Yes, a blender can be used instead of a juicer, providing you peel the skin off, but the end result is generally not that pleasing unless mixed with a lot of other fruits or vegetables and will contain a higher amount of pulp. The best citrus juicer will extract a larger amount of juice and leave the bits and fibrous parts in the pulp. A blender will cut everything into tiny pieces making a smoothie rather than a juice resulting in a thicker consistency.