Hello radon,

As you know rhea during an adiabatic process the temperature remains constant because the internal energy only depends on the temperature in that case. Moreover at constant temperature, the entropy will be proportional to the volume of the substance and therefore the entropy increases in this case, therefore this process will be an irreversible. This is due to the work energy is converted to internal energy which inturn makes a constant temperature at adiabatic process....

Hope this information was useful to you . ..

All the best