Pongamia pinnata as an eco-friendly, powerful scavenger for crystal violet from the waterbody

Inspired by the proven efficacy of phytosorbents, Pongamia pinnata flower (PPF) has been used for the removal of crystal violet dye from simulated and industrial wastewater. The adsorbent material was characterized using BET surface area and FESEM-EDX techniques, which suggested the presence of polyphenolic moieties and a modest porous nature. XRD and FT-IR techniques have been implemented to detect functional groups and the amorphous nature in the phytosorbent. The maximum uptake capacity of the material, 146.18 mg/g, was obtained at room temperature, and the uptake pathway followed the Freundlich isotherm (R²=0.997) and the pseudo-second-order kinetic model (R²=0.999), suggesting chemisorption and a heterogeneous mode. Spontaneity and endothermicity were confirmed with the Gibbs free energy (ΔG = -2.204 kJ/mol) and change in enthalpy (ΔH = 58.29 kJ/mol). Easy regeneration with 1:1 methanol has been seen. The presence of coexisting ions did not raise any performance concerns, which was further confirmed by testing in spiked water. The uptake mechanism is proposed to be a combination of weaker forces, including hydrogen bonding, π-π stacking, and modest electrostatic forces.