Nickel-based dual single atom electrocatalysts for the nitrate reduction reaction.

Electrochemical nitrate (NO3-) reduction reaction (NO3-RR) to ammonium (NH4+) or nitrogen (N2) provides a green route for nitrate remediation. However, nitrite generation and hydrogen evolution reactions hinder the feasibility of the process. Herein, dual single atom catalysts were rationally designed by introducing Ag/Bi/Mo atoms to atomically dispersed NiNC moieties supported by nitrogen-doped carbon nanosheet (NCNS) for the NO3-RR. Ni single atoms loaded on NCNS (Ni/NCNS) tend to reduce NO3- to valuable NH4+ with a high selectivity of 77.8 %. In contrast, the main product of NO3-RR catalyzing by NiAg/NCNS, NiBi/NCNS, and NiMo/NCNS was changed to N2, giving rise to N2 selectivity of 48.4, 47.1 and 47.5 %, respectively. Encouragingly, Ni/NCNS, NiBi/NCNS, and NiAg/NCNS showed excellent durability in acidic electrolytes, leading to nitrate conversion rates of 70.3, 91.1, and 93.2 % after a 10-h reaction. Simulated wastewater experiments showed that NiAg/NCNS could remove NO3- up to 97.8 % at -0.62 V after 9-h electrolysis. This work afforded a new strategy to regulate the reaction pathway and improve the conversion efficiency of the NO3-RR via engineering the dual atomic sites of the catalysts.

Enhancing the photocatalytic efficiency by the molecular modification effect derived from pollutant adsorption on highly crystalline BiOBr.

The adsorption of pollutants can not only promote the direct surface reaction, but also modify the catalyst itself to improve its photoelectric characteristics, which is rarely studied for water treatment with inorganic photocatalyst. A highly crystalline BiOBr (c-BiOBr) was synthesized by a two-step preparation process. Owing to the calcination, the highly crystalline enhanced the interface interaction between pollutant and c-BiOBr. The complex of organic pollutant and [Bi2O2]2+ could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes (h+). Moreover, the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons, which would coupling with the photoexcitation to promote generate more O2•-. The molecular modification effect derived from pollutant adsorption significantly improved the removal of pollutants. This work strongly deepens the understanding of the molecular modification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment.

Functionalized composite nanofiber membranes for selective steroid hormone micropollutants uptake from water: Role of cyclodextrin type.

Cyclodextrins (CD) entrapped in nanofiber composite membranes are potential selective adsorbing materials to remove steroid hormone (SHs) micropollutants from water. This study aims to elucidate the role of CD macrocyclic host type on the SHs inclusion complexation and uptake in filtration. Three CD types (α, ß, and γ) are cross-linked with epichlorohydrin to form polymers (αCDP, ßCDP and γCDP) and entrapped into a nanofiber composite membrane by electrospinning. TGA analysis confirmed the CD entrapment into the nanofiber without loss of CD molecules during filtration. The CD type plays a dominant role in controlling the removal of different SHs. A similar removal (range 33 to 50 %) was observed with αCDP, irrespective of the SH type. In contrast, removal and uptake dependent on SH type were observed for ß and γCDP, with the highest removal of 74 % for progesterone, followed by estradiol (46 %) and estrone (27 %) and the lowest removal of 3 % for testosterone. Molecular dynamic (MD) simulation revealed a stronger and more stable complex formed with ßCDP, as demonstrated by: i) the closer spatial distribution of SH molecules from the ßCDP cavity and, ii) the quantum chemistry calculations of the lower de-solvation energy (+6.0 kcal/mol), which facilitates the release of water molecules from interacting interface of CD molecule and hormone. Regarding γCDP, the highest de-solvation energy (+8.3 kcal/mol) poses an energetic barrier, which hinders the formation of the inclusion complex. In the case of αCDP, a higher interaction energy (-8.9 kcal/mol) compared to ßCDP (-4.9 kcal/mol) was obtained, despite the broader spatial distribution observed from the MD simulation attributed to a dominant hydrogen bonding interaction with the OH primary groups on the external surface cavity. The findings highlight the relevance of the CD type in designing selective adsorbing membranes for steroid hormone micropollutant uptake. Experimental results and MD simulation suggest that ßCD is the most suitable CD type for steroid hormone uptake, due to a more stable and stronger inclusion complexation than α and γCD.

Performance improvement and application of copper-based nanomaterials in membrane technology for water treatment: A review.

Membrane fouling, including organic, inorganic, and biological fouling, poses enormous challenges in membrane water treatment. Incorporation of copper-based nanomaterials in polymeric membranes is highly favored due to their exceptional antibacterial properties and capacity to improve membrane hydrophilicity. This review extensively explores the utilization of copper-based nanomaterials in membrane technology for water treatment, with a specific focus on enhancing anti-fouling performance. It elaborates on how copper-based nanomaterials improve the surface properties of membrane materials (such as porosity, hydrophilicity, surface charge, etc.) through physical and chemical processes. It summarizes the properties and potential antibacterial mechanisms of copper-based nanomaterials, primarily by disrupting microbial cell structures through the generation of reactive oxygen species (ROS). Furthermore, recent efforts to enhance the environmental sustainability, cost-effectiveness, and recyclability of copper-based nanomaterials are outlined. The attempts to offer insights for the advancement of anti-fouling practices in water treatment through the use of copper-modified polymer membranes.

The recent development of innovative photoelectro-Fenton processes for the effective and cost-effective remediation of organic pollutants in waters.

Wastewaters with toxic and recalcitrant organic contaminants are poorly remediated in conventional wastewater treatment plants. So, powerful processes need to be developed to destroy such organic pollutants to preserve the quality of the aquatic environment. This critical and comprehensive review presents the recent innovative development of photoelectro-Fenton (PEF) covering the period 2019-September 2024. This emerging photo-assisted Fenton-based electrochemical advanced oxidation process (EAOP) is an efficient and cost-effective treatment for water remediation. It possesses a great oxidation power because the in-situ generated hydroxyl radical as oxidant is combined with the photolysis of the organic by-products under UV or sunlight irradiation. The review is initiated by a brief description of the characteristics of the PEF process to stand out in the role of generated oxidizing agents. Further, the homogeneous PEF. PEF-like, solar PEF (SPEF), and SPEF-like processes with iron catalysts are discussed, taking examples of their application to the removal and mineralization of solutions of industrial chemicals, herbicides, dyes, pharmaceuticals, and direct real wastewaters. Novel heterogeneous PEF treatments of such pollutants with solid iron catalysts or functionalized cathodes are analyzed. Finally, novel hybrid processes including PEF/photocatalysis and PEF/photoelectrocatalysis, followed by novel and potent sequential processes like electrocoagulation-PEF and persulfate-PEF, are discussed. Throughout the manuscript, special attention was made to the total operating cost of PEF, which is more expensive than conventional electro-Fenton due to the high electric cost of the UV lamp, pointing to consider the much more cost-effective SPEF as a preferable alternative in practice.

Exploring performance and mechanism of modified metal-organic frameworks in calcium alginate/polyvinyl alcohol double-network hydrogels for effective dye wastewater treatment.

To address the growing problem of dye wastewater pollution, a novel MOFs adsorbent calcium alginate/polyvinyl alcohol@UiO-66 was developed using environmentally friendly polymers, sodium alginate and polyvinyl alcohol creating gel spheres with a double-network structure through cross-linking. UiO-66 metal-organic frameworks are then grown onto the gel spheres, resulting in the final CA/PVA@UiO-66 adsorbent. This adsorbent boasts a high surface area (17.4 m2/g) and a mesoporous-nested microporous structure. It effectively removes MB from water, the actual maximum adsorption capacity was measured at 275.8 mg/g, which surpasses most existing adsorbents. Remarkably, the adsorbent retains 93.9 % of its initial capacity even after 10 reuse cycles. The adsorption process adhered to the Redlich-Peterson model and the PFO model. The N2-Sorption isotherm, actual Methylene blue (MB) adsorption experiments, and model analysis further suggest that the adsorption process is a complex heterogeneous diffusion process involving simultaneous chemical and physical adsorption. Additionally, the adsorption process is endothermic, indicating that it can occur spontaneously at 298 K. Increasing the temperature promotes the forward progress of the adsorption reaction, thereby enhancing the adsorption capacity. The gel adsorbent exhibited excellent dye wastewater purification capabilities, coupled with commendable reusability.

Valorization of carbon soot ash for the selective capture of lead ions from industrial waste water-A waste to resource approach.

Landfills are struggling to accommodate the increasing amounts of carbon soot ash waste from oil refineries. Due to extensive industrial productions, large quantities of lead ions are released into the environment, which not only pollutes the environment but also affects flora and fauna. In this work, these urgent environmental issues will be tackled by studying the use of modified carbon soot ash for specific heavy metal adsorption. Carbon soot ash modified with chemical leaching and physical ball-milling was loaded onto the surface of graphene oxide. This adsorbent was found to selectively adsorb and remove toxic lead ions (>99%) from a mixed heavy metal solution. The adsorption efficiency was found to increase with temperature (20-60 °C) and pH (2-8). Langmuir isotherm and pseudo-second order kinetics were found to fit the adsorption process through curve fitting, where the adsorbent reached a maximum capacity of 194.55 mg/g. Potential mechanisms for lead adsorption and metal specificity are also discussed here. This work aligns with the waste-to-resource pathway, where waste carbon soot ash is diverted from landfilling and is formulated as a specific heavy metal adsorbent, that shows promise for environmental remediation.

Harnessing perovskite materials for water decontamination: a comprehensive review.

Perovskites have recently emerged as a promising class of materials with a wide range of applications, including solar cells, light-emitting diodes, and catalysts. In addition, perovskites have demonstrated significant potential for water decontamination due to their tunable properties and facile synthesis. This review article provides a comprehensive overview of perovskites, including their preparation techniques, crystal structure, and electronic properties. The article also highlights the various applications of perovskites, with a particular focus on their use in water decontamination. The different types of perovskites for water decontamination, including simple, substituted, and doped perovskites, as well as nanoscopic and supported perovskites, are discussed in detail. Furthermore, the article addresses the beneficial costs of perovskites and the environmental impacts associated with their use, including toxicity and end-of-life management. The aim of this review article is to provide a broad perspective on perovskites and their potential for water decontamination, as well as future prospects and challenges in various applications.

Combined application of hot water and hexanal-based formulations preserves the postharvest quality of mango fruits.

BACKGROUND: Mango fruits undergo numerous postharvest quality losses during storage. Hence, the present study aimed to increase the shelf life of mango fruits by applying hexanal-based enhanced freshness formulations (EFF) in combination with hot water treatment (HWT). RESULTS: The findings revealed that, among all the tested applications, the combination of EFF 1.0% + HWT reduced the weight loss, decay incidence, and activity of cell wall degrading enzymes of mango fruits. Also, the combined treatment was effective in maintaining the fruit quality parameters such as soluble solid contents, titratable acidity, ascorbic acid and activity of antioxidant compounds. CONCLUSION: The present study concludes that the postharvest application of EEF 1.0% in combination with HWT can be used in extending the shelf life of mango cv. 'Langra,' fruits stored at 12° C and 85-90% relative humidity for 35 days. © 2024 Society of Chemical Industry.

One story as part of the Global Conversation on Sustainability: dye adsorption studies using a novel bio-derived calcite material.

Many of the United Nations' Sustainable Development Goals (SDGs) can be addressed through chemistry. Researchers at Memorial University of Newfoundland, Canada, have been sharing their stories on September 25 for the past two years through the Global Conversation on Sustainability. This article describes the details of one of these stories. As the global population increases, food production including aquaculture is increasing to provide for this. At the same time, this means more waste is produced. Waste from aquaculture is often overlooked as a source of valuable chemicals. By-products from farming blue mussels (Mytilus edulis) is dominated by shells rich in calcite. A 'soft' calcite material prepared from waste mussels, via a combination of heat and acetic acid treatment, was investigated for its adsorptive properties and its possible use in wastewater remediation. The adsorption of two cationic dyes, methylene blue and safranin-O, on this material were evaluated through isothermal and kinetic modelling. The adsorption systems for both methylene blue and safranin-O can best be described using Langmuir isotherms and the respective adsorption capacities were 1.81 and 1.51 mg/g. The adsorption process was dominated by pseudo-second order rate kinetics. Comparisons are made with other mollusc-derived materials reported to date.

Engineering the Future: Unveiling Novel Paths in Heavy Metal Wastewater Remediation with Advanced Carbon-Based Nanomaterials - Beyond Performance Comparison, Tackling Challenges, and Exploring Opportunities.

This review addresses the pressing issue of heavy metal pollution in water, specifically focusing on the application of adsorption technology utilizing carbon materials such as biochar, carbon nanotubes, graphene, and carbon quantum dots. Utilizing bibliometric analysis with VOSviewer based on Web of Science core dataset, this study identifies research hotspots related to carbon-based materials in heavy metal applications over the past decade. However, existing literature still lacks sufficient comparative analysis of the potential of carbon-based materials' structural characteristics and inherent advantages in heavy metal applications. This review strategically addresses this gap, offering a comprehensive comparative analysis of these four materials from an engineering application perspective. It offers a thorough evaluation of their suitability for various water treatment applications, providing a detailed examination of their advantages and limitations in heavy metal application. Additionally, the review provides insights into performance comparisons, addresses challenges, and explores emerging opportunities in this field. Insights into potential application fields based on structural characteristics and inherent advantages are presented. This unique focus on a comprehensive comparative analysis distinguishes the article, offering a nuanced perspective on the strengths and future possibilities of carbon materials in tackling the global challenge of heavy metal pollution in water.

Corrigendum: Performance evaluation of Moringa oleifera seeds aqueous extract for removing Microcystis aeruginosa and microcystins from municipal treated-water.

[This corrects the article DOI: 10.3389/fbioe.2023.1329431.].

Applying a novel mechanistic framework for drinking water management to mitigate emerging contaminants.

A novel framework has been developed which summarizes the efficacy of treatment technologies for emerging contaminants (ECs) based on the general mitigation mechanisms of Removal, Inactivation/Degradation, and Destruction (i.e., RIDD). The RIDD framework allows for a concise critical evaluation of the efficacy of treatment processes for their mitigation potential, and provides an efficient methodology for drinking water system managers to identify knowledge gaps related to the management of ECs in water treatment with respect to current technologies available in practice. Additionally, the RIDD framework provides an understanding of the treatment processes which provide: (1) broad spectrum treatment, (2) effective mitigation for certain categories of contaminants or under certain circumstances, or (3) little or no mitigation of ECs. In the proposed format, this information is intended to assist water managers to make more informed treatment decisions. Four categories of ECs noted in recent literature as presently concerning to drinking water utilities, including both anthropogenic and microbial contaminants, were used in this study to provide examples of RIDD framework application. In many cases, broad-spectrum treatment barriers (e.g., high-pressure membranes) are expected to provide cost-effective management of a suite of ECs, which then can be compared to the costs and practicality of additional treatment barriers for individual ECs (e.g., selective ion exchange resins or tailored biological processes). Additionally, understanding the typical performance of existing treatment processes can help assist with capital planning for alternative treatment processes or upgrades, or for developing novel treatment approaches at the watershed scale such as integrated urban water management and One Water frameworks.

Biomimetic Hierarchies for Universal Surface Enhancement and Applications in Water Treatment.

Hierarchical superstructures, ubiquitously found in nature, offer enhanced efficiency in both substance reaction and mass transport owing to their unique multiscale features. Inspired by these natural systems, this research reports a general and scalable electrochemical scheme for creating highly branched, multilevel porous superstructures on various electrically conductive substrates. These structures exhibit cascading features from centimeters, submillimeters, micrometers, down to sub-100 nm, significantly increasing the surface area of substrates, such as foams, foils, and carbon cloth by 2 orders of magnitude─among the highest reported enhancements. This versatile and low-cost method, applicable to a range of electrically conductive substrates, enables innovative flow-assisted water purification with enhanced energy efficiency. The performance, successfully removing 99% of mercury within 0.5 h at 540 rpm and meeting the U.S. Environmental Protection Agency (EPA) safety standards for drinking water, further validates the advantages of these unique structures. Overall, the reported general, economical, and versatile scheme could broadly impact energy and environmental remediation.

Development and challenge of coal-based nanocarbon materials and their application in water treatment: a review.

Under the dual pressures of environmental protection and energy security, the development and application of coal-based nanocarbon materials, supported by the technical concepts of molecular chemical engineering and nanomaterial science, is of significant importance for achieving the high-value clean utilization of coal. Furthermore, it serves as an effective means to assist in the realization of dual carbon goals. Coal, with its abundant reserves, high carbon content, and aromatic and hydrogenated aromatic groups, exhibits great advantages and potential in the synthesis of nanocarbon materials. In addition to its applications in traditional power and chemical industries, coal-based nanocarbon materials also demonstrate significant value in the field of environmental pollution control. This article succinctly summarizes the preparation methods and properties of coal-based carbon nanotubes, coal-based carbon quantum dots, and coal-based graphene, elucidates their current applications in water pollution control and governance, and anticipates their development trends in water pollution control, aiming to provide support for the clean and efficient utilization of coal and water pollution control.

High-efficiency microplastic removal in water treatment based on short flow control of hydrocyclone: Mechanism and performance.

Microplastics have been identified as a potentially emerging threat to water environment and human health. Therefore, there is a pressing demand for effective strategies to remove microplastics from water. Hydrocyclone offers a rapid separation and low energy consumption alternative but require reduction of microparticle entrainment by short flow, which limits the effectiveness for small density differentials and ultralow concentrations separation. We proposed an enhanced mini-hydrocyclone with overflow microchannels (0.72 mm width) based on the active control of short flow in hydrocyclone for microplastic removal from water. The overflow microchannels effectively redirect the particles that would typically be entrained by the short flow, leading to higher separation efficiency. Simulation results show overflow microchannels effectively reduced short flow to 0.7 %, a reduction of up to 94 % compared to conventional hydrocyclones. The hydrocyclone with overflow microchannel demonstrated a removal efficiency exceeding 98 % for 8 µm plastic microbeads at ultralow concentrations (10 ppm), which is a 33.7 % improvement over conventional hydrocyclone. Compared with other methods (e.g., filtration, adsorption, coagulation) for microplastic removal, this work achieves rapid separation capability and long period operation, highlighting hydrocyclone as a promising approach for microplastic removal in industry-scale water treatment.

Compaction of Pressure-Driven Water Treatment Membranes: Real-Time Quantification and Analysis.

Water treatment membranes play crucial roles in applications such as desalination, wastewater treatment, and potable water reuse. In a prior study, we introduced a novel method, combining electrical impedance spectroscopy with dynamic mechanical analysis, to quantify single-layer homogeneous membrane compaction up to 12.5 psi. Now we extend the method's capabilities to quantify real-time compaction of multilayer heterogeneous nanofiltration and reverse osmosis (RO) membranes up to 330 psi. Our findings demonstrate that membrane compaction does not solely occur in the support/backing layer. The air pockets between the polysulfone support and the polyester backing layers, which were not discussed previously, account for up to 18% and 14% of total membrane compaction for the nanofiltration and RO membranes. For the nanofiltration membrane, the majority of compaction (up to 45%) occurs in the void spaces of the backing layer, while for the RO membrane, the majority of compaction (up to 40%) occurs in the solid material of the backing layer. We also confirm, with experimental results, the importance of using compressive testing instead of tensile testing to accurately characterize compaction. Membrane fatigue is characterized by experimental trends including: increasing irrevocable compaction, increasing creep/instantaneous compaction ratios, and increasing strains in hysteresis experiments.

Biocompatible bismuth-based biochar material for degrading environmental endocrine disrupting compounds: Performance study and enhanced electron transfer radical process.

Environmental endocrine disrupting compounds (EDCs) present a significant environmental threat and represent a major challenge in water pollution management. Photocatalysis is a promising method for the treatment of EDCs. Among them, bismuth-based photocatalysts have attracted attention due to their excellent visible light response, narrow band gap, and high efficiency. However, challenges such as easy recombination of photogenerated electrons and holes, low reaction rates, and difficulty in recycling powdered catalysts hinder their practical application. In this investigation, a swift microwave-assisted hydrothermal technique was utilized to fabricate a composite material comprising bismuth-based biochar (BC): BiVO4/AgI/BC. Using 17α-ethynylestradiol (EE2) and estradiol (E2) as model EDCs, the photocatalytic degradation efficiency of BiVO4/AgI/BC was evaluated, alongside an examination of its degradation mechanism and pathways. Remarkably, the incorporation of BiVO4/AgI onto BC significantly augmented the electron transfer rate, fostering the production of •O2-, resulting in a removal efficiency of 99.68% for EE2 and 99.44% for E2, surpassing that of other materials. Furthermore, BiVO4/AgI/BC demonstrated nos3reusability, stability, and low biotoxicity. Thus, BiVO4/AgI/BC exhibits substantial potential for the efficient and environmentally benign elimination of endocrine-disrupting compounds under realistic water conditions.

Model linkage to assess forest disturbance impacts on water quality: A wildfire case study using LANDIS(II)-VELMA.

Wildfires in western US forests increased over the last two decades, resulting in elevated solid and nutrient loadings to streams, and occasionally threatening drinking water supplies. We demonstrated that a linked LANDIS (LANDscape DIsturbance and Succession)-VELMA (Visualizing Ecosystem Land Management Assessments) modeling approach can simulate wildland fire effects on water quality using the 2002 Colorado Hayman Fire. Utilizing LANDIS-II's forest landscape model to simulate forest composition and VELMA's eco-hydrologic model to simulate pre- and post-fire water quantity and quality, the best calibration performance yielded a Nash-Sutcliffe Efficiency (NSE) of 0.621 during 2000-2006 (most optimal annual - 0.921) in comparison to North American Land Data Assimilation System (NLDAS) runoff. Pre-fire modeled runoff, nitrate, and surface water temperature (SWT) correlated with observations. Simulated post-fire runoff (229%) and SWT (20.6%) were elevated relative to pre-fire, with nitrate concentrations 34 times greater than the aquatic life threshold (0.01 mg N/L).

Household Water Treatment Practice and Associated Factors in Sub-Saharan Africa: A Systematic Review and Meta-Analysis.

Introduction: Household water treatment practices, also known as point-of-use water management, offer means to enhance the overall drinking water quality and reduce the prevalence of diarrheal diseases. Nevertheless, there is a scarcity of information on household water treatment practices and related factors in sub-Saharan Africa. Objective: This study aimed to determine the pooled prevalence of water treatment practices and associated factors in sub-Saharan Africa. Methods: We conducted a search of eligible primary studies in PubMed, Google Scholar, and Hinari, as well as gray literature available in online repositories. The Stata v.17 software was utilized to extract and analyze the data obtained from these studies. To determine the overall pooled prevalence of water treatment practices and their predictors, a weighted inverse-variance random-effects model was employed. We assessed variations across the included studies using forest plots, funnel plots, I 2 statistics, and Egger's tests. Results: In this study, we reviewed a total of 927 articles, 28 of which were eligible for inclusion. The overall pooled prevalence of water treatment practices in sub-Saharan Africa was 36.31(95% CI: 27.64, 44.98). The factors associated with water treatment practices included having formal education (AOR: 2.38, 95% CI: 1.70, 3.34), being male (AOR: 1.78, 95% CI: 1.39, 2.29), having a higher income (AOR: 2.12, 95% CI: 1.39, 3.25), and having received training in water treatment (AOR: 2.25, 95% CI: 1.59, 3.18). Conclusions: In this review, the pooled prevalence of water treatment practices in sub-Saharan Africa was found to be considerably low. Therefore, we recommend that household heads receive enhanced information on water treatment practices through strengthened health education and intensive training in small-scale water treatment practices.