Adsorption　behavior　of　ranitidine　hydrochloride　(RT)　on　a　Ca-montmorillonite　(SAz-1)　was　studied　in　aqueous　system　through　batch　experiments.　The　adsorption　kinetics　revealed　that　the　equilibrium　reached　within　0.25　h　and　the　data　fitted　well　to　the　pseudo-second　order　kinetic　equation　(R2　=　0.98).　The　maximum　RT　adsorption　capacity　of　SAz-1　was　369.2　mg/g　and　the　adsorption　isotherm　data　followed　the　Langmuir　model　(R2　=　0.99).　The　adsorption　of　RT　and　desorption　of　exchangeable　cations　from　the　clay　mineral　were　linearly　correlated,　suggesting　that　cation　exchange　was　the　dominant　mechanism　of　RT　adsorption.　The　XRD　examination　of　RT-adsorbed　SAz-1　samples　(unsaturated/saturated)　after　heating　enabled　the　calculation　of　RT　occupied　area　in　the　interlayer　of　the　clay　mineral.　The　results　suggested　that　adsorbed-RT　at　low　loading　rate　could　lay　on　the　internal　surfaces　in　a　free　style　to　reduce　the　basal　spacing　(d001　value)　of　SAz-1.　When　the　RT　loading　rate　was　increased,　a　limited　surface　space　enforced　more　RT　molecules　to　lay　in　a　tilted　style　and　caused　interlayer　swelling　of　SAz-1　increasing　the　d001　value.　The　trend　of　rising　decomposition　temperature　of　RT　with　increasing　RT　loading　rates　confirmed　intercalation　of　RT　molecules　in　SAz-1.　Infrared　spectral　analysis　revealed　the　participation　of　amide　and　furan　groups　of　RT　in　binding　between　RT　and　SAz-1.　Thus,　this　study　indicated　that　SAz-1　is　an　efficient　adsorbent　to　remove　RT　from　contaminated　water,　and　the　chain-like　molecular　structure　of　RT　could　cause　an　irregular　change　in　the　basal　spacing　of　swelling　type　clay　minerals.　©　2022　Elsevier　Inc.