The six jars were placed in an oven adjusted to a fixed temperature for 24 hours so as to bring the salt solutions to a constant temperature. Triplicate samples were used (2–3 g each) for both adsorption and desorption experiments. The air inside the desiccators was sucked with the help of a vacuum pump. These desiccators were kept in an incubator maintained at 20, 30, 40 °C thermostatically.