One-stage preparation of palm petiole-derived biochar: Characterization and application for adsorption of crystal violet dye in water

Abstract

Abstract This work aimed to develop the biochar (DPP-biochar) material through a direct pyrolysis of date palm petioles (DPP) at 700 °C and explore its feasibility for the removal of crystal violet (CV) dye from aqueous solution. The textural property, surface functional group, and surface chemistry of the biochar were analysed by the (Brunauer–Emmett–Teller BET) analyser, Fourier-transform infrared spectroscopy technique and X-ray photoelectron spectroscopy (XPS), and pH PZC , respectively. Results demonstrated that DPP-biochar was a highly carbonaceous porous material with high carbon content (86.61%) and large specific surface area (640 m2/g). The pH PZC of the biochar was 6.55. The amount of CV dye adsorbed onto the biochar ( q e ; mg/g) increased (by around 46%; from 18.8 mg/g to 27.4 mg/g) within an increase in solution pH solution (2.0–12), with average value q e being 24.36 mg/g ± 2.88. The CV adsorption capacity of DPP-biochar was less dependent on ionic strength from 0 M to 1.0 M. The adsorption process occurred very rapidly and reached an equilibrium after around 15 min of contact. The maximum adsorption capacity of DPP-biochar that was calculated from the Langmuir model was 209 mg/L at 30 °C and pH 7.0. The adsorption process occurred spontaneously ( Δ G ∘ = −22.8, −24.4, and −25.4 kJ/mol) at different solution temperatures (293 K, 303 K, and 313 K, respectively) and was endothermic ( Δ H ∘ = + 14 . 8 kJ/mol) in nature. It can be concluded that the application of developed biochar for removing CV dye from wastewater streams is highly feasible.