Microwave-assisted water harvesting by composite adsorbent of zeolite 13X and activated carbon

Water scarcity is a critical challenge in dry and desert climates while a plentiful quantity of water is present in the form of vapor in the air. So, water harvesting from air has attracted great attention in recent years. Essential concern of many studies is focused on sorption technique due to being a high-yield, low-energy-consuming, and eco-friendly technology [1]. Zeolite 13X is one of the most traditional adsorbents showing high water adsorption capacity because of its hydrophilic nature and large surface area. To promote zeolite features, many attempts have been made via modification. In this research, a composite of microporous zeolite 13X and activated carbon was provided, then adsorption and desorption of water vapor from air humidity were investigated through conventional and microwave heating methods. Zeolite was synthesized via hydrothermal reaction of appropriate aluminosilicate hydrogel. For the synthesis of composite adsorbent, a particular amount of activated carbon was added to the zeolitic hydrogel at room temperature. The obtained gel stirred for 24 hours and subsequently transferred to an autoclave at 95°C for 20 hours. The product was characterized using techniques as XRD, SEM, FT-IR, and EDX. A set-up was designed to measure the amount of water adsorbed by the sorbents. Airstreams with different initial humidity passed through a column containing adsorbent and the measurement of input and output humidity was continued until saturation occurred. According to the obtained data from adsorption diagram, with 15 (g/m3) absolute humidity, the adsorbent could adsorb 144% water of its own weight in five minutes.