Water decontamination using magnetic biochar produced from biomass and mineral processing waste

Abstract

Contamination from industrial wastewater is a serious environmental problem, often requiring innovative treatment methods beyond traditional technologies. This thesis explores the development of magnetic biochar (MBC), a carbon-rich, magnetically separable material produced by pyrolyzing biomass with iron sources as an efficient and sustainable solution for water decontamination. The research first reviews recent advances in biochar design, modification, and application for heavy metal removal, highlighting key factors like feedstock choice, pyrolysis conditions, and activation methods. In the experimental work, MBC was synthesized using different iron compounds and production methods. Among them, one-step co-pyrolysis of maple wood and FeO at 700 °C produced the most effective MBC for removing a model dye, Remazol Brilliant Blue R (RBBR), achieving nearly 100% removal under acidic conditions. Adsorption studies revealed that the process followed pseudo-second-order kinetics and fit the Langmuir isotherm model. Taking this a step further, a new approach was developed by co-pyrolyzing red mud, an industrial waste, rich in iron, with chemically activated biomass (treated with KOH and HNO3) to produce cost-effective MBC. The KOH-activated MBC demonstrated outstanding performance, achieving almost 100% removal of copper (Cu2+) and lead (Pb2+) ions from water, while also offering lower production costs compared to HNO3-activated MBC. Overall, this work demonstrates that properly engineered MBC materials, including those made from waste resources like red mud, offer a highly promising, low-cost, and eco-friendly solution for treating dye- and heavy metal-contaminated waters.