Electrostatic Separation of Ajwain ( Trachyspermum ammi L.) Seeds Using a Roll‐Type Corona Discharge System

Abstract

Abstract

ABSTRACT Impurities in seed‐based agricultural products reduce product quality and economic value, necessitating efficient postharvest separation technologies. Conventional mechanical separators, which rely mainly on differences in size and mass, are often ineffective when impurities physically resemble the target seeds. Electrostatic separation offers a dry and chemical‐free alternative by exploiting differences in charging behavior, dielectric response, and particle trajectory under an electric field. In this study, a roll‐type corona discharge electrostatic separator was evaluated for the purification of Ajwain ( Trachyspermum ammi L.) seeds containing physically similar impurities. A full factorial experimental design with three replications was employed to investigate the effects of applied voltage (8–16 kV), roller rotational speed (20–40 rpm), and corona electrode angle (30°–40°) on seed separation and seed purity. Statistical analysis showed that the operating parameters and several interactions significantly influenced the responses ( p < 0.05). Considering the simultaneous requirement of high seed separation and acceptable purity, the best practical condition was obtained at 8 kV, 20 rpm, and a 40° corona electrode angle, resulting in 96.3% seed separation and 90.6% seed purity. The results indicate that optimized roll‐type corona electrostatic separation can complement conventional postharvest cleaning systems for fine, high‐value seeds.