The presented finding offers a sustainable approach for the successful utilization of the pollutant soot in the form of waste black carbon (BC), collected from the exhausts of a diesel engine as an efficient adsorbent. The morphology of the as-isolated diesel particulate soot was observed in nanosize consisting of an Onion like Nano-Carbon (ONC) structure. The ONC were transformed into water-soluble Onion like Nano-Carbon (wsONC) via the simplest method of oxidation. For applicability as an adsorbent, wsONC was used for the removal of three cationic organic dyes, methylene blue (MB), crystal violet (CV), and rhodamine B (RhB). Among the three cationic dyes, MB showed significant results compared with the other two. A small amount of wsONC was found to be capable of removing similar to 100 mg L-1 of MB within the time of similar to 60 min. While with CV and RhB, the removal efficiency was observed to be similar to 60 mg L-1 and similar to 40 mg L-1 respectively. In a comparative adsorption analysis, the performance of wsONC was similar to 2.5 times higher than the as isolated ONC. Another novelty associated with the present finding is the uses of the treated wastewater for watering the Triticum aestivum (wheat) and Cicer arietinum (gram) plants for the initial 15 days. Compared to the dye water, the treated wastewater plants showed healthy growth.