A regenerative core-shell LTA@LDH adsorbent for indoor dehumidification and its improved adsorption performance

Abstract

Dehumidification is vital for human health and environmental sustainability. However, traditional moisture adsorbents have the problems like low adsorption capacity, high regeneration energy consumption and negative impacts to environment. As a result, it is demanding to develop environmentally friendly adsorbents with desirable adsorption capacity and convenient regeneration. Herein, a Linde type A zeolite@Mg-Al layered double hydroxides (LTA@LDH) with core-shell structure is synthesized by a facile in-situ co-precipitation method and used for indoor dehumidification. The LTA@LDH with hierarchically porous structure presents advantageous synergism of micro-mesopores, and exhibits a better adsorption and desorption performance than the pure LTA. The whole water uptake capacity of LTA@LDH is 0.339 g.g- 1 in relative humidity 95 % & 30 degrees C, much higher than that of pure LTA (0.248 g.g(-1)). The desorption activated energy of LTA@LDH is 53.92 kJ.mol(-1), nearly half of pure LTA (88.63 kJ.mol(-1)), indicating its superior desorption performance. The adsorption activity of LTA@LDH remains unchanged after fifteen consecutive adsorption-regeneration cycles. Based on various characterizations, a three-stage dehumidification model of LTA@LDH was proposed to reveal its unique sorption behaviors: (1) capillary condensation mainly in LTA's micropores; (2) mono-layer order water absorbed in LDH's mesopores; and (3) multi-layer water absorbed in LDH's mesopores. This work provides a new approach to design and develop zeolite-based adsorbents by introducing LDH and designing unique core-shell structure