Modified biochar derived from sewage sludge for purification of lead-contaminated water

Abstract The increase in wastewater collection and treatment systems has shown the need for adequate treatment and final disposal of the resulting sludge. Heat treatment through pyrolysis is an alternative, as it promotes the valorization of these wastes by converting them into biochar. Biochar is a multifunctional material that can serve as an adsorbent for many types of pollutants, including removing heavy metals. This study’s main aim is to produce, characterize, and evaluate the remedial potential of biochar resulting from the pyrolysis of sewage sludge (SS) in water polluted with lead. Pre-prepared sludge-derived biochar without any activation and biochar derived from SS activated with phosphoric acid (H3PO4) was prepared using a pre-chemical modification method by mixing a specified amount of H3PO4 with SS. The batch adsorption tests were used to verify the parameters of the adsorbent concentration, solution pH, contact time, and initial concentration. The adsorbent was characterized using X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, and energy dispersive spectrometer methods. The adsorption capacity was determined using the Langmuir and Freundlich models. The surface area of biochar increased from 35.769 m2/g for non-activated biochar to 136.04 m2/g for activated biochar with H3PO4. Biochar removed 87.36% of the lead. The activated biochar’s granular shape improved lead removal from the solution. This research has significant implications for removing lead from water using inexpensive sludge-based adsorbents.