Synthesis, Characterization and Performance Evaluation of Burmese Grape (Baccaurea ramiflora) Seed Biochar for Sustainable Wastewater Treatment

Biochar prepared from different bio-sources serves as a feasible solution for the decontamination of dye-contaminated wastewater. In this study, biochar was synthesized from a sustainable source, i.e., local fruit waste, Burmese grape seeds (BGSs). The seeds were collected from a local market, washed, pre-teated and finally converted into biochar by pyrolysis in a N2 furnace. The removal efficiency of the synthesized biochar was evaluated towards a cationic industrial azo dye, methylene blue (MB). The phosphoric acid (H3PO4) and potassium hydroxide (KOH) pretreated BGS were pyrolized at 500 °C for 3 h in a N2 furnace at a heating rate of 10 °C/min. The spectroscopic analysis confirmed the presence of multiple surface functional groups, e.g., R-OH, OH, -C=O, -COOH, etc. The surface of the biochar was randomized with porous tunnel-like structures. The specific surface area and pore volume obtained from BET analysis were 19.90 ± 1.20 m2/g and 5.85 cm3/g. The MB concentration (mg/L), contact duration (min) and pH were varied to assess the MB sorption phenomena. The optimum pH was found to be 8. During the first 20 min of contact time, adsorption was rapid and equilibrium was reached after 75 min. The adsorption was best described by pseudo-first-order kinetics with a good fit (R2 = 0.99). The maximum removal percentage was ~85%, and per gram of BGS can adsorb 166.30 mg of MB, which supports the Langmuir adsorption isotherm model. The obtained results were compared with the reported literature, and BGS showed its excellent candidacy to be industrially utilized in the tertiary stage of wastewater treatment plants.