*2.1. Materials*

To compare the coating efficiency, two types of raw clay were studied: a commercial clay from India (CCIn) provided from the Clay Craft India, Jaipur [25] and a local clay (RCKh) from Saudi Arabia's Khulays region, Jeddah. The RCKh was prepared by grinding raw rocks with a mortar and pestle to achieve a fine grain size in the micrometer range. X-ray Florescence (XRF, from Hitachi Company, Tokyo, Japan) was used to characterize both types of clay. The dominant CCIn components were montmorillonite (64.9%), kaolinite (10.6%), goethite (9.5%), hematite (9.4%), and boehmite (5.6%), as found earlier [25]. The XRD patterns of the RCKh show that the dominant components were montmorillonite (35.22%), mica (22.8%), kaolinite (13.33%), quartz (8.57%), feldspar (6.66%), and ilmenite (5.71%). Dolomite and gypsum (3.81%) and calcite (3.81%) were the remaining components [26].

Polystyrene (PS), with a molecular weight of 259,000 g/mol, was used to prepare the polymer clay nanocomposite in this study, and it was provided by the Sabic Company, Riyadh, Saudi Arabia.

Cetylpyridinium chloride (CPC) was purchased from the BDH Co., Istanbul, Turkey. It was used as a cationic surfactant in the production of organoclay (OC). The general formula is C21 H38ClN, and its molecular weight is 358.01 g/mol. The Avonchem Company, Cheshire, UK, provided toluene (C6H5CH3), with a high purity percentage of 99.5%, which was used as a solvent for the polymer matrix PS. The Win lab Company, Queensland, Australia, provided analytical-grade sodium chloride AR.

The carbon steel (C-steel) rods were provided by the ODS Co., Schleswig-Holstein, Germany. C-steel has a chemical composition of 98.468% Fe and 0.46% C [17].
