<p>Currently, the global community is confronting water contamination from several sources, which poses significant environmental challenges. The reutilisation of polluted water constitutes a feasible strategy for sustainable wastewater management. In the present study, Mn₃O₄ was synthesised via chemical precipitation using polyvinyl alcohol (PVA), cetyltrimethylammonium bromide (CTAB) and glycine as surfactants and without any surfactants. The synthesised Mn₃O₄ using Glycine(MNG) showed the best photocatalytic efficacy compared to other synthesised materials, about 93 ± 0.35% disintegration of Rhodamine B in 150&#xa0;min when illuminated with visible light. The progress of photodegradation was in conformity with the pseudo-first-order kinetic model with a velocity of 0.017&#xa0;min⁻¹. Photoelectrochemical investigations assessed charge transfer, stability, and light-harvesting behaviour of Mn₃O₄ catalysts, showing their improved performance beyond photocatalysis. Seed germination in the treated water, controlled and uncontrolled conditions, was compared to ensure the agricultural and environmental viability. Additionally, ~ 84.54% of total organic carbon removal was achieved. A conceivable degradation mechanism was suggested after the degraded intermediates were examined using high-performance liquid chromatography (HPLC) and the elution patterns and retention periods.</p> Graphical Abstract <p></p>