Toxic chromium adsorption from tannery wastewater on thermally activated Piper betle petiole adsorbent

Chrome tanning is popular due to the exceptional properties of the final leather products. Emitted wastewater discharged from chrome tanning contains a significant amount of chromium. The release of chromium-containing wastewater into the environment creates environmental pollution. In this work, Piper betle petiole Thermally Activated Adsorbent (PBPTAA) is utilized to remove chromium from tannery wastewater. The PBPTAA was characterized through surface chemistry (FT-IR), surface morphology (SEM), elemental composition (EDS), and point of zero charge (pHpzc). The batch test revealed the maximum chromium removal (99.9 %) using a dose of 16 g/L wastewater for 15 min of contact time at a relative pH of 8.5. The technique showed a significant reduction of COD (39.8 %), Cl⁻ (55.6 %), and BOD (33.7 %) in the emitted wastewater. SEM and EDS analysis combined illustrated the adsorption of Cr on PBPTAA. The pHpzc showed a negative adsorbent surface, which well explained the chromium adsorption mechanism on PBPTAA with complete and partial electronegative ions by electrostatic bonding. The ΔG° measurement (−19.49 kJ mol⁻¹) at 308 K revealed a spontaneous and favorable adsorption of Cr, whereas the Cr desorption rate using HNO₃ showed significance in the economical reusability of PBPTAA. Hence, this investigation demonstrated a novel method for removing Cr from tannery wastewater using PBPTAA, anticipating an environmentally sustainable waste processing.