The use of coal-derived activated carbon (AC) for water treatment applications demands more sustainable production methods, with chemical activation emerging as a promising alternative to thermal activation due to its higher AC quality, lower carbon burn-off, and higher yield. The study explored the effect of surface area, particle size and acid washing on the quality of AC derived from three seams of lower-rank Collie coal under the same activation conditions with potassium hydroxide (KOH). The quality of AC was determined by surface area and iodine number. The study demonstrates that Collie coal, suitable for AC production via KOH activation, yielded iodine numbers of 640 and 900 mg/g, with yields of 53 and 57 wt.%. Particle size influenced AC yield, with finer particle sizes yielding AC at 57–59 wt.%, whereas coarser ones yielded around 58–65 wt.%. SEM analysis shows the well-developed porous structure in Collie coal-derived activated carbons, with cleaner particles after acid washing. A positive correlation exists between coal surface area and AC iodine numbers, with higher values in coal samples correlating to increased iodine numbers in resulting AC. The regression model’s predicted values yield a coefficient of determination (R²) of 0.99.

Recovery of valuable metals from end-of-life cylindrical lithium-ion batteries (LiBs) by leaching using acetic acid in the presence of an organic reductant is a promising combination to overcome environmental concerns that arise from employing inorganic reagents. This study investigated the effect of using molasses as a reductant in acetic acid leaching of a mixture of cathode and anode materials (black mass) prepared using mechanical treatments from spent LiBs. The effects of temperature, solid/liquid ratio, stirring speed, and acid concentration on the leaching of target metals (Co, Ni, Mn, and Li), current collector metal foil elements (Al and Cu), and Fe from the battery casing, with and without reductant, were investigated to obtain the optimum leaching conditions. The effect of adding the molasses at the start of leaching and after 1 h of leaching was tested. Acid leaching without molasses extracted the target metals Li, Ni, Co, and Mn with an efficiency 96% at temperatures >50 °C. This is likely due to oxidation of the reducing sugars in the molasses that reduced the insoluble Co(III), Ni(III), and Mn(IV) components to soluble Co(II), Ni(II), and Mn(II) species, respectively. The kinetics of Co extraction in the presence of molasses were analysed, which has indicated that the rate-determining step in the Co leaching process is the reduction of Co(III) on the surface of particles in the black mass. Excess molasses can precipitate out target metals, especially Co, due to the presence of oxalic acid in the molasses. The reducing effect precipitated Cu(II) to Cu₂O, and could further reduce Co to metal, which suggests that leaching with the optimum dosage of acetic acid and molasses may selectively precipitate copper.

Copper smelting slag is a significant potential resource for cobalt and copper. The recovery of copper and cobalt from copper slag could significantly augment the supply of these metals, which are essential to facilitating the transition to green energy while simultaneously addressing environmental concerns regarding slag disposal. However, the complex mineral composition of copper slag poses an enormous challenge. This study investigated the mineralogical and chemical characteristics of copper slag, which are vital for devising the most effective processing techniques. XRD and FESEM-EDS were employed to examine the morphologies of copper slag before and after the reduction process. The effects of borax and charcoal (carbocatalytic) reduction on phase transformation were evaluated. The XRD analysis revealed that the primary phases in the copper slag were Fe₂SiO₄ and Fe₃O₄. The FESEM-EDS analysis verified the presence of these phases and yielded supplementary details regarding metal embedment in the Fe₂SiO₄, Fe₃O₄, and Cu phases. The carbocatalytic reduction process expedited the transformation of copper slag microstructures from crystalline dendritic to amorphous and metallic phases. Finally, leaching experiments demonstrated the potential benefits of carbocatalytic reduction by yielding high extractions of Cu, Co, and Fe.