Please solve in detail for mass transfer

Pine logs are dried to remove the moisture. The moisture content of the solid surface is in equilibrum with air and can be assumed constant at 5%. The initial concentration (moisture content) is 30% and the maximum permissible is 15%. If the and the maximum permissible is 12.2m long with a diameter of 0.3m, Determine the time necessary for them to dry. (Deff=1107m/s)