta potential analysis. The results indicated that the pH of dye solution had highly influenced their absorption over the BC surfaces. The pseudo-second-order kinetics was able to explain the interaction of MB dye with both \({\text{BC}}_{\text{L}}600\) ${\text{BC}}_{\text{L}}600$ and \({\text{BC}}_{\text{S}}600\) ${\text{BC}}_{\text{S}}600$ , implying the multi-step characteristics of the adsorption process. It was also postulated through the thermodynamic analysis that the adsorption process was spontaneous and exothermic in nature. It implies that the adsorption mechanism was related to electrostatic, hydrogen bond, n-π, and π-π interactions, i.e., Lantana BC may be an effective bio-sorbent for the treatment of contaminated wastewater from the dye industries.