Bacopa monnieri biochar derived carbon nanospheres for pendimethalin remediation from water

The study reports the rapid synthesis of carbon nanospheres (CNSs) from Bacopa monnieri leaf biochar via microwave irradiation for the removal of the Pendimethalin (PND) herbicide from water. The synthesized CNSs were characterized by SEM-EDS mapping (morphology and elemental distribution), XRD (crystalline structure and elemental composition), FTIR (functional groups), Zeta potential (surface charge), BET (surface area), and BJH (pore volume). Batch-mode adsorption experiments were conducted under various conditions of PND concentration (30 to 70 mg L^- 1), pH (2 to 12), contact time (0 to 120 min), and adsorbent dose (2.5 to 20 mg). The optimal removal of PND was 94.02%, achieved in 120 min at pH 10 with a PND concentration of 50 mg L-1 and a CNS dose of 10 mg. The presence of multivalent salt (CaCO₃ and MgCO₃) enhanced the removal efficiency through strong ionic interactions. Regeneration experiments demonstrated ~ 60% adsorption capacity after the 5th regeneration cycle. Adsorption followed pseudo-second-order kinetics and was fitted to the Langmuir and Freundlich model with a maximum capacity of 63.62 mg g^- 1, confirming multi-layered chemosorption and a pore-filling mechanism. The development of low-cost, biomass-derived CNSs for pesticide remediation aligns with Sustainable Development Goal 6 (clean water and sanitation) by improving water quality through sustainable, accessible treatment strategies.