Antimicrobial desiccant-crosslinked hydrogel beads for air dehumidification

Abstract

The rising demand for space cooling and the need to reduce carbon footprints have spurred interest in alternative air-conditioning systems. Desiccant systems, known for their energy efficiency and high moisture capture capacity, offer a promising solution. This study presents novel alginate beads, synthesized through crosslinking with magnesium chloride-potassium formate desiccant mixture at concentrations of 25 w/v% (B1), 50 w/v% (B2), and 75 w/v% (B3) for application in a desiccant system. The beads were characterized using FESEM, FTIR, XRD, DSC, and TGA to identify the optimal desiccant concentration while the absorption kinetics were modeled using the pseudo-second-order approach. Results indicated that B2 exhibited superior performance in absorption rate, thermal stability, and pore size distribution compared to B1 and B3. Additionally, all samples demonstrated antibacterial properties, enhancing air quality during dehumidification. Moisture removal performance was evaluated experimentally using a fixed bed dehumidifier system under varying air mass flow rate (m_a), specific humidity (ω), and temperature (T_a). Optimization through response surface methodology (RSM) identified the optimal conditions of m_a, ω and T_a as 0.374 kg/s, 0.0243 kg/kg, and 29.7 °C respectively, yielding a predicted maximum moisture removal rate (MRR) of 6.814 g/s. Experimental validation showed a deviation of ±4.3 %, confirming the accuracy and reliability of the results. The proposed hydrogel beads demonstrated notable advantages over traditional solid desiccants in terms of enhanced thermal stability and antibacterial properties, while maintaining significant moisture absorption capacity, making them an excellent choice for energy-efficient dehumidification.