Search Results (80)

To address the disposal challenges of waste SCR catalysts and the urgent need for sustainable solutions in heavy metal pollution control, this study proposes a green resource utilization strategy based on the sub-molten salt method to convert waste SCR catalysts into highly efficient lead ion adsorbents. Titanate-based adsorbent materials with a loose porous structure were successfully prepared by optimizing the process parameters (reaction temperature of 160 °C, NaOH concentration of 70%, and reaction time of 2 h). The experiments showed that the adsorption efficiency was as high as 99.65% and the maximum adsorption capacity was 76.08 mg/g under ambient conditions (adsorbent dosage of 1.2 g/L, initial Pb(II) concentration of 100 mg/L, contact time of 60 min, and pH = 4). Kinetic analysis showed that the quasi-second-order kinetic model (R² = 0.9985) could better describe the adsorption process, indicating chemisorption as the dominant mechanism. Characterization analysis confirmed that subsequent to the adsorption process, Pb₃(CO₃)₂(OH)₂ formed on the surface of the adsorbent material is the adsorption product of Pb(II) and C-O through ion exchange and surface complexation. This study transforms waste SCR catalysts into sustainable titanate adsorbents through a low-energy green process, providing an eco-efficient solution for heavy metal wastewater treatment while aligning with circular economy principles and sustainable industrial practices. Full article

Incessant urbanization and industrialization have resulted in several pollutants being increasingly produced and continuously discharged into the environment, altering its equilibrium, with a high risk for living organisms’ health. To restore it, new advanced materials for remediating gas streams, polluted soil, water, wastewater, groundwater and industrial waste are continually explored. Carbon-based nanomaterials (CNMs), including quantum dots, nanotubes, fullerenes and graphene, have displayed outstanding effectiveness in the decontamination of the environment by several processes. Carbon nanotubes (CNTs), due to their nonpareil characteristics and architecture, when included in absorbents, filter membranes, gas sensors, etc., have significantly improved the efficiency of these technologies in detecting and/or removing inorganic, organic and gaseous xenobiotics and pathogens from air, soil and aqueous matrices. Moreover, CNT-based membranes have displayed significant potential for efficient, fast and low-energy water desalination. However, despite CNTs serving as very potent instruments for environmental detoxification, their extensive utilization could, paradoxically, be highly noxious to the environment and, therefore, humans, due to their toxicity. The functionalization of CNTs (F-CNTs), in addition to further enhancing their absorption capacity and selectivity, has increased their hydrophilicity, thus minimizing their toxicity and carcinogenic effects. In this scenario, this review aims to provide evidence of both the enormous potential of CNTs in sustainable environmental remediation and the concerning hazards to the environment and living organisms that could derive from their extensive and uncontrolled utilization. To this end, an introduction to CNTs, including their eco-friendly production from biomass, is first reported. Several literature reports on CNTs’ possible utilization for environmental remediation, their potential toxicity due to environmental accumulation and the challenges of their regeneration are provided using several reader-friendly tools, to better capture readers’ attention and make reading easier. Full article

Diatoms in the Arabian Gulf region could contribute to various biological carbon pumps, playing crucial ecological roles and producing bioactive compounds beneficial to both humans and marine animals. Despite their significance, some diatoms pose risks to human health and the economy; however, research on their roles in Qatar remains limited. This review explores the roles of diatoms in the Arabian Gulf, highlighting their potential for remediating polluted seawater and their applications in pharmacology, biofuel production, and detoxification of chemical waste and hazardous metals. Among the 242 diatom species identified along the coastline of the Gulf and Qatar, several genera represent 50% of the identified species and have demonstrated notable efficiency in phycoremediation and bioactive compounds production. These include antibacterial agents with therapeutic potential, antioxidants to neutralize harmful free radicals, compounds that degrade toxic substances, and agents for remediating heavy metals. Additionally, diatoms contribute to the production of biofuels, nutritional agents, dyes, and extracellular polymeric substances, and some species serve as bioindicators of pollution stress. To fully utilize their potential requires significant efforts and comprehensive research. This review explores the reasons behind the current lack of such initiatives and highlights the importance of conducting targeted studies to address the environmental challenges facing the Arabian Gulf. Full article

The reclamation of illegal landfills poses a significant threat to the environment. An example of such a case is Łomianki near Warsaw, where an illegal landfill contained alarming levels of arsenic and chromium, posing a potential risk to the health of local residents due to the possibility of these metals contaminating a nearby drinking water source. Initial geochemical tests revealed high concentrations of these metals, with chromium reaching up to 24,660 mg/kg and arsenic up to 10,350 mg/kg, well above international environmental standards. This study presents effective reclamation strategies that can be used in similar situations worldwide. The reclamation allowed this land to be used for the construction of the M1 shopping center while minimizing environmental hazards. The study is based on a case study of the reclamation of this illegal landfill. The methods used in this project included the relocation of approximately 130,000 m³ of hazardous waste to a nearby site previously used for sand mining. Bentonite mats and geotextiles were used to prevent the migration of contaminants into the groundwater. The waste was layered with sand to assist in the structural stabilization of the site. In addition, proper waste segregation and drainage systems were implemented to manage water and prevent contamination. Eight years after the reclamation, post-remediation soil surveys showed significant improvements in soil quality and structural stability. Specifically, the Proctor Compaction Index (I_S) increased from an estimated 0.5–0.7 (for uncontrolled slope) to 0.98, indicating a high degree of compaction and soil stability, while arsenic and chromium levels were reduced by 98.4% and 98.1%, respectively. Reclamation also significantly reduced permeability and settlement rates, further improving the site’s suitability for construction. The cost-benefit analysis showed a cost saving of 37.7% through local waste relocation compared to off-site disposal, highlighting the economic efficiency and environmental benefits. The main conclusions of this study are that land reclamation effectively reduced environmental hazards; innovative solutions, such as bentonite mats, advanced waste sorting, geotextiles, and drainage systems, improved environmental quality; and the Łomianki case serves as a model for sustainable waste management practices. Full article

This study delves into the quality and quantity of sediment in the Great Bačka Canal near Vrbas, examining its physicochemical composition over a span of twenty years. The primary aim is to enhance sediment monitoring and risk assessment methodologies while advocating for a paradigm shift in sediment management—from treating sediments as waste to recognizing them as valuable resources. Analyzing sediment samples for heavy metals, including mercury, arsenic, cadmium, chromium, lead, zinc, nickel, and copper, alongside polycyclic aromatic hydrocarbons (PAHs), provides insights into contamination levels and trends. The results revealed that the concentrations of mercury, arsenic, cadmium, chromium, and lead were within the second risk class, indicating that there was no immediate environmental hazard, but ongoing monitoring is necessary. Zinc levels, after initial exceedance, have decreased and are now within acceptable limits, whereas nickel concentrations, though reduced, remain a potential ecological risk. Copper levels persistently exceed remediation thresholds, indicating severe contamination that requires intervention. PAH concentrations were generally below regulatory limits, suggesting moderate pollution with no significant threat to benthic communities. This study highlights the effectiveness of recent pollution control measures, but underscores ongoing challenges in sediment management. This study highlights the need for more integrated and sustainable sediment management approaches that align with international standards and circular economy principles. Recommendations include adopting comprehensive regulatory frameworks, exploring beneficial uses of sediment, and fostering innovation in sediment reuse to enhance environmental outcomes and sustainability. Full article

The accelerated growth of the electrical and electronic equipment market is a major driver behind increasing e-waste volumes worldwide. Although e-waste contains valuable resources, most remain unrecycled or improperly managed. Recycling efforts primarily focus on recovering metals, while plastic constituents remain overlooked. Furthermore, current e-waste plastic recycling approaches have led to environmental contamination by hazardous materials. Recent efforts for the valorisation of e-waste plastics have demonstrated the potential applications of these materials and their role in efforts towards implementing a more sustainable plastics economy. While the environmental impact and potential strategies for recycling e-waste plastics have been recently reviewed, a thorough discussion that accounts for the environmental impact, characterisation strategies, and potential biotechnological treatment options remains lacking. Accordingly, this review addresses this gap, discussing recent developments in the e-waste plastics field. It focuses on their environmental impacts, the collection of environmental samples and their characterisation, as well as innovative approaches for valorisation through biotechnological strategies. Specifically, the discussion is centred on studies that directly use or focus on plastics derived from e-waste. While progress has been made in the characterisation of environmental contaminants and remediation/bioprocessing strategies for this type of hazardous waste, challenges remain, including financial barriers, limited research volume compared to related fields (e.g., e-waste metals), and environmental impact and relevance concerns. This review identifies a need for increased research, interdisciplinary collaboration, and policy support to overcome these barriers and advance sustainable e-waste plastic management. Full article

Micro- and nanoplastic (MNP) pollution is a significant concern for ecosystems worldwide. The continuous generation and extensive utilization of synthetic plastics have led to the widespread contamination of water and food resources with MNPs. These pollutants originate from daily-use products and industrial waste. Remediation of such pollutants is essential to protect ecosystems and human health since these ubiquitous contaminants pose serious biological and environmental hazards by contaminating food chains, water sources, and the air. Various remediation techniques, including physical, chemical, sophisticated filtration, microbial bioremediation, and adsorption employing novel materials, provide encouraging avenues for tackling this worldwide issue. The biotechnological approaches stand out as effective, eco-friendly, and sustainable solutions for managing these toxic pollutants. However, the complexity of MNP pollution presents significant challenges in its management and regulation. Addressing these challenges requires cross-disciplinary research efforts to develop and implement more efficient, sustainable, eco-friendly, and scalable techniques for mitigating widespread MNP pollution. This review explores the various sources of micro- and nanoplastic contamination in water and food resources, their toxic impacts, remediation strategies—including advanced biotechnological approaches—and the challenges in treating these pollutants to alleviate their effects on ecosystems and human health. Full article

Developing a cost-effective approach for the remediation of wastewater containing uranyl [U(VI)] ions is essentially important to ecosystems and human health. In this study, a Zn-based ZIF-8 framework was fabricated from wasted batteries through an environmentally friendly ball milling process featuring a distinct microstructure compared to those synthesized from commercial Zn(II) sources. The as-obtained Zn-based ZIF-8 framework can effectively remove U(VI) ions from water, and a high removal efficiency of up to 99% is achieved across different process parameters, including initial dosage, pH values, and the presence of interfering ions. The superior U(VI) removal performance is attributed to the synergistic effect of microstructural features (e.g., crystallite size, specific surface area and pore diameter) and chemical interaction within the framework of Zn-based ZIF-8, resulting in the formation of the U···N chelates. This study integrates waste upcycling and hazardous U(VI) removal in an environmentally sound way, thereby promoting a circular economy. Full article

The global problem of water scarcity is exacerbated by the continued contamination of potable water sources. This preliminary study investigates the potential of a hazardous industrial jarosite waste to adsorb As(V) and Cr(III) from contaminated waters. The results showed that this mining waste effectively adsorbed both As(V) and Cr(III), demonstrating its potential as a low-cost and sustainable solution for water remediation along with the use of a hazardous waste that also contaminates. The adsorption process was optimized, and the effects of various parameters on the adsorption capacity were investigated. The findings of this study suggest that the use of toxic mining residues in porous concrete could provide a promising approach for the removal of toxic heavy metals from polluted water sources, contributing to the development of more sustainable and environmentally friendly water treatment technologies. A maximum adsorption of 90.6% of As(V) and 96.3% of Cr(III) was achieved, and it was verified that the industrial jarosite initially contained about 0.44% As, which was later leached during decomposition; again, the industrial jarosite was able to re-adsorb both As(V) and Cr(III). Full article

Soil pollution with hydrocarbons is a consequence of activities associated with the petroleum industry and related sectors. The effects of petroleum pollution are devastating, making the remediation of contaminated sites imperative. Consequently, soil decontamination represents a significant and costly challenge for the petroleum industry. The article proposes a dual-recovery bioremediation solution that is both efficient and cost-effective, exploring the potential use of dehydrated sewage sludge from municipal wastewater treatment plants to treat petroleum-contaminated soils. Over the three-month bioremediation experiment, changes in the density of indigenous bacteria in petroleum-contaminated soil samples, treated or untreated with sludge, were monitored along with the reduction in petroleum hydrocarbon concentrations. In parallel, the evolution of other contaminants, such as heavy metals, was monitored during the bioremediation experiment. Geotechnical tests were also conducted to evaluate the feasibility of returning the treated soil to its original location after the bioremediation experiment. Our results demonstrate that the proposed method effectively addresses both the remediation of petroleum-contaminated soils (hazardous waste) and the reuse of sewage sludge from municipal wastewater treatment plants. Full article

At present, contamination due to toxic metals is a global concern. The management of problems caused by heavy metals relies on stabilization/solidification, which is the most effective technique for the control of metal pollution in soil. This study examined the immobilization efficiency of various phosphate-based binders (Na₃PO₄, Na₂HPO₄, NaH₂PO₄), in addition to ordinary Portland cement (OPC), MgO, and CaO, for the stabilization of multi-metal-contaminated soils. Moreover, this study focused on the leachability of copper, nickel, zinc, lead, cadmium, and manganese (Cu, Ni, Zn, Pb, Cd, Mn, respectively) over different time periods and with different concentrations. Batch leaching experiments were conducted to determine the leaching ratios and percentages of the various metal concentrations, along with measuring the pH values of the leachates. Our results indicate that the use of OPC was validated due to its superior immobilization performance across all metals present in the soil, but particularly with regard to metals in high concentrations. This was due to the formation of stable hydroxides and the high pH values, which assisted in abating the metals’ solubility. Additionally, phosphate-based binders, despite being environmentally favorable, were found to be less effective, particularly for Pb and Cu, and the leaching results exceeded non-hazardous waste limits. MgO showed reasonable immobilization results but was less effective compared to OPC; on the other hand, CaO exhibited increased leaching over time. Therefore, the present research serves primarily to highlight that OPC is more suitable for soil remediation at industrial sites and in the construction of infrastructure. Meanwhile, phosphate-based binders are shown to be more appropriate for eco-friendly, non-load-bearing applications. Full article

Biomass waste, generated globally in vast quantities, represents an underutilized yet highly valuable resource for advanced material production. This study highlights a novel valorization pathway for waste tangerine peels, sourced from Jeju Island, South Korea, by converting them into high-performance activated carbon (T-AC) with exceptional pore characteristics, specifically designed for volatile organic compound (VOC) removal. Utilizing a unique combination of hydrothermal carbonization (HTC) and dry carbonization (DC) processes, the structural properties of the biomass were optimized, significantly enhancing the fixed carbon content. Subsequent chemical activation with an alkaline agent yielded T-AC with an outstanding specific surface area (1530–3375 m²/g) and total pore volume (0.73–2.00 cm³/g), with a tailored pore distribution favoring the sub-mesopore range (2.0–4.0 nm). The T-AC demonstrated remarkable performance in removing methylene chloride (MC), a hazardous VOC, with methylene chloride activity (MA) increasing from 44.7% to 76.3% as the activation agent ratio increased, while methylene chloride working capacity (MWC) improved significantly from 17.1% to 55.9%. These results underscore the transformative potential of tangerine peel-derived AC as a sustainable solution for VOC remediation, combining environmental waste management with advanced adsorption technology. The findings not only advance the field of biomass utilization but also offer a scalable approach for tackling pressing environmental and industrial challenges. Full article

The processes of coal mining and washing generate a substantial amount of coal gangue. During prolonged outdoor storage, this waste can lead to both direct and indirect environmental pollution, as well as geological hazards. Recent research has indicated that the redox processes of coal gangue are regulated by microorganisms. Techniques such as the application of biocides and the facilitation of microbial interactions have proven effective in controlling the acidic pollution of coal gangue in the short term. However, conventional doping methods that couple sulfate-reducing bacteria with biocides face challenges, including a short effective duration and poor stability. To address these issues, this study utilized corn straw biochar as a microbial attachment material and incorporated water-retaining agents as slow-release biocide carriers, resulting in the development of an environmentally friendly microbial remediation material. This study selected 0.6 g of biochar produced from the pyrolysis of corn straw at 700 °C to immobilize sulfate-reducing bacteria. Additionally, 0.6 g of polyacrylamide was used to prepare a slow-release bactericide with 100 mL of a sodium dodecyl sulfate solution at a concentration of 50 mg·L⁻¹. The composite remediation material successfully raises the pH of weathered coal gangue leachate from 4.32 to 6.88. Its addition notably reduces the sulfate ion concentration in the weathered coal gangue, with sulfate content decreasing by 86.45%. Additionally, the composite material effectively lowers the salinity of the weathered coal gangue. The composite immobilizes heavy metal ions within the weathered coal gangue, achieving an approximate removal rate of 80% over 30 days. Following the introduction of the composite material, significant changes were observed in the dominant microbial communities and population abundances on the surface of the coal gangue. The composite demonstrated the ability to rapidly, sustainably, and effectively remediate the acidification pollution associated with coal gangue. Full article

Amongst the many types of food waste, eggshells contain various minerals and bioactive materials, and they can become hazardous if not properly disposed of. However, they can be made useful for the environment and people by being converted to environmentally friendly catalytic materials or environmental purification agents. Simple calcination can enhance their properties and thereby render them suitable for catalytic and environmental applications. This work aimed to prepare CaO from waste eggshells and examine its effectiveness in photocatalytic pollution remediation, electrocatalytic activity, optical sensing, and antibacterial activities. As opposed to other techniques, this calcination process does not require any chemical reagents due to the high purity of CaCO₃ in eggshells. Calcium oxide nanoparticles were prepared by subjecting waste eggshells (ES) to high-temperature calcination, and the synthesized CaO nanoparticles were characterized for their structural, morphological, chemical, optical, and other properties. Furthermore, their photocatalytic degradation of methylene blue dye and antibacterial efficiency against Escherichia coli and Staphylococcus aureus were investigated. It was found that the green-converted CaO can be efficiently used in environmental applications, showing good catalytic properties. Full article

Methylene blue (MB) is a dye hazardous pollutant widely used in several industrial processes that represents a relevant source of water pollution. Thus, the research of new systems to avoid their environmental dispersion represents an important goal. In this work, an efficient and sustainable nanocomposite material based on green gold nanoparticles for MB water remediation was developed. Starting from the reducing and stabilizing properties of some compounds naturally present in Lambrusco winery waste (grape marc) extracts, green gold nanoparticles (GM-AuNPs) were synthesized and deposited on a supporting membrane to create an easy and stable system for water MB decontamination. GM-AuNPs, with a specific plasmonic band at 535 nm, and the modified membrane were first characterized by UV–vis spectroscopy, X-ray diffraction (XRD), and electron microscopy. Transmission electron microscopy analysis revealed the presence of two breeds of crystalline shapes, triangular platelets and round-shaped penta-twinned nanoparticles, respectively. The crystalline nature of GM-AuNPs was also confirmed from XRD analysis. The photocatalytic performance of the modified membrane was evaluated under natural sunlight radiation, obtaining a complete disappearance of MB (100%) in 116 min. The photocatalytic process was described from a pseudo-first-order kinetic with a rate constant (k) equal to 0.044 ± 0.010 min⁻¹. The modified membrane demonstrated high stability since it was reused up to 20 cycles, without any treatment for 3 months, maintaining the same performance. The GM-AuNPs-based membrane was also tested with other water pollutants (methyl orange, 4-nitrophenol, and rhodamine B), revealing a high selectivity towards MB. Finally, the photocatalytic performance of GM-AuNPs-based membrane was also evaluated in real samples by using tap and pond water spiked with MB, obtaining a removal % of 99.6 ± 1.2% and 98.8 ± 1.9%, respectively. Full article