Biodegradable sodium alginate-based nanohybrid: Tuning reaction conditions for maximum efficiency in wastewater...

Sodium alginate (SA) based nanohybrids are widely studied for their efficiency in wastewater treatment. In this context, a novel CaMn₂O₄/CaMn₃O₆/PANI/SA nanohybrid is synthesized to reduce and degrade toxic organic dyes. CaMn₂O₄/CaMn₃O₆ nanoparticles (NPs) are synthesized via a facile chemical reduction method using eggshell waste as a calcium source and fabricated with PANI/SA matrix to synthesize CaMn₂O₄/CaMn₃O₆/PANI/SA nanohybrid. The coexistence of CaMn₂O₄ and CaMn₃O₆ phases in a single entity without using a stabilizing agent is reported for the first time. The catalytic activity of synthesized products for the reduction of methyl orange (MO), methyl blue (MB), Eriochrome black-T (EBT) and reactive black-5 (RB-5) is compared based on apparent rate constant (k_app), reduction time (min), percentage reduction and half-life. Among all these substrates, the highest k_app (0.1431 min^-1) is observed for MO dye prompting a detailed study into the effects of various parameters, highlighting the best catalytic activity and optimizing reaction conditions for maximum reduction of MO dye. The impact of H₂O₂ concentration on the degradation of MO dye is also examined. Remarkably enhanced catalytic efficiency is exhibited by CaMn₂O₄/CaMn₃O₆/PANI/SA nanohybrid compared to CaMn₂O₄/CaMn₃O₆ NPs alone due to synergistic interactions within conductive polymer in nanohybrid. This study demonstrates promising catalytic potentials of CaMn₂O₄/CaMn₃O₆-based nanomaterials for wastewater treatment.