To sort your input column in the desired order, you have to be aware of the column-type. Your input is a string, and the sorter node treats it as a string.
You have convert your string-column to an integer-column, by using the String to Number node or the Table Manipulator node.
gr. Hans
good things come to those who wait: on behalf of our developers (praise goes to @hotzm !), I’m happy to announce that a alphanumeric sort order has been implemented in the sorter node, the table view, and most other places where sorting is done. Check it out in the new KNIME Version 4.7.1! Of course, backward compatibility is not broken, so e.g. the GroupBy/Pivot Nodes still sort strings the old fashioned way. Also, this was already available in 4.7.0 in case you didn’t notice