Effects of Biochar Production Methods and Biomass Types on Lead Removal from Aqueous Solution

Biochar has proven its potential in removing heavy metal ions from water. The objective of this study was to evaluate locally obtained biomass feedstocks for biochar production and their efficiency as a sorbent for aqueous lead (Pb2+) removal. The biomass feedstocks consisted of avocado seed, avocado peel, grapefruit peel, and brown seaweed, which represent agricultural and marine biomasses. The biochar materials were produced in two different methods: (1) a laboratory tube furnace at 300 °C and (2) a Do-It-Yourself (DIY) biochar maker, “BioCharlie Log”. The biochars were characterized for selected physicochemical properties, and batch adsorption tests with 10 mg Pb2+ L−1 were conducted. All biochars exhibited >90% Pb2+ removal with the avocado seed and grapefruit peel biochars being the most effective (99%) from the tube-furnace-produced biochars. BioCharlie-produced-biochars showed similar Pb2+ removal (90–97%) with brown seaweed and avocado seed biochars being the most effective (97%). Land-based biochars showed a higher carbon content (>53%) than the brown seaweed biochar (28%), which showed the highest ash content (68%). Our results suggested that oxygen-containing surface functional groups in land-based biochar and mineral (ash) fraction in marine-based biochar play a key role in Pb2+ removal.