The effect of airflow velocity on dispersion and triboelectric separation of fine food powders

Triboelectric separation is an energy efficient and environmentally sustainable technique for protein enrichment from raw food materials. However, particle aggregation can significantly reduce separation efficiency. This study investigates the dispersion and electrostatic separation behavior of fine food particles to elucidate the mechanisms underlying this limitation. First, the interaction forces between charged micron sized particles were analyzed using a double primary particle aggregation model (DPPAM), followed by an estimation of the range of dispersible particle sizes under varying airflow velocities. Subsequently, particle size analysis and optical microscopy were employed to examine the effects of airflow velocity on particle dispersion. The results indicate that high airflow velocity markedly enhances the dispersion of blending powders (BP), while showing limited effectiveness for well refined pea powder (WRPP80). This difference is primarily attributed to the higher abundance of fine particles (<5 μ m ) in WRPP80, which increases interparticle contacts and thus strengthens interaction forces, thereby impeding the effective dispersion of individual particles. Furthermore, the findings demonstrate a positive correlation between the degree of dispersion of charged particles and protein enrichment efficiency in airflow, as supported by theoretical analysis. Finally, comparative experiments revealed that the triboelectric polarity of protein and starch is consistent with the polymer triboelectric series; however, the inherent impurities of natural food particles diminish the polarity differences between particles enriched in these respective components. • The airflow velocity required to disperse agglomerated charged particles is strongly dependent on particle size. • Effective triboelectric separation is promoted by a well-dispersed particle state in the airstream. • Fine micron-sized particles resist dispersion by airflow, hindering triboelectric separation. • The triboelectric polarity of food particles is affected by the chemical composition of individual particles.