The growing dependence on desalination for freshwater production has led to a significant increase in rejected brine generation, creating critical environmental concerns due to its high salinity and temperature. Discharging such brine into marine environments disrupts osmotic balance, leading to cell dehydration and ecological damage. Conventional disposal methods, including deep-well injection, evaporation ponds, and sewage discharge, remain costly and environmentally unsustainable. Meanwhile, the global demand for carbon fiber--reinforced plastics (CFRPs) has expanded rapidly owing to their superior strength-to-weight ratio, corrosion resistance, and thermal stability, resulting in large volumes of non-biodegradable carbon fiber waste. This study introduces an innovative approach that simultaneously addresses brine management, carbon fiber waste utilization, and COQ capture. Waste carbon fibers were recycled through pyrolysis, followed by mechanical and chemical activation using alkaline and acidic treatments to enhance surface area and adsorption performance. The treated fibers were applied in a bubble reactor containing a brine-air mixture, enabling efficient salt adsorption and recovery. Mechanical cryogenic grinding increased surface roughness and adsorption capacity, while chemical treatment introduced new functional groups that improved ion affinity. Salt recovery efficiency was determined based on the fiber mass change before and after treatment, achieving a maximum recovery of 92.9% for NaOH-treated fibers and a minimum of 36.4% for untreated samples. Overall, the developed process demonstrates a promising and sustainable pathway for utilizing waste carbon fibers in effective brine treatment and COQ sequestration applications.

This study presents an integrated physical-chemical approach for brine desalination, carbon dioxide (CO2) capture, and the production of high-performance sulfur concrete (SC) utilizing industrial by-products. A novel aqueous carbonation process was developed, in which carbide lime waste (CLW), a highly alkaline byproduct of acetylene production, reacts with CO2 and desalination brine salts under optimized hydrodynamic and thermodynamic conditions. The process simultaneously reduces brine salinity, sequesters CO2 as stable carbonates, and yields solid products enriched in CaCO3 and NaHCO3. Thermodynamic analysis confirmed the spontaneous and exothermic carbonation over the temperature range of 10-90 degrees C, while Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy characterized the morphology, crystallinity, and functional groups of the recovered solids. These carbonated brine salts were incorporated as aggregates in molten sulfur matrices to produce SC with compressive, tensile, and flexural strengths of 60 MPa, 4 MPa, and 12 MPa, respectively, surpassing the benchmarks of Portland cement concrete (PCC). SC exhibited low porosity (1.569%) and moisture absorption (0.17%), with SEM confirming dense microstructural integration and Raman analysis verifying the incorporation of CaCO3. This waste-to-resource methodology couples carbonation chemistry with sustainable material synthesis, offering a scalable pathway for CO2 sequestration, brine management, and the production of durable, water-free construction materials suitable for harsh environments.

Alkaline-based carbonation technologies have emerged as versatile platforms for CO₂ capture, mineralization, and resource recovery in response to the growing demand for low-carbon industrial processes and sustainable brine management. This review provides a comprehensive, cross-disciplinary synthesis of chemical, electrochemical, catalytic, and materials-based innovations in next-generation alkaline carbonation systems, including modified Solvay-based processes, for CO₂ capture, brine desalination, and resource recovery. These systems encompass electrochemically regenerated alkalinity, waste-derived alkaline reagents, hybrid carbonation–electro conversion pathways, and catalytic carbonation strategies. The review examines different alkalinity sources, electrochemical pathways, and advanced materials, focusing on their roles in improving process efficiency and selectivity. Electrochemical approaches are highlighted for their ability to generate alkalinity in situ and reduce reliance on external chemical inputs. Recent material innovations further expand the technological scope and improve system performance.CO₂ capture efficiencies and effective ion removal have been reported across various system configurations. System performance is strongly influenced by operating conditions, energy inputs, and scalability constraints. These systems also enable resource recovery and support circular economy approaches. Collectively, this review consolidates fragmented progress into a unified framework, identifying the key bottlenecks, scaling considerations, mechanistic insights, and techno-economic trends that will shape next-generation alkaline carbonation systems. The findings position the modified Solvay process as a versatile, industrially relevant, and environmentally aligned platform capable of advancing global CO₂ mitigation and sustainable brine management. These findings highlight key trade-offs between efficiency, energy demand, and long-term stability.

Seawater desalination has grown significantly in recent years to meet the escalating freshwater demand. Reverse osmosis (RO), the predominantly used technology, has proven to be the most competitive among technologies; however, its effectiveness is highly dependent on pretreatment performance. Pretreatment, a key stage in seawater reverse osmosis (SWRO) plants, plays a major role in maintaining the desired quality upstream of RO systems. Dissolved air flotation (DAF) is widely adopted to mitigate the impact of algal blooms and protect downstream processes against elevated turbidity and suspended solids peaks. In this context, key considerations arise regarding when DAF is justified as a pretreatment option in SWRO, how it is configured and operated in practice, and what gaps hinder confident techno-economic selection. The integration of DAF into SWRO plants has demonstrated regional impact in large-scale SWRO plants. This work provides a comprehensive overview of the DAF system, including operational mechanism, design principles, key performance indicators, commercial aspects, and applications in pilot- and lab-scale systems and highlights its role in operating SWRO plants while identifying key technology providers. Overall, this review offers a focused evaluation of DAF for SWRO pretreatment, where standalone assessment remains limited despite increasing adoption in practice and ongoing research efforts worldwide.

This study presents a novel eco-smart composite fabricated entirely from recycled PLA waste, reclaimed aerospace-grade carbon fibers, and multifunctional inorganic fillers recovered from desalination brine. Brine-derived salts were obtained via an electrocoagulation-modified Solvay hybrid process and incorporated into a PLA matrix containing 10 wt% carbon fibers and 1-5 wt% mineral fillers. Composites were produced through melt compounding and injection molding and evaluated for mechanical, thermal, acoustic, moisture, and fire performance. The optimized 85% PLA-10% CF-5% brine formulation achieved a thermal resistance of 5.59 m center dot K/W (thermal conductivity: 0.179 W/(m center dot K)), alongside an 88% reduction in water absorption (0.086%) compared with neat PLA. Fire performance improved significantly, reaching a UL-94 V-2 rating and a limiting oxygen index (LOI) of 26%. TGA revealed enhanced thermal stability and increased char yield, with residual mass rising from similar to 1.2 wt% for neat PLA to similar to 5.3 wt% at 700 degrees C. FTIR analysis confirmed filler incorporation primarily through physical interfacial interactions. Acoustic testing showed a peak absorption coefficient of 0.93 at 2 kHz. Tensile properties improved up to 3 wt% brine loading, beyond which filler agglomeration reduced uniformity. This triple-waste composite demonstrates a scalable circular-economy pathway for sustainable, multifunctional building materials. [GRAPHICS] .

This study presents a novel approach for integrating hydroxyethyl cellulose (HEC) into a sustainable framework targeting three major challenges: brine treatment, carbon dioxide (CO2) capture, and enhanced oil recovery (EOR). Utilizing a modified Solvay process within an inert particle-spouted bed reactor, the research investigates the physicochemical interactions of HEC with high-salinity brine and CO2 gas under controlled experimental conditions. The incorporation of HEC significantly improved CO2 capture efficiency, reaching a maximum of 99.2 %, by enhancing carbonate precipitation and facilitating mass transfer between gaseous and aqueous phases. Simultaneously, HEC contributed to brine desalination by promoting ionic complexation and selective precipitation, achieving up to 32.4 % reduction in total salinity. Experimental measurements showed a significant reduction in brine ion concentrations including magnesium (Mg2+), and calcium (Ca2+) further validating the ionexchange and precipitation mechanisms facilitated by the process. In addition to water treatment and gas capture capabilities, HEC-treated brine exhibited favourable interfacial tension properties. Core flooding and interfacial tension measurements demonstrated that HEC could enhance oil recovery by up to 65 % due to its ability to alter wettability and stabilize displacement fronts in porous media. These combined results highlight the multifunctionality of HEC as a bio-derived, biodegradable additive that not only addresses environmental challenges associated with brine disposal and greenhouse gas emissions but also contributes to resource recovery in petroleum operations. The outcomes support the feasibility of integrating HEC into circular economy models that connect water treatment, climate mitigation, and energy recovery. This work lays the foundation for scaling up bio-polymer-enhanced desalination and carbon capture systems for real-world applications.

Agricultural residues from date palms and alkaline by-products from steelmaking are abundant yet underutilised wastes. This study couples both streams to produce functional adsorbents via a fully aqueous, low-energy activation: date-palm biochar is treated directly with minimally processed leachates from five steel residues (baghouse dust, ladle-furnace slag, cyclone dust, electric-arc-furnace slag, and carbide-lime slurry). Temperature-controlled adsorption tests (35–61 °C) assessed thermodynamic behaviour and its influence on kinetics and capacity at environmentally relevant, dilute methylene blue (MB) levels (≈5–21 mg L⁻¹). Kinetics follow pseudo-second-order (R² > 0.98), confirming chemisorption-dominated uptake. Under identical conditions, slurry- and EAF-activated carbons achieved the highest removals (~64% and ~58%), surpassing untreated biochar (~55%). Equilibrium data (400 min, 25 °C) fit Langmuir > Freundlich models, while pH ≈ 9 optimised uptake and finer fractions (38–150 µm) enhanced rates. SEM/FTIR/XRD revealed mesoporous textures and surface functionalities (–OH/–COO⁻ and metal–oxygen motifs) linked to leachate chemistry. A harmonised workflow connects ionic composition (K⁺/Na⁺/Mg²⁺-rich vs. Ca²⁺-dominant leachates) to activation strength and performance. This proof-of-concept demonstrates dual-waste valorisation yielding reproducible dye removal without added acids/bases or high-temperature calcination, offering a foundation for scalable, circular water treatment integrating regeneration and life-cycle assessment.

Polycarbonates are a flexible and transparent thermoplastic, have become indispensable in our everyday lives due to its outstanding qualities. This introduction sets the ground for an investigation of catalytic improvements in polycarbonate blends by highlighting their distinctive qualities, benefits over materials like polymethyl methacrylate (PMMA), and compatibility with other polymers. With exceptional physical and chemical properties, polycarbonates outperform PMMA in terms of heat tolerance and impact resistance. When combined with other polymers, they gain even more value, helping sectors like optical media and safety devices. In order to improve polycarbonate blends, speed up processes, and increase material stability, catalysts are essential. In this work, catalytic reactions in polycarbonate blends with PET, PLA, PBT, PMMA, ABS, LCP and PVC are examined. Understanding these systems enables the development of novel materials with the potential to enhance a variety of industries. In the next years, these catalysts are set to bring about profound changes to many leading industries.

This study presents a sustainable approach for synthesizing activated biochar (BC) from date palm waste and enhancing its carbon dioxide (CO2) capture capacity through integration with industrial alkaline waste, particularly ladle furnace slag (AW-LF). BC was produced via pyrolysis at 450 °C, 600 °C, and 750 °C and chemically activated using potassium carbonate (K2CO3) and hydrogen peroxide (H2O2). The materials were tested under CO2 gas flow (10 % CO2, 0.6 L/min, 1-2 bar, 22-25 °C) using a fluidized bed reactor. The highest CO2 capture capacity reached 0.94 mmol/g with H2O2-modified BC at a 10 % BC-to-AW-LF ratio. The cumulative CO2 uptake reached a maximum of 13.4 mol/L with K2CO3-activated BC, demonstrating approximately a 380 % increase compared to the performance of unmodified AW-LF slag. Kinetic analysis confirmed the modified Avrami model as the best fit (R2 > 0.99), with the highest rate constant (Kma = 0.0118) observed for H2O2-treated samples. The findings were validated through X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA), confirming stable CaCO3 formation and enhanced porosity. Preliminary TGA results suggest up to 8 % weight loss due to CO2 binding, confirming carbonation. The developed adsorbent is cost-effective, scalable, and derived from abundant agricultural and industrial wastes, supporting the circular economy and low-carbon technologies. A preliminary economic assessment estimated the cost of producing 100 g of hydrogen peroxide-modified BC at 6.6 AED (∼1.80 USD), highlighting its feasibility for large-scale applications.

Appropriate management of fermentation residues which comprise valuable components, such as nutrients, organic compounds, and energy-rich molecules minimizes the reliance on new raw materials and promotes circular economy principles. In this study, fermented date fruit pomace, a solid residue after the lactic acid fermentation of date fruit pomace is converted to a bioadsorbent for sulfate removal from high-salinity rejected brine, which is a major challenge for desalination plants; the high sulfate content in brine creates environmental issues. Brine with high sulfate content accelerates the corrosion of pipelines, equipment, and metal structures, resulting in increased maintenance costs, safety risks, and potential leaks. The proposed process converts the fermented date fruit pomace to activated carbon using sodium hydroxide. Sulfate removal of 90.9

In this study, we investigate the preliminary effect of bovine carbonic anhydrase (BCA) catalyst on CO2 capture via a reaction with potassium hydroxide (KOH) and reject brine under different operational conditions. Experiments were performed at a constant gauge pressure of 2 bar, with a CO2 inlet concentration of 10% and a CO2 flow rate of 776 mL/min. First, the impact of the BCA catalyst on CO2 capture in the absence of the alkaline material (KOH) was studied. Results showed that using 3-mg/L BCA increases the CO2 capture by 181% compared with the case without BCA. Second, the effect of BCA on CO2 uptake and ions reduction was examined in the presence of KOH. At a KOH concentration of 10-g/L, BCA concentration of 50-mg/L, and temperature of 40℃, a CO2 uptake value of 0.08 g CO2/g KOH was obtained. In comparison, adding 30-g/L KOH and 50-mg/L BCA increased the CO2 uptake by 737.5% (0.67 g CO2/g KOH). Furthermore, the sodium (Na+) reduction percentage reached a maximum of 40.8% at KOH and BCA concentrations of 30 g/L and 50 mg/L, respectively. However, increasing the BCA concentration to 100 mg/L negatively impacted CO2 capture and ion removal, indicating that the BCA concentration could be better optimized to achieve maximum efficiency. Additionally, when the BCA concentration was increased from 50 to 100 mg/L, the reaction rate remained nearly constant at 0.0047 mol/L·min.

The transition to a clean-energy economy in an effort to mitigate climate change has brought a need for intense mining exploration of a critical class of minerals, previously mined and used at a fraction of what is required today and for the upcoming decades. For some common metals, such as copper, major deficits are forecasted for 2030, and for some less common ones, such as rare earths, mined quantities have recently increased 32 times relative to those in the mid-1950s and are expected to increase sevenfold from current levels by 2040. This situation is expected to become more severe given the long time span needed for exploration of new sites, the declining ore grade of existing mines, the geographical distribution of these minerals and the environmental degradation caused by mining and mineral processing activities. It becomes, hence, critical to improve existing mining operations vastly, reduce waste volumes and fresh water use, reduce environmental impacts and recover increased quantities of minerals from mine tailings, as well as from the recycling of post-production products. This paper focuses on copper and rare earths to expound on their exploitation issues, their processes, the sustainable utilisation of mineral waste and tailings and their recovery from end-of-life consumer and industrial items.

This study explores gas-solid contact systems, specifically fluidized beds, crucial in various industries. The focus is understanding their 3D model, hydrodynamics, and particle interactions among changing gas flow conditions. Utilizing a Computational Fluid Dynamics (CFD) model with the Eulerian method, the research navigates the complexities of multiphase and turbulent flows. The approach employs distinct equations for each phase, facilitating interaction within the computational domain. Turbulence effects are incorporated through the realizable k-epsilon model, known for its precision in representing turbulent behaviors in multiphase flow. The investigation investigates the complex interactions between phases using the continuity equation, emphasizing mass conservation with mass transfer terms capturing substance movement between phases. The Discrete Phase Model (DPM) is integral in understanding particle behavior, employing massless inert particles for targeted insights into system behavior and gas-solid interaction. Observations reveal that introduced particles have a limited impact on pressure dynamics, a crucial aspect of reactor design and optimization. The study explores the influence of varying gas and particle velocities on system pressure, turbulence kinetic energy, and particle distribution within the reactor. Results show minimal effects on pressure dynamics due to changes in particle velocity, with system pressure ranging from 0.33 Pa at the lowest air velocity of 0.5 m/s to 12.08 Pa at the highest air velocity of 3 m/s, establishing a nearly linear relationship between air velocity and pressure. The research extends to experimental validation, showing commendable agreement with computational findings. While empirical investigations are in preliminary stages, they promise further research optimization. This study provides a comprehensive understanding of gas-solid contact systems, emphasizing the importance of precise control over air and particle velocities for optimal system performance. The findings carry practical implications across diverse industrial applications and suggest avenues for continued research and development.

This study explores gas-solid contact systems, specifically fluidized beds, crucial in various industries. The focus is understanding their 3D model, hydrodynamics, and particle interactions among changing gas flow conditions. Utilizing a Computational Fluid Dynamics (CFD) model with the Eulerian method, the research navigates the complexities of multiphase and turbulent flows. The approach employs distinct equations for each phase, facilitating interaction within the computational domain. Turbulence effects are incorporated through the realizable k–ε model, known for its precision in representing turbulent behaviors in multiphase flow. The investigation investigates the complex interactions between phases using the continuity equation, emphasizing mass conservation with mass transfer terms capturing substance movement between phases. The Discrete Phase Model (DPM) is integral in understanding particle behavior, employing massless inert particles for targeted insights into system behavior and gas-solid interaction. Observations reveal that introduced particles have a limited impact on pressure dynamics, a crucial aspect of reactor design and optimization. The study explores the influence of varying gas and particle velocities on system pressure, turbulence kinetic energy, and particle distribution within the reactor. Results show minimal effects on pressure dynamics due to changes in particle velocity, with system pressure ranging from 0.33 Pa at the lowest air velocity of 0.5 m/s to 12.08 Pa at the highest air velocity of 3 m/s, establishing a nearly linear relationship between air velocity and pressure. The research extends to experimental validation, showing commendable agreement with computational findings. While empirical investigations are in preliminary stages, they promise further research optimization. This study provides a comprehensive understanding of gas-solid contact systems, emphasizing the importance of precise control over air and particle velocities for optimal system performance. The findings carry practical implications across diverse industrial applications and suggest avenues for continued research and development.

Previous studies have investigated the overall performance of the modified Solvay process based on calcium oxide (CaO). In the modified process, calcium oxide (CaO) is reacted with brine salts and carbon dioxide. The results confirmed its effectiveness in capturing CO2 and managing reject brine in a single reaction. However, more attention is needed to overcome the low sodium (Na+) removal efficiency, which does not exceed 35 %. Therefore, the main objective of this research work to develop a novel technique where reject brine is passed through a total of seven stages. In each stage, a specific metal ion is recovered. In the first stage, a 100 % recovery of magnesium ions in the form of magnesium hydroxide solid was obtained by chemical reaction with ammonia (NH3) solution. Then, in the second stage, the ammoniated brine was treated based on the traditional Solvay process, where Na+ reduction, in the form of sodium bicarbonate (NaHCO3), and CO2 uptake reached almost 32.97 % and 37 g of CO2/1000 ml of treated brine, respectively. In the third stage, the electrocoagulation process (EC) was used to recover the sulfate ions (SO42-) in the form of pure calcium sulfate solid and also for the regeneration of NH3 as ammonium hydroxide leading to a total reduction of 96.5 % for SO42- ions. In the fourth stage, CaO was added to the treated brine according to the modified Solvay process. Reductions of 37.98 % and 27.97 % in Na+ and chloride (Cl) ions were achieved, respectively. In stage 5, more recovery of NaHCO3 was attained by adding ammonium bicarbonate, while in stage 6, the treated brine mixture was passed through a second modified Solvay process. The CO2 uptake reached up to 60 g of CO2/1000 ml. In addition, Na+, Ca2+, K+, and Cl removal was improved with 47.22 %, 56.33 %, 72.12 % and 34.41 %, respectively. In the last stage, the treated brine was inserted into the second EC process to recover CaCl2 solution and NH3 compounds. The overall reductions of for Na+, Ca2+, K+, and Cl were 51 %, 93.59, 79 %, and 43.63 %, respectively. Moreover, solid products from each stage were characterized using SEM, XRD, FTIR, and Raman analyses. The products of each stage have diverse industrial applications.

This study addresses the effect of storing carbon dioxide conditions using industrial hydrated lime on the produced calcium carbonate morphology and particle size. The investigated carbonation conditions were carbonation reaction temperature and initial pH. The structural and chemical characteristics of the produced calcium carbonate sample were investigated using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and Raman spectroscopy. The results indicated that all carbonated products exhibited a calcite crystal structure, but with specific morphologies dependent on the carbonation conditions. A high carbonation reaction temperature promoted scalenohedral morphology, while lower temperatures promoted submicrometric elongated agglomerates and truncated prismatic morphology. The initial pH of the carbide lime mixture also significantly affected the morphology; the formation of a rhombohedral morphology was obtained at a pH value of 10.9, and the presence of rhombohedral and submicrometric elongated agglomerates was determined at pH values of 11.75 and 12.7, respectively.

The increasing global demand for potable water has led to the increase of desalination plants. However, desalination processes, especially reverse osmosis and multi-stage flash distillation, produce large quantities of reject brine, a highly concentrated saline byproduct. This highly saline waste presents significant environmental challenges due to its potential to harm marine ecosystems, disrupt aquatic life, and degrade water quality when discharged into the ocean when discharged into the sea. This study explores the feasibility of transforming reject brine into a sustainable lightweight construction material. Through a series of initial experimental processes, reject brine was chemically treated, coated with plastic waste, and combined with lightweight aggregate to produce a lightweight material suitable for construction. Initial results indicate that the treated brine-based material exhibits promising characteristics and mechanical properties, including adequate compressive strength, reduced density, and good durability. This makes it a viable and economical alternative to traditional construction materials. This approach mitigates the environmental impact of desalination, reduces the construction industry’s carbon footprint, and contributes to the development of sustainable construction practices. Future research should focus on scaling up the production process, conducting long-term performance evaluations, and assessing the economic viability of this approach to facilitate its adoption in real-world applications.

Soda ash (Na2CO3) is produced using the traditional Solvay process. It entails the reaction of CO2 with high-salinity water in the presence of ammonia (NH3), which produces insoluble sodium bicarbonate (NaHCO3) and soluble ammonium chloride (NH4Cl). In the current work, a newly combined approach has been developed to effectively manage the removal of ammonia and sulfate from the effluent of the Solvay process. The devised technique centers on an electrochemical coagulation process, complemented with the utilization of calcium oxide (CaO) as a buffering reagent. This innovative approach excels at achieving high recovery rates for both ammonia and sulfate. The recovered ammonia holds the potential for recycling, thereby contributing to the sustainability of the Solvay process by reusing ammonia in its initial stages. Furthermore, sulfate ions are recuperated in the form of calcium sulfate, a value-added product boasting various industrial applications. The results gleaned from this study underscore the efficacy of the ammonia recovery process, particularly when operating at elevated current densities and with higher calcium oxide concentrations. On the other hand, sulfate recovery demonstrates superior performance when exposed to moderate current densities and limited calcium oxide concentrations. Consequently, the integration of both stages within a single, cohesive process necessitates the development of an optimization methodology to cater to varying operational conditions. To address this need, second-order polynomial equations were formulated and employed to anticipate ammonia and sulfate removal rates in the integrated approach. Four independent variables come into play: calcium oxide concentration, current density, temperature, and mixing rate. The findings reveal that most of these variables exert substantial influences on both ammonia and sulfate removal rates, underscoring the need for careful consideration and fine-tuning to optimize the overall process. The maximum ammonia and sulfate removal were found to reach 99.50% and 96.03%, respectively, at a calcium oxide concentration of 3.5 g/100 mL, a current density of 19.95 mA/cm2, a temperature of 35 °C, and a mixing rate of 0.76 R/s. The results are promising, and the developed process is also suitable for recovering high concentrations of sulfate and ammonia from various wastewater sources.