Treating seaweed before the fire made it five times better at trapping carbon

Seaweed is plentiful, grows without farmland, and can be heated without oxygen to make biochar — a charcoal-like material that traps carbon dioxide on its surface. The catch has been that seaweed biochar is usually full of poorly formed pores, so it does not capture much. A team led by Lina Liu at Taiyuan University of Science and Technology, in China, found that the order of one step changes everything: treating Sargassum seaweed with potassium hydroxide before heating it to 400 °C, rather than after, produced a material that captured 120.5 milligrams of carbon dioxide per gram — five times the 24.1 milligrams managed by untreated biochar made at the same temperature. It reached its full capture in about 11 minutes, roughly twice as fast as untreated samples, and after nine rounds of use it had lost only 1.1% of its capacity. The work, published in Biochar X, is still at laboratory stage — real exhaust gases are wet and mixed, and those tests come next — but it turns an unwanted seaweed into a reusable carbon trap with a simple change in sequence.

SDG 13 · Climate action — Mechanism: tech innovation