Effect of metal atom in zeolitic imidazolate frameworks (ZIF-8 & 67) for removal of Pb2+ & Hg2+ from water

Synthesis methods, structure, and recent trends of ZIF-8-based materials in the biomedical field

Zeolitic imidazolate framework-8 (ZIF-8) is a highly porous material with remarkable structural properties and high drug-loading capacity, and hence this material presents as an exceptional candidate for advanced drug delivery systems. Herein, we comprehensively review the recent developments in ZIF-8 synthesis techniques and critically discuss innovative approaches such as the use of green solvents and advanced methods such as microwave- and ultrasound-assisted syntheses. The multifunctional applications of ZIF-8-based biomaterials in biomedical engineering are critically explored with their pivotal roles in antibacterial and anticancer therapies, drug delivery systems, bone tissue engineering, and diagnostic platforms such as biosensing and bioimaging. The present review also clarifies some innovations of ZIF-8-based materials in pH-sensitive and glucose-responsive drug delivery systems and scaffolds for bone regeneration. Despite these promising advancements, we analyze critical concerns, such as the release of Zn(ii) ions, potential cytotoxicity, and biocompatibility challenges, which remain significant hurdles to the broader adoption of ZIF-8. Addressing these outlined challenges may be necessary in realizing the potential of ZIF-8 in biomedical applications.

Microwave modified sugar cane bagasse cellulose as an eco-friendly biosorbent for eliminating As(V) from aqueous medium

This work explores the potential of microwave assisted urea modified sugarcane bagasse (UMSCB) as an effective, environment-friendly biosorbent for removing As(V) from an aqueous medium. The synthesized biomaterial was characterized by FTIR analysis that showed the existence of various carboxyl, hydroxyl, and carbonyl functional groups; and SEM analysis of UMSCB showed much higher roughness before the As(V) adsorption of 40.78; indicating that As(V) intricately gets adsorbed onto surface of UMSCB. Batch adsorption experiments demonstrated a removal efficiency of approximately 95 % within 30 min at pH 5. However, UMSCB follows pseudo-second-order kinetics and chemisorption mechanism for removal of As(V). The intra-particle diffusion model indicated that more than one step influences the rate-limiting step. Adsorption equilibrium data shows that the Langmuir model provided the best fit, as determined by correlation coefficient (R2) and chi-square (χ2). Notably, the adsorption capacity (qe) of unmodified sugarcane bagasse (SCB) significantly increased from 4.8 mg/g to 52.8 mg/g upon microwave-assisted urea modification, demonstrating the substantial enhancement in As(V) uptake. Thermodynamic indicators indicated that the biosorption is spontaneous, endothermic, and feasible. The high adsorption efficiency, ease of regeneration, and potential for large-scale application highlight UMSCB as a promising solution for As(V) removal from wastewater.

Review on the utilization of metal organic frameworks (MOFs) for eliminating ibuprofen and naproxen from water sources

The increasing concern regarding pharmaceutical contaminants in the environment, particularly ibuprofen (IBU) and naproxen (NPX), has led to extensive research on effective methods for removing these pollutants. This review evaluates the use of metal organic frameworks (MOFs) for the removal of IBU and NPX from water, summarizing findings from studies published between 2010 and 2024, sourced from Google Scholar, ScienceDirect, and Scopus. The analysis shows that 68.3% of the reviewed studies focused on IBU and 31.7% on NPX. Analytical techniques such as XRD, FESEM, FTIR, XPS and BET were frequently used, appearing in 95.12, 78, 75.6, 56.1%, and 34.15% of the studies, respectively. This study demonstrated that MOFs, including Pd@MIL-100(Fe), UiO-67@β-CD-NP, HSO₃-MIL-53(Fe), and UiO-66-MOF, are capable of achieving complete removal of the targeted pharmaceuticals. The findings indicate that the key factors influencing removal efficiency include solution pH, MOF dosage, and adsorption mechanisms. This review concludes that MOFs, particularly those following the Langmuir adsorption isotherm model and PSO adsorption kinetics, are promising for the effective removal of IBU and NPX. These results highlight the potential of MOFs in addressing pharmaceutical contamination and suggest further research, particularly in optimizing MOF structures for environmental applications.

Tactical metal-organic frameworks (MOFs) adsorbent advantages in removal applications

Water pollution caused by the increasing concentration of toxic chemicals, such as heavy metal ions, pesticides, pharmaceutical waste, and plastic contaminants, has become a global issue. The rising levels of these pollutants pose significant health risks to humans and various species. Recently, adsorption has emerged as a promising method for removing these contaminants. This review focuses on metal-organic frameworks (MOFs) as adsorbents, highlighting their large surface areas and adjustable porosity, which optimize the adsorption process. The review analyzes the active sites within MOFs, their roles in adsorption mechanisms, and the underlying chemistry involved. It also discusses the structural chemistry of MOFs and its impact on pollutant removal efficiency. Furthermore, the review addresses stability, scalability, and economic feasibility challenges. Finally, it suggests future research directions for next-generation MOF materials to enhance their effectiveness in sustainable environmental remediation, ultimately improving our ability to combat contamination issues and protect healthy ecosystems.

Lead toxicity in Nicotiana tabacum L.: Damage antioxidant system and disturb plant metabolism

In this study, we treated tobacco seedlings with 0, 200, 400, and 800 mg/kg Pb2 +, and explored the response mechanism of tobacco under Pb stress through a combination of growth physiology and metabolomics analysis. The physiological results showed that compared with CK, with the increase of Pb concentration, Pb treatment inhibited tobacco growth, reduced the biomass and photosynthetic pigment content of tobacco seedlings, and severely damaged the chloroplast structure. In addition, compared with CK, the pore conductivity and pore density of Pb800 treatment decreased by 45.77 % and 93.55 %, respectively. Pb treatment disrupted the cell membrane system, and Pb800 treatment increased the content of malondialdehyde (MDA) in leaves and roots by 67.65 % and 31.90 %, respectively. Meanwhile, Pb treatment increased the activity of tobacco SOD and POD enzymes. Metabolomics results showed that Pb stress enhanced tryptophan metabolism, glutathione metabolism, alanine, aspartate, and glutamate metabolism, as well as cysteine and methionine metabolism pathways. These results indicate that increasing the content of photosynthetic pigments and hormones, clearing reactive oxygen species by enhancing antioxidant enzyme activity, and improving amino acid metabolism may play an important role in reducing the toxicity of Pb to tobacco.

Electrochemical conversion of CO2 using metalorganic frameworks-based materials: A review on recent progresses and outlooks

Global warming has been mainly attributed to the excessive release of carbon dioxide (CO2) to the atmosphere. Several CO2 capture and conversion technologies have been developed in the past few decades with their own merits and limitations. Electrochemical conversion of CO2 is one of the most attractive techniques for combating CO2 emissions. However, the efficacy of the electrochemical reduction of CO2 hinges on the efficiency of the utilized materials (i.e., electrocatalysts). Metal organic frameworks (MOFs)-based materials have recently emerged as attractive tools for various applications, including the electrochemical conversion of CO2. Although there are some review articles on CO2 capture and conversion using different materials, reviews focusing specifically on the electrochemical conversion of CO2 using MOFs-based materials are still comparatively lacking. Additionally, the field of electrochemical conversion of CO2 into valuable chemicals is currently gaining high momentum, requiring comprehensive and recent reviews, which would provide researchers/professionals with a quick and easy access to the recent developments in this rapidly evolving research area. Accordingly, this article comprehensively reviews recent studies on the electrochemical conversion of CO2 using pristine/modified/functionalized MOFs as well as composite materials containing MOFs. Additionally, single atom catalysts (SACs) derived from MOFs and their applications for the electrochemical conversion of CO2 has also been reviewed. Furthermore, obstacles, challenges, limitations, and remaining research gaps have been identified, and future works to tackle them have been highlighted. Overall, this review article provides valuable discussion and insights into the recent advancements in the field of electrochemical conversion of CO2 into chemicals using MOFs-based materials.

Unveiling the scope and perspectives of MOF-derived materials for cutting-edge applications

Although synthesis and design of MOFs are crucial factors to the successful implementation of targeted applications, there is still lack of knowledge among researchers about the synthesis of MOFs and their derived composites for practical applications. For example, many researchers manipulate study results, and it has become quite difficult to quit this habit specifically among the young researchers Undoubtedly, MOFs have become an excellent class of compounds but there are many challenges associated with their improvement to attain diverse applications. It has been noted that MOF-derived materials have gained considerable interest owing to their unique chemical properties. These compounds have exhibited excellent potential in various sectors such as energy, catalysis, sensing and environmental applications. It is worth mentioning that most of the researchers rely on commercially available MOFs for use as precursor supports, but it is an unethical and wrong practice because it prevents the exploration of the hidden diversity of similar materials. The reported studies have significant gaps and flaws, they do not have enough details about the exact parameters used for the synthesis of MOFs and their derived materials. For example, many young researchers claim that MOF-based materials cannot be synthesized as per the reported instructions for large-scale implementation. In this regard, current article provides a comprehensive review of the most recent advancements in the design of MOF-derived materials. The methodologies and applications have been evaluated together with their advantages and drawbacks. Additionally, this review suggests important precautions and solutions to overcome the drawbacks associated with their preparation. Applications of MOF-derived materials in the fields of energy, catalysis, sensing and environment have been discussed. No doubt, these materials have become excellent class but there are still many challenges ahead to specify it for the targeted applications.

Bimetal Cu/Ni-BTC@SiO2 metal-organic framework as high performance photocatalyst for degradation of azo dyes under visible light irradiation

There has been significant attention on the efficient degradation of pollutants in wastewater using metal-organic frameworks (MOFs) photocatalytic methods over the past decade. Herein, we examined the elimination of two different types of water-contaminating dyes, specifically cationic dye methylene blue (MB) and anionic dye methyl orange (MO), through the application of bimetal Cu/Ni-BTC@SiO2 MOF as high performance photocatalyst. The bimetal Cu/Ni-BTC@SiO2 photocatalyst was synthesized and characterized by XRD, FTIR, SEM, TEM, TGA, BET, DRS, and VSM techniques. The examination of the impact of different operational factors on the elimination of pollutants involved a comprehensive analysis of variables including the photocatalyst type, initial pollutant concentration, quantity of photocatalyst, and pH levels. The highest removal efficiency for MO and MB dyes by the photocatalyst was found to be 98 and 71%, respectively, within 60 min. In the fifth reaction stage, degradation efficiency for MO and MB was 76 and 56% respectively. Kinetic investigations demonstrated that, in the context of the uptake of MB and MO dyes, the interparticle diffusion, and pseudo-second-order models emerged as possessing the most robust correlation coefficients with the experimental data, registering values of 0.988 and 0.961, respectively. The examination of isotherms reveals that the isotherm models proposed by BET, and Anderson (V) demonstrate the highest level of conformity with the empirical data for the decomposition of MB and MO dyes, correspondingly. The TOC levels decreased significantly from 51 to 14 and 47 to 3 mg/L for MB and MO dyes, indicating the effective mineralization process using Cu/Ni-BTC@SiO2.

Neurotoxic effects of low dose ranges of environmental metal mixture in a rat model: The benchmark approach

Metals exert detrimental effects on various systems within the body, including the nervous system. Nevertheless, the dose-response relationship concerning the administration of low doses of metal mixtures remains inadequately explored. The assessment of neurotoxic effects of lead, cadmium, mercury, and arsenic mixture (MIX) administered at low dose ranges, was conducted using an in vivo approach. A subacute study was conducted on a rat model consisting of a control and five treatment groups subjected to oral exposure with gradually increasing doses (from MIX 1 to MIX 5). The results indicated that behavioural patterns in an already developed nervous system displayed a reduced susceptibility to the metal mixture exposure with tendency of higher doses to alter short term memory. However, the vulnerability of the mature brain to even minimal amounts of the investigated metal mixture was evident, particularly in the context of oxidative stress. Moreover, the study highlights superoxide dismutase's sensitivity as an early-stage neurotoxicity marker, as indicated by dose-dependent induction of oxidative stress in the brain revealed through Benchmark analysis. The narrowest Benchmark Dose Interval (BMDI) for superoxide dismutase (SOD) activity (1e-06 - 3.18e-05 mg As/kg b.w./day) indicates that arsenic may dictate the alterations in SOD activity when co-exposed with the other examined metals. The predicted Benchmark doses for oxidative stress parameters were very low, supporting "no-threshold" concept. Histopathological alterations were most severe in the groups treated with higher doses of metal mixture. Similarly, the brain acetylcholinesterase (AChE) activity demonstrated a dose-dependent decrease significant in higher doses, while BMDI suggested Cd as the main contributor in the examined metal mixture. These findings imply varying susceptibility of neurotoxic endpoints to different doses of environmentally relevant metal mixtures, advocating for risk assessment and regulatory measures to address metal pollution and enhance remediation strategies.

Adsorptive removal of heavy metals from aqueous solutions: Progress of adsorbents development and their effectiveness

Increased levels of heavy metals (HMs) in aquatic environments poses serious health and ecological concerns. Hence, several approaches have been proposed to eliminate/reduce the levels of HMs before the discharge/reuse of HMs-contaminated waters. Adsorption is one of the most attractive processes for water decontamination; however, the efficiency of this process greatly depends on the choice of adsorbent. Therefore, the key aim of this article is to review the progress in the development and application of different classes of conventional and emerging adsorbents for the abatement of HMs from contaminated waters. Adsorbents that are based on activated carbon, natural materials, microbial, clay minerals, layered double hydroxides (LDHs), nano-zerovalent iron (nZVI), graphene, carbon nanotubes (CNTs), metal organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs) are critically reviewed, with more emphasis on the last four adsorbents and their nanocomposites since they have the potential to significantly boost the HMs removal efficiency from contaminated waters. Furthermore, the optimal process conditions to achieve efficient performance are discussed. Additionally, adsorption isotherm, kinetics, thermodynamics, mechanisms, and effects of varying adsorption process parameters have been introduced. Moreover, heavy metal removal driven by other processes such as oxidation, reduction, and precipitation that might concurrently occur in parallel with adsorption have been reviewed. The application of adsorption for the treatment of real wastewater has been also reviewed. Finally, challenges, limitations and potential areas for improvements in the adsorptive removal of HMs from contaminated waters are identified and discussed. Thus, this article serves as a comprehensive reference for the recent developments in the field of adsorptive removal of heavy metals from wastewater. The proposed future research work at the end of this review could help in addressing some of the key limitations facing this technology, and create a platform for boosting the efficiency of the adsorptive removal of heavy metals.

Zeolitic imidazolate frameworks (ZIFs): Advanced nanostructured materials to enhance the functional performance of food packaging materials

Zeolite imidazole framework (ZIF) materials are a class of metallic organic framework (MOF) materials that have several potential applications in the food and other industries. They consist of metal ions or clusters of metal ions coordinated with imidazole-based organic linkers, creating a three-dimensional solid structure with well-defined pores and channels. ZIFs possess several important features, including high porosity, tunable pore sizes, high surface areas, adjustable surface chemistries, and good stabilities. These characteristics make them highly versatile materials that can be used in a variety of applications, including smart and active food packaging. Based on their controllable compositions, dimensions, and pore sizes, the properties of ZIFs can be tailored for a diverse range of applications, including energy storage, sensing, separation, encapsulation, and catalysis. In this article, we focus on recent progress and potential applications of ZIFs in food packaging materials. Previous studies have shown that ZIFs can significantly improve the optical, mechanical, barrier, thermal, sustainability, and preservative properties of packaging materials. Moreover, ZIFs can be used as carriers to encapsulate, protect, and control the release of bioactive agents in packaging materials. ZIFs are capable of selectively adsorbing and releasing molecules based on their size, shape, and surface properties. These unique characteristics make them particularly suitable for smart or active food packaging applications. By selectively removing gases (such as oxygen, carbon dioxide, water, or ethylene) ZIFs can improve the shelf life and quality of packaged foods. In addition, they can be employed to control the growth of spoilage microorganisms and minimize oxidation reactions, thereby enhancing the freshness and extending the shelf life of foods. They may also be used to create sensors capable of detecting and indicating food spoilage. For instance, ZIFs that change color or release specific compounds when spoilage products are present can provide visual or chemical indications of food deterioration. This feature is especially valuable in ensuring the safety and quality of packaged food, as it enables consumers and retailers to easily identify spoiled products. ZIFs can be functionalized using various additives, including antioxidants, antimicrobials, pigments, and flavors, which can improve the preservative and sensory properties of packaged foods. Moreover, ZIF-based packaging materials offer sustainability benefits. Unlike traditional plastic packaging, ZIFs are biodegradable and can easily be disposed of without causing harm to the environment, thereby reducing the adverse effects of plastic waste materials. The application of ZIFs in smart/active food packaging offers exciting possibilities for enhancing the shelf life, quality, and safety of foods. With further research and development, ZIF-based packaging could become a sustainable alternative to plastic-based packaging in the food industry. An important aim of this review article is to stimulate further research on the development and application of ZIFs within food packaging materials.

Cobalt metal replaces Co-ZIF-8 mesoporous material for effective adsorption of arsenic from wastewater

The high cost and low adsorption capacity of primary metal-organic frameworks (ZIF-8) limit their application in heavy metal removal. In this paper, Co/Zn bimetallic MOF materials were synthesized with excellent adsorption performance for As5+. The adsorption reached equilibrium after 180 min and the maximum adsorption was 250.088 mg/g. In addition, Co-ZIF-8 showed strong selective adsorption of As5+. The adsorption process model of Co-ZIF-8 fits well with the pseudo-second-order kinetic model (R2=0.997) and Langmuir isotherm model (R2=0.994), and it is demonstrated that the adsorption behavior of the adsorbent is a single layer of chemical adsorption. In addition, when the adsorbent enters the arsenic-containing solution, the surface of Co-ZIF-8 is hydrolyzed to produce a large number of Co-OH active sites, and As5+ arrives at the surface of Co-ZIF-8 by electrostatic adsorption and combines with the active sites to generate the arsenic-containing complex As-O-Co. After four cycles, Co-ZIF-8 showed 80% adsorption of As5+. This study not only provides a new method to capture As5+ in water by preparing MOF with partial replacement of the central metal, but also has great significance for the harmless disposal of polluted water.

Improved anti-cancer effects of luteolin@ZIF-8 in cervical and prostate cancer cell lines

Luteolin, a naturally occurring pharmaceutical compound with significant antitumor properties, faces challenges in clinical applications due to its low solubility in water and limited bioavailability. To address these issues, a one-step synthesis method was employed to encapsulate luteolin within ZIF-8. The successful preparation of luteolin@ ZIF-8 nanoparticles was confirmed through various analytical techniques, including fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), laser size distribution analysis, X-ray diffraction (XRD), and release curve assessment. Results indicate that the formulated luteolin@ ZIF-8 nanoparticles exhibited high drug loading (1360 mg/g) and demonstrated selective drug release in acidic microenvironments. Furthermore, the encapsulation of luteolin increased the size of ZIF-8 from 168.4 ± 0.2 nm to 384.7 ± 1.4 nm, but did not change its crystalline structure significantly. Notably, the results of in vitro anti-cervical and prostate cancers experiments revealed that luteolin@ ZIF-8 had better efficacy in inhibiting the proliferation and migration of HeLa and PC3 cells than free luteolin. The antitumor activity of luteolin@ ZIF-8 was sustained for 72 h, with a particularly pronounced inhibitory effect on HeLa cells as compared to PC3 cells. This study underscores the effective enhancement of luteolin's antitumor activity through encapsulation in ZIF-8, offering substantial implications for improving its clinical applications.

Biomonitoring of heavy metals and their phytoremediation by duckweeds: Advances and prospects

Heavy metals (HMs) contamination of water bodies severely threatens human and ecosystem health. There is growing interest in the use of duckweeds for HMs biomonitoring and phytoremediation due to their fast growth, low cultivation costs, and excellent HM uptake efficiency. In this review, we summarize the current state of knowledge on duckweeds and their suitability for HM biomonitoring and phytoremediation. Duckweeds have been used for phytotoxicity assays since the 1930s. Some toxicity tests based on duckweeds have been listed in international guidelines. Duckweeds have also been recognized for their ability to facilitate HM phytoremediation in aquatic environments. Large-scale screening of duckweed germplasm optimized for HM biomonitoring and phytoremediation is still essential. We further discuss the morphological, physiological, and molecular effects of HMs on duckweeds. However, the existing data are clearly insufficient, especially in regard to dissection of the transcriptome, metabolome, proteome responses and molecular mechanisms of duckweeds under HM stresses. We also evaluate the influence of environmental factors, exogenous substances, duckweed community composition, and HM interactions on their HM sensitivity and HM accumulation, which need to be considered in practical application scenarios. Finally, we identify challenges and propose approaches for improving the effectiveness of duckweeds for bioremediation from the aspects of selection of duckweed strain, cultivation optimization, engineered duckweeds. We foresee great promise for duckweeds as phytoremediation agents, providing environmentally safe and economically efficient means for HM removal. However, the primary limiting issue is that so few researchers have recognized the outstanding advantages of duckweeds. We hope that this review can pique the interest and attention of more researchers.

Recent trends in wastewater treatment by using metal-organic frameworks (MOFs) and their composites: A critical view-point

Respecting the basic need of clean and safe water on earth for every individual, it is necessary to take auspicious steps for waste-water treatment. Recently, metal-organic frameworks (MOFs) are considered as promising material because of their intrinsic features including the porosity and high surface area. Further, structural tunability of MOFs by following the principles of reticular chemistry, the MOFs can be functionalized for the high adsorption performance as well as adsorptive removal of target materials. However, there are still some major concerns associated with MOFs limiting their commercialization as promising adsorbents for waste-water treatment. The cost, toxicity and regenerability are the major issues to be addressed for MOFs to get insightful results. In this article, we have concise the current strategies to enhance the adsorption capacity of MOFs during the water-treatment for the removal of toxic dyes, pharmaceuticals, and heavy metals. Further, we have also discussed the role of metallic nodes, linkers and associated functional groups for effective removal of toxic water pollutants. In addition to conformist overview, we have critically analyzed the MOFs as adsorbents in terms of toxicity, cost and regenerability. These factors are utmost important to address before commercialization of MOFs as adsorbents for water-treatment. Finally, some future perspectives are discussed to give directions for potential research.

Isolation of Sensing Units and Adsorption Groups Based on MOF-on-MOF Hierarchical Structure for Both Highly Sensitive Detection and Removal of Hg2

Bifunctional materials have attracted ongoing interest in the field of detection and removal of contaminants because of their integration of two functions, but they exhibit commonly exceptional performance in only one of these two aspects. The interaction between the two functional units of the bifunctional materials may compromise their sensing and adsorption abilities. Guided by the concept of domain building blocks (DBBs), a hierarchical metal-organic framework (MOF)-on-MOF hybrid was designed by growing gold nanoclusters (AuNCs)-embedded zeolitic imidazolate framework 8 (AuNCs/ZIF-8) on the surface of Zr-MOF (UiO-66-NH2) for the simultaneous detection and removal of Hg2+. In the hybrid, the amino groups (-NH2) and AuNCs─which were the adsorption groups and sensing units, respectively, were isolated from each other. Specifically, the adsorption groups (-NH2) were assembled in the inner UiO-66-NH2 layer, while the sensing units (AuNCs) were confined in the outer ZIF-8 layer. This hierarchical structure not only spatially hindered the electron transfer between these two units but also triggered the aggregation-induced emission of AuNCs because of the confinement of ZIF-8 on the AuNCs, thus changing the fluorescence of AuNCs from quenching to enhancement. The newly prepared UiO-66-NH2@AuNCs/ZIF-8 hybrid, as expected, showed an ultralow detection limit (0.42 ppb) and a high adsorption capacity (129.9 mg·g-1) for Hg2+. Overall, this work provides a feasible approach to improve the integrated performance of MOF-based composites based on DBBs.

Selective removal of Pb(II) from yellow rice wine using magnetic carbon-based adsorbent

BACKGROUND

The non-distilled property and prolonged production period of yellow rice wine have significantly increased the metal residue problem, posing a threat to human health. In this study, a magnetic carbon-based adsorbent, named magnetic nitrogen-doped carbon (M-NC), was developed for the selective removal of lead(II) (Pb(II)) from yellow rice wine.

RESULTS

The results showed that the uniformly structured M-NC could be easily separated from the solution, exhibiting a high Pb(II) adsorption capacity of 121.86 mg g-1 . The proposed adsorption treatment showed significant Pb(II) removal efficiencies (91.42-98.90%) for yellow rice wines in 15 min without affecting their taste, odor, and physicochemical characteristics of the wines. The adsorption mechanism studied by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) analyses indicated that the selective removal of Pb(II) could be attributed to the electrostatic interaction and covalent interaction between the empty orbital of Pb(II) and the π electrons of the N species on M-NC. Additionally, the M-NC showed no significant cytotoxicity on the Caco-2 cell lines.

CONCLUSION

Selective removal of Pb(II) from yellow rice wine was achieved using magnetic carbon-based adsorbent. This facile and recyclable adsorption operation could potentially address the challenge of toxic metal pollution in liquid foods. © 2023 Society of Chemical Industry.

Cypermethrin adsorption by Lactiplantibacillus plantarum and its behavior in a simulated fecal fermentation model

The presence of cypermethrin in the environment and food poses a significant threat to human health. Lactic acid bacteria have shown promise as effective absorbents for xenobiotics and well behaved in wide range of applications. This study aimed to characterize the biosorption behavior of cypermethrin by Lactiplantibacillus plantarum RS60, focusing on cellular components, functional groups, kinetics, and isotherms. Results indicated that RS60 exopolysaccharides played a crucial role removing cypermethrin, with the cell wall and protoplast contributing 71.50% and 30.29% to the overall removal, respectively. Notably, peptidoglycans exhibited a high affinity for cypermethrin binding. The presence of various cellular surface groups including -OH, -NH, -CH3, -CH2, -CH, -P = O, and -CO was responsible for the efficient removal of pollutants. Additionally, the biosorption process demonstrated a good fit with pseudo-second-order and Langmuir-Freundlich isotherm. The biosorption of cypermethrin by L. plantarum RS60 involved complex chemical and physical interactions, as well as intraparticle diffusion and film diffusion. RS60 also effectively reduced cypermethrin residues in a fecal fermentation model, highlighting its potential in mitigating cypermethrin exposure in humans and animals. These findings provided valuable insights into the mechanisms underlying cypermethrin biosorption by lactic acid bacteria and supported the advancement of their application in environmental and health-related contexts. KEY POINTS: • Cypermethrin adsorption by L. plantarum was clarified. • Cell wall and protoplast showed cypermethrin binding ability. • L. plantarum can reduce cypermethrin in a fecal fermentation model.

Recent Advances in Metal-Organic Framework (MOF)-Based Photocatalysts: Design Strategies and Applications in Heavy Metal Control

The heavy metal contamination of water systems has become a major environmental concern worldwide. Photocatalysis using metal-organic frameworks (MOFs) has emerged as a promising approach for heavy metal remediation, owing to the ability of MOFs to fully degrade contaminants through redox reactions that are driven by photogenerated charge carriers. This review provides a comprehensive analysis of recent developments in MOF-based photocatalysts for removing and decontaminating heavy metals from water. The tunable nature of MOFs allows the rational design of composition and features to enhance light harvesting, charge separation, pollutant absorptivity, and photocatalytic activities. Key strategies employed include metal coordination tuning, organic ligand functionalization, heteroatom doping, plasmonic nanoparticle incorporation, defect engineering, and morphology control. The mechanisms involved in the interactions between MOF photocatalysts and heavy metal contaminants are discussed, including light absorption, charge carrier separation, metal ion adsorption, and photocatalytic redox reactions. The review highlights diverse applications of MOF photocatalysts in treating heavy metals such as lead, mercury, chromium, cadmium, silver, arsenic, nickel, etc. in water remediation. Kinetic modeling provides vital insights into the complex interplay between coupled processes such as adsorption and photocatalytic degradation that influence treatment efficiency. Life cycle assessment (LCA) is also crucial for evaluating the sustainability of MOF-based technologies. By elucidating the latest advances, current challenges, and future opportunities, this review provides insights into the potential of MOF-based photocatalysts as a sustainable technology for addressing the critical issue of heavy metal pollution in water systems. Ongoing efforts are needed to address the issues of stability, recyclability, scalable synthesis, and practical reactor engineering.

Synthesis of a novel multifunctional organic-inorganic nanocomposite for metal ions and organic dye removals

In this study, we used solvent assisted mechano-synthesis strategies to form multifunctional organic-inorganic nanocomposites capable of removing both organic and inorganic contaminants. A zeolite X (Ze) and activated carbon (AC) composite was synthesized via state-of-the-art mechanical mixing in the presence of few drops of water to form Ze/AC. The second composite (Ze/L/AC) was synthesized in a similar fashion, however this composite had the addition of disodium terephthalate as a linker. Both materials, Ze/AC and Ze/L/AC, were characterized using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Powdered X-ray diffraction (P-XRD), Fourier-transform infrared spectrometry (FTIR), Accelerated Surface Area and Porosimetry System (ASAP), and thermal gravimetric analysis (TGA). The SEM-EDS displayed the surface structure and composition of each material. The sodium, oxygen and carbon contents increased after linker connected Ze and AC. The P-XRD confirmed the crystallinity of each material as well as the composites, while FTIR indicated the function groups (C=C, O-H) in Ze/L/AC. The contaminant adsorption experiments investigated the effects of pH, temperature, and ionic strength on the adsorption of methylene blue (MB) and Co(II) for each material. In MB adsorption, the first-order reaction rate of Ze/L/AC (0.02 h-1) was double that of Ze/AC (0.01 h-1). The reaction rate of Ze/L/AC (4.8 h-1) was also extraordinarily higher than that of Ze/AC (0.6 h-1) in the adsorption of Co(II). Ze/L/AC composite achieved a maximum adsorption capacity of 44.8 mg/g for MB and 66.6 mg/g for Co(II) ions. The MB adsorption of Ze/AC and Ze/L/AC was best fit in Freundlich model with R2 of 0.96 and 0.97, respectively, which indicated the multilayer adsorption. In the Co(II) adsorption, the data was highly fit in Langmuir model with R2 of 0.94 and 0.92 which indicated the monolayer adsorption. These results indicated both materials exhibited chemisorption. The activation energy of Ze/L/AC in MB adsorption (34.9 kJ mol-1) was higher than that of Ze/L/AC in Co (II) adsorption (26 kJ mol-1).

Screening of MnO2 with desired facet and its behavior in highly selective adsorption of aqueous Pb (II): Theoretical and experimental studies

In this study, Density Functional Theory (DFT) calculations and experimental methods were used to evaluate MnO₂ with 5 different facets for their selective adsorption of Pb (II) from wastewater containing Cd (II), Cu (II), Pb (II), and Zn (II). The DFT calculations were used to screen the selective adsorption capability of the facets and demonstrated that the MnO₂ (3 1 0) facet has an excellent performance in selective adsorption of Pb (II) among all facets. The validity of DFT calculations was verified by comparing with the experimental results. MnO₂ with different facets was prepared in a controlled manner and the characterizations confirmed that the lattice indices of the fabricated MnO₂ have the desired facets. Adsorption performance experiments illustrated a high adsorption capacity (320.0 mg/g) on the (3 1 0) facet MnO₂. The selectivity of adsorption of Pb (II) was 3-32 times greater than that of the other coexisting ions, i.e., Cd (II), Cu (II), and Zn (II)), which is consistent with results of the DFT calculations. Furthermore, DFT calculations of the adsorption energy, charge density difference, and projected density of states (PDOS) showed that the adsorption of Pb (II) on the MnO₂ (3 1 0) facet is non-activated chemisorption. This study shows that it is feasible to use DFT calculations to quickly screen suitable adsorbents for environmental applications.

Pyrolyzed magnetic NiO/carbon-derived nanocomposite from a hierarchical nickel-based metal-organic framework with ultrahigh adsorption capacity

Herein, a simple one-pot solvothermal approach is used to create magnetic porous carbon nanocomposites which obtained from a nickel-based metal-organic framework (Ni-MOF) and examined for their ability to uptake methyl orange (MO) dye. Derived carbons with exceptional porosity and magnetic properties were created during the different pyrolysis temperatures of Ni-MOF (700, 800, and 900 °C) under a nitrogen atmosphere. The black powders were given the names CDM-700, CDM-800, and CDM-900 after they were obtained. A variety of analysis methods, including FESEM, EDS, XRD, FTIR, VSM, and N₂ adsorption-desorption were used to characterize as-prepared powders. Furthermore, adsorbent dosage, contact time, pH variation, and initial dye concentration effects was investigated. The maximum adsorption capacities were 307.38, 5976.35, 4992.39, and 2636.54 mg/g for Ni-MOF, CDM-700, CDM-800, and CDM-900, respectively, which show the ultrahigh capacity of the resulted nanocomposites compared to newest materials. The results showed that not only the crystallinity turned but also the specific surface area was increased about four times after paralyzing. The results showed that the maximum adsorption capacity of MO dye for CDM-700 was obtained at adsorbent dosage of 0.083 g/L, contact time of 60 min, feed pH of 3, and temperature of 45 °C. The Langmuir model has the best match and suggests the adsorption process as a single layer. According to the results of reaction kinetic studies using well-known models, the pseudo-second-order model (R² = 0.9989) displayed high agreement with the experimental data. The synthesized nanocomposite is introduced as a promising superadsorbent for eliminating dyes from contaminated water due to strong recycling performance up to the fifth cycle.

Aqueous Pb(II) Removal Using ZIF-60: Adsorption Studies, Response Surface Methodology and Machine Learning Predictions

Zeolitic imidazolate frameworks (ZIFs) are increasingly gaining attention in many application fields due to their outstanding porosity and thermal stability, among other exceptional characteristics. However, in the domain of water purification via adsorption, scientists have mainly focused on ZIF-8 and, to a lesser extent, ZIF-67. The performance of other ZIFs as water decontaminants is yet to be explored. Hence, this study applied ZIF-60 for the removal of lead from aqueous solutions; this is the first time ZIF-60 has been used in any water treatment adsorption study. The synthesized ZIF-60 was subjected to characterization using FTIR, XRD and TGA. A multivariate approach was used to investigate the effect of adsorption parameters on lead removal and the findings revealed that ZIF-60 dose and lead concentration are the most significant factors affecting the response (i.e., lead removal efficiency). Further, response surface methodology-based regression models were generated. To further explore the adsorption performance of ZIF-60 in removing lead from contaminated water samples, adsorption kinetics, isotherm and thermodynamic investigations were conducted. The findings revealed that the obtained data were well-fitted by the Avrami and pseudo-first-order kinetic models, suggesting that the process is complex. The maximum adsorption capacity (q_max) was predicted to be 1905 mg/g. Thermodynamic studies revealed an endothermic and spontaneous adsorption process. Finally, the experimental data were aggregated and used for machine learning predictions using several algorithms. The model generated by the random forest algorithm proved to be the most effective on the basis of its significant correlation coefficient and minimal root mean square error (RMSE).

Titanium lanthanum three oxides decorated magnetic graphene oxide for adsorption of lead ions from aqueous media

The current study presents a viable and straightforward method for synthesizing titanium lanthanum three oxide nanoparticles (TiLa) and their decoration onto the ferrous graphene oxide sheets to produce FeGO-TiLa as efficient magnetic adsorbent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibration sample magnetometer (VSM) were used to evaluate the physical and chemical properties of the produced nanocomposites. The FeGO-TiLa was used to enhance the removal of lead ions from aqueous solution. The FeGO-TiLa nanocomposite exhibited a much higher removal efficiency (93%) for lead ions than pure TiLa nanoparticles (81%) and magnetic graphene oxide (74%). The influence of FeGO-TiLa dosage, contact time, solution pH, solution temperature, and starting quantity on the lead ions was evaluated and adjusted. The investigations demonstrated that a pH 6 with 40 mg adsorbent resulted in >91% removal of lead ions at ambient temperature after 120 min. Isotherm models were used to analyze experimental results, and Langmuir model fitted the data well as compared Freundlich model with a maximum adsorption capacity of 109.89 mg g^-1. Kinetic and studies are performed the lead adsorption over FeGO-TiLa follow pseudo-second-order rate. Langmuir and Free energy suggested the lead ions uptake with FeGO-TiLa was monolayer and physical adsorption mechnaism, respectively. Finally, the FeGO-TiLa nanocompoiste can be used as an alternative adsorbent for water remediation.

Rational synthesis and characterization of highly water stable MOF@GO composite for efficient removal of mercury (Hg2+) from water

The present study is aimed at adsorptive removal of Mercury (Hg²⁺) using highly functionalized nanomaterials based on Graphene Oxide Zeolitic Imidazolate Framework composite (ZIF-67@GO). Solvothermal methodology was used to synthesize ZIF-67@GO composite. Synthesized compounds were confirmed by FTIR, SEM, PXRD and EDX analysis. The as-prepared ZIF-67@GO was tested as efficient adsorbent for effective removal of Mercury (Hg²⁺) from aquatic environment. The atomic adsorption spectrophotometer was used to monitor the process of adsorption of Hg⁺² on ZIF-67@GO. From the adsorption data, the maximum removal efficiency achieved was 91.1% using 10 mg amount of composite for 50 mL using 20 ppm Mercury (Hg²⁺) solution. Different parameters like pH, contact time, concentration, adsorption kinetics and isotherm were also examined to explore adsorption process. Adsorption data fitted well for Freundlich Model having R² value of 0.9925 than Langmuir Isotherm with R² value of 0.9238. Kinetics were rapid and excellently described via 2nd order model with R² = 0.99946 than 1st order model with R² value of 0.8836. Freundlich and pseudo 2nd order models validated that multilayer chemisorption occurs during adsorption process due to the presence of highly functionalized sites on ZIF-67@GO composite. The synthesized composite material has shown excellent reusability. Thus, water stable ZIF-67@GO composites can efficiently be used for Mercury (Hg²⁺) confiscation from water.

Adsorption of Heavy Metals in Contaminated Water Using Zeolite Derived from Agro-Wastes and Clays: A Review

Due to climate change and anthropogenic activities such as agriculture, mining, and urbanization, water contamination has become a very real modern problem. Modern solutions such as activated carbon, reverse osmosis, and ultrafiltration, among others, have been employed in the decontamination of water. These methods are, however, expensive to set up and maintain and therefore have proved a challenge to implement in developing countries. Zeolite materials exhibit excellent structural properties, such as high ion exchange capacity, porosity, and relative surface area, which make them attractive to water decontamination processes. However, conventional zeolites are expensive, and recent research has focused on utilizing low-cost materials such as agro-wastes and clays as raw materials for the synthesis of zeolites. This review aims to discuss the role of low-cost zeolites in their removal of heavy metals and the feasibility of agro-wastes and natural clays in the synthesis of zeolites. Recent research studies based on the synthesis of zeolites from clays and agro-wastes and their application in heavy metal removal have been reviewed and discussed. Agro-wastes such as rice husk ash and sugarcane bagasse ash and layered silicate clays such as kaolinite and smectites are particularly of interest to zeolite synthesis due to their high silica to alumina ratio. Zeolites synthesized through various methods such as hydrothermal, molten salt, and microwave irradiation synthesis have been discussed with their effect on the adsorption of various heavy metals.

Arsenic in drinking water: overview of removal strategies and role of chitosan biosorbent for its remediation

Accessibility to clean drinking water often remains a crucial task at times. Among other water pollutants, arsenic is considered a more lethal contaminant and has become a serious threat to human life globally. This review discussed the sources, chemistry, distribution, and toxicity of arsenic and various conventional technologies that are in option for its removal from the water system. Nowadays, biosorbents are considered the best option for arsenic-contaminated water treatment. We have mainly focused on the need and potential of biosorbents especially the role of chitosan-based composites for arsenic removal. The chitosan-based sorbents are economically more efficient in terms of their, low toxicity, cost-effectiveness, biodegradability, eco-friendly nature, and reusability. The role of various modification techniques, such as physical and chemical, has also been evaluated to improve the physicochemical properties of biosorbent. The importance of adsorption kinetic and isotherm models and the role of solution pH and pHPZC for arsenic uptake from the polluted water have also been investigated. Some other potential applications of chitosan-based biosorbents have also been discussed along with its sustainability aspect. Finally, some suggestions have been highlighted for further improvements in this field.

Metal-Organic Frameworks Derived Electrocatalysts for Oxygen and Carbon Dioxide Reduction Reaction

The increasing demands of energy and environmental concerns have motivated researchers to cultivate renewable energy resources for replacing conventional fossil fuels. The modern energy conversion and storage devices required high efficient and stable electrocatalysts to fulfil the market demands. In previous years, we are witness for considerable developments of scientific attention in Metal-organic Frameworks (MOFs) and their derived nanomaterials in electrocatalysis. In current review article, we have discussed the progress of optimistic strategies and approaches for the manufacturing of MOF-derived functional materials and their presentation as electrocatalysts for significant energy related reactions. MOFs functioning as a self-sacrificing template bid different benefits for the preparation of metal nanostructures, metal oxides and carbon-abundant materials promoting through the porous structure, organic functionalities, abundance of metal sites and large surface area. Thorough study for the recent advancement in the MOF-derived materials, metal-coordinated N-doped carbons with single-atom active sites are emerging candidates for future commercial applications. However, there are some tasks that should be addressed, to attain improved, appreciative and controlled structural parameters for catalytic and chemical behavior.

Arsenic removal approaches: A focus on chitosan biosorption to conserve the water sources

Globally, millions of people have no access to clean drinking water and are either striving for that or oppressed to intake polluted water. Arsenic is considered one of the most hazardous contaminants in water bodies that reaches there due to various natural and anthropogenic activities. Modified chitosan has gained much attention from researchers due to its potential for arsenic removal. This review focuses on the need and potential of chitosan-based biosorbents for arsenic removal from water systems. Chitosan is a low-cost, abundant, biodegradable biopolymer that possesses unique structural aspects and functional sites for the adsorption of contaminants like arsenic species from contaminated water. The chitosan-based biosorbents had also been modified using various techniques to enhance their arsenic removal efficiencies. This article reviews various forms of chitosan and parameters involved in chitosan modification which eventually affect the arsenic removal efficiency of the resultant sorbents. The literature revealed that the modified chitosan-based sorbents could express higher adsorption efficiency compared to those prepared from native chitosan. The sustainability of the chitosan-based sorbents has also been considered in terms of reusability. Finally, some recommendations have been underlined for further improvements in this domain.

Cr(VI) Adsorption from Aqueous Solution by UiO-66 Modified Corncob

To adsorb hexavalent chromium (Cr(VI)) in polluted water, this paper prepared a UiO-66 (Zr6O4(OH)4(BDC)12) modified granular corncob composite adsorbent by hydrothermal method with in situ loading of UiO-66 on pretreated corncob particles. The physicochemical properties of the synthesized samples were characterized. Batch adsorption experiments were conducted to investigate the adsorption process of aqueous Cr(VI) under various conditions (different ionic strength, pH and co-existing anions). The results showed that UiO-66 was successfully loaded on the modified corncob particles. The isothermal adsorption data of Cr(VI) adsorption by the UiO-66 modified corncob fit well with the Langmuir model with the maximum adsorption capacity of Cr(VI) on UiO-66@Corn+ being 90.04 mg/g. UiO-66 loading could increase Cr(VI) adsorption capacity of Corn+. The kinetic study showed that the equilibrium time for Cr(VI) adsorption on UiO-66 modified corncob was about 180 min and the kinetic data followed the pseudo-secondary kinetic model. The Cr(VI) adsorption capacity on UiO-66@Corn+ decreased with the increasing solution pH, and the optimum pH range was 4–6. The ionic strength has little effect on the Cr(VI) adsorption capacity, but the coexistence of CO32−, SO42− and PO43− in the solution could significantly decrease the equilibrium adsorption capacity of Cr(VI). The adsorption mechanism analysis showed that Cr(VI) was adsorbed on the surface of adsorbents through electrostatic attraction and was reduced further to the less toxic Cr(III) by the electron donor on the surface of adsorbent. The electrostatic interaction was the main force affecting the adsorption of Cr(VI) by UiO-66. UiO-66@Corn+ had an excellent removal efficiency of Cr(VI) and excellent reusability. UiO-66@Corn+ could effectively remove Cr(VI) from water and have a promising application.

Water stable graphene oxide metal-organic frameworks composite (ZIF-67@GO) for efficient removal of malachite green from water

Malachite green (MG) is extensively applied in aquaculture worldwide as a therapeutic agent. MG and its primary metabolite leucomalachite green (LMG) are commonly detected in aquaculture products. MG can cause serious health concerns (in vivo carcinogenic/genotoxic). The extensive water solubility of MG leads to water pollution and hence it is mandatory to remove MG from water. The current study explores adsorptive removal of MG from water using highly water stable Zeolitic Imidazolate framework/graphene oxide composites (ZIF-67@GO). Adsorption performance of newly synthesized composites is justified for MG removal with excellent results of pseudo second order (R² = 0.99955) which is well-fitted in this case. ZIF-67@GO data of adsorption isotherm for MG is observed using Freundlich Model (R² = 0.99999) and with adsorption capacity value observed (134.79 mg/g) with removal efficiency of 99.18%, indicates π-staking and electrostatic association between ZIF-67@GO and MG molecules. Synthesized material has retained reusability while removal efficiency reduced only by 6% after many cycles. Furthermore, factors effecting absorption like contact time, pH, adsorbent dose and quantity and temperature are also determined.