The sulphuric acid disintegrated the leaves. Most of the substances in the leaves are reduced to carbon after two hours. Charring takes place by adding sulphuric acid and by the action of heat, charring removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon. It also helps to remove the moist content in the leaves. The pollution problem may not be takes place.
First of all, authors have to attach a EDX mapping images before/after sorption of chromium ions.