Search Results (2,236)

Temperature Swing Absorption (TSA) is the primary candidate for the Isotope Rebalancing and Protium Removal (IRPR) system within the envisioned EU-DEMO fusion reactor fuel cycle. TSA separates a mixed hydrogen isotope stream into two product streams using a semi-continuous process. One stream, enriched in heavy isotopes, is used to re-establish the required deuterium-to-tritium fuel ratio. The second, enriched in protium, is stripped off from the fuel cycle to counteract the protium build-up. Separation is achieved by cycling an isotope mixture between two columns filled with metallic absorption materials that have opposite isotope effects of metal hydride formation. The selection of these materials, the operation parameters and the column geometry allow for adjusting the resulting enrichments. To identify suitable operation parameters, a TSA process model is developed which depicts the process dynamics and interactions between the columns. A modified process operation mode is introduced, which enables higher system throughputs and non-cryogenic operation, i.e., operational temperatures between 0 to 130 °C, while reducing the tritium inventory due to shorter cycling times by reduced amplitudes of the temperature swings. Finally, simulations of a TSA system at relevant scale confirm the suitability of TSA technology for the separation task of the EU-DEMO IRPR system. Full article

Developing sustainable and molecularly selective adsorbents for heavy-metal removal remains a critical challenge in water purification. Herein, we report a green molecular-engineering approach for fabricating aza-crown ether functionalized sodium alginate aerogels (ACSA) capable of highly selective Cu²⁺ capture. The aerogels were synthesized via saccharide-ring oxidation, Cu²⁺-templated self-assembly, and reductive amination, enabling the covalent integration of aza-crown ether motifs within a hierarchically porous biopolymer matrix. Structural analyses (FTIR, ¹³C NMR, XPS, SEM, TGA) confirmed the in situ formation of macrocyclic N/O coordination sites. Owing to their interconnected porosity and chemically stable framework, ACSA exhibited rapid sorption kinetics following a pseudo-second-order model (R² = 0.999) and a Langmuir maximum adsorption capacity of 150.82 mg·g⁻¹. The material displayed remarkable Cu²⁺ selectivity over Zn²⁺, Cd²⁺, and Ni²⁺, arising from the precise alignment between Cu²⁺ ionic radius (0.73 Å) and crown-cavity dimensions, synergistic N/O chelation, and Jahn-Teller stabilization. Over four regeneration cycles, ACSA retained more than 80% of its original adsorption capacity, confirming excellent durability and reusability. This saccharide-ring modification strategy eliminates crown-ether leaching and weak anchoring, offering a scalable and environmentally benign route to bio-based adsorbents that combine molecular recognition with structural stability for efficient Cu²⁺ remediation and beyond. Full article

Heavy metals are major toxic anthropogenic contaminants released into the environment mainly through wastewater discharges. Adsorption is one of the most effective and widely applied methods for their removal from aqueous systems. However, although activated carbon is commonly used, its high cost and limited regenerability motivate the search for cheaper and more environmentally friendly alternatives. In this study, selected natural and waste-derived materials were evaluated for Cu²⁺ removal from both model solutions and atypical textile wastewater. Coffee grounds, chestnut seeds, acorns, potato peels, eggshells, marine shells, and poultry bones were tested and compared with commercial activated carbon. Their structural and functional properties were characterised using specific surface area measurements, optical microscopy, SEM-EDS, and FTIR analyses. Two adsorption isotherm models (Langmuir and Freundlich) were used to analyse the experimental data for the selected adsorbents, and model parameters were determined by linear regression. Based on model solution tests, two materials showed the highest Cu²⁺ sorption potential: coarse poultry bones (97.0% at 24 h) and fine cockle shells (96.2% at 24 h). When applied to real textile wastewater, the bone-derived material achieved the highest Cu²⁺ removal efficiency (79.4%). Although this efficiency is lower than typical values obtained in laboratory solutions, it demonstrates the feasibility of waste-derived materials as low-cost adsorbents and suggests that further optimisation could further improve their performance. Full article

Pb²⁺ and Cd²⁺ represent common heavy metal contaminants in aquatic environments, posing significant risks to ecosystem stability and human health. To develop efficient adsorbents for removing Cd²⁺ and Pb²⁺ while achieving resource utilization of industrial by-products (red mud and distiller’s grains), this study synthesized a novel composite biochar—red mud–Lactobacillus plantarum composite biochar (RM)—by immobilizing red mud and Lactobacillus plantarum onto biochar derived from distiller’s grains. The structural and chemical properties of RM were characterized using SEM-EDS, XRD, and FTIR. Batch adsorption experiments were conducted to evaluate the effects of various experimental factors on Cd²⁺ and Pb²⁺ adsorption. The adsorption process was further elucidated through kinetic and isothermal models, revealing that it follows the pseudo-second-order kinetic model. Equilibrium data were best described by the Langmuir model for Cd²⁺ and the Freundlich model for Pb²⁺. The maximum adsorption capacities reached 12.13 mg/g for Cd²⁺ and 130.10 mg/g for Pb²⁺. The primary mechanisms involved in Cd²⁺ and Pb²⁺ adsorption by RM include surface complexation, cation–π interactions, ion exchange, and coprecipitation. These findings demonstrate that RM represents a promising and effective adsorbent for the remediation of heavy metal-contaminated water. Full article

Floods and wildfires are two extreme environmental events with significant yet different impacts on soil health and on two particularly important soil pollutants, heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs), which are directly associated with ishytoxic properties and their ability to enter the food chain. The present study includes a methodological approach that was based on a literature review of published studies conducted worldwide regarding these two phenomena. The main forms of both pollutants, their possible sources and inevitable deposition onto the soil surface, along with their behavior–transport–mobility, and their residence time in soil were investigated. Furthermore, the changes that both HMs and PAHs induce in the physicochemical properties of post-flood and post-fire soils (in soil pH, Cation Exchange Capacity (CEC), organic matter content, porosity, mineralogical alterations, etc.), are investigated after a literature review of various case studies. Wildfires, in contrast to floods, can more easily remove large quantities of heavy metals into the soil ecosystem, most likely due to the intense erosion they cause. At the same time, floods appear to significantly burden soils with PAHs. In wildfires, the largest mean increases were observed for Mn (386%), Zn (300%), and Cu (202%). In floods, Pb showed the highest mean increase (534%), with Cd also rising substantially (236%). Regarding total PAHs, mean post-event concentrations reached 482.3 μg/kg after wildfires, compared to 4384 μg/kg after floods. Changes in the structure and chemical composition of flooded and burned soils may also affect the mobility and bioavailability of the pollutants under study. Overall, these two phenomena significantly alter soil quality, affecting both ecological processes and potential health impacts. Full article

Urease-producing bacteria (UPB) have great potential for the bioremediation of heavy-metal pollution through biomineralization and adsorption. In this study, a strain of UPB, C7-12, was isolated from heavy-metal-contaminated soil in a lead–zinc mining area and identified as Serratia marcescens. The heavy-metal removal ability, influencing factors, and precipitation mode of this UPB strain in solution were investigated. The cadmium (Cd) removal rate in a Cd (1 mg/L) solution from C7-12 reached 85%, and pH was the main influencing factor. With urea mediation, S. marcescens C7-12 biomineralizes the Cd²⁺ in solution to form CdCO₃ and removes it through extracellular precipitation and surface adsorption. Furthermore, the removal rates of Cd²⁺, Pb²⁺, Zn²⁺ and Cu²⁺ in solution by S. marcescens C7-12 were 33–65%, 28–32%, 22–49%, and 38–44%, respectively. The precipitation mode involves coprecipitation of multiple heavy metals to form a mineral. These heavy metals are adsorbed on the surface of bacteria through the participation of carboxyl, amino, and phosphate functional groups and extracellular polymeric substances. Therefore, S. marcescens C7-12 has strong biomineralization and adsorption capacity for heavy-metal ions in solution, which can provide potential resources for the bioremediation of heavy-metal-contaminated soil and water. Full article

Soil co-contamination with cadmium (Cd) and zinc (Zn) poses serious threats to environmental safety and public health. This study investigates the enhancement effect and underlying mechanism of the biodegradable chelator Ethylenediamine-N,N′-disuccinic acid (EDDS) on phytoremediation of Cd-Zn contaminated soil using Sedum lineare. The results demonstrate that EDDS application (3.65 g·L⁻¹) effectively alleviated metal-induced phytotoxicity by enhancing chlorophyll synthesis, activating antioxidant enzymes (catalase and dismutase), regulating S-nitrosoglutathione reductase activity, and promoting leaf protein synthesis, thereby improving photosynthetic performance and cellular integrity. The combined treatment significantly increased the bioavailability of Cd and Zn in soil, promoted their transformation into exchangeable fraction, and resulted in removal rates of 30.8% and 28.9%, respectively. EDDS also modified the interaction patterns between heavy metals and essential nutrients, particularly the competitive relationships through selective chelation between Cd/Zn and Fe/Mn during plant uptake. Soil health was substantially improved, as evidenced by reduced electrical conductivity, enhanced cation exchange capacity, and enriched beneficial microbial communities including Sphingomonadaceae. Based on the observed ion antagonism during metal uptake and translocation, this study proposes a novel “Nutrient Regulation Assisted Remediation” strategy to optimize heavy metal accumulation and improve remediation efficiency through rhizosphere nutrient management. These findings confirm the EDDS–S. lineare system as an efficient and sustainable solution for remediation of Cd–Zn co-contaminated soils. Full article

Heavy metals released from industrial effluents accumulate in the human body through the ecosystem, causing several health disorders. This study investigated the removal of cadmium (Cd²⁺) using Micellar-Enhanced Ultrafiltration (MEUF). This study employed sodium dodecyl sulfate (SDS) and flat-sheet polyethersulfone (PES) ultrafiltration membranes to separate Cd²⁺ ions from lab-simulated water. The experiments involved examining the removal efficiency of membranes without SDS usage, optimizing SDS concentration for Cd²⁺ removal, and evaluating the long-term membrane performance. Other parameters include analyzing the removal percentage of varying Cd²⁺ at constant SDS dosage, examining the effect of pH, and electrolyte concentrations on the removal of Cd²⁺. Several analytical characterizations were performed, such as FT-IR, and SEM. The FTIR confirms the aromatic C-H group at 620–867 cm⁻¹, the sulfone group at 1100–1200 cm⁻¹, and the ether group at 1230–1270 cm⁻¹ and the SEM analysis indicates no significant fouling, which aligns with the stable flux observed over time. The result showed that the optimum SDS concentration for Cd²⁺ removal was 1 Critical Micellar Concentration (CMC), achieving over 99% removal. The presence of an electrolyte decreased Cd²⁺ removal efficiency, while the pH (3 to 9) had no effect on removal. Our findings suggest that the SDS-aided ultrafiltration process is suitable for eliminating Cd²⁺ from wastewater. Full article

Sewage sludge (SS) management and wastewater (WW) treatment remain among the most critical environmental challenges. The pyrolysis of sewage sludge to produce biochar (BC) represents a sustainable and circular strategy for waste valorization and pollution mitigation. This scoping review provides a comprehensive overview of BC derived from SS (BCxSS), with particular emphasis on how pyrolysis conditions affect key physicochemical characteristics such as yield, ash content, pH, surface area, and functional groups. Although substantial research has focused on the removal of heavy metals and organic pollutants using BCxSS, far less attention has been directed toward its potential for pathogen adsorption and inactivation, revealing a notable research gap. Recent studies highlight BCxSS as a versatile material with considerable promise in adsorption and catalysis. However, its application in pathogen removal remains insufficiently investigated, underscoring the need for further investigation into sorption mechanisms and biochar–microbe interactions. Full article

The sustainable management of sewage sludge remains a key environmental challenge for rapidly urbanizing regions such as Kazakhstan. This study explores the potential of sewage sludge-derived biochar as an efficient, low-cost adsorbent for removing Rhodamine B (RhB) dye and toxic metals from water. Sewage sludge was pyrolyzed at 700 °C (BC) and subsequently activated with hydrochloric acid (BCH) and sodium hydroxide (BCN) to improve its surface functionality and porosity. The morphology, surface area, porosity, and functional groups of the obtained biochars were characterized using SEM-EDS, BET, FTIR, and XRD analyses. Batch adsorption experiments demonstrated that the pseudo-second-order kinetic model (R² = 0.99) best described the data, indicating chemisorption-controlled uptake. Experimental RhB adsorption capacity was 14.53 mg/g for BCH at RhB concentration of 75 mg/L after 120 min. Moreover, BCH exhibited enhanced metal adsorption capacities of 22.85 mg/g (Cu²⁺), 17.55 mg/g (Zn²⁺), 15.08 mg/g (Cd²⁺), 7.97 mg/g (Cr³⁺), and 3.68 mg/g (As³⁺). These results confirm that acid activation significantly improves adsorption efficiency compared with pristine biochar due to increased surface area and the introduction of oxygen-containing functional groups. Overall, sewage sludge-derived biochar shows strong potential as a sustainable adsorbent for dye and heavy metal removal. Full article

The textile industry is one of the largest consumers of water worldwide and generates highly complex and pollutant-rich textile wastewater (TWW). Due to its high load of recalcitrant organic compounds, dyes, salts, and heavy metals, TWW represents a major environmental concern and a challenge for conventional treatment processes. Among advanced alternatives, electrooxidation (EO) and membrane technologies have shown great potential for the efficient removal of dyes, organic matter, and salts. This review provides a critical overview of the application of EO and membrane processes for TWW treatment, highlighting their mechanisms, advantages, limitations, and performance in real industrial scenarios. Special attention is given to the integration of EO and membrane processes as combined or hybrid systems, which have demonstrated synergistic effects in pollutant degradation, fouling reduction, and water recovery. Challenges such as energy consumption, durability of electrode and membrane materials, fouling, and concentrate management are also addressed. Finally, future perspectives are proposed, emphasizing the need to optimize hybrid configurations and ensure cost-effectiveness, scalability, and environmental sustainability, thereby contributing to the development of circular water management strategies in the textile sector. Full article

Chromium (Cr) is a widespread heavy metal contaminant in aquatic environments, posing serious risks to phytoplankton due to its persistence, biotoxicity, and mutagenic potential. Microalgae have emerged as promising biological agents for Cr remediation. In this study, the Cr removal potential of living Dunaliella salina (D. salina) was evaluated by examining the toxic effects and adsorption behavior of trivalent Cr(III) and hexavalent Cr(VI) through short-term exposure experiments. This study elucidated the mechanisms by which Cr disrupts key photosynthetic metabolic pathways, quantified the short-term toxicity thresholds of Cr(III) and Cr(VI) to D. salina, and characterized the saturation adsorption capacity and adsorption kinetics of Cr on algal cells. The results showed that Cr(VI) at concentrations of 5–20 mg/L inhibited the growth of D. salina in a dose-dependent manner throughout the culture period, with inhibition rates ranging from 22.8% to 70.9%. After 72 h of exposure, the maximum growth inhibition rates caused by Cr(III) and Cr(VI) reached 42.5% and 52%, respectively. Interestingly, low concentrations of Cr(VI) (0.1–1 mg/L) slightly enhanced the growth of D. salina. However, Cr(VI) exhibited stronger biotoxicity than Cr(III). Exposure to both Cr species significantly reduced the levels of chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoids (Car), resulting in damage to the photosynthetic reaction centers and suppression of the photosynthetic electron transport system. The adsorption of Cr(VI) by D. salina followed a pseudo-second-order kinetic model, with a maximum adsorption capacity of 38.09 mg/g. The process was primarily governed by monolayer chemisorption. These findings elucidate the toxic mechanisms of Cr in D. salina and highlight its potential application as an effective bioremediation agent for heavy metal pollution, particularly Cr(VI), in marine environments. Full article

Some mining sites generate acid mine drainage (AMD)—a highly acidic, metal-rich waste stream that affects bodies of water. Passive treatment systems are widely being adapted, particularly for abandoned or closed mines, due to their cost-effectiveness and lower environmental impact. However, novel strategies and approaches still need to be developed, especially in their implementation. Through batch experiments, this study identifies the effective sequence of three locally available treatment media, namely limestone (LS), steel slag (SS), and activated carbon (AC), using various water quality and pollution indices (WQPIs). The performance of the sequences was assessed based on their ability to improve various in situ parameters (pH, oxidation–reduction potential (ORP), dissolved oxygen (DO), and electrical conductivity (EC)) and their efficiency in removing Fe, Mn, Cu, and SO₄²⁻. Six sequences of media were identified and ranked by calculating a score based on comparisons with the Philippine General Effluent Standard (GES) by normalization and specific WQPIs for AMD and AMD-impacted waters, such as the CCMEWQI, MAMDI, and WPI-AMD. Analysis showed that the sequence of LS-AC-SS and SS-LS-AC yielded the highest removal for heavy metals (98.78% for Fe and Mn and 89.92% for Cu). However, limited removal of SO₄²⁻ was observed (14.96%), which suggests that additional treatment beyond the materials explored must be considered. Considering all the parameters and assessing them through normalization and WQPIs, the sequence of SS-LS-AC achieved the overall best treatment performance. Differences were observed in the ranking between the methods, with WQPIs successfully capturing actual water quality, demonstrating its robustness as an assessment tool. This study shows that the treatment media sequence is a factor in treating AMD, specifically utilizing AC, SS, and LS. Full article

The increasing contamination of water resources by wastewater has stimulated extensive research into advanced methods for effluent analysis, monitoring, and treatment. Heavy metals are among the most concerning pollutants due to their toxicity, persistence, and potential for bioaccumulation and biomagnification in living organisms. This study investigates the use of purple ipe (Handroanthus impetiginosus) leaves as a biosorbent for the removal of Co(II) and Cd(II) ions from aqueous solutions. The biosorbent was characterized using FTIR, NMR, EDX, SEM, and elemental analysis, revealing a porous and heterogeneous surface with functional groups suitable for metal adsorption. The point of zero charge (pH_PZC) was 5.8, and the zeta potential was −14.7 mV, indicating a negatively charged surface at higher pH values. Maximum removal efficiency was observed in the pH range of 5–6. Kinetic data showed the best fit to a pseudo-second order model, while adsorption equilibrium was most accurately described by the Langmuir isotherm, suggesting a monolayer adsorption process. The maximum adsorption capacities were 0.823 mmol g⁻¹ for Co(II) and 0.270 mmol g⁻¹ for Cd(II). The results demonstrate that purple ipe leaves are a sustainable, efficient, and low-cost biosorbent for wastewater treatment, showing great potential for mitigating environmental impacts associated with heavy metal pollution. Full article

Electroplating wastewater poses a serious environmental threat due to its high concentrations of heavy metals and persistent organic pollutants. This study evaluated the efficiency of a combined coagulation and activated carbon filtration process for the treatment of real electroplating wastewater containing Ni²⁺, Zn²⁺, Cu²⁺, and Cr⁶⁺ ions. The research was conducted in two stages. In the first stage, laboratory-scale experiments were performed to determine the optimal coagulant type (Fe- and Al-based), dosage, and pH (5.0–10.0) for contaminant removal. In the second stage, the selected operating conditions were applied and validated under real industrial plant conditions at a pilot scale. The laboratory studies demonstrated that the highest Cr removal efficiency was achieved using an iron-based coagulant (PIX), while polyaluminum chloride (PAX) proved most effective for the removal of Ni and Zn. Subsequent filtration through activated carbon further enhanced heavy metal removal, increasing overall efficiencies to above 90%. The reported removal efficiencies represent the overall performance of the integrated treatment process. The results confirm that the integration of chemical coagulation and activated carbon filtration is an effective, environmentally friendly, and economically viable approach for treating real electroplating wastewater, enabling compliance with current environmental standards. Full article