Complex sentence: Bone char possesses a low decolouration capacity and must be used in large quantities, however it is also able to remove various inorganic impurities; most importantly sulfates and the ions of magnesium and calcium.
Split into simpler sentences: Bone char possesses a low decolouration capacity and must be used in large quantities. However, it is also able to remove various inorganic impurities; most importantly sulfates and the ions of magnesium and calcium.