Synthesis and Characterization of Alginate–Silica Gel Composites for Adsorption Dehumidification

Abstract

Desiccant coated heat exchanger (DCHE)-based adsorption dehumidification systems have great potential for energy conservation and emission reduction. The selection of desiccant materials can greatly impact the overall performance of DCHE systems. However, the unsatisfied adsorption quantity of widely used silica gel at middle relative humidity range and the possible corrosion problem of salt-supported silica gel are bottlenecks for the engineering application. A strategy for synthesizing novel alginate–silica gel composites that have fair adsorption quantity without corrosion is demonstrated. Textural properties suggested that silica gel particles can be well distributed in the surface of composite samples with the liquid–solid mixing and post cross-linking method. Dynamic water adsorption test showed that the composite with a sodium alginate-to-silica gel mass ratio of 5:1 possessed the best water adsorption kinetics. Water adsorption quantity difference of the composite between a typical adsorption condition (80% RH) and a regeneration condition (30% RH) is more than twice that of silica gel. Dehumidification capacities of the composite-coated DCHE were 34–60% higher than those of a silica gel-coated DCHE under set simulation conditions. This method offers a promising way of material synthesis for researchers who are interested in the area of coatings, separations, dehumidification, etc.