Currently, carbon nanomaterials are found to possess various shapes and sizes, where their potentiality is mainly governed by the functional groups and design parameters. The alteration of the material features through postprocessing or reformulation can produce these nanostructures for utilization in air/wastewater treatment, dyes, pharmaceuticals, pesticides, and so forth. In this work, three isomeric structures of toluidine were chosen, which contain a ─CH3 at the o‐, m‐, and p‐positions of the benzene ring along with an ─NH2 group. SEM and TEM images confirmed the formation of carbon nanoparticles at different times and temperatures under optimized reaction conditions. It was observed that uniform size of carbon quantum dots was obtained from all the isomeric structures, namely, after 60, 90, and 60 min in case of o‐, m‐, and p‐toluidine, respectively. The efficiency of the synthesized carbon nanoparticles for the degradation of toxic organochlorine pesticides, namely DDT, lindane, and fenvalerate was also studied. Interestingly, the synthesized carbon quantum dots were found to degrade the DDT up to 98.5%, lindane up to 83.02%, and fenvalerate up to 74.34% under visible light exposure. However, only 63.23%, 20.25%, and 30.41% degradation were observed under dark conditions for DDT, lindane, and fenvalerate, respectively.