Production, modification, and application of biochar from lignocellulosic biomass for adsorptive removal of selected metals in Acid Mine Drainage (AMD) water

Abstract

Acid mine drainage (AMD) is still a significant source of water pollution in the mining industry, which can occur anywhere sulphide materials are exposed in highway and tunnel construction and other deep excavations, resulting in mineralised materials being disturbed, leading to water pollution. Many scientists use carbonaceous materials such as activated carbon, biochar, and pyro char for AMD treatment. This thesis describes a challenge-based innovation of lignocellulose waste pyrolysis for biochar production and synthesis, as well as evidence of its use as a low-cost, novel adsorbent for the remediation of AMD water. Empty fruit bunch oil palm (EFBOP), a lignocellulose waste, is a valuable source of alternative biofuel, chemicals and helpful material for catalysts and bio-sorbents or biochar but has been recognised as a major contributor to global threats such as methane gas generation, soil acidification and other threats to human and ecosystem health. In 2014, it was estimated that nearly 23 million tonnes of EFBOP were produced globally, and this number will increase again with more palm oil plantation development. Slow pyrolysis is the most suitable technology for converting EFBOP into biochar due to its high yield. The EFBOP was pyrolysed at five different temperatures, and the highest yield was reached at a low temperature. The activation of biochar products with alkali solution at low temperatures enhanced specific chemical functional groups and enlarged surface area. The potential biochar from EFBOP (BC-EFBOPs) and alkali biochar was studied in detail for the manganese adsorption process in aqueous media. Moreover, this thesis explored alkali biochar for the adsorption of seven multi-metal cations in the water body, batch and continuous. In this thesis, different characterisation techniques were used, including Thermal Gravimetric Analysis (TGA), elemental analysis, Scanning Electron Microscopy Energy Dispersive X-Ray (SEM-EDX), surface area, Fourier-transform InfraRed spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and zeta potential. Alkali modification succeeded in adding more chemical functional groups, which also advanced the adsorption capacity of manganese ion single system in aqueous media. Lastly, the performance of alkali biochar for multi-metal adsorption in acid water is considered a potentially low-cost biosorbent for AMD water remediation.