Adsorption on quartz surface in recovery of gold from cyani̇de solutions and comparison with different activated carbon types

In this thesis study, cyanide gold solutions were prepared using waste materials obtained from gold mines operating in the Port Sudan region of Sudan; additionally, silver-containing solutions dissolved in an ammonium acetate medium under the effect of hydrogen peroxide were used. In both metal solutions, the adsorption performances of activated carbon samples produced from different biomass sources—such as almond shell, walnut shell, apricot kernel shell, and black cumin residue—were comparatively investigated alongside the adsorption behaviors of quartz samples with different particle sizes. Within the scope of the study, the effectiveness of adsorption-based treatment methods aimed at reducing environmental risks arising from Sudanese gold mining wastes was evaluated, and the potential usability of activated carbon and quartz as adsorbent materials for the removal of gold and silver ions was demonstrated. The analyses showed that the surface morphology and pore structure of the activated carbon samples varied significantly depending on the type of raw material and the activation conditions. FTIR analyses confirmed the presence of functional groups such as hydroxyl, carboxyl, C–O, C≡C, and aromatic rings on the activated carbon surfaces, and these groups were found to enhance the adsorption capacity. The activated carbon derived from apricot kernel shells exhibited the highest surface area, reaching 984 m²/g, while the sample produced from black cumin residue showed a carbon content of 68.8% after carbonization at 800 °C. Applying a KOH activation ratio of 1:1 significantly increased the surface area and porosity. In adsorption experiments conducted with cyanide gold solutions, activated carbons derived from walnut and almond shells exhibited adsorption efficiencies of 90.14% and nearly 100%, respectively. The activated carbon produced from black cumin residue demonstrated the fastest kinetic performance, achieving 100% adsorption efficiency within only 1–2 minutes, particularly at 45 °C. This result revealed that black cumin residue possesses a structurally high surface activity after carbonization. In the quartz studies, it was determined that the adsorption behavior of gold and silver ions in quartz samples ground to different particle sizes was directly related to particle size. Medium-sized quartz fractions (–106 +75 µm) showed the highest efficiency at a contact time of 90 minutes, whereas a decrease in adsorption rate was observed in finer-grained fractions. In silver solutions, 100% adsorption efficiency was achieved after 15 minutes of shaking with 1 g of quartz sample. Overall, the results indicate that biomass-derived activated carbons exhibit high effectiveness in the removal of precious metal ions due to their high surface area, rich functional group structure, and rapid adsorption kinetics, while quartz shows variable adsorption behavior depending on particle size. This study demonstrates that biomass wastes can be used as a sustainable alternative for activated carbon production and offer an environmentally friendly, economical, and efficient solution for the removal of metal ions.