Integrated Photocatalytic Reduction and Oxidation of Perfluorooctanoic Acid by Metal-Organic Frameworks: Key Insights into the Degradation Mechanisms

Comparative analysis of UV-initiated ARPs for degradation of the emerging substitute of perfluorinated compounds: Does defluorination mean the sole factor?

Due to the increasing attention for the residual of per- and polyfluorinated compounds in environmental water, Sodium p-Perfluorous Nonenoxybenzenesulfonate (OBS) have been considered as an alternative solution for perfluorooctane sulfonic acid (PFOS). However, recent detections of elevated OBS concentrations in oil fields and Frontal polymerization foams have raised environmental concerns leading to the decontamination exploration for this compound. In this study, three advanced reduction processes including UV-Sulfate (UV-SF), UV-Iodide (UV-KI) and UV-Nitrilotriacetic acid (UV-NTA) were selected to evaluate the removal for OBS. Results revealed that hydrated electrons (eaq-) dominated the degradation and defluorination of OBS. Remarkably, the UV-KI exhibited the highest removal rate (0.005 s-1) and defluorination efficiency (35 %) along with the highest concentration of eaq- (K = -4.651). Despite that nucleophilic attack from eaq- on sp2 carbon and H/F exchange were discovered as the general mechanism, high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF-MS) analysis with density functional theory (DFT) calculations revealed the diversified products and routes. Intermediates with lowest fluorine content for UV-KI were identified, the presence nitrogen-containing intermediates were revealed in the UV-NTA. Notably, the nitrogen-containing intermediates displayed the enhanced toxicity, and the iodine poly-fluorinated intermediates could be a potential-threat compared to the superior defluorination performance for UV-KI.

Biphenyl tetracarboxylic acid-based metal-organic frameworks: a case of topology-dependent thermal expansion

The large inherent flexibility and highly modular nature of metal-organic frameworks (MOFs) make them ideal candidates for the study of negative thermal expansion (NTE). Among diverse organic ligands, the biphenyl unit, which can unrestrictedly rotate along its C-C single bond, can largely enhance the structural flexibility. Herein, we explored the thermal expansion behaviors of four indium biphenyl tetracarboxylates (BPTCs). Owing to the different dihedral angles of BPTC ligands and coordination mode of In3+, they show distinct topologies: InOF-1 (nti), InOF-2 (unc), InOF-12 (pts) and InOF-13 (nou). Intriguingly, it is found that the thermal expansion is highly dependent on the specific topology. The MOFs featuring mononuclear nodes show normal positive thermal expansion (PTE), and the magnitudes of coefficients follow the trend of InOF-2 < InOF-12 < InOF-13, inversely related to averaged molecular volumes. In contrast, the InOF-1, composed of a 1D chain of corner-shared InO6 octahedrons, shows pronounced NTE. Detailed high-resolution synchrotron powder X-ray diffraction and lattice dynamic analyses shed light on the fact that NTE in the InOF-1 is a synergy effect of the spring-like distortion of the inorganic 1D helical chain and twisting of the BPTC ligands. The present work shows how the topological arrangement of building blocks governs the thermal expansion behaviors.

Effective Reduction of CO2 with Aromatic Amines into N-Formamides Triggered by Noble-Free Metal-Organic Framework Catalysts Under Mild Conditions

The reductive transformation of carbon dioxide (CO2) into high-valued N‑formamides matches well with the atom economy and the sustainable development intention. Nevertheless, developing a noble-free metal catalyst under mild reaction conditions is desirable and challenging. Herein, a caged metal-organic framework (MOFs) [H2N(CH3)2]2{[Ni3(µ3-O)(XN)(BDC)3]·6DMF}n (1) (XN = 6″-(pyridin-4-yl)-4,2″:4″,4″'-terpyridine), H2BDC = terephthalic acid) is harvested, presenting high thermal and chemical stabilities. Catalytic investigation reveals that 1 as a renewable noble-free MOFs catalyst can catalyze the CO2 reduction conversion with aromatic amines tolerated by broad functional groups at least ten times, resulting in various formamides in excellent yields and selectivity under the mildest reaction system (room temperature and 1 bar CO2). Density functional theory (DFT) theoretical studies disclose the applicable reaction path, in which the CO2 hydrosilylation process is initiated by the [Ni3] cluster interaction with CO2 via η2-C, O coordination mode. This work may open up an avenue to seek high-efficiency noble-free catalysts in CO2 chemical reduction into high value-added chemicals.

Zirconium-Based Metal-Organic Frameworks with Free Hydroxy Groups for Enhanced Perfluorooctanoic Acid Uptake in Water

Perfluorooctanoic acid (PFOA) is a highly recalcitrant organic pollutant, and its bioaccumulation severely endangers human health. While various methods are developed for PFOA removal, the targeted design of adsorbents with high efficiency and reusability remains largely unexplored. Here the rational design and synthesis of two novel zirconium-based metal‒organic frameworks (MOFs) bearing free ortho-hydroxy sites, namely noninterpenetrated PCN-1001 and twofold interpenetrated PCN-1002, are presented. Single crystal analysis of the pure ligand reveals that intramolecular hydrogen bonding plays a pivotal role in directing the formation of MOFs with free hydroxy groups. Furthermore, the transformation from PCN-1001 to PCN-1002 is realized. Compared to PCN-1001, PCN-1002 displays higher chemical stability due to interpenetration, thereby demonstrating an exceptional PFOA adsorption capacity of up to 632 mg g-1 (1.53 mmol g-1), which is comparable to the reported record values. Moreover, PCN-1002 shows rapid kinetics, high selectivity, and long-life cycles in PFOA removal tests. Solid-state nuclear magnetic resonance results and density functional theory calculations reveal that multiple hydrogen bonds between the free ortho-hydroxy sites and PFOA, along with Lewis acid-base interaction, work collaboratively to enhance PFOA adsorption.

Insights into PFAS environmental fate through computational chemistry: A review

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that exhibit exceptional chemical and thermal stability. However, their resistance to degradation has led to their widespread environmental contamination. PFAS also negatively affect the environment and other organisms, highlighting the need for effective remediation methods to mitigate their presence and prevent further contamination. Computational chemistry methods, such as Density Functional Theory (DFT) and Molecular Dynamics (MD) offer valuable tools for studying PFAS and simulating their interactions with other molecules. This review explores how computational chemistry methods contribute to understanding and tackling PFAS in the environment. PFAS have been extensively studied using DFT and MD, each method offering unique advantages and computational limitations. MD simulates large macromolecules systems however it lacks the ability model chemical reactions, while DFT provides molecular insights however at a high computational cost. The integration of DFT with MD shows promise in predicting PFAS behavior in different environments. This work summarizes reported studies on PFAS compounds, focusing on adsorption, destruction, and bioaccumulation, highlighting contributions of computational methods while discussing the need for continued research. The findings emphasize the importance of computational chemistry in addressing PFAS contamination, guiding risk assessments, and informing future research and innovations in this field.

Electrostatic Field in Contact-Electro-Catalysis Driven C-F Bond Cleavage of Perfluoroalkyl Substances

Perfluoroalkyl substances (PFASs) are persistent and toxic to human health. It is demanding for high-efficient and green technologies to remove PFASs from water. In this study, a novel PFAS treatment technology was developed, utilizing polytetrafluoroethylene (PTFE) particles (1-5 μm) as the catalyst and a low frequency ultrasound (US, 40 kHz, 0.3 W/cm2) for activation. Remarkably, this system can induce near-complete defluorination for different structured PFASs. The underlying mechanism relies on contact electrification between PTFE and water, which induces cumulative electrons on PTFE surface, and creates a high surface voltage (tens of volts). Such high surface voltage can generate abundant reactive oxygen species (ROS, i.e., O2⋅-, HO⋅, etc.) and a strong interfacial electrostatic field (IEF of 109~1010 V/m). Consequently, the strong IEF significantly activates PFAS molecules and reduces the energy barrier of O2⋅- nucleophilic reaction. Simultaneously, the co-existence of surface electrons (PTFE*(e-)) and HO⋅ enables synergetic reduction and oxidation of PFAS and its intermediates, leading to enhanced and thorough defluorination. The US/PTFE method shows compelling advantages of low energy consumption, zero chemical input, and few harmful intermediates. It offers a new and promising solution for effectively treating the PFAS-contaminated drinking water.

Controllable chemical redox reactions to couple microbial degradation for organic contaminated sites remediation: A review

Global environmental concern over organic contaminated sites has been progressively conspicuous during the process of urbanization and industrial restructuring. While traditional physical or chemical remediation technologies may significantly destroy the soil structure and function, coupling moderate chemical degradation with microbial remediation becomes a potential way for the green, economic, and efficient remediation of contaminated sites. Hence, this work systematically elucidates why and how to couple chemical technology with microbial remediation, mainly focused on the controllable redox reactions of organic contaminants. The rational design of materials structure, selective generation of reactive oxygen species, and estimation of degradation pathway are described for chemical oxidation. Meanwhile, current progress on efficient and selective reductions of organic contaminants (i.e., dechlorination, defluorination, -NO2 reduction) is introduced. Combined with the microbial remediation of contaminated sites, several consideration factors of how to couple chemical and microbial remediation are proposed based on both fundamental and practical points of view. This review will advance the understanding and development of chemical-microbial coupled remediation for organic contaminated sites.

Exceptionally High Perfluorooctanoic Acid Uptake in Water by a Zirconium-Based Metal-Organic Framework through Synergistic Chemical and Physical Adsorption

Perfluorooctanoic acid (PFOA) is an environmental contaminant ubiquitous in water resources, which as a xenobiotic and carcinogenic agent, severely endangers human health. The development of techniques for its efficient removal is therefore highly sought after. Herein, we demonstrate an unprecedented zirconium-based MOF (PCN-999) possessing Zr6 and biformate-bridged (Zr6)2 clusters simultaneously, which exhibits an exceptional PFOA uptake of 1089 mg/g (2.63 mmol/g), representing a ca. 50% increase over the previous record for MOFs. Single-crystal X-ray diffraction studies and computational analysis revealed that the (Zr6)2 clusters offer additional open coordination sites for hosting PFOA. The coordinated PFOAs further enhance the interaction between coordinated and free PFOAs for physical adsorption, boosting the adsorption capacity to an unparalleled high standard. Our findings represent a major step forward in the fundamental understanding of the MOF-based PFOA removal mechanism, paving the way toward the rational design of next-generation adsorbents for per- and polyfluoroalkyl substance (PFAS) removal.

Novel Defluorination Pathways of Perfluoroether Compounds (GenX): α-Fe2O3 Nanoparticle Layer Retains Higher Concentrations of Effective Hydrated Electrons

The development of efficient defluorination technology is an important issue because the kind of emerging pollutant of hexafluoropropylene oxide dimer acid (GenX) as an alternative to perfluorooctanoic acid (PFOA) has the higher environmental risks. In the UV/bisulfite system, we first developed a hydrophobic confined α-Fe2O3 nanoparticle layer rich in oxygen vacancies, which accelerated the enrichment of HSO3- and GenX on the surface and pores through electrostatic attraction and hydrophobic interaction, retaining more hydrated electrons (eaq-) and rapidly destroying GenX under UV excitation. Especially, under anaerobic and aerobic conditions, the degradation percentage of GenX obtain nearly 100%, defluorination of GenX to 88 and 57% respectively. It was amazed to find that the three parallel H/F exchange pathways triggered by the rapid reactions of eaq- and GenX, which were unique to anaerobic conditions, improved the efficiency of fluoride removal and weaken the interference of dissolved oxygen and H+. Therefore, this study provided an available material and mechanism for sustainable fluoride removal from wastewater in aerobic and anaerobic conditions.

Pioneering Piezoelectric-Driven Atomic Hydrogen for Efficient Dehalogenation of Halogenated Organic Pollutants

The electrocatalytic hydrodehalogenation (EHDH) process mediated by atomic hydrogen (H*) is recognized as an efficient method for degrading halogenated organic pollutants (HOPs). However, a significant challenge is the excessive energy consumption resulting from the recombination of H* to H2 production in the EHDH process. In this study, a promising strategy was proposed to generate piezo-induced atomic H*, without external energy input or chemical consumption, for the degradation and dehalogenation of HOPs. Specifically, sub-5 nm Ni nanoparticles were subtly dotted on an N-doped carbon layer coating on BaTiO3 cube, and the resulted hybrid nanocomposite (Ni-NC@BTO) can effectively break C-X (X = Cl and F) bonds under ultrasonic vibration or mechanical stirring, demonstrating high piezoelectric driven dehalogenation efficiencies toward various HOPs. Mechanistic studies revealed that the dotted Ni nanoparticles can efficiently capture H* to form Ni-H* (Habs) and drive the dehalogenation process to lower the toxicity of intermediates. COMSOL simulations confirmed a "chimney effect" on the interface of Ni nanoparticle, which facilitated the accumulation of H+ and enhanced electron transfer for H* formation by improving the surface charge of the piezocatalyst and strengthening the interfacial electric field. Our work introduces an environmentally friendly dehalogenation method for HOPs using the piezoelectric process independent of the external energy input and chemical consumption.

Efficient Decomposition of Perfluoroalkyl Substances by Low Concentration Indole: New Insights into the Molecular Mechanisms

Perfluoroalkyl substances (PFAS) are a class of persistent organic pollutants known as "forever chemicals". Currently, the hydrated electron-based advanced reduction process (ARP) holds promise for the elimination of PFAS. However, the efficiency of ARP is often challenged by an oxygen-rich environment, resulting in the consumption of hydrated electron source materials in exchange for the high PFAS decomposition efficiency. Herein, we developed a ternary system constructed by indole and isopropyl alcohol (IPA), and the addition of IPA significantly enhanced the PFOA degradation and defluorination efficiency in the presence of low-concentration indole (<0.4 mM). Meanwhile, opposite results were obtained with a higher amount of indole (>0.4 mM). Further exploring the molecular mechanism of the reaction system, the addition of IPA played two roles. On one hand, IPA built an anaerobic reaction atmosphere and improved the yield and utilization efficiency of hydrated electrons with a low concentration of indole. On the other hand, IPA suppressed the attraction between indole and PFOA, thus reducing the hydrated electron transfer efficiency, especially with more indole. In general, the indole/PFAS/IPA system significantly improved the PFAS destruction efficiency with a small amount of hydrated electron donors, which provided new insights for development of simple and efficient techniques for the treatment of PFAS-contaminated wastewater.

Emerging environmentally friendly bio-based nanocomposites for the efficient removal of dyes and micropollutants from wastewater by adsorption: a comprehensive review

Water scarcity will worsen due to population growth, urbanization, and climate change. Addressing this issue requires developing energy-efficient and cost-effective water purification technologies. One approach is to use biomass to make bio-based materials (BBMs) with valuable attributes. This aligns with the goal of environmental conservation and waste management. Furthermore, the use of biomass is advantageous because it is readily available, economical, and has minimal secondary environmental impact. Biomass materials are ideal for water purification because they are abundant and contain important functional groups like hydroxyl, carboxyl, and amino groups. Functional groups are important for modifying and absorbing contaminants in water. Single-sourced biomass has limitations such as weak mechanical strength, limited adsorption capacity, and chemical instability. Investing in research and development is crucial for the development of efficient methods to produce BBMs and establish suitable water purification application models. This review covers BBM production, modification, functionalization, and their applications in wastewater treatment. These applications include oil-water separation, membrane filtration, micropollutant removal, and organic pollutant elimination. This review explores the production processes and properties of BBMs from biopolymers, highlighting their potential for water treatment applications. Furthermore, this review discusses the future prospects and challenges of developing BBMs for water treatment and usage. Finally, this review highlights the importance of BBMs in solving water purification challenges and encourages innovative solutions in this field.

Strategies to improve adsorption and photocatalytic performance of metal-organic frameworks (MOFs) for perfluoroalkyl and polyfluoroalkyl substances (PFASs) removal from water: A review

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) represent a category of persistent and hazardous organic pollutants extensively prevalent across aquatic environments. The combination of adsorption and photocatalytic degradation has been identified as an effective approach for removing trace amounts of PFASs from water. Among the various materials explored for this purpose, metal-organic frameworks (MOFs) have structural solid tunability, and suitable modification methods could endow them with rich adsorption capabilities and excellent photocatalytic performance, which has potential for applications involving the treatment of trace, multi-chain-length PFASs in water. The research within this realm is currently in its nascent phase, and a holistic knowledge of modification methods can provide a comprehensive framework for future studies. Therefore, this review intends to (1) summarize the mechanism underlying the adsorption and photocatalytic removal of PFASs by MOFs; (2) present various modification methods aimed at enhancing the adsorption and photocatalytic performance of MOFs in alignment with the goal mentioned above; (3) provide an outlook on the prospects of utilizing MOFs for PFASs removal based on current trends and data. Ultimately, the findings from these studies will contribute to advancing knowledge in this area and facilitate the development of effective strategies for addressing PFASs contamination in water systems.

Molecular Cu Electrocatalyst Escalates Ambient Perfluorooctanoic Acid Degradation

Groundwater reservoirs contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFASs) need purifying remedies. Perfluorooctanoic acid (PFOA) is the most abundant PFAS in drinking water. Although different degradation strategies for PFOA have been explored, none of them disintegrates the PFOA backbone rapidly under mild conditions. Herein, we report a molecular copper electrocatalyst that assists in the degradation of PFOA up to 93% with a 99% defluorination rate within 4 h of cathodic controlled-current electrolysis. The current-normalized pseudo-first-order rate constant has been estimated to be quite high for PFOA decomposition (3.32 L h-1 A-1), indicating its fast degradation at room temperature. Furthermore, comparatively, rapid decarboxylation over the first 2 h of electrolysis has been suggested to be the rate-determining step in PFOA degradation. The related Gibbs free energy of activation has been calculated as 22.6 kcal/mol based on the experimental data. In addition, we did not observe the formation of short-alkyl-chain PFASs as byproducts that are typically found in chain-shortening PFAS degradation routes. Instead, free fluoride (F-), trifluoroacetate (CF3COO-), trifluoromethane (CF3H), and tetrafluoromethane (CF4) were detected as fragmented PFOA products along with the evolution of CO2 using gas chromatography (GC), ion chromatography (IC), and gas chromatography-mass spectrometry (GC-MS) techniques, suggesting comprehensive cleavage of C-C bonds in PFOA. Hence, this study presents an effective method for the rapid degradation of PFOA into small ions/molecules.

Significantly Accelerated Photochemical Perfluorooctanoic Acid Decomposition at the Air-Water Interface of Microdroplets

The efficient elimination of per- and polyfluoroalkyl substances (PFASs) from the environment remains a huge challenge and requires advanced technologies. Herein, we demonstrate that perfluorooctanoic acid (PFOA) photochemical decomposition could be significantly accelerated by simply carrying out this process in microdroplets. The almost complete removal of 100 and 500 μg/L PFOA was observed after 20 min of irradiation in microdroplets, while this was achieved after about 2 h in the corresponding bulk phase counterpart. To better compare the defluorination ratio, 10 mg/L PFOA was used typically, and the defluorination rates in microdroplets were tens of times faster than that in the bulk phase reaction system. The high performances in actual water matrices, universality, and scale-up applicability were demonstrated as well. We revealed in-depth that the great acceleration is due to the abundance of the air-water interface in microdroplets, where the reactants concentration enrichment, ultrahigh interfacial electric field, and partial solvation effects synergistically promoted photoreactions responsible for PFOA decomposition, as evidenced by simulated Raman scattering microscopy imaging, vibrational Stark effect measurement, and DFT calculation. This study provides an effective approach and highlights the important roles of air-water interface of microdroplets in PFASs treatment.

New Indole Derivative Heterogeneous System for the Synergistic Reduction and Oxidation of Various Per-/Polyfluoroalkyl Substances: Insights into the Degradation/Defluorination Mechanism

The hydrated electron (eaq-) system is typically suitable for degrading perfluoroalkyl substances (PFASs). To enhance eaq- utilization, we synthesized a new indole compound (DIHA) that forms stable nanospheres (100-200 nm) in water via a supramolecular assembly. Herein, the DIHA nanoemulsion system exhibits high degradation efficiencies toward a broad category of PFASs, regardless of the headgroup, chain length, and branching structure, under UV (254 nm) irradiation. The strong adsorption of PFAS on the DIHA surface ensures its effective degradation/defluorination. Quenching experiments further demonstrated that the reaction took place on the surface of DIHA nanospheres. This specific heterogeneous surface reaction unveiled novel PFAS degradation and defluorination mechanisms that differ from previously reported eaq- systems. First, the photogenerated surface electrons nonselectively attacked multiple C-F bonds of the -CF2- chain. This plays a dominant degrading/defluorinating role in the DIHA system. Second, abundant hydroxyl radicals (•OH) were also produced, leading to synergistic reduction (by surface electron) and oxidation (by surface •OH) in a single system. This facilitates faster and deeper defluorination of different structured PFASs through multiple pathways. The new mechanism inspires the design of innovative organo-heterogeneous eaq- systems possessing synergistic reduction and oxidation functions, thereby making them potentially effective for treating PFAS-contaminated water.

A critical review on selenium removal capacity from water using emerging non-conventional biosorbents

Anthropogenic-driven selenium (Se) contamination of natural waters has emerged as severe health and environmental concern. Lowering Se levels to safe limits of 40 μg-L-1 (recommended by WHO) presents a critical challenge for the scientific community, necessitating reliable and effective methods for Se removal. The primary obectives of this review are to evaluate the efficiency of different biosorbents in removing Se, understand the mechanism of adsorption, and identify the factors influencing the biosorption process. A comprehensive literature review is conducted to analyze various studies that have explored the use of modified biochars, iron oxides, and other non-conventional biosorbents for selenium removal. The assessed biosorbents include biomass, microalgae-based, alginate compounds, peats, chitosan, and biochar/modified biochar-based adsorbents. Quantitative data from the selected studies analyzed Se adsorption capacities of biosorbents, were collected considering pH, temperature, and environmental conditions, while highlighting advantages and limitations. The role of iron impregnation in enhancing the biosorption efficiency is investigated, and the mechanisms of Se adsorption on these biosorbents at different pH levels are discussed. A critical literature assessment reveals a robust understanding of the current state of Se biosorption and the effectiveness of non-conventional biosorbents for Se removal, providing crucial information for further research and practical applications in water treatment processes. By understanding the strengths and limitations of various biosorbents, this review is expected to scale-up targeted research on Se removal, promoting the development of innovative and cost-effective adsorbents, efficient and sustainable approaches for Se removal from water.

Comparison of the photocatalytic degradability of PFOA, PFOS and GenX using Fe-zeolite in water

Knowledge on the photocatalytic degradability of the emerging poly- and perfluorinated alkyl substances (PFAS) in water, specifically GenX, is limited. GenX has been detected globally in river water and is considered potentially more toxic than legacy PFAS. In this study, we compared the photocatalytic degradability of GenX with the legacy compounds perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) using Fe-zeolite photocatalysts. After 7 h of irradiation, GenX showed lower removal (79%) and defluorination (33%) as compared to PFOA (100% removal and 69% defluorination) and PFOS (100% removal and 51% defluorination). The quasi-first-order degradation rate of GenX (1.5 h1) was 12 and 1.2 times lower than PFOA (18.4 h-1) and PFOS (1.8 h-1), respectively. Additionally, PFOA's defluorination rate (0.9 h-1) was approximately 2.6 and 9 times higher than GenX (0.35 h-1) and PFOS (0.1 h-1), respectively. These outcomes correlate with GenX's lower hydrophobicity, leading to reduced adsorption (40%) compared to PFOA (99%) and PFOS (87%). Based on identified transformation products, we proposed a GenX degradation pathway, resulting in ultra-short-chain PFASs with a chain length of 2 and 3 carbon atoms, while PFOA and PFOS degraded stepwise, losing 1 carbon-fluorine bond at a time, leading to gradually shorter chain lengths (from 7 to 2 carbon atoms). In conclusion, GenX is more challenging to remove and degrade due to its lower adsorption on the photocatalyst, potential steric hindrance, and higher production of persistent ultra-short-chain transformation products through photocatalysis.

Photocatalytic C(sp3)-H bond functionalization by Cu(I) halide cluster-mediated O2 activation

Photocatalytic C-H bond activation is a challenging approach to selectively functionalize C(sp3)-H bonds with dioxygen under mild conditions. Herein, by merging transition metal- and photo-catalysis, photoactive Cu(I)-halide(X) (X = Cl, Br, I) clusters are employed to effectively catalyse the selective monooxygenation and C-C oxidative cross-coupling of C(sp3)-H bonds with unreactive O2 upon light irradiation. This modern protocol promises a photoinduced SET process between Cu(I)-clusters and O2, and possibly forms Cu(II)-O2˙- species for abstracting the H-atom from the C(sp3)-H bond. This process produces alkyl radicals to react with -OOH or nucleophiles for oxidation or cross-coupling products, advancing the Cu(I)-cluster mediated photoredox catalysis toward functional fine chemicals with pursued selectivity.

Non-targeted identification and semi-quantitation of emerging per- and polyfluoroalkyl substances (PFAS) in US rainwater

High-resolution mass spectrometry was used to screen for emerging per- and polyfluorinated alkyl substances (PFAS) in precipitation samples collected in summer 2019 at seven sites in the United States. We previously quantified the concentration of ten PFAS in the rainwater samples using the method of isotopic dilution (Pike et al., 2021). Nine of these targeted analytes belonged to the U.S. Environmental Protection Agency Regional Screening Level list, herein referred to as EPA-monitored analytes. In this new work, we identify emerging PFAS compounds by liquid chromatography quadrupole time-of-flight mass spectrometry. Several emerging PFAS were detected across all samples, with the most prevalent compounds being C3-C8 hydrogen-substituted perfluorocarboxylic acids (H-PFCAs) and fluorotelomer carboxylic acids (FTCAs). Concentrations of emerging PFAS were in the 10-1000 ng L-1 range (approximately 1-2 orders of magnitude greater than EPA-monitored PFAS) at all sites except Wooster, OH, where concentrations were even higher, with a maximum estimated ΣPFAS of 16 400 ng L-1. The elevated levels of emerging PFAS in the Wooster samples were predominantly even and odd chain-length H-PFCAs and FTCAs comprised of complex mixtures of branched isomers. This unique composition did not match any known manufactured PFAS formulation reported to date, but it could represent thermally transformed by-products emitted by a local point source. Overall, the results indicate that PFAS outside of the standard analyte lists make up a significant and previously unappreciated fraction of contaminants in rainwater collected within the central U.S.-and potentially world-wide-especially in proximity to localized point sources.

Reticular framework materials for photocatalytic organic reactions

Photocatalytic organic reactions, harvesting solar energy to produce high value-added organic chemicals, have attracted increasing attention as a sustainable approach to address the global energy crisis and environmental issues. Reticular framework materials, including metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), are widely considered as promising candidates for photocatalysis owing to their high crystallinity, tailorable pore environment and extensive structural diversity. Although the design and synthesis of MOFs and COFs have been intensively developed in the last 20 years, their applications in photocatalytic organic transformations are still in the preliminary stage, making their systematic summary necessary. Thus, this review aims to provide a comprehensive understanding and useful guidelines for the exploration of suitable MOF and COF photocatalysts towards appropriate photocatalytic organic reactions. The commonly used reactions are categorized to facilitate the identification of suitable reaction types. From a practical viewpoint, the fundamentals of experimental design, including active species, performance evaluation and external reaction conditions, are discussed in detail for easy experimentation. Furthermore, the latest advances in photocatalytic organic reactions of MOFs and COFs, including their composites, are comprehensively summarized according to the actual active sites, together with the discussion of their structure-property relationship. We believe that this study will be helpful for researchers to design novel reticular framework photocatalysts for various organic synthetic applications.

Products, reactive species and mechanisms of PFOA degradation in a self-pulsing discharge (SPD) plasma reactor

Non-thermal plasma is a promising tool for novel technologies to treat water contaminated by recalcitrant pollutants. We report here on products, reactive species and mechanisms of the efficient degradation of perfluorooctanoic acid (PFOA) achieved with a self-pulsing discharge developed previously in our lab. Air or argon were used as plasma feed gas, ultrapure or tap water as aqueous medium. Identified organic intermediate products arise from chain-shortening and defluorination reactions, the latter achieving not only C-F to C-H exchange (hydro-de-fluorination), as reported in the literature, but also C-F to C-OH exchange (hydroxy-de-fluorination). In contrast with chain-shortening, yielding lower homologues of PFOA via selective cleavage of the C-C bond at the carboxylate group, defluorination occurs at various sites of the alkyl chain giving mixtures of different isomeric products. Plasma generated reactive species were investigated under all experimental conditions tested, using specific chemical probes and optical emission spectroscopy. Cross-analysis of the results revealed a striking direct correlation of energy efficiency for PFOA degradation and for production of plasma electrons. In contrast, no correlation was observed for emission bands of either Ar+ or OH radical. These results indicate a prevalent role of plasma electrons in initiating PFOA degradation using self-pulsing discharge plasma above the liquid.

Alcohols radicals can efficiently reduce recalcitrant perfluorooctanoic acid

Alcohols are commonly used as eluents for the regeneration of per/poly-fluoroalkyl substances (PFASs) adsorbents, but their potential effects on the subsequent treatment of these eluates have not been fully explored. This work investigated the effect of alcohols on perfluorooctanoic acid (PFOA) degradation by persulfate (PS) based advanced oxidation processes. The results showed that ethanol significantly promoted PFOA degradation in thermal/PS system. Under anoxic conditions, 25.5±1.4% or 91.2±1.6% of PFOA was degraded within 48 h in the absence or presence of ethanol. Electron paramagnetic resonance (EPR) detection, free radical quenching experiments, and chemical probe studies clearly demonstrated that the sulfate radicals (SO4•-) generated from PS activation would react with ethanol to form alcohol radicals, which could efficiently degrade PFOA. The transformation pathways of PFOA were proposed based on degradation products analysis and density function theory (DFT) calculation. The reaction between SO4•- and other alcohols could also induce the formation of alcohol radicals and facilitate to the degradation of PFOA. This work represents the positive roles of alcohols in the degradation of PFASs, providing new insights into developing simple and efficient treatments for PFASs eluate or PFAS-contaminated water.

Water-Stable Fluorous Metal-Organic Frameworks with Open Metal Sites and Amine Groups for Efficient Urea Electrocatalytic Oxidation

Urea oxidation reaction (UOR) is one of the promising alternative anodic reactions to water oxidation that has attracted extensive attention in green hydrogen production. The application of specifically designed electrocatalysts capable of declining energy consumption and environmental consequences is one of the major challenges in this field. Therefore, the goal is to achieve a resistant, low-cost, and environmentally friendly electrocatalyst. Herein, a water-stable fluorinated Cu(II) metalorganic framework (MOF) {[Cu2 (L)(H2 O)2 ]·(5DMF)(4H2 O)}n (Cu-FMOF-NH2 ; H4 L = 3,5-bis(2,4-dicarboxylic acid)-4-(trifluoromethyl)aniline) is developed utilizing an angular tetracarboxylic acid ligand that incorporates both trifluoromethyl (-CF3 ) and amine (-NH2 ) groups. The tailored structure of Cu-FMOF-NH2 where linkers are connected by fluoride bridges and surrounded by dicopper nodes reveals a 4,24T1 topology. When employed as electrocatalyst, Cu-FMOF-NH2 requires only 1.31 V versus reversible hydrogen electrode (RHE) to deliver 10 mA cm-2 current density in 1.0 m KOH with 0.33 m urea electrolyte and delivered an even higher current density (50 mA cm-2 ) at 1.47 V versus RHE. This performance is superior to several reported catalysts including commercial RuO2 catalyst with overpotential of 1.52 V versus RHE. This investigation opens new opportunities to develop and utilize pristine MOFs as a potential electrocatalyst for various catalytic reactions.

Photo-Induced Construction and Recovery of Cu+ Sites in Metal-Organic Frameworks

The adjustment of the valence state of metal ions is crucial for various applications because peculiar activity originates from metal ions with specific valence. Cu+ can interact with molecules possessing unsaturated bonds like CO via π-complexation, while Cu2+ doesn't have such ability. Meanwhile, Cu+ sites are easily oxidized to Cu2+ , leading to the loss of activity. Despite great efforts, the development of a facile method to construct and recover Cu+ sites remains a pronounced challenge. Here, for the first time a facile photo-induced strategy is reported to fabricate Cu+ sites in metal-organic frameworks (MOFs) and recover Cu+ after oxidation. The Cu2+ precursor was loaded on NH2 -MIL-125, a typical visible-light responsive Ti-based MOF. Visible light irradiation triggers the formation of Ti3+ from Ti4+ in framework, which reduces the supported Cu2+ in the absence of any additional reducing agent, thus simplifying the process for Cu+ generation significantly. Due to π-complexation interaction, the presence of Cu+ results in remarkably enhanced CO capture capacity (1.16 mmol g-1 ) compared to NH2 -MIL-125 (0.49 mmol g-1 ). More importantly, Cu+ can be recovered conveniently via re-irradiation when it is oxidized to Cu2+ , and the oxidation-recovery process is reversible.

Highly efficient conversion of CO2 into N-formamides catalyzed by a noble-metal-free aluminum-based MOF under mild conditions

Formamides have critical application value in the chemical industry serving as solvents or reagents for the synthesis of pharmaceuticals, agrochemicals, and dyes. Herein, we selected a green-synthesis produced aluminum-based metal-organic framework (Al-MOF) material CAU-10pydc as a catalyst to study its performance in CO2 formylation reaction. At room temperature and in the green solvent acetonitrile, CAU-10pydc could highly effectively catalyze the reaction of CO2 and N-methylaniline to N-methyl-N-phenylformamide under mild conditions. CAU-10pydc could maintain its efficient catalytic performance after five catalytic cycles, and PXRD and SEM measurements demonstrated that CAU-10pydc is stable after cyclic catalysis. The universality of this catalyst was illustrated by nine substrates with high yields. The reaction mechanism was further analyzed by DFT calculations. To our knowledge, this work is the first example of a CO2 formylation reaction being catalyzed highly effectively by an Al-MOF under green conditions.

Amine-Functionalized A-Center Sphalerite for Selective and Efficient Destruction of Perfluorooctanoic Acid

Perfluorochemicals (PFCs), especially perfluorooctanoic acid (PFOA), have contaminated the ground and surface waters throughout the world. Efficient removal of PFCs from contaminated waters has been a major challenge. This study developed a novel UV-based reaction system to achieve fast PFOA adsorption and decomposition without addition of sacrificial chemicals by using synthetic photocatalyst sphalerite (ZnS-[N]) with sufficient surface amination and defects. The obtained ZnS-[N] has the capability of both reduction and oxidation due to the suitable band gap and photo-generated hole-trapping properties created by surface defects. The cooperated organic amine functional groups on the surface of ZnS-[N] play a crucial role in the selective adsorption of PFOA, which guarantee the efficient destruction of PFOA subsequently, and 1 μg L^-1 PFOA could be degraded to <70 ng L^-1 after 3 h in the presence of 0.75 g L^-1 ZnS-[N] under 500 W UV irradiation. In this process, the photogenerated electrons (reduction) and holes (oxidation) on the ZnS-[N] surface work in a synergistic manner to achieve complete defluorination of PFOA. This study not only provides promising green technology for PFC-pollution remediation but also highlights the significance of developing a target system capable of both reduction and oxidation for PFC degradation.

Confined water-encapsulated activated carbon for capturing short-chain perfluoroalkyl and polyfluoroalkyl substances from drinking water

The global ecological crisis of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water has gradually shifted from long-chain to short-chain PFASs; however, the widespread established PFAS adsorption technology cannot cope with the impact of such hydrophilic pollutants given the inherent defects of solid-liquid mass transfer. Herein, we describe a reagent-free and low-cost strategy to reduce the energy state of short-chain PFASs in hydrophobic nanopores by employing an in situ constructed confined water structure in activated carbon (AC). Through direct (driving force) and indirect (assisted slip) effects, the confined water introduced a dual-drive mode in the confined water-encapsulated activated carbon (CW-AC) and completely eliminated the mass transfer barrier (3.27 to 5.66 kcal/mol), which caused the CW-AC to exhibit the highest adsorption capacity for various short-chain PFASs (C-F number: 3-6) among parent AC and other adsorbents reported. Meanwhile, benefiting from the chain length- and functional group-dependent confined water-binding pattern, the affinity of the CW-AC surpassed the traditional hydrophobicity dominance and shifted toward hydrophilic short-chain PFASs that easily escaped treatment. Importantly, the ability of CW-AC functionality to directly transfer to existing adsorption devices was verified, which could treat 21,000 bed volumes of environment-related high-load (~350 ng/L short-chain PFAS each) real drinking water to below the World Health Organization's standard. Overall, our results provide a green and cost-effective in situ upgrade scheme for existing adsorption devices to address the short-chain PFAS crisis.

Enhanced biodegradation of perfluorooctanoic acid in a dual biocatalyzed microbial electrosynthesis system

The toxic perfluorooctanoic acid (PFOA) is widely spread in terrestrial and aquatic habitats owing to its resistance to conventional degradation processes. Advanced techniques to degrade PFOA requires drastic conditions with high energy cost. In this study, we investigated PFOA biodegradation in a simple dual biocatalyzed microbial electrosynthesis system (MES). Different PFOA loadings (1, 5, and 10 ppm) were tested and a biodegradation of 91% was observed within 120 h. Propionate production improved and short-carbon-chain PFOA intermediates were detected, which confirmed PFOA biodegradation. However, the current density decreased, indicating an inhibitory effect of PFOA. High-throughput biofilm analysis revealed that PFOA regulated the microbial flora. Microbial community analysis showed enrichment of the more resilient and PFOA adaptive microbes, including Methanosarcina and Petrimonas. Our study promotes the potential use of dual biocatalyzed MES system as an environment-friendly and inexpensive method to remediate PFOA and provides a new direction for bioremediation research.

Nanomaterial-Based Advanced Oxidation/Reduction Processes for the Degradation of PFAS

This review focuses on a critical analysis of nanocatalysts for advanced reductive processes (ARPs) and oxidation processes (AOPs) designed for the degradation of poly/perfluoroalkyl substances (PFAS) in water. Ozone, ultraviolet and photocatalyzed ARPs and/or AOPs are the basic treatment technologies. Besides the review of the nanomaterials with greater potential as catalysts for advanced processes of PFAS in water, the perspectives for their future development, considering sustainability, are discussed. Moreover, a brief analysis of the current state of the art of ARPs and AOPs for the treatment of PFAS in water is presented.

Constructing a Photocatalyst for Selective Oxidation of Benzyl Alcohol to Benzaldehyde by Photo-Fenton-like Catalysis

A photoactive metal-organic framework (MOF), [K(H₂O)][Cu(DPNDI)][Cu(DPNDI)(CH₃CN)(H₂O)] [Cu_1.5(DPNDI)_1.5H_1.5P₂W₁₈O₆₂]·2H₂O (Cu(Ι)W-DPNDI), was prepared by combining a functional photosensitizer N, N'-bis(4-pyridylmethyl)naphthalene diimide (DPNDI), copper(I) ions, and an oxidation catalyst [P₂W₁₈O₆₂]^6- into a single framework via a hydrothermal process. Cu(Ι)W-DPNDI exhibited a stable structure, strong light absorption capacity, a suitable band gap, and photoelectric properties, which provided favorable conditions for photocatalysis. In the confined space, the well-aligned Cu(I) ions and POM polyanions played a synergetic effect in the electron-transfer process and reactive oxygen species generation. By coupling photocatalysis and heterogeneous Fenton-like catalysis, Cu(Ι)W-DPNDI displayed high efficiency for the selective oxidation of aromatic alcohols, with up to >99% selectivity and 75% yield.

Synthesis of Fluoro-Bridged Ho3+ and Gd3+ 1,3,5-Tris(4-carboxyphenyl)benzene Metal-Organic Frameworks from Perfluoroalkyl Substances

A new fluoro-bridged rare-earth (RE) metal-organic framework consisting of 15-connected nonanuclear and 9-connected trinuclear clusters {[RE₉-(μ₃-F)₁₄(H₂O)₆][RE₃(μ₃-F)(H₂O)₃](HCO₂)₃-(BTB)₆}·(solvent)x 2 (RE = Ho³⁺ and Gd³⁺) was synthesized through the transformation of a dimeric complex formulated as bis(2,2'-bipyridine)tetrakis(μ-2-fluorobenzoato-O,O')-bis(2-fluorobenzoato)diRE(III) 1 with the bridging linker 1,3,5-tris(4-carboxyphenyl)benzene (H₃BTB). The rare-earth metal ions Ho³⁺ and Gd³⁺ were also found to remove fluorine from other organo-fluorine compounds such as perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA), resulting in the new fluoro-bridged RE-MOFs.

Porous Materials for Water Purification

Water pollution is a growing threat to humanity due to the pervasiveness of contaminants in water bodies. Significant efforts have been made to separate these hazardous components to purify polluted water through various methods. However, conventional remediation methods suffer from limitations such as low uptake capacity or selectivity, and current water quality standards cannot be met. Recently, advanced porous materials (APMs) have shown promise in improved segregation of contaminants compared to traditional porous materials in uptake capacity and selectivity. These materials feature merits of high surface area and versatile functionality, rendering them ideal platforms for the design of novel adsorbents. This Review summarizes the development and employment of APMs in a variety of water treatments accompanied by assessments of task-specific adsorption performance. Finally, we discuss our perspectives on future opportunities for APMs in water purification.

Effects of physicochemical properties and co-existing zinc agrochemicals on the uptake and phytotoxicity of PFOA and GenX in lettuce

Even though the potential toxicity and treatment methods for per- and polyfluoroalkyl substances (PFAS) have attracted extensive attention, the plant uptake and accumulation of PFAS in edible plant tissues as a potential pathway for human exposure received little attention. Our study in a hydroponic system demonstrated that perfluorooctanoic acid (PFOA) and its replacing compound, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoic acid (GenX) displayed markedly different patterns of plant uptake and accumulation. For example, the root concentration factor (RCF) of PFOA in lettuce is almost five times of that of GenX while the translocation factor (TF) of GenX is about 66.7% higher than that for PFOA. The co-presence of zinc amendments affected the phyto-effect of these two compounds and their accumulation in plant tissues, and the net effect on their plant accumulation depended on both the properties of Zn amendments and PFAS. Zinc oxide nanoparticles (ZnONPs) at 100 mg/L did not affect the uptake of PFOA in either lettuce roots or shoots; however, Zn2+ at the same concentration significantly increased PFOA accumulation in both tissues. In contrast, both Zn amendments significantly lowered the accumulation of GenX in lettuce roots, but only ZnONPs significantly hindered the GenX accumulation in lettuce shoots. The co-exposure to ZnONPs and PFOA/GenX resulted in lower oxidative stress than the plants exposed to PFOA or GenX alone. However, both zinc agrochemicals with or without PFAS led to lower root dry biomass. The results shed light on the property-dependent plant uptake of PFAS and the potential impact of co-existing nanoagrochemicals and their dissolved ions on plant uptake of PFOA and GenX.

Efficient Recognition and Removal of Persistent Organic Pollutants by a Bifunctional Molecular Material

Persistent organic pollutants (POPs) exist widely in the environment and place significant impact on human health by bioaccumulation. Efficient recognition of POPs and their removal are highly challenging tasks because their specific structures interact often very weakly with the capture materials. Herein, a molecular nanocage (1) is studied as an efficient sensing and sorbent material for POPs, which is demonstrated by a representative and stable perfluorooctane sulfonate (PFOS) substrate containing a hydrophilic sulfonic group and a hydrophobic fluoroalkyl chain. A highly sensitive and unusual turn-on fluorescence response within 10 s and a 97% total removal of PFOS from water in 20 min have been achieved owing to the strong host-guest interactions between 1 and PFOS. The binding constant of 1 to PFOS is 2 orders of magnitude higher than state-of-the-art adsorbents for PFOS and thus represents a new benchmark material for the recognition and removal of PFOS. The host-guest interaction has been elucidated by solid-state NMR spectroscopy and single-crystal X-ray diffraction, which provide key insights at a molecular level for the design of new advanced sensing/sorbent materials for POPs.

Pillared-MOF@NiV-LDH Composite as a Remarkable Electrocatalyst for Water Oxidation

Oxygen evolution reaction (OER) represents a highly important electrochemical transformation in energy storage and conversion technologies. Considering the low rate of this four-electron half-reaction, there is a demand for efficient, stable, and noble-metal-free electrocatalysts to improve the kinetic and economical parameters. In this work, a new pillared-MOF@NiV-LDH nanocomposite based on a Co^II metal-organic framework (pillared-MOF) and heterometallic Ni/V-layered double hydroxide (NiV-LDH) was assembled via a simple protocol, characterized, and explored as an electrocatalyst in OER. A remarkable electrocatalytic efficiency of pillared-MOF@NiV-LDH in 1 M KOH is evidenced by a low overpotential (238 mV at 10 mA cm^-2 current density) and a small value of the Tafel slope (62 mV dec^-1). These parameters are very close to those of the reference IrO₂ electrocatalyst and are superior to the majority of the LDH- and MOF-based systems previously applied for OER. Excellent stability of pillared-MOF@NiV-LDH was confirmed by the chronopotentiometry tests for 70 h and linear-sweep voltammetry after 7000 cycles. Features such as rich electroactive sites, porous structure, high surface area, and synergic effect between pillared-MOF and NiV-LDH are likely responsible for the remarkable electrocatalytic efficiency of this electrocatalyst in OER. Despite prior reports on the application of NiV-LDH in OER, the present study describes the first example where this type of LDH is blended with MOF to generate a nanocomposite material. The interface between the two components of the composite can improve the electronic structure and, in turn, the electrocatalytic behavior. The introduction of this composite paves the way toward the synthesis of other multicomponent materials with potential applications in different energy fields.

Fluorine extraction from organofluorine molecules to make fluorinated clusters in yttrium MOFs

A new rare earth based two-dimensional coordination network and a three-dimensional metal-organic framework (MOF) have been synthesized using bicinchoninic acid (BCA) and yttrium(iii) ions. Yttrium dimer nodes are formed in the absence of a modulator, resulting in a 2D layered coordination network (Y-BCA-2D). The presence of fluorinating agents, e.g., 2-fluorobenzoic acid (2-FBA), 2,6-difluorobenzoic acid (2,6-DFBA), and perfluorohexanoic acid (PFHxA) result in μ₃-F bridged metal hexaclusters (Y₆F₈) that form a three-dimensional MOF (Y-BCA-3D). It was found that Y³⁺ can break highly stable C-F bonds in aromatic and aliphatic fluorinated compounds. Single-crystal X-ray diffraction (SC-XRD) shows the presence of fluorine in the metal cluster which was confirmed by energy dispersive X-ray spectroscopy (EDS). High resolution X-ray photoelectron spectroscopy (XPS) and ¹⁹F Nuclear Magnetic Resonance (NMR) also verify the presence of metal-fluorine bonds in the cluster. The Y-BCA-3D MOF selectively adsorbs CO₂ but not N₂.

Spectrophotometric Determination of Trace Amount of Total FeII/FeIII and Live Cell Imaging of a Carboxylato Zn(II) Coordination Polymer

The coordination polymer, (Zn(II)-CP, 1), {[Zn(2,6-NDC)(4-Cltpy)](H₂O)₄} (1) (2,6-H₂NDC = 2,6-naphthalene dicarboxylic acid and 4-Cltpy = 4'-chloro-[2,2';6',2″]terpyridine) is structurally characterized by single crystal X-ray diffraction measurement and other physicochemical studies (PXRD, FTIR, thermal analysis, microanalytical data). 4-Cltpy acts as end-capping ligand, and NDC^2- is a carboxylato bridging motif to constitute ZnN₃O₂ distorted trigonal bipyramid core that propagates to construct 1D chain. The coordination polymer, 1, detects total iron (Fe³⁺ and Fe²⁺) in aqueous solution by visual color change, colorless to pink. Absorption spectrophotometric technique in aqueous medium measures the limit of detection (LOD) 0.11 μM (Fe²⁺) and 0.15 μM (Fe³⁺), and binding constants (K_d) are 6.7 × 10⁴ M^-1 (Fe³⁺) and 3.33 × 10⁴ M^-1 (Fe²⁺). Biocompatibility of 1 is examined in live cells, and intracellular Fe²⁺ and Fe³⁺ are detected in MDA-MB 231 cells. Zn(II) substitution is assumed upon addition of Fe^III/Fe^II solution to the suspension of the coordination polymer, 1, in water-acetonitrile (41:1) (LZn^II + Fe^III/II → LFe^III + Zn^II, where L is defined as coordinated ligands), which is accompanied by changing from colorless to pink at room temperature. The color of the mixture may be assumed to the charge transfer transition from carboxylate-O to Cltpy via Fe(II/III) bridging center (carboxylate-O-Fe-CltPy). The product isolated from the reaction is finally characterized as Fe(III)@1-CP. It is presumed that product Fe(II)@1-CP may undergo fast aerial oxidation to transform Fe(III)@1-CP. The Fe^III exchanged framework (Fe(III)@1-CP) has been characterized by PXRD, IR, TGA and energy dispersive X-ray analysis (EDX)-SEM. The MTT assay calculates the cell viability (%), and the tolerance limit is 100 μM to total Fe²⁺ and Fe³⁺.

Design of biomass-based renewable materials for environmental remediation

Various materials have been used to remove environmental contaminants for decades and have been an effective strategy for environmental cleanups. The current nonrenewable materials used for this purpose could impose secondary hazards and challenges in further downstream treatments. Biomass-based materials present viable, renewable, and sustainable solutions for environmental remediation. Recent biotechnology advances have developed biomaterials with new capacities, such as highly efficient biodegradation and treatment train integration. This review systemically discusses how biotechnology has empowered biomass-derived and bioinspired materials for environmental remediation sustainably and cost-effectively.