In this study, density functional theory (DFT) calculations were employed to investigate the effects of Ag substitution in the galena lattice on the electronic structure and adsorption mechanisms of flotation reagents. The results show that substitution of Pb by Ag in the galena lattice shifts the valence band toward the conduction band and causes it to cross the Fermi level (E f ), thereby enhancing the electrochemical activity of the Ag-bearing galena surface. Compared with surface Pb sites, surface Ag sites are more favourable for the adsorption of the collector potassium butyl xanthate (KBX), with an adsorption energy of -0.3061 eV. This behaviour can be attributed to the smaller energy gap ΔE (E HOMO - E LUMO ) between the collector and the surface Ag site. Both OH - and CaOH + adsorb more strongly on the Ag-bearing galena surface than on the pure galena surface. This enhanced adsorption is mainly associated with the more covalent character of the Ag-O bond relative to the Pb-O bond, as confirmed by the markedly higher Mulliken population of the Ag-O bond. In addition, Ca 2+ in CaOH + can interact with a surface S site through the formation of a Ca-S bond, resulting in a stronger depressing effect of CaOH + than OH - . These results explain why Ag-bearing galena exhibits better floatability than pure galena but is also more susceptible to depression by OH - or CaOH + . The findings provide a theoretical basis for optimising flotation conditions to improve silver recovery from lead-zinc ores.
The discharge of pharmaceutical pollutants, such as ciprofloxacin (CIP), into water bodies poses a significant threat to global water security. This research introduces a circular economy approach by synthesizing a magnetic cancrinite-type zeolite (MZ-3) from coal fly ash (CFA) and red mud (RM) via a streamlined alkali fusion-hydrothermal route (160°C for 9 h). The resulting composite exhibited high crystallinity, a mesoporous framework, and a strong negative zeta potential (-51 mV), which facilitates CIP adsorption. Experimental results demonstrated that MZ-3 can adsorb up to 62.75 mg g -1 of CIP at pH 7.1, where CIP predominantly exists in its zwitterionic form. The adsorption data were best described by the Sips isotherm (R 2 = 0.99087), indicating heterogeneous surface energy. The incorporation of magnetic iron oxide from red mud enabled efficient solid-liquid separation using a magnetic field, thereby eliminating the need for energy-intensive filtration. The adsorbent maintained structural stability during operation; regeneration with a saturated NaCl solution restored active sites, increasing removal efficiency to 93.2% by the second cycle. These findings establish MZ-3 as a high-performance, cost-effective, and sustainable material for the remediation of antibiotic-contaminated wastewater, thereby effectively converting industrial waste into a valuable water-treatment resource.
This study presents the first investigation of Mimosa pigra L. seeds, a readily available invasive plant in Vietnam, as a biosorbent for methylene blue (MB) removal. The seed powder was characterized using FT-IR, SEM–EDX, XRD, particle-size distribution, and N 2 adsorption–desorption analyses. Its adsorption performance was evaluated under different solution pH and adsorbent dosages, followed by kinetic and equilibrium isotherm analyses. The adsorption kinetics were best described by the pseudo-second-order model, with an initial uptake rate of 13.7 mg g -1 min -1 . The Langmuir model provided the best fit to the equilibrium data, yielding a maximum adsorption capacity of 121.9 mg g -1 . Comparative characterization before and after adsorption, together with the adsorption results, suggested that electrostatic attraction, hydrogen bonding, and π–π interactions contributed to MB uptake. Overall, raw M. pigra seed powder is a promising, low-cost biosorbent because of its simple preparation and reasonable reusability.
The discharge of synthetic dyes into water bodies presents a significant environmental concern owing to their toxic nature, long-term stability and potential carcinogenic effects. Traditional wastewater treatment methods often fall short in effectively removing these complex compounds. Microbial fuel cells (MFCs) are gaining attention as an eco-friendly technology capable of treating wastewater while producing energy at the same time. This review explores the potential of MFCs in degrading various dye pollutants, highlighting their operational principles, types and mechanisms. It also discusses the influence of factors such as inoculum source, dye concentration, contact time and electrode materials on the efficiency of dye removal. Furthermore, the synergistic relationship between microbial activity and electricity production is analyzed, offering insights into system optimization for enhanced performance.
In this study, two different biocomposites (Bsp-GOS and Pe-GOS) were created by immobilizing Green Olive Stone with Bacillus sp. and Pleurotus eryngii. The removal of methylene blue (MB) from aqueous solutions was investigated using these materials. The structural and surface properties of the biocomposites were characterized by FTIR, SEM, and EDX analyses. FTIR results showed that hydroxyl, carbonyl, and ether groups played an active role in the biosorption mechanism; SEM-EDX analyses showed porous structure and morphological changes occurring on the surface. Experimentally, the effects of parameters such as pH, contact time, initial dye concentration, and biocomposite amount on biosorption efficiency were evaluated. The optimum pH of Bsp-GOS and Pe-GOS biocomposites was determined as 7.0 and 6.0, respectively. The contact time was determined as 60 minutes for both biocomposites. Isotherm analyses showed that Bsp-GOS fit the Langmuir model better, while Pe-GOS fit the Freundlich model better. Kinetic data showed a fit to a pseudosecond-order model for both systems. In conclusion, the developed biocomposites were evaluated as biosorbents prepared from agricultural waste.
