The Congo Red dye was removed from a simulated textile wastewater solution using fly ash from a local power plant. The characterisation of fly ash was studied in detail by SEM, EDX, XRD, FTIR, BET surface area and TGA techniques. The influence of four parameters (contact time, initial concentration, adsorbent dose, and temperature) was analysed, the results showing that the adsorption capacity depends on these parameters. Thermodynamic and regeneration investigations as well are presented. The fit to pseudo-second-order kinetics models suggests that the removal process is a chemical adsorption. The Langmuir model fitted the experimental data, with a maximum adsorption capacity of 22.12 mg/g. The research is a preliminary case study that highlights that fly ash posed a very good potential as a material for Congo Red dye removal.

The initial characteristics of Romanian fly ash from the CET II Holboca power plant show the feasibility of its application for the production of a new material with applicability in environmental decontamination. The material obtained was characterized using standard techniques: scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), instrumental neutron activation analysis (INAA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET) surface area, and thermogravimetric differential thermal analysis (TG-DTA). The adsorption capacity of the obtained material was evaluated in batch systems with different values of the initial Cu(II) ion concentration, pH, adsorbent dose, and contact time in order to optimize the adsorption process. According to the experimental data presented in this study, the adsorbent synthesized has a high adsorption capacity for copper ions (q_max = 27.32–58.48 mg/g). The alkali treatment of fly ash with NaOH improved the adsorption capacity of the obtained material compared to that of the untreated fly ash. Based on the kinetics results, the adsorption of copper ions onto synthesized material indicated the chemisorption mechanism. Notably, fly ash can be considered an important beginning in obtaining new materials with applicability to wastewater treatment.

The effectiveness of a Fe₃O₄-loaded fly ash composite for the adsorption of Congo red dye was assessed in this work. The structure and properties of the magnetic adsorbent were established by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The magnetic results showed a saturation magnetization value of 6.51 emu/g and superparamagnetic behavior. The main parameters that influence the removal of Congo red dye adsorbent such as dose, initial concentration, and contact time were examined. The Freundlich adsorption isotherm and pseudo-second-order kinetic model provided the best fit for the experimental findings. The Congo red dye’s maximum adsorption capacity of 154 mg/g was reported in the concentration range of 10–100 mg/L, using the proposed magnetic adsorbent. The results of the recyclability investigation demonstrated that the circular economy idea is valid. The adsorbent that was synthesized was also further characterized by XRD and FTIR techniques after Congo red dye adsorption.

Fly ash/magnetite material was used for the adsorption of copper ions from synthetic wastewater. The obtained material was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area, and vibrating sample magnetometer (VSM). Batch adsorption experiments were employed in order to investigate the effects of adsorbent dose, initial Cu (II) concentration and contact time over adsorption efficiency. The experimental isotherms were modeled using Langmuir (four types of its linearization), Freundlich, Temkin, and Harkins–Jura isotherm models. The fits of the results are estimated according to the Langmuir isotherm, with a maximum adsorption capacity of 17.39 mg/g. The pseudo-second-order model was able to describe kinetic results. The data obtained throughout the study prove that this novel material represents a potential low-cost adsorbent for copper adsorption with improved adsorption capacity and magnetic separation capability compared with raw fly ash.

This study investigated the adsorption capacity of one material based on the treatment of fly ash with sodium hydroxide as a novel adsorbent for toxic Cu²⁺ ion removal from aqueous media. The adsorbent was obtained through direct activation of fly ash with 2M NaOH at 90 °C and 6 h of contact time. The adsorbent was characterized by recognized techniques for solid samples. The influence of adsorption parameters such as adsorbent dose, copper initial concentration and contact time was analyzed in order to establish the best adsorption conditions. The results revealed that the Langmuir model fitted with the copper adsorption data. The maximum copper adsorption capacity was 53.5 mg/g. The adsorption process followed the pseudo-second-order kinetic model. The results indicated that the mechanism of adsorption was chemisorption. The results also showed the copper ion removal efficiencies of the synthesized adsorbents. The proposed procedure is an innovative and economical method, which can be used for toxicity reduction by capitalizing on abundant solid waste and treatment wastewater.

The increasing contamination of water bodies by fats, oils, and grease (FOG) poses significant environmental and operational challenges, necessitating the development of advanced remediation technologies. Aerogels, with their ultra-lightweight structure, high porosity, and tunable surface chemistry, have emerged as promising sorbents for efficient FOG removal. This comprehensive review explores recent advancements in aerogel materials, highlighting novel formulations, functional modifications, and nanotechnology integrations that enhance sorption capacity and reusability. It delves into the mechanistic aspects of FOG sorption, providing insights into how surface interactions and structural properties influence performance. The sustainability of aerogels is emphasized, particularly the use of bio-based and eco-friendly materials that align with green remediation strategies. A comparative analysis with conventional sorbents underscores the advantages of aerogels in terms of efficiency, environmental impact, and cost-effectiveness. Furthermore, real-world applications, including oil spill cleanup and wastewater treatment, are discussed alongside challenges, regulatory considerations, and future research directions. By offering a holistic perspective on the potential of aerogels in water remediation, this review serves as a valuable resource for researchers and industry professionals seeking innovative and sustainable solutions for FOG management.