Heavy metals generally refer to more than 60 elements with a density of more than 4 or 45 elements with a density of more than 5. However, because the toxicity of different heavy metals in water and soil is very different, in the field of environmental science, people usually pay attention to vanadium, chromium and nickel. , cobalt, copper, zinc, cadmium, tin, mercury, lead and other metal ions. Heavy metal ions can accumulate in the human body and lead to poisoning, cancer and damage to the nervous system, so it is particularly important to do a good job of heavy metal pollution control.
Graphene oxide is a carbon nano material prepared from natural graphite with a structure similar to carbon nanotubes. Compared with the adsorption capacity of activated carbon, carbon nanotubes and graphene materials for low-concentration lead-containing wastewater, the adsorption capacity of graphene oxide for lead is as high as 800 mg/g, which is much higher than that of activated carbon, which is 60 to 120 mg/g. It has extremely strong regeneration capacity, and the adsorption capacity drops only 5 to 10% after repeated adsorption/elution cycles.
Why does graphene oxide have such a strong heavy metal adsorption capacity? There are two reasons: one is that graphene oxide is a two-dimensional nano material with a thickness of one atomic layer, and its specific surface area can theoretically reach 2600 square meters/g, which is the largest among all carbon nano materials; During the preparation process, a large number of active groups such as carboxyl group, carbonyl group, hydroxyl group, epoxy group, etc. are formed on its surface. Therefore, graphene oxide has the most basic elements required for an excellent adsorbent: a sufficiently large specific surface area and a sufficiently high density of surface functional groups.
The use of graphene oxide material can reduce the discharge concentration of lead-containing wastewater in the lead-acid battery industry from the current 100-1000ppb to 1-10ppb, increase the lead recovery rate to 95%-99%, and reduce the total environmental discharge of lead by 90% compared with the existing technology. %. The achievement can be effectively extended to other heavy metal pollution systems such as cadmium, nickel, arsenic, copper, chromium, and radioactive elements, and has considerable economic and social benefits. https://www.hwnanomaterial.com/