Composite material-based a clay for adsorption desalination and cooling applications

Abstract

This paper studies improving the performance of an adsorption system by improving raw bentonite as an adsorbent. Acid treatment has been used for the pretreatment of raw bentonite. Then, a composite and activated adsorbents are prepared by bentonite impregnated in salt hydrates (CaCl2 and (NH4)2CO3). XRD, nitrogen adsorption isotherm, water vapor adsorption isotherm and kinetics are used to characterize raw and modified bentonite. Experimental results of adsorption isotherms and kinetics have been fitted using Dubinin–Astakhov equilibrium model and linear driving force model. MATLAB software has been used to solve a simulation model of an adsorption desalination system with and without heat recovery (HR). The effect of the modified adsorbents on the adsorption system performance has been investigated. The results illustrated that the surface area and pore volume of Bent/CaCl2 increased by about 200% and 500%, respectively, compared to raw bentonite. The Bent/CaCl2 was predicted to have the highest water uptake (0.82 kgH2O.kg−1). Bent/CaCl2 was predicted to have a SDWP of 11.5 m3.ton−1 per day with SCP 326 W.kg−1 and COP 0.52 at 85 °C desorption temperature. Also, the SDWP was predicted to achieve 26 m3.ton−1 per day with HR under the same conditions. The SDWP can be increased to 29 m3.ton−1 at 95 °C desorption temperature.