Evaluation of Air Dehumidification-Assisted Drying of Red Seaweed (Gracilaria verrucosa) in Biomass-Fueled Fixed-Bed Dryer

Drying of Gracilaria verrucosa remains challenging because its high initial moisture content and moisture-binding matrix prolong drying, increase energy demand, and affect product quality. This study investigated the effect of zeolite-assisted air dehumidification in a fixed-bed dryer through an integrated evaluation of drying behavior, moisture adsorption, moisture transport, energy utilization, and product quality. Drying experiments were conducted at target air temperatures of 30 – 60 °C with and without zeolite dehumidification and were compared with open sun drying. Zeolite-assisted drying lowered the relative humidity of the drying air and enhanced moisture removal, with the 60-Z treatment reaching a final moisture content of 5.25% (wet basis) after 6 h compared with 16.82% for the corresponding non-zeolite treatment. The Page model adequately described the drying kinetics, while the effective moisture diffusivity increased with drying temperature and remained consistently higher under zeolite-assisted drying. Correspondingly, the apparent activation energy decreased from 49.63 to 36.55 kJ/mol. At 50 °C, zeolite-assisted drying reduced the final specific energy consumption and CO 2 emissions by 22.3% and 21.9%, respectively. Lower drying temperatures better preserved the hydration properties of the dried seaweed, whereas FTIR analysis indicated no detectable changes in the major functional groups after drying up to 60 °C. Collectively, these results clarify the influence of air dehumidification on drying performance, moisture transport, energy utilization, and quality characteristics of G. verrucosa , providing an experimental basis for evaluating zeolite-assisted dehumidification in seaweed drying under the investigated conditions.