Desalination of Caspian Sea water by using graphene oxide-based covalent organic frameworks and HDTMA-modified Iranian natural Zeolite

Abstract

The depletion of freshwater resources emphasizes the significance of water desalination, while the high energy consumption and operating costs associated with existing desalination methods necessitate the search for cost-effective solutions. Therefore, this study presents a unique and innovative solution by employing advanced materials, specifically the combination of graphene oxide (GO)-based covalent organic frameworks (COF) and hexadecyltrimethylammonium bromide (HDTMA)-modified Iranian natural zeolite in the desalination of Caspian Sea water and well water in the Dark area of Isfahan. In this regard, GO was synthesized using Homer’s modified method and subsequently functionalized with COF and the clinoptilolite zeolite was modified with HDTMA. A series of 28 column experiments were carried out using response surface methodology (RSM) to examine the elimination of electrical conductivity (EC), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), and chloride (Cl−) under the influence of five operational parameters: initial salinity (7.3−9.6 ds/m), flow rates (1−5 mL/min), GO amounts (0−30 mg), HDTMA quantities (0−13 g), and COF quantities (0−30 mg). The results revealed that the initial salinity concentration had the most significant impact on the reduction of EC, Na+, K+, and Mg2+. Conversely, the quantities of COF had the greatest influence on the reduction of Ca2+. Regarding Cl−, the interaction between HDTMA and salinity exhibited the most notable effect. Overall, this study highlights the potential of utilizing GO and HDTMA-modified Iranian zeolite for desalination purposes, offering a promising approach for addressing water scarcity and salinity challenges in arid regions.