Fly Ash Coated with Magnetic Materials: Improved Adsorbent for Cu (II) Removal from Wastewater

Impact of High-Frequency Traveling-Wave Magnetic Fields on Low-Conductivity Liquids: Investigation and Potential Applications in the Chemical Industry

High-frequency traveling-wave magnetic fields refer to alternating magnetic fields that propagate through space in a wave-like manner at high frequencies. These magnetic fields are characterized by their ability to generate driving forces and induce currents in conductive materials, such as liquids or metals. This article investigates the application and approaches of a unique form of high-frequency traveling-wave magnetic fields to low-conductivity liquids with conductivity ranging from 1 to 102 S/m. Experiments were conducted using four representative electrolytic solutions commonly employed in the chemical industry: sulfuric acid (H2SO4), sodium hydroxide (NaOH), sodium chloride (NaCl), and ionic liquid ([Bmim]BF4). The investigation focuses on the impact of high-frequency magnetic fields on these solutions at the optimal operating point of the system, considering the effects of Joule heating. The findings reveal that the high-frequency traveling magnetic field exerts a significant volumetric force on all four low-conductivity liquids. This technology, characterized by its non-contact and pollution-free nature, high efficiency, large driving volume, and rapid driving speeds (up to several centimeters per second), also provides uniform velocity distribution and notable thermal effects. It holds considerable promise for applications in the chemical industry, metallurgy, and other sectors where enhanced three-phase transfer processes are essential.

An overview of the application of electrocoagulation for mine wastewater treatment

One of the challenges of the twenty-first century is related to the discharge and disposal of mine effluents and wastewater resulting from mine dewatering, precipitation, and surface runoff in mines, especially acidic effluents that contain a variety of toxic and heavy metals and are the main sources of surface and groundwater pollution. Various physical, chemical, and biological methods have been developed and used to treat mine effluents. All proposed methods have their own disadvantages that make their use challenging. One of the new methods used for wastewater treatment is the electrical coagulation process, which has attracted the attention of researchers in recent years due to its advantages such as simplicity, environmental friendliness, and low cost. The present review focused on the applications of electrocoagulation for mine wastewater treatment as well as metals recovery. In addition, the main mechanisms, advantages, and weaknesses of electrocoagulation were reviewed.

Low-Cost RSAC and Adsorption Characteristics in the Removal of Copper Ions from Wastewater

Adsorption is a typical method for treating copper-containing wastewater. Fly ash and steel slag both have a good adsorption performance, and activated clay is added in this study, too. In this study, the performance of residue and soil adsorption composite (RSAC) particles for copper ion adsorption was discussed through the substrate ratio and the influence mechanism, to achieve the win–win effect of industrial waste reuse and copper ion wastewater treatment. The results indicated that adsorption time, dosage, initial copper ion concentration, coexisting ions, and temperature showed different effects on the adsorption, respectively. Additionally, the adsorption kinetic study showed the removal of copper ions by adsorption of RSAC particles was in accordance with quasi-primary kinetic model and quasi-secondary kinetic model. The adsorption thermodynamics study shows the adsorption process of ΔG0 < 0, ΔH0 > 0 and ΔS0 > 0, indicating that the process of copper ion adsorption by RSAC particles was spontaneous, heat-absorbing, and entropy-increasing. The research demonstrates that RSAC particles have a certain adsorption capacity for copper ion.

Recent advances in removal of Congo Red dye by adsorption using an industrial waste

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 Removal of Atrazine and Benalaxyl by the Fly Ash Released from Kosovo A Power Plant

The development of low-cost adsorbent coal FA (Kosovo A) for pesticide removal is an important area of scientific research. With this study, we show the potential of adsorption of coal FA (Kosovo A) for the removal of benalaxyl and atrazine from water. We have found that the amount of adsorbed benalaxyl and atrazine increases with an increasing amount of coal FA (Kosovo A) in solution. The maximum capacity coal FA (Kosovo A) to adsorb benalaxyl and atrazine was found to be 0.46 and 0.45 mg/g according to the Freundlich equation and 3.48 and 3.33 mg/g according to the Langmuir equation. The Freundlich adsorption equation better explains the adsorption results of pesticides (benalaxyl and atrazine) in coal FA (Kosovo A), as the values of the recovery coefficient (R2) were higher in Freundlich equation than the Langmuir equation. The adsorption isotherms were of type L and show that the adsorption efficiency of the coal FA (Kosovo A) depends on the initial concentration of benalaxyl and atrazine in solution and the maximum removal of benalaxyl and atrazine was achieved at concentrations less than 10 µg/ml. This study’s results are expected to have implications for the use of coal FA (Kosovo A) for the removal of pesticides from water.

Using Fly Ash Wastes for the Development of New Building Materials with Improved Compressive Strength

Fly ash wastes (silica, aluminum and iron-rich materials) could be smartly valorized by their incorporation in concrete formulation, partly replacing the cement. The necessary binding properties can be accomplished by a simple procedure: an alkali activation process, involving partial hydrolysis, followed by gel formation and polycondensation. The correlations between the experimental fly ash processing conditions, particle characteristics (size and morphology) and the compressive strength values of the concrete prepared using this material were investigated by performing a parametric optimization study to deduce the optimal processing set of conditions. The alkali activation procedure included the variation of the NaOH solutions concentration (8–12 M), temperature values (25–65 °C) and the liquid/solid ratio (1–3). The activation led to important modifications of the crystallography of the samples (shown by powder XRD analysis), their morphologies (seen by SEM), particle size distribution and Blaine surface values. The values of the compressive strength of concrete prepared using fly ash derivatives were between 16.8–22.6 MPa. Thus, the processed fly ash qualifies as a proper potential building material, solving disposal-associated problems, as well as saving significant amounts of cement consumed in concrete formulation.

Removal of Toxic Copper Ion from Aqueous Media by Adsorption on Fly Ash-Derived Zeolites: Kinetic and Equilibrium Studies

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.

Fabrication and Application of Zeolite/Acanthophora Spicifera Nanoporous Composite for Adsorption of Congo Red Dye from Wastewater

Systematic investigations involving laboratory, analytical, and field trials were carried out to obtain the most efficient adsorbent for the removal of congo red (CR) dye from industrial effluent. Modification of the zeolite (Z) by the Acanthophora Spicifera algae (AS; marine algae) was evaluated in terms of adsorption capability of the zeolite to remove CR dye from aqueous solution. The zeolite/algae composite (ZAS) was fabricated using the wet impregnation technique. The AS, Z, and the synthesized ZAS composite were analyzed utilizing various characterization techniques. The newly synthesized ZAS composite has an adsorption capacity that is significantly higher than that of Z and AS, particularly at low CR concentrations. Batch experiments were carried out to explore the effects of different experimental factors, as well as the dye adsorption isotherms and kinetics. Owing to the presence of intermolecular interactions, the computational analysis showed that the adsorption of the CR molecule on zeolite surfaces is exothermic, energetically favorable, and spontaneous. Furthermore, growing the zeolite surface area has no discernible effect on the adsorption energies in all configurations. The ZAS composite may be used as a low-cost substitute adsorbent for the removal of anionic dyes from industrial wastewater at lower dye concentrations, according to the experimental results. Adsorption of CR dye onto Z, AS, and ZAS adsorbents was adequately explained by pseudo-second-order kinetics and the Langmuir isotherm. The sorption mechanism was also evaluated using Weber's intra-particle diffusion module. Finally, field testing revealed that the newly synthesized adsorbent was 98.0% efficient at extracting dyes from industrial wastewater, proving the foundation of modern eco-friendly materials that aid in the reuse of industrial wastewater.

High Efficiency of the Removal Process of Pb(II) and Cu(II) Ions with the Use of Fly Ash from Incineration of Sunflower and Wood Waste Using the CFBC Technology

In these research studies, fly ash (SW-FA) resulting from the incineration of sunflower (20%) and wood (80%) waste employing the circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Pb(II) and Cu(II) ions in adsorption processes. Currently, great emphasis is placed on circular economy, zero waste or climate neutrality strategies. The use of low-cost SW-FA waste seems to fit well with pro-ecological, economic and energy-saving trends. Hence, this material was characterized by various techniques, such as granulation analysis, bulk density, SEM-EDX, XRD and XRF analysis, BET, BJH, thermogravimetry, zeta potential, SEM morphology and FT-IR spectrometry. As a result of the conducted research, the factors influencing the effectiveness of the adsorption process, such as adsorbent dosage, initial and equilibrium pH, initial metal concentration and contact time, were analyzed. The maximum removal efficiency were achieved at the level of 99.8% for Pb(II) and 99.6% for Cu(II), respectively. The kinetics analysis and isotherms showed that the pseudo-second-order equation and the Freundlich isotherm models better describe these processes. The experiments proved that SW-FA can act as an appropriate adsorbent for highly effective removal of lead and copper from wastewater and improvement of water quality.

Magnetic Solid-Phase Extraction of Cadmium Ions by Hybrid Self-Assembled Multicore Type Nanobeads

Novel hybrid inorganic CoFe₂O₄/carboxymethyl cellulose (CMC) polymeric framework nanobeads-type adsorbents with tailored magnetic properties were synthesized by a combination of coprecipitation and flash-cooling technology. Precise self-assembly engineering of their shape and composition combined with deep testing for cadmium removal from wastewater are investigated. The development of a single nanoscale object with controllable composition and spatial arrangement of CoFe₂O₄ (CF) nanoparticles in carboxymethyl cellulose (CMC) as polymeric matrix, is giving new boosts to treatments of wastewaters containing heavy metals. The magnetic nanobeads were characterized by means of scanning electron microscopy (SEM), powder X-ray diffraction analysis (XRD), thermogravimetric analysis (TG), and vibrational sample magnetometer (VSM). The magnetic properties of CF@CMC sample clearly exhibit ferromagnetic nature. Value of 40.6 emu/g of saturation magnetization would be exploited for magnetic separation from aqueous solution. In the adsorptions experiments the assessment of equilibrium and kinetic parameters were carried out by varying adsorbent dosage, contact time and cadmium ion concentration. The kinetic behavior of adsorption process was best described by pseudo-second-order model and the Langmuir isotherm was fitted best with maximum capacity uptake of 44.05 mg/g.